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cryptoutil.go
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cryptoutil.go
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package cryptoutil
import (
"crypto/aes"
"crypto/cipher"
crand "crypto/rand"
"crypto/sha256"
"fmt"
cconv "github.com/agl/ed25519/extra25519"
"github.com/libp2p/go-libp2p-core/crypto"
pb "github.com/libp2p/go-libp2p-core/crypto/pb"
"golang.org/x/crypto/ed25519"
"golang.org/x/crypto/scrypt"
"berty.tech/berty/v2/go/pkg/errcode"
)
const (
KeySize = 32 // Key size required by box
NonceSize = 24 // Nonce size required by box
ScryptIterations = 1 << 15
ScryptR = 8
ScryptP = 1
ScryptKeyLen = 32
)
func ConcatAndHashSha256(slices ...[]byte) *[sha256.Size]byte {
var concat []byte
for _, slice := range slices {
concat = append(concat, slice...)
}
checksum := sha256.Sum256(concat)
return &checksum
}
func GenerateNonce() (*[NonceSize]byte, error) {
var nonce [NonceSize]byte
size, err := crand.Read(nonce[:])
if size != NonceSize {
err = fmt.Errorf("size read: %d (required %d)", size, NonceSize)
}
if err != nil {
return nil, errcode.ErrCryptoRandomGeneration.Wrap(err)
}
return &nonce, nil
}
func GenerateNonceSize(size int) ([]byte, error) {
nonce := make([]byte, size)
readSize, err := crand.Read(nonce)
if readSize != size {
err = fmt.Errorf("size read: %d (required %d)", readSize, size)
}
if err != nil {
return nil, errcode.ErrCryptoRandomGeneration.Wrap(err)
}
return nonce, nil
}
func NonceSliceToArray(nonceSlice []byte) (*[NonceSize]byte, error) {
var nonceArray [NonceSize]byte
if l := len(nonceSlice); l != NonceSize {
return nil, errcode.ErrInvalidInput.Wrap(fmt.Errorf("invalid nonce size, expected %d bytes, got %d", NonceSize, l))
}
copy(nonceArray[:], nonceSlice)
return &nonceArray, nil
}
func KeySliceToArray(keySlice []byte) (*[KeySize]byte, error) {
var keyArray [KeySize]byte
if l := len(keySlice); l != KeySize {
return nil, errcode.ErrInvalidInput.Wrap(fmt.Errorf("unable to convert slice to array, unexpected slice size: %d (expected %d)", l, KeySize))
}
copy(keyArray[:], keySlice)
return &keyArray, nil
}
func SeedFromEd25519PrivateKey(key crypto.PrivKey) ([]byte, error) {
// Similar to (*ed25519).Seed()
if key.Type() != pb.KeyType_Ed25519 {
return nil, errcode.ErrInvalidInput
}
r, err := key.Raw()
if err != nil {
return nil, errcode.ErrSerialization.Wrap(err)
}
if len(r) != ed25519.PrivateKeySize {
return nil, errcode.ErrInvalidInput
}
return r[:ed25519.PrivateKeySize-ed25519.PublicKeySize], nil
}
// EdwardsToMontgomery converts ed25519 priv/pub keys to X25519 keys.
func EdwardsToMontgomery(privKey crypto.PrivKey, pubKey crypto.PubKey) (*[32]byte, *[32]byte, error) {
mongPriv, err := EdwardsToMontgomeryPriv(privKey)
if err != nil {
return nil, nil, err
}
mongPub, err := EdwardsToMontgomeryPub(pubKey)
if err != nil {
return nil, nil, err
}
return mongPriv, mongPub, nil
}
// EdwardsToMontgomeryPub converts ed25519 pub key to X25519 pub key.
func EdwardsToMontgomeryPub(pubKey crypto.PubKey) (*[KeySize]byte, error) {
var edPub, mongPub [KeySize]byte
if pubKey.Type() != pb.KeyType_Ed25519 {
return nil, errcode.ErrInvalidInput
}
pubKeyBytes, err := pubKey.Raw()
if err != nil {
return nil, errcode.ErrSerialization.Wrap(err)
} else if len(pubKeyBytes) != KeySize {
return nil, errcode.ErrInvalidInput
}
copy(edPub[:], pubKeyBytes)
if !cconv.PublicKeyToCurve25519(&mongPub, &edPub) {
return nil, errcode.ErrInvalidInput.Wrap(err)
}
return &mongPub, nil
}
// EdwardsToMontgomeryPriv converts ed25519 priv key to X25519 priv key.
func EdwardsToMontgomeryPriv(privKey crypto.PrivKey) (*[KeySize]byte, error) {
var edPriv [64]byte
var mongPriv [KeySize]byte
if privKey.Type() != pb.KeyType_Ed25519 {
return nil, errcode.ErrInvalidInput
}
privKeyBytes, err := privKey.Raw()
if err != nil {
return nil, errcode.ErrSerialization.Wrap(err)
} else if len(privKeyBytes) != 64 {
return nil, errcode.ErrInvalidInput
}
copy(edPriv[:], privKeyBytes)
cconv.PrivateKeyToCurve25519(&mongPriv, &edPriv)
return &mongPriv, nil
}
// AESGCMEncrypt use AES+GCM to encrypt plaintext data.
//
// The generated output will be longer than the original plaintext input.
func AESGCMEncrypt(key, data []byte) ([]byte, error) {
blockCipher, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
gcm, err := cipher.NewGCM(blockCipher)
if err != nil {
return nil, err
}
nonce, err := GenerateNonceSize(gcm.NonceSize())
if err != nil {
return nil, err
}
ciphertext := gcm.Seal(nonce, nonce, data, nil)
return ciphertext, nil
}
// AESGCMDecrypt uses AES+GCM to decrypt plaintext data.
func AESGCMDecrypt(key, data []byte) ([]byte, error) {
blockCipher, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
gcm, err := cipher.NewGCM(blockCipher)
if err != nil {
return nil, err
}
nonce, ciphertext := data[:gcm.NonceSize()], data[gcm.NonceSize():]
plaintext, err := gcm.Open(nil, nonce, ciphertext, nil)
if err != nil {
return nil, err
}
return plaintext, nil
}
// AESCTRStream returns a CTR stream that can be used to produce ciphertext without padding.
func AESCTRStream(key, iv []byte) (cipher.Stream, error) {
if key == nil || iv == nil {
return nil, errcode.ErrInvalidInput
}
blockCipher, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
stream := cipher.NewCTR(blockCipher, iv)
return stream, nil
}
// DeriveKey takes a passphrase of any length and returns a key of fixed size.
//
// If no salt is provided, a new one will be created and returned.
func DeriveKey(passphrase, salt []byte) ([]byte, []byte, error) {
if salt == nil {
var err error
salt, err = GenerateNonceSize(ScryptKeyLen)
if err != nil {
return nil, nil, err
}
}
key, err := scrypt.Key(passphrase, salt, ScryptIterations, ScryptR, ScryptP, ScryptKeyLen)
if err != nil {
return nil, nil, err
}
return key, salt, nil
}