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Code Issues Releases Wiki Activity

Remove custom Encrypt/Decrypt methods

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This commit is contained in:
Alexander Neumann 2017-10-28 11:24:09 +02:00
parent 6fc133ad6a
commit a5f0e9ab65
1 changed files with 0 additions and 87 deletions
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87
internal/crypto/crypto.go
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@ -373,93 +373,6 @@ func (k *Key) Open(dst, nonce, ciphertext, additionalData []byte) ([]byte, error
return dst, nil
}
// Encrypt encrypts and authenticates data. Stored in ciphertext is IV || Ciphertext ||
// MAC. Encrypt returns the new ciphertext slice, which is extended when
// necessary. ciphertext and plaintext may not point to (exactly) the same
// slice or non-intersecting slices.
func (k *Key) Encrypt(ciphertext []byte, plaintext []byte) ([]byte, error) {
if !k.Valid() {
return nil, errors.New("invalid key")
}
ciphertext = ciphertext[:cap(ciphertext)]
// test for same slice, if possible
if len(plaintext) > 0 && len(ciphertext) > 0 && &plaintext[0] == &ciphertext[0] {
return nil, ErrInvalidCiphertext
}
// extend ciphertext slice if necessary
if len(ciphertext) < len(plaintext)+Extension {
ext := len(plaintext) + Extension - len(ciphertext)
ciphertext = append(ciphertext, make([]byte, ext)...)
}
iv := NewRandomNonce()
copy(ciphertext, iv[:])
c, err := aes.NewCipher(k.EncryptionKey[:])
if err != nil {
panic(fmt.Sprintf("unable to create cipher: %v", err))
}
e := cipher.NewCTR(c, ciphertext[:ivSize])
e.XORKeyStream(ciphertext[ivSize:], plaintext)
// truncate to only cover iv and actual ciphertext
ciphertext = ciphertext[:ivSize+len(plaintext)]
mac := poly1305MAC(ciphertext[ivSize:], ciphertext[:ivSize], &k.MACKey)
ciphertext = append(ciphertext, mac...)
return ciphertext, nil
}
// Decrypt verifies and decrypts the ciphertext. Ciphertext must be in the form
// IV || Ciphertext || MAC. plaintext and ciphertext may point to (exactly) the
// same slice.
func (k *Key) Decrypt(plaintext []byte, ciphertextWithMac []byte) (int, error) {
if !k.Valid() {
return 0, errors.New("invalid key")
}
// check for plausible length
if len(ciphertextWithMac) < Extension {
return 0, errors.Errorf("trying to decrypt invalid data: ciphertext too small")
}
// check buffer length for plaintext
plaintextLength := len(ciphertextWithMac) - Extension
if len(plaintext) < plaintextLength {
return 0, errors.Errorf("plaintext buffer too small, %d < %d", len(plaintext), plaintextLength)
}
// extract mac
l := len(ciphertextWithMac) - macSize
ciphertextWithIV, mac := ciphertextWithMac[:l], ciphertextWithMac[l:]
// extract iv
iv, ciphertext := ciphertextWithIV[:ivSize], ciphertextWithIV[ivSize:]
// verify mac
if !poly1305Verify(ciphertext, iv, &k.MACKey, mac) {
return 0, ErrUnauthenticated
}
if len(ciphertext) != plaintextLength {
panic("plaintext and ciphertext lengths do not match")
}
// decrypt data
c, err := aes.NewCipher(k.EncryptionKey[:])
if err != nil {
panic(fmt.Sprintf("unable to create cipher: %v", err))
}
e := cipher.NewCTR(c, iv)
e.XORKeyStream(plaintext, ciphertext)
return plaintextLength, nil
}
// Valid tests if the key is valid.
func (k *Key) Valid() bool {
return k.EncryptionKey.Valid() && k.MACKey.Valid()