71 lines
2.0 KiB
Go
71 lines
2.0 KiB
Go
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package crypto
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import (
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"bytes"
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"crypto/ecdsa"
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"crypto/elliptic"
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"crypto/rand"
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"io"
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secp256k1 "github.com/ipsn/go-secp256k1"
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)
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// PrivateKeyBytes is the size of a serialized private key.
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const PrivateKeyBytes = 32
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// PublicKeyBytes is the size of a serialized public key.
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const PublicKeyBytes = 65
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// PublicKey returns the public key for this private key.
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func PublicKey(sk []byte) []byte {
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x, y := secp256k1.S256().ScalarBaseMult(sk)
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return elliptic.Marshal(secp256k1.S256(), x, y)
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}
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// Sign signs the given message, which must be 32 bytes long.
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func Sign(sk, msg []byte) ([]byte, error) {
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return secp256k1.Sign(msg, sk)
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}
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// Equals compares two private key for equality and returns true if they are the same.
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func Equals(sk, other []byte) bool {
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return bytes.Equal(sk, other)
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}
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// Verify checks the given signature and returns true if it is valid.
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func Verify(pk, msg, signature []byte) bool {
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if len(signature) == 65 {
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// Drop the V (1byte) in [R | S | V] style signatures.
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// The V (1byte) is the recovery bit and is not apart of the signature verification.
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return secp256k1.VerifySignature(pk[:], msg, signature[:len(signature)-1])
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}
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return secp256k1.VerifySignature(pk[:], msg, signature)
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}
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// GenerateKeyFromSeed generates a new key from the given reader.
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func GenerateKeyFromSeed(seed io.Reader) ([]byte, error) {
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key, err := ecdsa.GenerateKey(secp256k1.S256(), seed)
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if err != nil {
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return nil, err
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}
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privkey := make([]byte, PrivateKeyBytes)
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blob := key.D.Bytes()
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// the length is guaranteed to be fixed, given the serialization rules for secp2561k curve points.
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copy(privkey[PrivateKeyBytes-len(blob):], blob)
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return privkey, nil
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}
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// GenerateKey creates a new key using secure randomness from crypto.rand.
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func GenerateKey() ([]byte, error) {
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return GenerateKeyFromSeed(rand.Reader)
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}
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// EcRecover recovers the public key from a message, signature pair.
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func EcRecover(msg, signature []byte) ([]byte, error) {
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return secp256k1.RecoverPubkey(msg, signature)
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}
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