status-im/status-go

package common

import (
    "crypto/aes"
    "crypto/cipher"
    "crypto/ecdsa"
    "crypto/rand"
    "errors"
    "io"
    "math/big"

    "golang.org/x/crypto/sha3"

    "github.com/ethereum/go-ethereum/crypto/ecies"

    "github.com/status-im/status-go/eth-node/crypto"
    "github.com/status-im/status-go/eth-node/types"
)

const (
    nonceLength                = 12
    defaultECHDSharedKeyLength = 16
    defaultECHDMACLength       = 16
)

var (
    ErrInvalidCiphertextLength = errors.New("invalid cyphertext length")

    letterRunes       = []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
    numberRunes       = []rune("0123456789")
    alphanumericRunes = append(numberRunes, letterRunes...)
)

func HashPublicKey(pk *ecdsa.PublicKey) []byte {
    return Shake256(crypto.CompressPubkey(pk))
}

func Decrypt(cyphertext []byte, key []byte) ([]byte, error) {
    if len(cyphertext) < nonceLength {
        return nil, ErrInvalidCiphertextLength
    }

    c, err := aes.NewCipher(key)
    if err != nil {
        return nil, err
    }

    gcm, err := cipher.NewGCM(c)
    if err != nil {
        return nil, err
    }

    nonce := cyphertext[:nonceLength]
    return gcm.Open(nil, nonce, cyphertext[nonceLength:], nil)
}

func Encrypt(plaintext []byte, key []byte, reader io.Reader) ([]byte, error) {
    c, err := aes.NewCipher(key)
    if err != nil {
        return nil, err
    }

    gcm, err := cipher.NewGCM(c)
    if err != nil {
        return nil, err
    }

    nonce := make([]byte, gcm.NonceSize())
    if _, err = io.ReadFull(reader, nonce); err != nil {
        return nil, err
    }

    return gcm.Seal(nonce, nonce, plaintext, nil), nil
}

func Shake256(buf []byte) []byte {
    h := make([]byte, 64)
    sha3.ShakeSum256(h, buf)
    return h
}

// IsPubKeyEqual checks that two public keys are equal
func IsPubKeyEqual(a, b *ecdsa.PublicKey) bool {
    // the curve is always the same, just compare the points
    return a.X.Cmp(b.X) == 0 && a.Y.Cmp(b.Y) == 0
}

func PubkeysToHex(keys []*ecdsa.PublicKey) []string {
    var result []string
    for _, k := range keys {
        result = append(result, PubkeyToHex(k))
    }
    return result
}

func PubkeyToHex(key *ecdsa.PublicKey) string {
    return types.EncodeHex(crypto.FromECDSAPub(key))
}

func PubkeyToHexBytes(key *ecdsa.PublicKey) types.HexBytes {
    return crypto.FromECDSAPub(key)
}

func HexToPubkey(pk string) (*ecdsa.PublicKey, error) {
    bytes, err := types.DecodeHex(pk)
    if err != nil {
        return nil, err
    }
    return crypto.UnmarshalPubkey(bytes)
}

func MakeECDHSharedKey(yourPrivateKey *ecdsa.PrivateKey, theirPubKey *ecdsa.PublicKey) ([]byte, error) {
    return ecies.ImportECDSA(yourPrivateKey).GenerateShared(
        ecies.ImportECDSAPublic(theirPubKey),
        defaultECHDSharedKeyLength,
        defaultECHDMACLength,
    )
}

func randomString(choice []rune, n int) (string, error) {
    max := big.NewInt(int64(len(choice)))
    rr := rand.Reader

    b := make([]rune, n)
    for i := range b {
        pos, err := rand.Int(rr, max)
        if err != nil {
            return "", err
        }
        b[i] = choice[pos.Int64()]
    }
    return string(b), nil
}

func RandomAlphabeticalString(n int) (string, error) {
    return randomString(letterRunes, n)
}

func RandomAlphanumericString(n int) (string, error) {
    return randomString(alphanumericRunes, n)
}