feat: turns out, PayloadEncoding can be multiple values for EIP191

perf(constants): avoid allocating a map for each Decode*() call

.github/workflows/pre-commit.yaml

@@ -1,9 +1,7 @@
 name: pre-commit
 
 on:
-  pull_request:
   push:
-    # branches: [main]
 
 jobs:
   pre-commit:

LICENSE

@@ -1,201 +1,25 @@
-                                 Apache License
-                           Version 2.0, January 2004
-                        http://www.apache.org/licenses/
+The contents of this repository are Copyright (c) corresponding authors and
+contributors, licensed under the `Permissive License Stack` meaning either of:
 
-   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+- Apache-2.0 Software License: https://www.apache.org/licenses/LICENSE-2.0
+  ([...4tr2kfsq](https://dweb.link/ipfs/bafkreiankqxazcae4onkp436wag2lj3ccso4nawxqkkfckd6cg4tr2kfsq))
 
-   1. Definitions.
+- MIT Software License: https://opensource.org/licenses/MIT
+  ([...vljevcba](https://dweb.link/ipfs/bafkreiepofszg4gfe2gzuhojmksgemsub2h4uy2gewdnr35kswvljevcba))
 
-      "License" shall mean the terms and conditions for use, reproduction,
-      and distribution as defined by Sections 1 through 9 of this document.
+You may not use the contents of this repository except in compliance
+with one of the listed Licenses. For an extended clarification of the
+intent behind the choice of Licensing please refer to
+https://protocol.ai/blog/announcing-the-permissive-license-stack/
 
-      "Licensor" shall mean the copyright owner or entity authorized by
-      the copyright owner that is granting the License.
+Unless required by applicable law or agreed to in writing, software
+distributed under the terms listed in this notice is distributed on
+an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
+either express or implied. See each License for the specific language
+governing permissions and limitations under that License.
 
-      "Legal Entity" shall mean the union of the acting entity and all
-      other entities that control, are controlled by, or are under common
-      control with that entity. For the purposes of this definition,
-      "control" means (i) the power, direct or indirect, to cause the
-      direction or management of such entity, whether by contract or
-      otherwise, or (ii) ownership of fifty percent (50%) or more of the
-      outstanding shares, or (iii) beneficial ownership of such entity.
+<!--- SPDX-License-Identifier: Apache-2.0 OR MIT -->
 
-      "You" (or "Your") shall mean an individual or Legal Entity
-      exercising permissions granted by this License.
+`SPDX-License-Identifier: Apache-2.0 OR MIT`
 
-      "Source" form shall mean the preferred form for making modifications,
-      including but not limited to software source code, documentation
-      source, and configuration files.
-
-      "Object" form shall mean any form resulting from mechanical
-      transformation or translation of a Source form, including but
-      not limited to compiled object code, generated documentation,
-      and conversions to other media types.
-
-      "Work" shall mean the work of authorship, whether in Source or
-      Object form, made available under the License, as indicated by a
-      copyright notice that is included in or attached to the work
-      (an example is provided in the Appendix below).
-
-      "Derivative Works" shall mean any work, whether in Source or Object
-      form, that is based on (or derived from) the Work and for which the
-      editorial revisions, annotations, elaborations, or other modifications
-      represent, as a whole, an original work of authorship. For the purposes
-      of this License, Derivative Works shall not include works that remain
-      separable from, or merely link (or bind by name) to the interfaces of,
-      the Work and Derivative Works thereof.
-
-      "Contribution" shall mean any work of authorship, including
-      the original version of the Work and any modifications or additions
-      to that Work or Derivative Works thereof, that is intentionally
-      submitted to Licensor for inclusion in the Work by the copyright owner
-      or by an individual or Legal Entity authorized to submit on behalf of
-      the copyright owner. For the purposes of this definition, "submitted"
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-      to the Licensor or its representatives, including but not limited to
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-      and issue tracking systems that are managed by, or on behalf of, the
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-      excluding communication that is conspicuously marked or otherwise
-      designated in writing by the copyright owner as "Not a Contribution."
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-      on behalf of whom a Contribution has been received by Licensor and
-      subsequently incorporated within the Work.
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-   2. Grant of Copyright License. Subject to the terms and conditions of
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-      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
-      copyright license to reproduce, prepare Derivative Works of,
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-      Work and such Derivative Works in Source or Object form.
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-   3. Grant of Patent License. Subject to the terms and conditions of
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-      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
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-      where such license applies only to those patent claims licensable
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-      Contribution(s) alone or by combination of their Contribution(s)
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-      institute patent litigation against any entity (including a
-      cross-claim or counterclaim in a lawsuit) alleging that the Work
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-      or contributory patent infringement, then any patent licenses
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-      as of the date such litigation is filed.
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-          stating that You changed the files; and
-
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-          pertain to any part of the Derivative Works, in at least one
-          of the following places: within a NOTICE text file distributed
-          as part of the Derivative Works; within the Source form or
-          documentation, if provided along with the Derivative Works; or,
-          within a display generated by the Derivative Works, if and
-          wherever such third-party notices normally appear. The contents
-          of the NOTICE file are for informational purposes only and
-          do not modify the License. You may add Your own attribution
-          notices within Derivative Works that You distribute, alongside
-          or as an addendum to the NOTICE text from the Work, provided
-          that such additional attribution notices cannot be construed
-          as modifying the License.
-
-      You may add Your own copyright statement to Your modifications and
-      may provide additional or different license terms and conditions
-      for use, reproduction, or distribution of Your modifications, or
-      for any such Derivative Works as a whole, provided Your use,
-      reproduction, and distribution of the Work otherwise complies with
-      the conditions stated in this License.
-
-   5. Submission of Contributions. Unless You explicitly state otherwise,
-      any Contribution intentionally submitted for inclusion in the Work
-      by You to the Licensor shall be under the terms and conditions of
-      this License, without any additional terms or conditions.
-      Notwithstanding the above, nothing herein shall supersede or modify
-      the terms of any separate license agreement you may have executed
-      with Licensor regarding such Contributions.
-
-   6. Trademarks. This License does not grant permission to use the trade
-      names, trademarks, service marks, or product names of the Licensor,
-      except as required for reasonable and customary use in describing the
-      origin of the Work and reproducing the content of the NOTICE file.
-
-   7. Disclaimer of Warranty. Unless required by applicable law or
-      agreed to in writing, Licensor provides the Work (and each
-      Contributor provides its Contributions) on an "AS IS" BASIS,
-      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
-      implied, including, without limitation, any warranties or conditions
-      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
-      PARTICULAR PURPOSE. You are solely responsible for determining the
-      appropriateness of using or redistributing the Work and assume any
-      risks associated with Your exercise of permissions under this License.
-
-   8. Limitation of Liability. In no event and under no legal theory,
-      whether in tort (including negligence), contract, or otherwise,
-      unless required by applicable law (such as deliberate and grossly
-      negligent acts) or agreed to in writing, shall any Contributor be
-      liable to You for damages, including any direct, indirect, special,
-      incidental, or consequential damages of any character arising as a
-      result of this License or out of the use or inability to use the
-      Work (including but not limited to damages for loss of goodwill,
-      work stoppage, computer failure or malfunction, or any and all
-      other commercial damages or losses), even if such Contributor
-      has been advised of the possibility of such damages.
-
-   9. Accepting Warranty or Additional Liability. While redistributing
-      the Work or Derivative Works thereof, You may choose to offer,
-      and charge a fee for, acceptance of support, warranty, indemnity,
-      or other liability obligations and/or rights consistent with this
-      License. However, in accepting such obligations, You may act only
-      on Your own behalf and on Your sole responsibility, not on behalf
-      of any other Contributor, and only if You agree to indemnify,
-      defend, and hold each Contributor harmless for any liability
-      incurred by, or claims asserted against, such Contributor by reason
-      of your accepting any such warranty or additional liability.
-
-   END OF TERMS AND CONDITIONS
-
-   APPENDIX: How to apply the Apache License to your work.
-
-      To apply the Apache License to your work, attach the following
-      boilerplate notice, with the fields enclosed by brackets "[]"
-      replaced with your own identifying information. (Don't include
-      the brackets!)  The text should be enclosed in the appropriate
-      comment syntax for the file format. We also recommend that a
-      file or class name and description of purpose be included on the
-      same "printed page" as the copyright notice for easier
-      identification within third-party archives.
-
-   Copyright [yyyy] [name of copyright owner]
-
-   Licensed under the Apache License, Version 2.0 (the "License");
-   you may not use this file except in compliance with the License.
-   You may obtain a copy of the License at
-
-       http://www.apache.org/licenses/LICENSE-2.0
-
-   Unless required by applicable law or agreed to in writing, software
-   distributed under the License is distributed on an "AS IS" BASIS,
-   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-   See the License for the specific language governing permissions and
-   limitations under the License.
+Verbatim copies of both licenses are included in the LICENSE-APACHE-2.0 and LICENSE-MIT files.

LICENSE-APACHE-2.0

@@ -0,0 +1,201 @@
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
+      the copyright owner. For the purposes of this definition, "submitted"
+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
+      excluding communication that is conspicuously marked or otherwise
+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
+      publicly display, publicly perform, sublicense, and distribute the
+      Work and such Derivative Works in Source or Object form.
+
+   3. Grant of Patent License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
+      use, offer to sell, sell, import, and otherwise transfer the Work,
+      where such license applies only to those patent claims licensable
+      by such Contributor that are necessarily infringed by their
+      Contribution(s) alone or by combination of their Contribution(s)
+      with the Work to which such Contribution(s) was submitted. If You
+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
+      modifications, and in Source or Object form, provided that You
+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
+          attribution notices from the Source form of the Work,
+          excluding those notices that do not pertain to any part of
+          the Derivative Works; and
+
+      (d) If the Work includes a "NOTICE" text file as part of its
+          distribution, then any Derivative Works that You distribute must
+          include a readable copy of the attribution notices contained
+          within such NOTICE file, excluding those notices that do not
+          pertain to any part of the Derivative Works, in at least one
+          of the following places: within a NOTICE text file distributed
+          as part of the Derivative Works; within the Source form or
+          documentation, if provided along with the Derivative Works; or,
+          within a display generated by the Derivative Works, if and
+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "[]"
+      replaced with your own identifying information. (Don't include
+      the brackets!)  The text should be enclosed in the appropriate
+      comment syntax for the file format. We also recommend that a
+      file or class name and description of purpose be included on the
+      same "printed page" as the copyright notice for easier
+      identification within third-party archives.
+
+   Copyright 2025 UCAN Working Group - All right reserved
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.

