feat(did): add to/from public key

did/crypto.go

@@ -0,0 +1,39 @@
+package did
+
+import (
+	"errors"
+
+	crypto "github.com/libp2p/go-libp2p/core/crypto"
+	"github.com/libp2p/go-libp2p/core/crypto/pb"
+	"github.com/multiformats/go-multicodec"
+	"github.com/multiformats/go-varint"
+)
+
+func FromPrivKey(privKey crypto.PrivKey) (DID, error) {
+	return FromPubKey(privKey.GetPublic())
+}
+
+func FromPubKey(pubKey crypto.PubKey) (DID, error) {
+	code, ok := map[pb.KeyType]multicodec.Code{
+		pb.KeyType_Ed25519:   multicodec.Ed25519Pub,
+		pb.KeyType_RSA:       multicodec.RsaPub,
+		pb.KeyType_Secp256k1: multicodec.Secp256k1Pub,
+		pb.KeyType_ECDSA:     multicodec.Es256,
+	}[pubKey.Type()]
+	if !ok {
+		return Undef, errors.New("Blah")
+	}
+
+	buf := varint.ToUvarint(uint64(code))
+
+	pubBytes, err := pubKey.Raw()
+	if err != nil {
+		return Undef, err
+	}
+
+	return DID{
+		str:  string(append(buf, pubBytes...)),
+		code: uint64(code),
+		key:  true,
+	}, nil
+}