Add dependencies/vendor (whatsapp)

vendor/go.mau.fi/libsignal/ecc/Curve.go

@@ -0,0 +1,109 @@
+package ecc
+
+import (
+	"crypto/rand"
+	"errors"
+	"fmt"
+	"io"
+
+	"golang.org/x/crypto/curve25519"
+
+	"go.mau.fi/libsignal/logger"
+)
+
+// DjbType is the Diffie-Hellman curve type (curve25519) created by D. J. Bernstein.
+const DjbType = 0x05
+
+var ErrBadKeyType = errors.New("bad key type")
+
+// DecodePoint will take the given bytes and offset and return an ECPublicKeyable object.
+// This is used to check the byte at the given offset in the byte array for a special
+// "type" byte that will determine the key type. Currently only DJB EC keys are supported.
+func DecodePoint(bytes []byte, offset int) (ECPublicKeyable, error) {
+	keyType := bytes[offset] & 0xFF
+
+	switch keyType {
+	case DjbType:
+		keyBytes := [32]byte{}
+		copy(keyBytes[:], bytes[offset+1:])
+		return NewDjbECPublicKey(keyBytes), nil
+	default:
+		return nil, fmt.Errorf("%w %d", ErrBadKeyType, keyType)
+	}
+}
+
+func CreateKeyPair(privateKey []byte) *ECKeyPair {
+	var private, public [32]byte
+	copy(private[:], privateKey)
+
+	private[0] &= 248
+	private[31] &= 127
+	private[31] |= 64
+
+	curve25519.ScalarBaseMult(&public, &private)
+
+	// Put data into our keypair struct
+	djbECPub := NewDjbECPublicKey(public)
+	djbECPriv := NewDjbECPrivateKey(private)
+	keypair := NewECKeyPair(djbECPub, djbECPriv)
+
+	logger.Debug("Returning keypair: ", keypair)
+	return keypair
+}
+
+// GenerateKeyPair returns an EC Key Pair.
+func GenerateKeyPair() (*ECKeyPair, error) {
+	// logger.Debug("Generating EC Key Pair...")
+	// Get cryptographically secure random numbers.
+	random := rand.Reader
+
+	// Create a byte array for our public and private keys.
+	var private, public [32]byte
+
+	// Generate some random data
+	_, err := io.ReadFull(random, private[:])
+	if err != nil {
+		return nil, err
+	}
+
+	// Documented at: http://cr.yp.to/ecdh.html
+	private[0] &= 248
+	private[31] &= 127
+	private[31] |= 64
+
+	curve25519.ScalarBaseMult(&public, &private)
+
+	// Put data into our keypair struct
+	djbECPub := NewDjbECPublicKey(public)
+	djbECPriv := NewDjbECPrivateKey(private)
+	keypair := NewECKeyPair(djbECPub, djbECPriv)
+
+	// logger.Debug("Returning keypair: ", keypair)
+
+	return keypair, nil
+}
+
+// VerifySignature verifies that the message was signed with the given key.
+func VerifySignature(signingKey ECPublicKeyable, message []byte, signature [64]byte) bool {
+	logger.Debug("Verifying signature of bytes: ", message)
+	publicKey := signingKey.PublicKey()
+	valid := verify(publicKey, message, &signature)
+	logger.Debug("Signature valid: ", valid)
+	return valid
+}
+
+// CalculateSignature signs a message with the given private key.
+func CalculateSignature(signingKey ECPrivateKeyable, message []byte) [64]byte {
+	logger.Debug("Signing bytes with signing key")
+	// Get cryptographically secure random numbers.
+	var random [64]byte
+	r := rand.Reader
+	io.ReadFull(r, random[:])
+
+	// Get the private key.
+	privateKey := signingKey.Serialize()
+
+	// Sign the message.
+	signature := sign(&privateKey, message, random)
+	return *signature
+}