LICENSE-MIT

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2025 UCAN Working Group - All rights reserved
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

@@ -2,12 +2,14 @@
 
 `go-varsig` implements the upcoming v1.0.0 release of the [`varsig` specification](https://github.com/ChainAgnostic/varsig/pull/18)
 with limited (and soon to be deprecated) support for the `varsig` < v1.0
-specification.  This is predominatly included to support the UCAN v1.0
+specification.  This is predominantly included to support the UCAN v1.0
 use-case.
 
+Built with ❤️ by [Consensys](https://consensys.io/).
+
 ## Usage
 
-Include the `go-varsig` library  by running the following command:
+Include the `go-varsig` library by running the following command:
 
 ```bash
 go get github.com/ucan-wg/go-varsig@latest
@@ -29,7 +31,7 @@ asdf install
 
 ### Checks
 
-This repository contains an set of pre-commit hooks that are run prior to
+This repository contains a set of pre-commit hooks that are run prior to
 each `git commit`.  You can also run these checks manually using the
 following command:
 
@@ -54,3 +56,10 @@ Since there's only one workflow, the simplest command to test it is:
 ```bash
 act
 ```
+
+## License
+
+This project is dual-licensed under Apache 2.0 and MIT terms:
+
+- Apache License, Version 2.0, ([LICENSE-APACHE](https://github.com/ucan-wg/go-varsig/blob/master/LICENSE-APACHE-2.0) or http://www.apache.org/licenses/LICENSE-2.0)
+- MIT license ([LICENSE-MIT](https://github.com/ucan-wg/go-varsig/blob/master/LICENSE-MIT) or http://opensource.org/licenses/MIT)

common.go

@@ -1,41 +1,73 @@
 package varsig
 
-// Ed25519 produces a varsig that describes the associated algorithm defined
-// by the [IANA JOSE specification].
-//
+import "fmt"
+
 // [IANA JOSE specification]: https://www.iana.org/assignments/jose/jose.xhtml#web-signature-encryption-algorithms
-func Ed25519(payloadEncoding PayloadEncoding, opts ...Option) (*EdDSAVarsig, error) {
-	return NewEdDSAVarsig(CurveEd25519, HashAlgorithmSHA512, payloadEncoding, opts...)
+
+// Ed25519 produces a varsig for EdDSA using Ed25519 curve.
+// This algorithm is defined in [IANA JOSE specification].
+func Ed25519(payloadEncoding PayloadEncoding, opts ...Option) (EdDSAVarsig, error) {
+	return NewEdDSAVarsig(CurveEd25519, HashSha2_512, payloadEncoding, opts...)
 }
 
-// Ed448 produces a varsig that describes the associated algorithm defined
-// by the [IANA JOSE specification].
-//
-// [IANA JOSE specification]: https://www.iana.org/assignments/jose/jose.xhtml#web-signature-encryption-algorithms
-func Ed448(payloadEncoding PayloadEncoding, opts ...Option) (*EdDSAVarsig, error) {
-	return NewEdDSAVarsig(CurveEd448, HashAlgorithmShake256, payloadEncoding, opts...)
+// Ed448 produces a varsig for EdDSA using Ed448 curve.
+// This algorithm is defined in [IANA JOSE specification].
+func Ed448(payloadEncoding PayloadEncoding, opts ...Option) (EdDSAVarsig, error) {
+	return NewEdDSAVarsig(CurveEd448, HashShake_256, payloadEncoding, opts...)
 }
 
-// RS256 produces a varsig that describes the associated algorithm defined
-// by the [IANA JOSE specification].
-//
-// [IANA JOSE specification]: https://www.iana.org/assignments/jose/jose.xhtml#web-signature-encryption-algorithms
-func RS256(keyLength uint64, payloadEncoding PayloadEncoding, opts ...Option) (*RSAVarsig, error) {
-	return NewRSAVarsig(HashAlgorithmSHA256, keyLength, payloadEncoding, opts...)
+// RS256 produces a varsig for RSASSA-PKCS1-v1_5 using SHA-256.
+// This algorithm is defined in [IANA JOSE specification].
+func RS256(keyLength uint64, payloadEncoding PayloadEncoding, opts ...Option) (RSAVarsig, error) {
+	return NewRSAVarsig(HashSha2_256, keyLength, payloadEncoding, opts...)
 }
 
-// RS384 produces a varsig that describes the associated algorithm defined
-// by the [IANA JOSE specification].
-//
-// [IANA JOSE specification]: https://www.iana.org/assignments/jose/jose.xhtml#web-signature-encryption-algorithms
-func RS384(keyLength uint64, payloadEncoding PayloadEncoding, opts ...Option) (*RSAVarsig, error) {
-	return NewRSAVarsig(HashAlgorithmSHA384, keyLength, payloadEncoding, opts...)
+// RS384 produces a varsig for RSASSA-PKCS1-v1_5 using SHA-384.
+// This algorithm is defined in [IANA JOSE specification].
+func RS384(keyLength uint64, payloadEncoding PayloadEncoding, opts ...Option) (RSAVarsig, error) {
+	return NewRSAVarsig(HashSha2_384, keyLength, payloadEncoding, opts...)
 }
 
-// RS512 produces a varsig that describes the associated algorithm defined
-// by the [IANA JOSE specification].
-//
-// [IANA JOSE specification]: https://www.iana.org/assignments/jose/jose.xhtml#web-signature-encryption-algorithms
-func RS512(keyLength uint64, payloadEncoding PayloadEncoding, opts ...Option) (*RSAVarsig, error) {
-	return NewRSAVarsig(HashAlgorithmSHA512, keyLength, payloadEncoding, opts...)
+// RS512 produces a varsig for RSASSA-PKCS1-v1_5 using SHA-512.
+// This algorithm is defined in [IANA JOSE specification].
+func RS512(keyLength uint64, payloadEncoding PayloadEncoding, opts ...Option) (RSAVarsig, error) {
+	return NewRSAVarsig(HashSha2_512, keyLength, payloadEncoding, opts...)
+}
+
+// ES256 produces a varsig for ECDSA using P-256 and SHA-256.
+// This algorithm is defined in [IANA JOSE specification].
+func ES256(payloadEncoding PayloadEncoding, opts ...Option) (ECDSAVarsig, error) {
+	return NewECDSAVarsig(CurveP256, HashSha2_256, payloadEncoding, opts...)
+}
+
+// ES256K produces a varsig for ECDSA using secp256k1 curve and SHA-256.
+// This algorithm is defined in [IANA JOSE specification].
+func ES256K(payloadEncoding PayloadEncoding, opts ...Option) (ECDSAVarsig, error) {
+	return NewECDSAVarsig(CurveSecp256k1, HashSha2_256, payloadEncoding, opts...)
+}
+
+// ES384 produces a varsig for ECDSA using P-384 and SHA-384.
+// This algorithm is defined in [IANA JOSE specification].
+func ES384(payloadEncoding PayloadEncoding, opts ...Option) (ECDSAVarsig, error) {
+	return NewECDSAVarsig(CurveP384, HashSha2_384, payloadEncoding, opts...)
+}
+
+// ES512 produces a varsig for ECDSA using P-521 and SHA-512.
+// This algorithm is defined in [IANA JOSE specification].
+func ES512(payloadEncoding PayloadEncoding, opts ...Option) (ECDSAVarsig, error) {
+	return NewECDSAVarsig(CurveP521, HashSha2_512, payloadEncoding, opts...)
+}
+
+// EIP191 produces a varsig for ECDSA using the Secp256k1 curve, Keccak256 and encoded
+// with the "personal_sign" format defined by [EIP191].
+// payloadEncoding must be either PayloadEncodingEIP191Raw or PayloadEncodingEIP191Cbor.
+// [EIP191]: https://eips.ethereum.org/EIPS/eip-191
+func EIP191(payloadEncoding PayloadEncoding, opts ...Option) (ECDSAVarsig, error) {
+	switch payloadEncoding {
+	case PayloadEncodingEIP191Raw, PayloadEncodingEIP191Cbor:
+	default:
+		return ECDSAVarsig{}, fmt.Errorf("%w for EIP191: %v", ErrUnsupportedPayloadEncoding, payloadEncoding)
+	}
+
+	return NewECDSAVarsig(CurveSecp256k1, HashKeccak256, payloadEncoding, opts...)
 }

common_test.go

@@ -1,63 +1,147 @@
 package varsig_test
 
 import (
+	"encoding/hex"
 	"testing"
 
-	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 
 	"github.com/ucan-wg/go-varsig"
 )
 
-func TestEd25519(t *testing.T) {
-	t.Parallel()
+func TestRoundTrip(t *testing.T) {
+	for _, tc := range []struct {
+		name      string
+		varsig    varsig.Varsig
+		dataHex   string
+		dataBytes []byte
+	}{
+		// Arbitrary use of presets
+		{
+			name:    "Ed25519",
+			varsig:  must(varsig.Ed25519(varsig.PayloadEncodingDAGCBOR)),
+			dataHex: "3401ed01ed011371",
+		},
+		{
+			name:    "Ed448",
+			varsig:  must(varsig.Ed448(varsig.PayloadEncodingDAGCBOR)),
+			dataHex: "3401ed0183241971",
+		},
+		{
+			name:    "RS256",
+			varsig:  must(varsig.RS256(0x100, varsig.PayloadEncodingDAGCBOR)),
