143 lines
4.1 KiB
Go
143 lines
4.1 KiB
Go
package walletconnect
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import (
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"crypto/ecdsa"
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"crypto/elliptic"
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"crypto/rand"
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"encoding/binary"
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"encoding/hex"
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crypto "git.frostfs.info/TrueCloudLab/frostfs-crypto"
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)
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const (
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// saltSize is the salt size added to signed message.
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saltSize = 16
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// signatureLen is the length of RFC6979 signature.
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signatureLen = 64
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)
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// SignedMessage contains mirrors `SignedMessage` struct from the WalletConnect API.
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// https://neon.coz.io/wksdk/core/modules.html#SignedMessage
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type SignedMessage struct {
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Data []byte
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Message []byte
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PublicKey []byte
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Salt []byte
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}
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// Sign signs message using WalletConnect API. The returned signature
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// contains RFC6979 signature and 16-byte salt.
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func Sign(p *ecdsa.PrivateKey, msg []byte) ([]byte, error) {
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sm, err := SignMessage(p, msg)
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if err != nil {
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return nil, err
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}
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return append(sm.Data, sm.Salt...), nil
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}
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// Verify verifies message using WalletConnect API.
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func Verify(p *ecdsa.PublicKey, data, sign []byte) bool {
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if len(sign) != signatureLen+saltSize {
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return false
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}
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salt := sign[signatureLen:]
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return VerifyMessage(p, SignedMessage{
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Data: sign[:signatureLen],
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Message: createMessageWithSalt(data, salt),
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Salt: salt,
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})
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}
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// SignMessage signs message with a private key and returns structure similar to
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// `signMessage` of the WalletConnect API.
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// https://github.com/CityOfZion/wallet-connect-sdk/blob/89c236b/packages/wallet-connect-sdk-core/src/index.ts#L496
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// https://github.com/CityOfZion/neon-wallet/blob/1174a9388480e6bbc4f79eb13183c2a573f67ca8/app/context/WalletConnect/helpers.js#L133
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func SignMessage(p *ecdsa.PrivateKey, msg []byte) (SignedMessage, error) {
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var salt [saltSize]byte
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_, _ = rand.Read(salt[:])
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msg = createMessageWithSalt(msg, salt[:])
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sign, err := crypto.SignRFC6979(p, msg)
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if err != nil {
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return SignedMessage{}, err
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}
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return SignedMessage{
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Data: sign,
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Message: msg,
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PublicKey: elliptic.MarshalCompressed(p.Curve, p.X, p.Y),
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Salt: salt[:],
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}, nil
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}
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// VerifyMessage verifies message with a private key and returns structure similar to
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// `verifyMessage` of WalletConnect API.
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// https://github.com/CityOfZion/wallet-connect-sdk/blob/89c236b/packages/wallet-connect-sdk-core/src/index.ts#L515
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// https://github.com/CityOfZion/neon-wallet/blob/1174a9388480e6bbc4f79eb13183c2a573f67ca8/app/context/WalletConnect/helpers.js#L147
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func VerifyMessage(p *ecdsa.PublicKey, m SignedMessage) bool {
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if p == nil {
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x, y := elliptic.UnmarshalCompressed(elliptic.P256(), m.PublicKey)
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if x == nil || y == nil {
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return false
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}
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p = &ecdsa.PublicKey{
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Curve: elliptic.P256(),
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X: x,
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Y: y,
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}
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}
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return crypto.VerifyRFC6979(p, m.Message, m.Data) == nil
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}
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func createMessageWithSalt(msg, salt []byte) []byte {
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// 4 byte prefix + length of the message with salt in bytes +
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// + salt + message + 2 byte postfix.
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saltedLen := hex.EncodedLen(len(salt)) + len(msg)
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data := make([]byte, 4+getVarIntSize(saltedLen)+saltedLen+2)
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n := copy(data, []byte{0x01, 0x00, 0x01, 0xf0}) // fixed prefix
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n += putVarUint(data[n:], uint64(saltedLen)) // salt is hex encoded, double its size
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n += hex.Encode(data[n:], salt[:]) // for some reason we encode salt in hex
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n += copy(data[n:], msg)
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copy(data[n:], []byte{0x00, 0x00})
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return data
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}
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// Following functions are copied from github.com/nspcc-dev/neo-go/pkg/io package
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// to avoid having another dependency.
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// getVarIntSize returns the size in number of bytes of a variable integer.
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// Reference: https://github.com/neo-project/neo/blob/26d04a642ac5a1dd1827dabf5602767e0acba25c/src/neo/IO/Helper.cs#L131
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func getVarIntSize(value int) int {
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var size uintptr
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if value < 0xFD {
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size = 1 // unit8
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} else if value <= 0xFFFF {
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size = 3 // byte + uint16
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} else {
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size = 5 // byte + uint32
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}
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return int(size)
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}
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// putVarUint puts val in varint form to the pre-allocated buffer.
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func putVarUint(data []byte, val uint64) int {
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if val < 0xfd {
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data[0] = byte(val)
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return 1
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}
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if val <= 0xFFFF {
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data[0] = byte(0xfd)
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binary.LittleEndian.PutUint16(data[1:], uint16(val))
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return 3
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}
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data[0] = byte(0xfe)
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binary.LittleEndian.PutUint32(data[1:], uint32(val))
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return 5
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}
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