synapsecns/sanguine

package types

import (
    "context"
    "fmt"
    "math/big"

    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/crypto"
    "github.com/synapsecns/sanguine/core"
    "github.com/synapsecns/sanguine/ethergo/signer/signer"
)

// SignEncoder encodes a type, and signs it with the given salt.
func signEncoder(ctx context.Context, signer signer.Signer, encoder Encoder, salt string) (signer.Signature, []byte, common.Hash, error) {
    // Encode the given type.
    encoded, err := encoder.Encode()
    if err != nil {
        return nil, nil, common.Hash{}, fmt.Errorf("could not encode: %w", err)
    }

    // Hash the encoded type, and concatenate with hashed salt.
    hashedEncoded := crypto.Keccak256Hash(encoded).Bytes()
    toSign := append(crypto.Keccak256Hash([]byte(salt)).Bytes(), hashedEncoded...)
    hashedDigest, err := HashRawBytes(toSign)
    if err != nil {
        return nil, nil, common.Hash{}, fmt.Errorf("could not hash: %w", err)
    }

    // Sign the message.
    sig, err := signer.SignMessage(ctx, core.BytesToSlice(hashedDigest), false)
    if err != nil {
        return nil, nil, common.Hash{}, fmt.Errorf("could not sign: %w", err)
    }

    sig = NewSignature(new(big.Int).Add(big.NewInt(27), sig.V()), sig.R(), sig.S())
    return sig, encoded, hashedDigest, nil
}