+			dataHex: "3401852412800271",
+		},
+		{
+			name:    "RS384",
+			varsig:  must(varsig.RS384(0x100, varsig.PayloadEncodingDAGCBOR)),
+			dataHex: "3401852420800271",
+		},
+		{
+			name:    "RS512",
+			varsig:  must(varsig.RS512(0x100, varsig.PayloadEncodingDAGCBOR)),
+			dataHex: "3401852413800271",
+		},
+		{
+			name:    "ES256",
+			varsig:  must(varsig.ES256(varsig.PayloadEncodingDAGCBOR)),
+			dataHex: "3401ec0180241271",
+		},
+		{
+			name:    "ES256K",
+			varsig:  must(varsig.ES256K(varsig.PayloadEncodingDAGCBOR)),
+			dataHex: "3401ec01e7011271",
+		},
+		{
+			name:    "ES384",
+			varsig:  must(varsig.ES384(varsig.PayloadEncodingDAGCBOR)),
+			dataHex: "3401ec0181242071",
+		},
+		{
+			name:    "ES512",
+			varsig:  must(varsig.ES512(varsig.PayloadEncodingDAGCBOR)),
+			dataHex: "3401ec0182241371",
+		},
+		{
+			name:    "EIP191",
+			varsig:  must(varsig.EIP191(varsig.PayloadEncodingEIP191Raw)),
+			dataHex: "3401ec01e7011b91c3035f",
+		},
 
-	in := mustVarsig[varsig.EdDSAVarsig](t)(varsig.Ed25519(varsig.PayloadEncodingDAGCBOR))
-	out := roundTrip(t, in, "3401ed01ed011371")
-	assertEdDSAEqual(t, in, out)
+		// from https://github.com/hugomrdias/iso-repo/blob/main/packages/iso-ucan/test/varsig.test.js
+		{
+			name:      "RS256+RAW",
+			varsig:    must(varsig.RS256(256, varsig.PayloadEncodingVerbatim)),
+			dataBytes: []byte{52, 1, 133, 36, 18, 128, 2, 95},
+		},
+		{
+			name:      "ES256+RAW",
+			varsig:    must(varsig.ES256(varsig.PayloadEncodingVerbatim)),
+			dataBytes: []byte{52, 1, 236, 1, 128, 36, 18, 95},
+		},
+		{
+			name:      "ES512+RAW",
+			varsig:    must(varsig.ES512(varsig.PayloadEncodingVerbatim)),
+			dataBytes: []byte{52, 1, 236, 1, 130, 36, 19, 95},
+		},
+		{
+			name:      "ES256K+RAW",
+			varsig:    must(varsig.ES256K(varsig.PayloadEncodingVerbatim)),
+			dataBytes: []byte{52, 1, 236, 1, 231, 1, 18, 95},
+		},
+		{
+			name:      "EIP191+RAW",
+			varsig:    must(varsig.EIP191(varsig.PayloadEncodingEIP191Raw)),
+			dataBytes: []byte{52, 1, 236, 1, 231, 1, 27, 145, 195, 3, 95},
+		},
+		{
+			name:      "EIP191+DAG-CBOR",
+			varsig:    must(varsig.EIP191(varsig.PayloadEncodingEIP191Cbor)),
+			dataBytes: []byte{52, 1, 236, 1, 231, 1, 27, 145, 195, 3, 113},
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			// round-trip encode and back
+			data := tc.varsig.Encode()
+
+			if tc.dataBytes != nil {
+				require.Equal(t, tc.dataBytes, data)
+			}
+			if tc.dataHex != "" {
+				require.Equal(t, tc.dataHex, hex.EncodeToString(data))
+			}
+
+			rt, err := varsig.Decode(data)
+			require.NoError(t, err)
+
+			require.Equal(t, tc.varsig.Version(), rt.Version())
+			require.Equal(t, tc.varsig.Discriminator(), rt.Discriminator())
+			require.Equal(t, tc.varsig.PayloadEncoding(), rt.PayloadEncoding())
+			require.Equal(t, tc.varsig.Signature(), rt.Signature())
+
+			switch vs := tc.varsig.(type) {
+			case varsig.EdDSAVarsig:
+				rt := rt.(varsig.EdDSAVarsig)
+				require.Equal(t, vs.Curve(), rt.Curve())
+				require.Equal(t, vs.Hash(), rt.Hash())
+			case varsig.ECDSAVarsig:
+				rt := rt.(varsig.ECDSAVarsig)
+				require.Equal(t, vs.Curve(), rt.Curve())
+				require.Equal(t, vs.Hash(), rt.Hash())
+			case varsig.RSAVarsig:
+				rt := rt.(varsig.RSAVarsig)
+				require.Equal(t, vs.Hash(), rt.Hash())
+				require.Equal(t, vs.KeyLength(), rt.KeyLength())
+			default:
+				t.Fatalf("unexpected varsig type: %T", vs)
+			}
+		})
+	}
 }
 
-func TestEd448(t *testing.T) {
-	t.Parallel()
-
-	in := mustVarsig[varsig.EdDSAVarsig](t)(varsig.Ed448(varsig.PayloadEncodingDAGCBOR))
-	out := roundTrip(t, in, "3401ed0183241971")
-	assertEdDSAEqual(t, in, out)
-}
-
-func TestRS256(t *testing.T) {
-	t.Parallel()
-
-	in := mustVarsig[varsig.RSAVarsig](t)(varsig.RS256(0x100, varsig.PayloadEncodingDAGCBOR))
-	out := roundTrip(t, in, "3401852412800271")
-	assertRSAEqual(t, in, out)
-}
-
-func TestRS384(t *testing.T) {
-	t.Parallel()
-
-	in := mustVarsig[varsig.RSAVarsig](t)(varsig.RS384(0x100, varsig.PayloadEncodingDAGCBOR))
-	out := roundTrip(t, in, "3401852420800271")
-	assertRSAEqual(t, in, out)
-}
-
-func TestRS512(t *testing.T) {
-	t.Parallel()
-
-	in := mustVarsig[varsig.RSAVarsig](t)(varsig.RS512(0x100, varsig.PayloadEncodingDAGCBOR))
-	out := roundTrip(t, in, "3401852413800271")
-	assertRSAEqual(t, in, out)
-}
-
-func assertEdDSAEqual(t *testing.T, in, out *varsig.EdDSAVarsig) {
-	t.Helper()
-
-	assert.Equal(t, in.Curve(), out.Curve())
-	assert.Equal(t, in.HashAlgorithm(), out.HashAlgorithm())
-}
-
-func assertRSAEqual(t *testing.T, in, out *varsig.RSAVarsig) {
-	t.Helper()
-
-	assert.Equal(t, in.HashAlgorithm(), out.HashAlgorithm())
-	assert.Equal(t, in.KeyLength(), out.KeyLength())
+func must[T any](v T, err error) T {
+	if err != nil {
+		panic(err)
+	}
+	return v
 }

constant.go

@@ -1,126 +1,206 @@
 package varsig
 
 import (
-	"bytes"
 	"encoding/binary"
 	"fmt"
-
-	"github.com/multiformats/go-multicodec"
 )
 
-// Prefix is the multicodec.Code for the varsig's varuint prefix byte.
-const Prefix = uint64(multicodec.Varsig)
+// Prefix is the value for the varsig's varuint prefix byte.
+const Prefix = uint64(0x34)
 
-// HashAlgorithm is the multicodec.Code that specifies the hash algorithm
-// that's used to reduced the signed content
-type HashAlgorithm uint64
+// Hash is the value that specifies the hash algorithm
+// that's used to reduce the signed content
+type Hash uint64
 
-// Constant multicodec.Code values that allow Varsig implementations to
-// specify how the payload content is hashed before the signature is
-// generated.
+// Constant values that allow Varsig implementations to specify how
+// the payload content is hashed before the signature is generated.
 const (
-	HashAlgorithmUnspecified HashAlgorithm = 0x00
-	HashAlgorithmSHA256                    = HashAlgorithm(multicodec.Sha2_256)
-	HashAlgorithmSHA384                    = HashAlgorithm(multicodec.Sha2_384)
-	HashAlgorithmSHA512                    = HashAlgorithm(multicodec.Sha2_512)
-	HashAlgorithmShake256                  = HashAlgorithm(multicodec.Shake256)
+	HashUnspecified Hash = 0x00
+
+	HashSha2_224 = Hash(0x1013)
+	HashSha2_256 = Hash(0x12)
+	HashSha2_384 = Hash(0x20)
+	HashSha2_512 = Hash(0x13)
+
+	HashSha3_224 = Hash(0x17)
+	HashSha3_256 = Hash(0x16)
+	HashSha3_384 = Hash(0x15)
+	HashSha3_512 = Hash(0x14)
+
+	HashSha512_224 = Hash(0x1014)
+	HashSha512_256 = Hash(0x1015)
+
+	HashBlake2s_256 = Hash(0xb260)
+	HashBlake2b_256 = Hash(0xb220)
+	HashBlake2b_384 = Hash(0xb230)
+	HashBlake2b_512 = Hash(0xb240)
+
+	HashShake_256 = Hash(0x19)
+
+	HashKeccak256 = Hash(0x1b)
+	HashKeccak512 = Hash(0x1d)
 )
 
 // DecodeHashAlgorithm reads and validates the expected hash algorithm
 // (for varsig types include a variable hash algorithm.)
-func DecodeHashAlgorithm(r *bytes.Reader) (HashAlgorithm, error) {
+func DecodeHashAlgorithm(r BytesReader) (Hash, error) {
 	u, err := binary.ReadUvarint(r)
 	if err != nil {
-		return HashAlgorithmUnspecified, fmt.Errorf("%w: %w", ErrUnknownHashAlgorithm, err)
+		return HashUnspecified, fmt.Errorf("%w: %w", ErrUnknownHash, err)
 	}
 
-	h := HashAlgorithm(u)
+	h := Hash(u)
 
-	if _, ok := map[HashAlgorithm]struct{}{
-		HashAlgorithmUnspecified: {},
-		HashAlgorithmSHA256:      {},
-		HashAlgorithmSHA384:      {},
-		HashAlgorithmSHA512:      {},
-		HashAlgorithmShake256:    {},
-	}[h]; !ok {
-		return HashAlgorithmUnspecified, fmt.Errorf("%w: %x", ErrUnknownHashAlgorithm, h)
+	switch h {
+	case HashSha2_224,
+		HashSha2_256,
+		HashSha2_384,
+		HashSha2_512,
+		HashSha3_224,
+		HashSha3_256,
+		HashSha3_384,
+		HashSha3_512,
+		HashSha512_224,
+		HashSha512_256,
+		HashBlake2s_256,
+		HashBlake2b_256,
+		HashBlake2b_384,
+		HashBlake2b_512,
+		HashShake_256,
+		HashKeccak256,
+		HashKeccak512:
