crypto.go

package crypto

import (
	"bytes"
	"crypto"
	"crypto/rand"
	"errors"
	"io"

	secpEc "gitlab.com/yawning/secp256k1-voi/secec"
)

// PrivateKeyBytes is the size of a serialized private key.
const PrivateKeyBytes = 32

// PublicKeyBytes is the size of a serialized public key.
const PublicKeyBytes = 65

var (
	ErrInvalidMsgLength = errors.New("filecoin/go-crypto: invalid message length")
)

// PublicKey returns the public key for this private key.
func PublicKey(sk []byte) []byte {
	pk, err := secpEc.NewPrivateKey(sk)
	if err != nil {
		panic(err)
	}

	return pk.PublicKey().Bytes()
}

// Sign signs the given message, which must be 32 bytes long.
func Sign(sk, msg []byte) ([]byte, error) {
	pk, err := secpEc.NewPrivateKey(sk)
	if err != nil {
		return nil, err
	}
	// Encoding is set to "EncodingCompactRecoverable" to ensure the signature is in [R | S | V] style.
	// The V (1byte) is the recovery bit and is not apart of the signature verification, rather prevents malleable signatures by inverting them.
	return pk.Sign(rand.Reader, msg, &secpEc.ECDSAOptions{Encoding: secpEc.EncodingCompactRecoverable, RejectMalleable: true, Hash: crypto.SHA256})
}

// Equals compares two private key for equality and returns true if they are the same.
func Equals(sk, other []byte) bool {
	return bytes.Equal(sk, other)
}

// Verify checks the given signature and returns true if it is valid.
func Verify(pk, msg, signature []byte) bool {
	pubKey, err := EcRecover(msg, signature)
	if err != nil {
		return false
	}

	return string(pubKey) == string(pk)
}

// GenerateKeyFromSeed generates a new key from the given reader.
// Deprecated: use GenerateKey instead - the given reader is no longer used.
func GenerateKeyFromSeed(io.Reader) ([]byte, error) {
	return GenerateKey()
}

// GenerateKey creates a new key using secure randomness from crypto.rand.
func GenerateKey() ([]byte, error) {
	key, err := secpEc.GenerateKey()
	if err != nil {
		return nil, err
	}

	return key.Bytes(), nil
}

// EcRecover recovers the public key from a message, signature pair.
func EcRecover(msg, signature []byte) ([]byte, error) {
	// assert that msg is 32 bytes exactly. The underlying library will truncate to 32 bytes but won't fail if there's garbage data.
	if len(msg) != 32 {
		return nil, ErrInvalidMsgLength
	}

	// the underlying `ParseCompactRecoverableSignature` will fail if sig is not 65 bytes exactly
	// to future dev: 64 byte signatures are supported by the underlying lib,
	// but we did not use them in order to maintain identical behavior with the original library
	r, s, v, err := secpEc.ParseCompactRecoverableSignature(signature)
	if err != nil {
		return nil, err
	}

	// `RecoverPublicKey` will fail if the v bit is incorrectly set
	pk, err := secpEc.RecoverPublicKey(msg, r, s, v)
	if err != nil {
		return nil, err
	}

	return pk.Bytes(), nil
}