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crypto.go
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crypto.go
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package crypto
import (
"context"
"crypto/aes"
"crypto/cipher"
"crypto/ecdsa"
"crypto/rand"
"encoding/hex"
"errors"
"fmt"
"golang.org/x/crypto/sha3"
types "github.com/status-im/status-go/eth-node/types"
gethcrypto "github.com/ethereum/go-ethereum/crypto"
)
const (
aesNonceLength = 12
)
// Sign calculates an ECDSA signature.
//
// This function is susceptible to chosen plaintext attacks that can leak
// information about the private key that is used for signing. Callers must
// be aware that the given digest cannot be chosen by an adversery. Common
// solution is to hash any input before calculating the signature.
//
// The produced signature is in the [R || S || V] format where V is 0 or 1.
func Sign(digestHash []byte, prv *ecdsa.PrivateKey) (sig []byte, err error) {
return gethcrypto.Sign(digestHash, prv)
}
// SignBytes signs the hash of arbitrary data.
func SignBytes(data []byte, prv *ecdsa.PrivateKey) (sig []byte, err error) {
return Sign(Keccak256(data), prv)
}
// SignBytesAsHex signs the Keccak256 hash of arbitrary data and returns its hex representation.
func SignBytesAsHex(data []byte, identity *ecdsa.PrivateKey) (string, error) {
signature, err := SignBytes(data, identity)
if err != nil {
return "", err
}
return hex.EncodeToString(signature), nil
}
// SignStringAsHex signs the Keccak256 hash of arbitrary string and returns its hex representation.
func SignStringAsHex(data string, identity *ecdsa.PrivateKey) (string, error) {
return SignBytesAsHex([]byte(data), identity)
}
// VerifySignatures verifies tuples of signatures content/hash/public key
func VerifySignatures(signaturePairs [][3]string) error {
for _, signaturePair := range signaturePairs {
content := Keccak256([]byte(signaturePair[0]))
signature, err := hex.DecodeString(signaturePair[1])
if err != nil {
return err
}
publicKeyBytes, err := hex.DecodeString(signaturePair[2])
if err != nil {
return err
}
publicKey, err := UnmarshalPubkey(publicKeyBytes)
if err != nil {
return err
}
recoveredKey, err := SigToPub(
content,
signature,
)
if err != nil {
return err
}
if PubkeyToAddress(*recoveredKey) != PubkeyToAddress(*publicKey) {
return errors.New("identity key and signature mismatch")
}
}
return nil
}
// ExtractSignatures extract from tuples of signatures content a public key
// DEPRECATED: use ExtractSignature
func ExtractSignatures(signaturePairs [][2]string) ([]string, error) {
response := make([]string, len(signaturePairs))
for i, signaturePair := range signaturePairs {
content := Keccak256([]byte(signaturePair[0]))
signature, err := hex.DecodeString(signaturePair[1])
if err != nil {
return nil, err
}
recoveredKey, err := SigToPub(
content,
signature,
)
if err != nil {
return nil, err
}
response[i] = fmt.Sprintf("%x", FromECDSAPub(recoveredKey))
}
return response, nil
}
// ExtractSignature returns a public key for a given data and signature.
func ExtractSignature(data, signature []byte) (*ecdsa.PublicKey, error) {
dataHash := Keccak256(data)
return SigToPub(dataHash, signature)
}
func EncryptSymmetric(key, plaintext []byte) ([]byte, error) {
block, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
// Never use more than 2^32 random nonces with a given key because of the risk of a repeat.
salt, err := generateSecureRandomData(aesNonceLength)
if err != nil {
return nil, err
}
aesgcm, err := cipher.NewGCM(block)
if err != nil {
return nil, err
}
encrypted := aesgcm.Seal(nil, salt, plaintext, nil)
return append(encrypted, salt...), nil
}
func DecryptSymmetric(key []byte, cyphertext []byte) ([]byte, error) {
// symmetric messages are expected to contain the 12-byte nonce at the end of the payload
if len(cyphertext) < aesNonceLength {
return nil, errors.New("missing salt or invalid payload in symmetric message")
}
salt := cyphertext[len(cyphertext)-aesNonceLength:]
block, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
aesgcm, err := cipher.NewGCM(block)
if err != nil {
return nil, err
}
decrypted, err := aesgcm.Open(nil, salt, cyphertext[:len(cyphertext)-aesNonceLength], nil)
if err != nil {
return nil, err
}
return decrypted, nil
}
func containsOnlyZeros(data []byte) bool {
for _, b := range data {
if b != 0 {
return false
}
}
return true
}
func validateDataIntegrity(k []byte, expectedSize int) bool {
if len(k) != expectedSize {
return false
}
if containsOnlyZeros(k) {
return false
}
return true
}
func generateSecureRandomData(length int) ([]byte, error) {
res := make([]byte, length)
_, err := rand.Read(res)
if err != nil {
return nil, err
}
if !validateDataIntegrity(res, length) {
return nil, errors.New("crypto/rand failed to generate secure random data")
}
return res, nil
}
// TextHash is a helper function that calculates a hash for the given message that can be
// safely used to calculate a signature from.
//
// The hash is calulcated as
// keccak256("\x19Ethereum Signed Message:\n"${message length}${message}).
//
// This gives context to the signed message and prevents signing of transactions.
func TextHash(data []byte) []byte {
hash, _ := TextAndHash(data)
return hash
}
// TextAndHash is a helper function that calculates a hash for the given message that can be
// safely used to calculate a signature from.
//
// The hash is calulcated as
// keccak256("\x19Ethereum Signed Message:\n"${message length}${message}).
//
// This gives context to the signed message and prevents signing of transactions.
func TextAndHash(data []byte) ([]byte, string) {
msg := fmt.Sprintf("\x19Ethereum Signed Message:\n%d%s", len(data), string(data))
hasher := sha3.NewLegacyKeccak256()
_, _ = hasher.Write([]byte(msg))
return hasher.Sum(nil), msg
}
func EcRecover(ctx context.Context, data types.HexBytes, sig types.HexBytes) (types.Address, error) {
// Returns the address for the Account that was used to create the signature.
//
// Note, this function is compatible with eth_sign and personal_sign. As such it recovers
// the address of:
// hash = keccak256("\x19${byteVersion}Ethereum Signed Message:\n${message length}${message}")
// addr = ecrecover(hash, signature)
//
// Note, the signature must conform to the secp256k1 curve R, S and V values, where
// the V value must be be 27 or 28 for legacy reasons.
//
// https://github.com/ethereum/go-ethereum/wiki/Management-APIs#personal_ecRecover
if len(sig) != 65 {
return types.Address{}, fmt.Errorf("signature must be 65 bytes long")
}
if sig[64] != 27 && sig[64] != 28 {
return types.Address{}, fmt.Errorf("invalid Ethereum signature (V is not 27 or 28)")
}
sig[64] -= 27 // Transform yellow paper V from 27/28 to 0/1
hash := TextHash(data)
rpk, err := SigToPub(hash, sig)
if err != nil {
return types.Address{}, err
}
return PubkeyToAddress(*rpk), nil
}