+		return h, nil
+	default:
+		return HashUnspecified, fmt.Errorf("%w: %x", ErrUnknownHash, h)
 	}
-
-	return h, nil
 }
 
 // PayloadEncoding specifies the encoding of the data being (hashed and)
 // signed.  A canonical representation of the data is required to produce
 // consistent hashes and signatures.
-type PayloadEncoding uint64
+type PayloadEncoding int
 
-// Constant multicodec.Code values that allow Varsig implementations to
-// specify how the payload content is encoded before being hashed.  In
-// varsig >= v1, only canonical encoding is allowed.
+// Constant values that allow Varsig implementations to specify how the
+// payload content is encoded before being hashed.
+// In varsig >= v1, only canonical encoding is allowed.
 const (
-	PayloadEncodingUnspecified PayloadEncoding = 0x00
-	PayloadEncodingVerbatim    PayloadEncoding = 0x5f
-	PayloadEncodingDAGPB                       = PayloadEncoding(multicodec.DagPb)
-	PayloadEncodingDAGCBOR                     = PayloadEncoding(multicodec.DagCbor)
-	PayloadEncodingDAGJSON                     = PayloadEncoding(multicodec.DagJson)
-	PayloadEncodingEIP191                      = PayloadEncoding(multicodec.Eip191)
-	PayloadEncodingJWT         PayloadEncoding = 0x6a77
+	PayloadEncodingUnspecified = PayloadEncoding(iota)
+	PayloadEncodingVerbatim
+	PayloadEncodingDAGPB
+	PayloadEncodingDAGCBOR
+	PayloadEncodingDAGJSON
+	PayloadEncodingEIP191Raw
+	PayloadEncodingEIP191Cbor
+	PayloadEncodingJWT
+)
+
+const (
+	encodingSegmentVerbatim = uint64(0x5f)
+	encodingSegmentDAGPB    = uint64(0x70)
+	encodingSegmentDAGCBOR  = uint64(0x71)
+	encodingSegmentDAGJSON  = uint64(0x0129)
+	encodingSegmentEIP191   = uint64(0xe191)
+	encodingSegmentJWT      = uint64(0x6a77)
 )
 
 // DecodePayloadEncoding reads and validates the expected canonical payload
 // encoding of the data to be signed.
-func DecodePayloadEncoding(r *bytes.Reader, vers Version) (PayloadEncoding, error) {
-	u, err := binary.ReadUvarint(r)
+func DecodePayloadEncoding(r BytesReader, vers Version) (PayloadEncoding, error) {
+	seg1, err := binary.ReadUvarint(r)
 	if err != nil {
 		return PayloadEncodingUnspecified, fmt.Errorf("%w: %w", ErrUnsupportedPayloadEncoding, err)
 	}
 
-	payEnc := PayloadEncoding(u)
-
 	switch vers {
 	case Version0:
-		return decodeEncodingInfoV0(payEnc)
+		switch seg1 {
+		case encodingSegmentVerbatim:
+			return PayloadEncodingVerbatim, nil
+		case encodingSegmentDAGPB:
+			return PayloadEncodingDAGPB, nil
+		case encodingSegmentDAGCBOR:
+			return PayloadEncodingDAGCBOR, nil
+		case encodingSegmentDAGJSON:
+			return PayloadEncodingDAGJSON, nil
+		case encodingSegmentEIP191:
+			seg2, err := binary.ReadUvarint(r)
+			if err != nil {
+				return PayloadEncodingUnspecified, fmt.Errorf("%w: incomplete EIP191 encoding: %w", ErrUnsupportedPayloadEncoding, err)
+			}
+			switch seg2 {
+			case encodingSegmentVerbatim:
+				return PayloadEncodingEIP191Raw, nil
+			case encodingSegmentDAGCBOR:
+				return PayloadEncodingEIP191Cbor, nil
+			default:
+				return PayloadEncodingUnspecified, fmt.Errorf("%w: version=%d, encoding=%x+%x", ErrUnsupportedPayloadEncoding, vers, seg1, seg2)
+			}
+		case encodingSegmentJWT:
+			return PayloadEncodingJWT, nil
+		default:
+			return PayloadEncodingUnspecified, fmt.Errorf("%w: version=%d, encoding=%x", ErrUnsupportedPayloadEncoding, vers, seg1)
+		}
 	case Version1:
-		return decodeEncodingInfoV1(payEnc)
+		switch seg1 {
+		case encodingSegmentVerbatim:
+			return PayloadEncodingVerbatim, nil
+		case encodingSegmentDAGCBOR:
+			return PayloadEncodingDAGCBOR, nil
+		case encodingSegmentDAGJSON:
+			return PayloadEncodingDAGJSON, nil
+		case encodingSegmentEIP191:
+			seg2, err := binary.ReadUvarint(r)
+			if err != nil {
+				return PayloadEncodingUnspecified, fmt.Errorf("%w: incomplete EIP191 encoding: %w", ErrUnsupportedPayloadEncoding, err)
+			}
+			switch seg2 {
+			case encodingSegmentVerbatim:
+				return PayloadEncodingEIP191Raw, nil
+			case encodingSegmentDAGCBOR:
+				return PayloadEncodingEIP191Cbor, nil
+			default:
+				return PayloadEncodingUnspecified, fmt.Errorf("%w: version=%d, encoding=%x+%x", ErrUnsupportedPayloadEncoding, vers, seg1, seg2)
+			}
+		default:
+			return PayloadEncodingUnspecified, fmt.Errorf("%w: version=%d, encoding=%x", ErrUnsupportedPayloadEncoding, vers, seg1)
+		}
 	default:
 		return 0, ErrUnsupportedVersion
 	}
 }
 
-// https://github.com/ChainAgnostic/varsig#4-payload-encoding
-func decodeEncodingInfoV0(payEnc PayloadEncoding) (PayloadEncoding, error) {
-	if _, ok := map[PayloadEncoding]struct{}{
-		PayloadEncodingVerbatim: {},
-		PayloadEncodingDAGPB:    {},
-		PayloadEncodingDAGCBOR:  {},
-		PayloadEncodingDAGJSON:  {},
-		PayloadEncodingJWT:      {},
-		PayloadEncodingEIP191:   {},
-	}[payEnc]; !ok {
-		return PayloadEncodingUnspecified, fmt.Errorf("%w: version=%d, encoding=%x", ErrUnsupportedPayloadEncoding, Version0, payEnc)
+// EncodePayloadEncoding returns the PayloadEncoding as serialized bytes.
+// If enc is not a valid PayloadEncoding, this function will panic.
+func EncodePayloadEncoding(enc PayloadEncoding) []byte {
+	res := make([]byte, 0, 8)
+	switch enc {
+	case PayloadEncodingVerbatim:
+		res = binary.AppendUvarint(res, encodingSegmentVerbatim)
+	case PayloadEncodingDAGPB:
+		res = binary.AppendUvarint(res, encodingSegmentDAGPB)
+	case PayloadEncodingDAGCBOR:
+		res = binary.AppendUvarint(res, encodingSegmentDAGCBOR)
+	case PayloadEncodingDAGJSON:
+		res = binary.AppendUvarint(res, encodingSegmentDAGJSON)
+	case PayloadEncodingEIP191Raw:
+		res = binary.AppendUvarint(res, encodingSegmentEIP191)
+		res = binary.AppendUvarint(res, encodingSegmentVerbatim)
+	case PayloadEncodingEIP191Cbor:
+		res = binary.AppendUvarint(res, encodingSegmentEIP191)
+		res = binary.AppendUvarint(res, encodingSegmentDAGCBOR)
+	case PayloadEncodingJWT:
+		res = binary.AppendUvarint(res, encodingSegmentJWT)
+	default:
+		panic(fmt.Sprintf("invalid encoding: %v", enc))
 	}
 
-	return payEnc, nil
+	return res
 }
 
-// https://github.com/expede/varsig/blob/main/README.md#payload-encoding
-func decodeEncodingInfoV1(payEnc PayloadEncoding) (PayloadEncoding, error) {
-	if _, ok := map[PayloadEncoding]struct{}{
-		PayloadEncodingVerbatim: {},
-		PayloadEncodingDAGCBOR:  {},
-		PayloadEncodingDAGJSON:  {},
-		PayloadEncodingEIP191:   {},
-	}[payEnc]; !ok {
-		return PayloadEncodingUnspecified, fmt.Errorf("%w: version=%d, encoding=%x", ErrUnsupportedPayloadEncoding, Version1, payEnc)
-	}
-
-	return payEnc, nil
-}
-
-// Discriminator is (usually) the multicodec.Code representing the public
-// key type of the algorithm used to create the signature.
+// Discriminator is (usually) the value representing the public key type of
+// the algorithm used to create the signature.
 //
-// There is not set list of constants here, nor is there a decode function
+// There is no set list of constants here, nor is there a decode function
 // as the author of an implementation should include the constant with the
 // implementation, and the decoding is handled by the Handler, which uses
 // the Discriminator to choose the correct implementation.  Also note that

constant_test.go

@@ -18,27 +18,35 @@ func TestDecodeHashAlgorithm(t *testing.T) {
 
 		hashAlg, err := varsig.DecodeHashAlgorithm(bytes.NewReader([]byte{0x12}))
 		require.NoError(t, err)
-		require.Equal(t, varsig.HashAlgorithmSHA256, hashAlg)
+		require.Equal(t, varsig.HashSha2_256, hashAlg)
 	})
 
 	t.Run("fails - truncated varsig (no bytes)", func(t *testing.T) {
 		t.Parallel()
 
 		hashAlg, err := varsig.DecodeHashAlgorithm(bytes.NewReader([]byte{}))
-		require.ErrorIs(t, err, varsig.ErrUnknownHashAlgorithm)
+		require.ErrorIs(t, err, varsig.ErrUnknownHash)
 		require.ErrorIs(t, err, io.EOF)
