74 lines
1.6 KiB
Go
74 lines
1.6 KiB
Go
package varsig
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import (
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"encoding/binary"
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)
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// DiscriminatorRSA is the value specifying an RSA signature.
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const DiscriminatorRSA = Discriminator(0x1205)
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var _ Varsig = RSAVarsig{}
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// RSAVarsig is a varsig that encodes the parameters required to describe
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// an RSA signature.
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type RSAVarsig struct {
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varsig
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hashAlg Hash
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keyLen uint64
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}
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// NewRSAVarsig creates and validates an RSA varsig with the provided
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// hash algorithm, key length and payload encoding.
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func NewRSAVarsig(hashAlgorithm Hash, keyLen uint64, payloadEncoding PayloadEncoding) RSAVarsig {
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return RSAVarsig{
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varsig: varsig{
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disc: DiscriminatorRSA,
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payEnc: payloadEncoding,
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},
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hashAlg: hashAlgorithm,
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keyLen: keyLen,
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}
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}
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// Encode returns the encoded byte format of the RSAVarsig.
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func (v RSAVarsig) Encode() []byte {
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buf := v.encode()
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buf = binary.AppendUvarint(buf, uint64(v.hashAlg))
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buf = binary.AppendUvarint(buf, v.keyLen)
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buf = append(buf, EncodePayloadEncoding(v.payEnc)...)
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return buf
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}
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// Hash returns the value describing the hash algorithm used to hash
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// the payload content before the signature is generated.
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func (v RSAVarsig) Hash() Hash {
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return v.hashAlg
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}
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// KeyLength returns the length of the RSA key used to sign the payload
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// content.
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func (v RSAVarsig) KeyLength() uint64 {
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return v.keyLen
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}
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func decodeRSA(r BytesReader) (Varsig, error) {
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hashAlg, err := DecodeHashAlgorithm(r)
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if err != nil {
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return nil, err
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}
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keyLen, err := binary.ReadUvarint(r)
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if err != nil {
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return nil, err
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}
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payEnc, err := DecodePayloadEncoding(r)
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if err != nil {
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return nil, err
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}
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return NewRSAVarsig(hashAlg, keyLen, payEnc), nil
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}
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