status-im/status-go

package typeddata

import (
    "crypto/ecdsa"
    "fmt"
    "math/big"

    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/common/hexutil"
    "github.com/ethereum/go-ethereum/crypto"

    signercore "github.com/ethereum/go-ethereum/signer/core/apitypes"
)

var (
    // x19 to avoid collision with rlp encode. x01 version byte defined in EIP-191
    messagePadding = []byte{0x19, 0x01}
)

func encodeData(typed TypedData) (rst common.Hash, err error) {
    domainSeparator, err := hashStruct(eip712Domain, typed.Domain, typed.Types)
    if err != nil {
        return rst, err
    }
    primary, err := hashStruct(typed.PrimaryType, typed.Message, typed.Types)
    if err != nil {
        return rst, err
    }
    return crypto.Keccak256Hash(messagePadding, domainSeparator[:], primary[:]), nil
}

func encodeDataV4(typedData signercore.TypedData, chain *big.Int) ([]byte, error) {
    domainSeparator, err := typedData.HashStruct("EIP712Domain", typedData.Domain.Map())
    if err != nil {
        return nil, err
    }
    typedDataHash, err := typedData.HashStruct(typedData.PrimaryType, typedData.Message)
    if err != nil {
        return nil, err
    }
    rawData := []byte(fmt.Sprintf("\x19\x01%s%s", string(domainSeparator), string(typedDataHash)))
    sighash := crypto.Keccak256(rawData)
    return sighash, nil
}

func HashTypedDataV4(typedData signercore.TypedData, chain *big.Int) (common.Hash, error) {
    hashBytes, err := encodeDataV4(typedData, chain)
    if err != nil {
        return common.Hash{}, err
    }
    return common.BytesToHash(hashBytes), nil
}

func SignTypedDataV4(typedData signercore.TypedData, prv *ecdsa.PrivateKey, chain *big.Int) (hexutil.Bytes, error) {
    sighash, err := HashTypedDataV4(typedData, chain)
    if err != nil {
        return nil, err
    }
    sig, err := crypto.Sign(sighash[:], prv)
    if err != nil {
        return nil, err
    }
    sig[64] += 27
    return sig, nil
}

// Sign TypedData with a given private key. Verify that chainId in the typed data matches currently selected chain.
func Sign(typed TypedData, prv *ecdsa.PrivateKey, chain *big.Int) ([]byte, error) {
    hash, err := ValidateAndHash(typed, chain)
    if err != nil {
        return nil, err
    }
    sig, err := crypto.Sign(hash[:], prv)
    if err != nil {
        return nil, err
    }
    sig[64] += 27
    return sig, nil
}