-		require.Equal(t, varsig.HashAlgorithmUnspecified, hashAlg)
+		require.Equal(t, varsig.HashUnspecified, hashAlg)
 	})
 
 	t.Run("fails - unknown hash algorithm", func(t *testing.T) {
 		t.Parallel()
 
 		hashAlg, err := varsig.DecodeHashAlgorithm(bytes.NewReader([]byte{0x42}))
-		require.ErrorIs(t, err, varsig.ErrUnknownHashAlgorithm)
-		require.Equal(t, varsig.HashAlgorithmUnspecified, hashAlg)
+		require.ErrorIs(t, err, varsig.ErrUnknownHash)
+		require.Equal(t, varsig.HashUnspecified, hashAlg)
 	})
 }
 
+func BenchmarkDecodeHashAlgorithm(b *testing.B) {
+	b.ReportAllocs()
+	data := []byte{0x12}
+	for i := 0; i < b.N; i++ {
+		_, _ = varsig.DecodeHashAlgorithm(bytes.NewReader(data))
+	}
+}
+
 func TestDecodePayloadEncoding(t *testing.T) {
 	t.Parallel()
 
@@ -105,3 +113,11 @@ func TestDecodePayloadEncoding(t *testing.T) {
 		}
 	})
 }
+
+func BenchmarkDecodePayloadEncoding(b *testing.B) {
+	b.ReportAllocs()
+	data := []byte{0x5f}
+	for i := 0; i < b.N; i++ {
+		_, _ = varsig.DecodePayloadEncoding(bytes.NewReader(data), varsig.Version1)
+	}
+}

ecdsa.go

@@ -1,9 +1,155 @@
 package varsig
 
-// Stub
-const (
-	DiscriminatorECDSASecp256k1 Discriminator = 0xe7
-	DiscriminatorECDSAP256      Discriminator = 0x1200
-	DiscriminatorECDSAP384      Discriminator = 0x1201
-	DiscriminatorECDSAP521      Discriminator = 0x1202
+import (
+	"encoding/binary"
+	"fmt"
 )
+
+// DiscriminatorECDSA is the value specifying an ECDSA signature.
+const DiscriminatorECDSA = Discriminator(0xec)
+
+// ECDSACurve are values that specify which ECDSA curve is used when
+// generating the signature.
+type ECDSACurve uint64
+
+// Constants describing the values for each specific ECDSA curve that can
+// be encoded into a Varsig.
+const (
+	CurveSecp256k1 = ECDSACurve(0xe7)
+	CurveP256      = ECDSACurve(0x1200)
+	CurveP384      = ECDSACurve(0x1201)
+	CurveP521      = ECDSACurve(0x1202)
+)
+
+func decodeECDSACurve(r BytesReader) (ECDSACurve, error) {
+	u, err := binary.ReadUvarint(r)
+	if err != nil {
+		return 0, err
+	}
+
+	switch curve := ECDSACurve(u); curve {
+	case CurveSecp256k1, CurveP256, CurveP384, CurveP521:
+		return curve, nil
+	default:
+		return 0, fmt.Errorf("%w: %x", ErrUnknownECDSACurve, u)
+	}
+}
+
+var _ Varsig = ECDSAVarsig{}
+
+// ECDSAVarsig is a varsig that encodes the parameters required to describe
+// an ECDSA signature.
+type ECDSAVarsig struct {
+	varsig
+
+	curve   ECDSACurve
+	hashAlg Hash
+}
+
+// NewECDSAVarsig creates and validates an ECDSA varsig with the provided
+// curve, hash algorithm and payload encoding.
+func NewECDSAVarsig(curve ECDSACurve, hashAlgorithm Hash, payloadEncoding PayloadEncoding, opts ...Option) (ECDSAVarsig, error) {
+	options := newOptions(opts...)
+
+	var (
+		vers = Version1
+		disc = DiscriminatorECDSA
+		sig  []byte
+	)
+
+	if options.ForceVersion0() {
+		vers = Version0
+		disc = Discriminator(curve)
+		sig = options.Signature()
+	}
+
+	v := ECDSAVarsig{
+		varsig: varsig{
+			vers:   vers,
+			disc:   disc,
+			payEnc: payloadEncoding,
+			sig:    sig,
+		},
+		curve:   curve,
+		hashAlg: hashAlgorithm,
+	}
+
+	switch curve {
+	case CurveSecp256k1, CurveP256:
+		return validateSig(v, 64)
+	case CurveP384:
+		return validateSig(v, 96)
+	case CurveP521:
+		return validateSig(v, 132)
+	default:
+		return ECDSAVarsig{}, fmt.Errorf("%w: %x", ErrUnknownECDSACurve, curve)
+	}
+}
+
+// Curve returns the elliptic curve used to generate the ECDSA signature.
+func (v ECDSAVarsig) Curve() ECDSACurve {
+	return v.curve
+}
+
+// Hash returns the value describing the hash algorithm used to hash
+// the payload content before the signature is generated.
+func (v ECDSAVarsig) Hash() Hash {
+	return v.hashAlg
+}
+
+// Encode returns the encoded byte format of the ECDSAVarsig.
+func (v ECDSAVarsig) Encode() []byte {
+	buf := v.encode()
+
+	if v.vers != Version0 {
+		buf = binary.AppendUvarint(buf, uint64(v.curve))
+	}
+
+	buf = binary.AppendUvarint(buf, uint64(v.hashAlg))
+	buf = append(buf, EncodePayloadEncoding(v.payEnc)...)
+	buf = append(buf, v.Signature()...)
+
+	return buf
+}
+
+func decodeECDSA(r BytesReader, vers Version, disc Discriminator) (Varsig, error) {
+	curve := ECDSACurve(disc)
+	if vers != Version0 {
+		var err error
+
+		curve, err = decodeECDSACurve(r)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	hashAlg, err := DecodeHashAlgorithm(r)
+	if err != nil {
+		return nil, err
+	}
+
+	v := ECDSAVarsig{
+		varsig: varsig{
+			vers: vers,
+			disc: disc,
+		},
+		curve:   curve,
+		hashAlg: hashAlg,
+	}
+
+	v.payEnc, v.sig, err = v.decodePayEncAndSig(r)
+	if err != nil {
+		return nil, err
+	}
+
+	switch curve {
+	case CurveSecp256k1, CurveP256:
+		return validateSig(v, 64)
+	case CurveP384:
+		return validateSig(v, 96)
+	case CurveP521:
+		return validateSig(v, 132)
+	default:
+		return ECDSAVarsig{}, fmt.Errorf("%w: %x", ErrUnknownECDSACurve, curve)
+	}
+}

eddsa.go

@@ -1,51 +1,59 @@
 package varsig
 
 import (
-	"bytes"
 	"crypto/ed25519"
 	"encoding/binary"
-
-	"github.com/multiformats/go-multicodec"
+	"fmt"
 )
 
-// Constants containing multicodec.Code values that specify EdDSA signatures.
-const (
-	DiscriminatorEdDSA   = Discriminator(multicodec.Ed25519Pub)
-	DiscriminatorEd25519 = Discriminator(multicodec.Ed25519Pub)
-	DiscriminatorEd448   = Discriminator(multicodec.Ed448Pub)
-)
+// DiscriminatorEdDSA is the value specifying an EdDSA signature.
+const DiscriminatorEdDSA = Discriminator(0xed)
 
-// EdDSACurve are multicodec.Code values that specify which Edwards curve
-// is used when generating the signature.
+// EdDSACurve are values that specify which Edwards curve is used when
+// generating the signature.
 type EdDSACurve uint64
 
-// Constants describing the multicodec.Code for each specific Edwards
-// curve that can be encoded into a Varsig.
+// Constants describing the values for each specific Edwards curve that can
+// be encoded into a Varsig.
 const (
-	CurveEd25519 = EdDSACurve(multicodec.Ed25519Pub)
-	CurveEd448   = EdDSACurve(multicodec.Ed448Pub)
+	CurveEd25519 = EdDSACurve(0xed)
+	CurveEd448   = EdDSACurve(0x1203)
 )
 
-var _ Varsig = (*EdDSAVarsig)(nil)
+func decodeEdDSACurve(r BytesReader) (EdDSACurve, error) {
+	u, err := binary.ReadUvarint(r)
+	if err != nil {
+		return 0, err
+	}
+
+	switch curve := EdDSACurve(u); curve {
+	case CurveEd25519, CurveEd448:
+		return curve, nil
+	default:
+		return 0, fmt.Errorf("%w: %x", ErrUnknownEdDSACurve, u)
+	}
+}
+
+var _ Varsig = EdDSAVarsig{}
 
 // EdDSAVarsig is a varsig that encodes the parameters required to describe
 // an EdDSA signature.
 type EdDSAVarsig struct {
-	varsig[EdDSAVarsig]
+	varsig
 
 	curve   EdDSACurve
-	hashAlg HashAlgorithm
+	hashAlg Hash
 }
 
 // NewEdDSAVarsig creates and validates an EdDSA varsig with the provided
 // curve, hash algorithm and payload encoding.
-func NewEdDSAVarsig(curve EdDSACurve, hashAlgorithm HashAlgorithm, payloadEncoding PayloadEncoding, opts ...Option) (*EdDSAVarsig, error) {
+func NewEdDSAVarsig(curve EdDSACurve, hashAlgorithm Hash, payloadEncoding PayloadEncoding, opts ...Option) (EdDSAVarsig, error) {
 	options := newOptions(opts...)
 
 	var (
 		vers = Version1
 		disc = DiscriminatorEdDSA
-		sig  = []byte{}
+		sig  []byte
 	)
 
 	if options.ForceVersion0() {
@@ -54,8 +62,8 @@ func NewEdDSAVarsig(curve EdDSACurve, hashAlgorithm HashAlgorithm, payloadEncodi
 		sig = options.Signature()
 	}
 
-	v := &EdDSAVarsig{
-		varsig: varsig[EdDSAVarsig]{
+	v := EdDSAVarsig{
+		varsig: varsig{
 			vers:   vers,
 			disc:   disc,
 			payEnc: payloadEncoding,
@@ -65,17 +73,24 @@ func NewEdDSAVarsig(curve EdDSACurve, hashAlgorithm HashAlgorithm, payloadEncodi
 		hashAlg: hashAlgorithm,
 	}
 
-	return v.validateSig(v, ed25519.PrivateKeySize)
+	switch curve {
+	case CurveEd25519:
+		return validateSig(v, ed25519.SignatureSize)
+	case CurveEd448:
+		return validateSig(v, 114)
+	default:
+		return EdDSAVarsig{}, fmt.Errorf("%w: %x", ErrUnknownEdDSACurve, curve)
+	}
 }
 
 // Curve returns the Edwards curve used to generate the EdDSA signature.
-func (v *EdDSAVarsig) Curve() EdDSACurve {
+func (v EdDSAVarsig) Curve() EdDSACurve {
 	return v.curve
 }
 
-// HashAlgorithm returns the multicodec.Code describing the hash algorithm
-// used to hash the payload content before the signature is generated.
-func (v *EdDSAVarsig) HashAlgorithm() HashAlgorithm {
+// Hash returns the value describing the hash algorithm used to hash
+// the payload content before the signature is generated.
+func (v EdDSAVarsig) Hash() Hash {
 	return v.hashAlg
 }
 
@@ -88,37 +103,48 @@ func (v EdDSAVarsig) Encode() []byte {
 	}
 
 	buf = binary.AppendUvarint(buf, uint64(v.hashAlg))
-	buf = binary.AppendUvarint(buf, uint64(v.payEnc))
+	buf = append(buf, EncodePayloadEncoding(v.payEnc)...)
 	buf = append(buf, v.Signature()...)
 
 	return buf
 }
 
-func decodeEd25519(r *bytes.Reader, vers Version, disc Discriminator) (Varsig, error) {
-	curve := uint64(disc)
+func decodeEdDSA(r BytesReader, vers Version, disc Discriminator) (Varsig, error) {
+	curve := EdDSACurve(disc)
 	if vers != Version0 {
-		u, err := binary.ReadUvarint(r)
+		var err error
 
+		curve, err = decodeEdDSACurve(r)
 		if err != nil {
-			return nil, err // TODO: wrap error?
+			return nil, err
 		}
-
-		curve = u
 	}
 
-	hashAlg, err := binary.ReadUvarint(r)
+	hashAlg, err := DecodeHashAlgorithm(r)
 	if err != nil {
-		return nil, err // TODO: wrap error?
+		return nil, err
 	}
 
-	v := &EdDSAVarsig{
-		varsig: varsig[EdDSAVarsig]{
+	v := EdDSAVarsig{
+		varsig: varsig{
 			vers: vers,
 			disc: disc,
 		},
-		curve:   EdDSACurve(curve),
-		hashAlg: HashAlgorithm(hashAlg),
+		curve:   curve,
+		hashAlg: hashAlg,
 	}
 
-	return v.decodePayEncAndSig(r, v, ed25519.PrivateKeySize)
+	v.payEnc, v.sig, err = v.decodePayEncAndSig(r)
+	if err != nil {
+		return nil, err
+	}
+
+	switch curve {
+	case CurveEd25519:
+		return validateSig(v, ed25519.SignatureSize)
+	case CurveEd448:
+		return validateSig(v, 114)
+	default:
+		return EdDSAVarsig{}, fmt.Errorf("%w: %x", ErrUnknownEdDSACurve, curve)
+	}
 }

eddsa_test.go

@@ -1,6 +1,7 @@
 package varsig_test
 
 import (
+	"encoding/base64"
 	"encoding/hex"
 	"testing"
 
@@ -31,14 +32,14 @@ func TestDecodeEd25519(t *testing.T) {
 			require.NoError(t, err)
 			require.NotNil(t, v)
 			assert.Equal(t, varsig.Version0, v.Version())
-			assert.Equal(t, varsig.DiscriminatorEd25519, v.Discriminator())
+			assert.Equal(t, varsig.DiscriminatorEdDSA, v.Discriminator())
 			assert.Equal(t, varsig.PayloadEncodingDAGCBOR, v.PayloadEncoding())
 			assert.Len(t, v.Signature(), 64)
 
-			impl, ok := v.(*varsig.EdDSAVarsig)
+			impl, ok := v.(varsig.EdDSAVarsig)
 			require.True(t, ok)
 			assert.Equal(t, varsig.CurveEd25519, impl.Curve())
-			assert.Equal(t, varsig.HashAlgorithmSHA512, impl.HashAlgorithm())
+			assert.Equal(t, varsig.HashSha2_512, impl.Hash())
 		})
 
 		t.Run("Encode", func(t *testing.T) {
@@ -46,7 +47,7 @@ func TestDecodeEd25519(t *testing.T) {
 
 			v, err := varsig.NewEdDSAVarsig(
 				varsig.CurveEd25519,
-				varsig.HashAlgorithmSHA512,
+				varsig.HashSha2_512,
 				varsig.PayloadEncodingDAGCBOR,
 				varsig.WithForceVersion0(sig),
 			)
@@ -56,3 +57,44 @@ func TestDecodeEd25519(t *testing.T) {
 		})
 	})
 }
+
+func TestUCANExampleV1(t *testing.T) {
+	t.Parallel()
+
+	// This test is the value shown in the UCAN v1.0.0 example, which is
+	// an EdDSA varsig = v1 with the Ed25519 curve, SHA2_256 hashing and
+	// DAG-CBOR content encoding.
+	example, err := base64.RawStdEncoding.DecodeString("NAHtAe0BE3E")
+	require.NoError(t, err)
+
+	t.Run("Decode", func(t *testing.T) {
+		t.Parallel()
+
+		v, err := varsig.Decode(example)
+		require.NoError(t, err)
+
+		ed25519V, ok := v.(varsig.EdDSAVarsig)
+		require.True(t, ok)
+
+		assert.Equal(t, varsig.Version1, ed25519V.Version())
+		assert.Equal(t, varsig.DiscriminatorEdDSA, ed25519V.Discriminator())
+		assert.Equal(t, varsig.CurveEd25519, ed25519V.Curve())
+		assert.Equal(t, varsig.HashSha2_512, ed25519V.Hash())
+		assert.Equal(t, varsig.PayloadEncodingDAGCBOR, ed25519V.PayloadEncoding())
+		assert.Len(t, ed25519V.Signature(), 0)
+	})
+
+	t.Run("Encode", func(t *testing.T) {
+		t.Parallel()
+
+		edDSAVarsig, err := varsig.NewEdDSAVarsig(
+			varsig.CurveEd25519,
+			varsig.HashSha2_512,
+			varsig.PayloadEncodingDAGCBOR,
+		)
+		require.NoError(t, err)
+
+		assert.Equal(t, example, edDSAVarsig.Encode())
+		t.Log(base64.RawStdEncoding.EncodeToString(edDSAVarsig.Encode()))
+	})
+}

error.go

@@ -13,7 +13,7 @@ var ErrMissingSignature = errors.New("missing signature expected in varsig v0")
 var ErrNotYetImplemented = errors.New("not yet implemented")
 
 // ErrUnexpectedSignaturePresent is returned when a signature is present
-// in  a varsig >= v1.
+// in a varsig >= v1.
 var ErrUnexpectedSignaturePresent = errors.New("unexpected signature present in varsig >= v1")
 
 // ErrUnexpectedSignatureSize is returned when the length of the decoded
@@ -21,23 +21,31 @@ var ErrUnexpectedSignaturePresent = errors.New("unexpected signature present in
 // signing algorithm or sent via a Varsig field.
 var ErrUnexpectedSignatureSize = errors.New("unexpected signature size in varsig v0")
 
-// ErrUnknownHashAlgoritm is returned when an unexpected value is provided
+// ErrUnknownHash is returned when an unexpected value is provided
 // while decoding the hashing algorithm.
-var ErrUnknownHashAlgorithm = errors.New("unknown hash algorithm")
+var ErrUnknownHash = errors.New("unknown hash algorithm")
 
 // ErrUnsupportedPayloadEncoding is returned when an unexpected value is
 // provided while decoding the payload encoding field.  The allowed values
 // for this field may vary based on the varsig version.
 var ErrUnsupportedPayloadEncoding = errors.New("unsupported payload encoding")
 
-// ErrUnknowndiscorith is returned when the Registry doesn't have a
+// ErrUnknownDiscriminator is returned when the Registry doesn't have a
 // parsing function for the decoded signing algorithm.
 var ErrUnknownDiscriminator = errors.New("unknown signing algorithm")
 
+// ErrUnknownEdDSACurve is returned when the decoded uvarint isn't either
+// CurveEd25519 or CurveEd448.
+var ErrUnknownEdDSACurve = errors.New("unknown Edwards curve")
+
+// ErrUnknownECDSACurve is returned when the decoded uvarint isn't either
+// CurveSecp256k1, CurveP256, CurveP384 or CurveP521.
+var ErrUnknownECDSACurve = errors.New("unknown ECDSA curve")
+
 // ErrUnsupportedVersion is returned when an unsupported varsig version
 // field is present.
 var ErrUnsupportedVersion = errors.New("unsupported version")
 
 // ErrBadPrefix is returned when the prefix field contains a value other
-// than 0x34 (encoded as a uvarint).
+// than 0x34 (encoded as an uvarint).
 var ErrBadPrefix = errors.New("varsig prefix not found")

go.mod

@@ -1,11 +1,10 @@
 module github.com/ucan-wg/go-varsig
 
-go 1.24.4
+go 1.23.10
 
-require (
-	github.com/multiformats/go-multicodec v0.9.2
-	github.com/stretchr/testify v1.10.0
-)
+toolchain go1.24.4
+
+require github.com/stretchr/testify v1.10.0
 
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect

go.sum

@@ -6,8 +6,6 @@ github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
 github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/google/renameio v0.1.0 h1:GOZbcHa3HfsPKPlmyPyN2KEohoMXOhdMbHrvbpl2QaA=
 github.com/google/renameio v0.1.0/go.mod h1:KWCgfxg9yswjAJkECMjeO8J8rahYeXnNhOm40UhjYkI=
-github.com/multiformats/go-multicodec v0.9.2 h1:YrlXCuqxjqm3bXl+vBq5LKz5pz4mvAsugdqy78k0pXQ=
-github.com/multiformats/go-multicodec v0.9.2/go.mod h1:LLWNMtyV5ithSBUo3vFIMaeDy+h3EbkMTek1m+Fybbo=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=

registry.go

@@ -6,11 +6,11 @@ import (
 	"fmt"
 )
 
-// Version represents which version of the vasig specification was used
+// Version represents which version of the varsig specification was used
 // to produce Varsig value.
 type Version uint64
 
-// Constancts for the existing varsig specifications
+// Constants for the existing varsig specifications
 const (
 	Version0 Version = 0
 	Version1 Version = 1
@@ -18,9 +18,9 @@ const (
 
 // DecodeFunc is a function that parses the varsig representing a specific
 // signing algorithm.
-type DecodeFunc func(*bytes.Reader, Version, Discriminator) (Varsig, error)
+type DecodeFunc func(BytesReader, Version, Discriminator) (Varsig, error)
 
-// Registry contains a mapping between known signing algorithms, and
+// Registry contains a mapping between known signing algorithms and
 // functions that can parse varsigs for that signing algorithm.
 type Registry map[Discriminator]DecodeFunc
 
@@ -28,12 +28,9 @@ type Registry map[Discriminator]DecodeFunc
 // signing algorithms which have an implementation within this library.
 func DefaultRegistry() Registry {
 	return map[Discriminator]DecodeFunc{
-		DiscriminatorRSA:            decodeRSA,
-		DiscriminatorEdDSA:          decodeEd25519,
-		DiscriminatorEd448:          decodeEd25519,
-		DiscriminatorECDSAP256:      notYetImplementedVarsigDecoder,
-		DiscriminatorECDSASecp256k1: notYetImplementedVarsigDecoder,
-		DiscriminatorECDSAP521:      notYetImplementedVarsigDecoder,
+		DiscriminatorRSA:   decodeRSA,
+		DiscriminatorEdDSA: decodeEdDSA,
+		DiscriminatorECDSA: decodeECDSA,
 	}
 }
 
@@ -56,7 +53,7 @@ func (rs Registry) Decode(data []byte) (Varsig, error) {
 
 // DecodeStream converts data read from the provided io.Reader into one
 // of the registered Varsig types.
-func (rs Registry) DecodeStream(r *bytes.Reader) (Varsig, error) {
+func (rs Registry) DecodeStream(r BytesReader) (Varsig, error) {
 	pre, err := binary.ReadUvarint(r)
 	if err != nil {
 		return nil, fmt.Errorf("%w: %w", ErrBadPrefix, err)
@@ -79,7 +76,7 @@ func (rs Registry) DecodeStream(r *bytes.Reader) (Varsig, error) {
 	return decodeFunc(r, vers, disc)
 }
 
-func (rs Registry) decodeVersAnddisc(r *bytes.Reader) (Version, Discriminator, error) {
+func (rs Registry) decodeVersAnddisc(r BytesReader) (Version, Discriminator, error) {
 	vers, err := binary.ReadUvarint(r)
 	if err != nil {
 		return Version(vers), 0, err
@@ -97,7 +94,3 @@ func (rs Registry) decodeVersAnddisc(r *bytes.Reader) (Version, Discriminator, e
 
 	return Version(vers), Discriminator(disc), err
 }
-
-func notYetImplementedVarsigDecoder(_ *bytes.Reader, vers Version, disc Discriminator) (Varsig, error) {
-	return nil, fmt.Errorf("%w: Version: %d, Discriminator: %x", ErrNotYetImplemented, vers, disc)
-}

registry_test.go

@@ -61,7 +61,7 @@ func testRegistry(t *testing.T) varsig.Registry {
 func testDecodeFunc(t *testing.T) varsig.DecodeFunc {
 	t.Helper()
 
-	return func(r *bytes.Reader, vers varsig.Version, disc varsig.Discriminator) (varsig.Varsig, error) {
+	return func(r varsig.BytesReader, vers varsig.Version, disc varsig.Discriminator) (varsig.Varsig, error) {
 		v := &testVarsig{
 			vers: vers,
 			disc: disc,
@@ -71,7 +71,7 @@ func testDecodeFunc(t *testing.T) varsig.DecodeFunc {
 	}
 }
 
-var _ varsig.Varsig = (*testVarsig)(nil)
+var _ varsig.Varsig = testVarsig{}
 
 type testVarsig struct {
 	vers   varsig.Version
@@ -80,22 +80,22 @@ type testVarsig struct {
 	sig    []byte
 }
 
-func (v *testVarsig) Version() varsig.Version {
+func (v testVarsig) Version() varsig.Version {
 	return v.vers
 }
 
-func (v *testVarsig) Discriminator() varsig.Discriminator {
+func (v testVarsig) Discriminator() varsig.Discriminator {
 	return v.disc
 }
 
-func (v *testVarsig) PayloadEncoding() varsig.PayloadEncoding {
+func (v testVarsig) PayloadEncoding() varsig.PayloadEncoding {
 	return v.payEnc
 }
 
-func (v *testVarsig) Signature() []byte {
+func (v testVarsig) Signature() []byte {
 	return v.sig
 }
 
-func (v *testVarsig) Encode() []byte {
+func (v testVarsig) Encode() []byte {
 	return nil
 }

rsa.go

@@ -1,33 +1,30 @@
 package varsig
 
 import (
-	"bytes"
 	"encoding/binary"
-
-	"github.com/multiformats/go-multicodec"
 )
 
-// DiscriminatorRSA is the multicodec.Code specifying an RSA signature.
-const DiscriminatorRSA = Discriminator(multicodec.RsaPub)
+// DiscriminatorRSA is the value specifying an RSA signature.
+const DiscriminatorRSA = Discriminator(0x1205)
 
-var _ Varsig = (*RSAVarsig)(nil)
+var _ Varsig = RSAVarsig{}
 
 // RSAVarsig is a varsig that encodes the parameters required to describe
 // an RSA signature.
 type RSAVarsig struct {
-	varsig[RSAVarsig]
-	hashAlg HashAlgorithm
+	varsig
+	hashAlg Hash
 	sigLen  uint64
 }
 
 // NewRSAVarsig creates and validates an RSA varsig with the provided
 // hash algorithm, key length and payload encoding.
-func NewRSAVarsig(hashAlgorithm HashAlgorithm, keyLength uint64, payloadEncoding PayloadEncoding, opts ...Option) (*RSAVarsig, error) {
+func NewRSAVarsig(hashAlgorithm Hash, keyLength uint64, payloadEncoding PayloadEncoding, opts ...Option) (RSAVarsig, error) {
 	options := newOptions(opts...)
 
 	var (
 		vers = Version1
-		sig  = []byte{}
+		sig  []byte
 	)
 
 	if options.ForceVersion0() {
@@ -35,8 +32,8 @@ func NewRSAVarsig(hashAlgorithm HashAlgorithm, keyLength uint64, payloadEncoding
 		sig = options.Signature()
 	}
 
-	v := &RSAVarsig{
-		varsig: varsig[RSAVarsig]{
+	v := RSAVarsig{
+		varsig: varsig{
 			vers:   vers,
 			disc:   DiscriminatorRSA,
 			payEnc: payloadEncoding,
@@ -46,7 +43,7 @@ func NewRSAVarsig(hashAlgorithm HashAlgorithm, keyLength uint64, payloadEncoding
 		sigLen:  keyLength,
 	}
 
-	return v.validateSig(v, v.sigLen)
+	return validateSig(v, v.sigLen)
 }
 
 // Encode returns the encoded byte format of the RSAVarsig.
@@ -54,24 +51,25 @@ func (v RSAVarsig) Encode() []byte {
 	buf := v.encode()
 	buf = binary.AppendUvarint(buf, uint64(v.hashAlg))
 	buf = binary.AppendUvarint(buf, v.sigLen)
-	buf = binary.AppendUvarint(buf, uint64(v.payEnc))
+	buf = append(buf, EncodePayloadEncoding(v.payEnc)...)
 	buf = append(buf, v.Signature()...)
 
 	return buf
 }
 
-// HashAlgorithm returns the hash algorithm used to has the payload content.
-func (v *RSAVarsig) HashAlgorithm() HashAlgorithm {
+// Hash returns the value describing the hash algorithm used to hash
+// the payload content before the signature is generated.
+func (v RSAVarsig) Hash() Hash {
 	return v.hashAlg
 }
 
 // KeyLength returns the length of the RSA key used to sign the payload
 // content.
-func (v *RSAVarsig) KeyLength() uint64 {
+func (v RSAVarsig) KeyLength() uint64 {
 	return v.sigLen
 }
 
-func decodeRSA(r *bytes.Reader, vers Version, disc Discriminator) (Varsig, error) {
+func decodeRSA(r BytesReader, vers Version, disc Discriminator) (Varsig, error) {
 	hashAlg, err := DecodeHashAlgorithm(r)
 	if err != nil {
 		return nil, err
@@ -82,14 +80,19 @@ func decodeRSA(r *bytes.Reader, vers Version, disc Discriminator) (Varsig, error
 		return nil, err
 	}
 
-	vs := &RSAVarsig{
-		varsig: varsig[RSAVarsig]{
+	vs := RSAVarsig{
+		varsig: varsig{
 			vers: vers,
 			disc: disc,
 		},
-		hashAlg: HashAlgorithm(hashAlg),
+		hashAlg: hashAlg,
 		sigLen:  sigLen,
 	}
 
-	return vs.decodePayEncAndSig(r, vs, sigLen)
+	vs.payEnc, vs.sig, err = vs.decodePayEncAndSig(r)
+	if err != nil {
+		return nil, err
+	}
+
+	return validateSig(vs, vs.sigLen)
 }

rsa_test.go

@@ -26,12 +26,12 @@ func TestRSAVarsig(t *testing.T) {
 		vs, err := varsig.Decode(example)
 		require.NoError(t, err)
 
-		rsaVs, ok := vs.(*varsig.RSAVarsig)
+		rsaVs, ok := vs.(varsig.RSAVarsig)
 		require.True(t, ok)
 
 		assert.Equal(t, varsig.Version1, rsaVs.Version())
 		assert.Equal(t, varsig.DiscriminatorRSA, rsaVs.Discriminator())
-		assert.Equal(t, varsig.HashAlgorithmSHA256, rsaVs.HashAlgorithm())
+		assert.Equal(t, varsig.HashSha2_256, rsaVs.Hash())
 		assert.Equal(t, varsig.PayloadEncodingDAGCBOR, rsaVs.PayloadEncoding())
 		assert.Equal(t, uint64(keyLen), rsaVs.KeyLength())
 		assert.Len(t, rsaVs.Signature(), 0)
@@ -41,7 +41,7 @@ func TestRSAVarsig(t *testing.T) {
 		t.Parallel()
 
 		rsaVarsig, err := varsig.NewRSAVarsig(
-			varsig.HashAlgorithmSHA256,
+			varsig.HashSha2_256,
 			keyLen,
 			varsig.PayloadEncodingDAGCBOR,
 		)
@@ -52,7 +52,7 @@ func TestRSAVarsig(t *testing.T) {
 	})
 }
 
-func TestUCANExample(t *testing.T) {
+func TestUCANExampleV0(t *testing.T) {
 	t.Parallel()
 
 	const keyLen = 0x100
@@ -69,12 +69,12 @@ func TestUCANExample(t *testing.T) {
 		vs, err := varsig.Decode(example)
 		require.ErrorIs(t, err, varsig.ErrMissingSignature)
 
-		rsaVs, ok := vs.(*varsig.RSAVarsig)
+		rsaVs, ok := vs.(varsig.RSAVarsig)
 		require.True(t, ok)
 
 		assert.Equal(t, varsig.Version0, rsaVs.Version())
 		assert.Equal(t, varsig.DiscriminatorRSA, rsaVs.Discriminator())
-		assert.Equal(t, varsig.HashAlgorithmSHA256, rsaVs.HashAlgorithm())
+		assert.Equal(t, varsig.HashSha2_256, rsaVs.Hash())
 		assert.Equal(t, varsig.PayloadEncodingDAGCBOR, rsaVs.PayloadEncoding())
 		assert.Equal(t, uint64(keyLen), rsaVs.KeyLength())
 		assert.Len(t, rsaVs.Signature(), 0)
@@ -84,7 +84,7 @@ func TestUCANExample(t *testing.T) {
 		t.Parallel()
 
 		rsaVarsig, err := varsig.NewRSAVarsig(
-			varsig.HashAlgorithmSHA256,
+			varsig.HashSha2_256,
 			keyLen,
 			varsig.PayloadEncodingDAGCBOR,
 			varsig.WithForceVersion0([]byte{}),

varsig.go

@@ -19,21 +19,29 @@
 package varsig
 
 import (
-	"bytes"
 	"encoding/binary"
+	"errors"
 	"io"
 )
 
 // Varsig represents types that describe how a signature was generated
 // and thus how to interpret the signature and verify the signed data.
 type Varsig interface {
-	// accessors for fields that are common to all varsig
+	// Version returns the varsig's version field.
 	Version() Version
+
+	// Discriminator returns the algorithm used to produce the corresponding signature.
 	Discriminator() Discriminator
+
+	// PayloadEncoding returns the codec that was used to encode the signed data.
 	PayloadEncoding() PayloadEncoding
+
+	// Signature returns the cryptographic signature of the signed data.
+	// This value is never present in a varsig >= v1 and must either be a valid
+	// signature with the correct length or empty in varsig < v1.
 	Signature() []byte
 
-	// Operations that are common to all varsig
+	// Encode returns the encoded byte format of the varsig.
 	Encode() []byte
 }
 
@@ -45,11 +53,11 @@ func Decode(data []byte) (Varsig, error) {
 
 // DecodeStream converts data read from the provided io.Reader into one
 // of the Varsig types provided by the DefaultRegistry.
-func DecodeStream(r *bytes.Reader) (Varsig, error) {
+func DecodeStream(r BytesReader) (Varsig, error) {
 	return DefaultRegistry().DecodeStream(r)
 }
 
-type varsig[T Varsig] struct {
+type varsig struct {
 	vers   Version
 	disc   Discriminator
 	payEnc PayloadEncoding
@@ -57,31 +65,34 @@ type varsig[T Varsig] struct {
 }
 
 // Version returns the varsig's version field.
-func (v varsig[_]) Version() Version {
+func (v varsig) Version() Version {
 	return v.vers
 }
 
-// Discriminator returns the algorithm used to produce corresponding
+// Discriminator returns the algorithm used to produce the corresponding
 // signature.
-func (v varsig[_]) Discriminator() Discriminator {
+func (v varsig) Discriminator() Discriminator {
 	return v.disc
 }
 
 // PayloadEncoding returns the codec that was used to encode the signed
 // data.
-func (v varsig[_]) PayloadEncoding() PayloadEncoding {
+func (v varsig) PayloadEncoding() PayloadEncoding {
 	return v.payEnc
 }
 
 // Signature returns the cryptographic signature of the signed data. This
 // value is never present in a varsig >= v1 and must either be a valid
 // signature with the correct length or empty in varsig < v1.
-func (v varsig[_]) Signature() []byte {
+func (v varsig) Signature() []byte {
 	return v.sig
 }
 
-func (v *varsig[_]) encode() []byte {
-	var buf []byte
+func (v varsig) encode() []byte {
+	// Pre-allocate to the maximum size to avoid re-allocating.
+	// I think the maximum is 10 bytes, but it's all the same for go to allocate 16 (due to the small
+	// size allocation class), so we might as well get some headroom for bigger varints.
+	buf := make([]byte, 0, 16)
 
 	buf = binary.AppendUvarint(buf, Prefix)
 
@@ -94,37 +105,51 @@ func (v *varsig[_]) encode() []byte {
 	return buf
 }
 
-func (v *varsig[T]) decodePayEncAndSig(r *bytes.Reader, varsig *T, expectedLength uint64) (*T, error) {
+func (v varsig) decodePayEncAndSig(r BytesReader) (PayloadEncoding, []byte, error) {
 	payEnc, err := DecodePayloadEncoding(r, v.Version())
 	if err != nil {
-		return nil, err
+		return 0, nil, err
 	}
 
-	v.payEnc = payEnc
-
-	signature, err := io.ReadAll(r)
-	if err != nil {
-		return nil, err
+	var signature []byte
+	switch v.Version() {
+	case Version0:
+		signature, err = io.ReadAll(r)
+		if err != nil {
+			return 0, nil, err
+		}
+	case Version1:
+		_, err := r.ReadByte()
+		if err != nil && !errors.Is(err, io.EOF) {
+			return 0, nil, err
+		}
+		if err == nil {
+			return 0, nil, ErrUnexpectedSignaturePresent
+		}
+	default:
+		return 0, nil, ErrUnsupportedVersion
 	}
 
-	v.sig = signature
-
-	return v.validateSig(varsig, expectedLength)
+	return payEnc, signature, nil
 }
 
-func (v *varsig[T]) validateSig(varsig *T, expectedLength uint64) (*T, error) {
-	if v.Version() == Version0 && len(v.sig) == 0 {
-		return varsig, ErrMissingSignature
+func validateSig[T Varsig](v T, expectedLength uint64) (T, error) {
+	if v.Version() == Version0 && len(v.Signature()) == 0 {
+		return v, ErrMissingSignature
 	}
 
-	if v.Version() == Version0 && uint64(len(v.sig)) != expectedLength {
-		return nil, ErrUnexpectedSignatureSize
+	if v.Version() == Version0 && uint64(len(v.Signature())) != expectedLength {
+		return *new(T), ErrUnexpectedSignatureSize
 	}
 
-	if v.Version() == Version1 && len(v.sig) != 0 {
-		return nil, ErrUnexpectedSignaturePresent
+	if v.Version() == Version1 && len(v.Signature()) != 0 {
+		return *new(T), ErrUnexpectedSignaturePresent
 	}
 
-	return varsig, nil
-
+	return v, nil
+}
+
+type BytesReader interface {
+	io.ByteReader
+	io.Reader
 }

varsig_test.go

@@ -2,7 +2,6 @@ package varsig_test
 
 import (
 	"encoding/hex"
-	"errors"
 	"io"
 	"testing"
 
@@ -133,7 +132,7 @@ func TestDecode(t *testing.T) {
 
 		vs, err := varsig.Decode(data)
 		require.ErrorIs(t, err, varsig.ErrUnexpectedSignatureSize)
-		assert.Nil(t, vs)
+		assert.Zero(t, vs)
 	})
 
 	t.Run("fails - unexpected signature present - v1", func(t *testing.T) {
@@ -157,32 +156,3 @@ func TestDecode(t *testing.T) {
 		assert.NotNil(t, vs) // varsig is still returned with just "header"
 	})
 }
-
-func mustVarsig[T varsig.Varsig](t *testing.T) func(*T, error) *T {
-	t.Helper()
-
-	return func(v *T, err error) *T {
-		if err != nil && ((*v).Version() != varsig.Version0 || !errors.Is(err, varsig.ErrMissingSignature)) {
-			t.Error(err)
-		}
-
-		return v
-	}
-}
-
-func roundTrip[T varsig.Varsig](t *testing.T, in T, expEncHex string) T {
-	data := in.Encode()
-	assert.Equal(t, expEncHex, hex.EncodeToString(data))
-
-	out, err := varsig.Decode(in.Encode())
-	if err != nil && (out.Version() != varsig.Version0 || !errors.Is(err, varsig.ErrMissingSignature)) {
-		t.Fail()
-	}
-
-	assert.Equal(t, in.Version(), out.Version())
-	assert.Equal(t, in.Discriminator(), out.Discriminator())
-	assert.Equal(t, in.PayloadEncoding(), out.PayloadEncoding())
-	assert.Equal(t, in.Signature(), out.Signature())
-
-	return out.(T)
-}