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Code Issues Releases Activity

Ensure Cipher.Decrypt doesn't mangle input ciphertext []byte

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This commit is contained in:
Nick Meves
2020-05-11 12:27:27 -07:00
parent e823d874b0
commit 7bb5fc0a81
2 changed files with 16 additions and 6 deletions
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14
pkg/encryption/cipher.go
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@@ -50,7 +50,7 @@ func NewBase64Cipher(initCipher func([]byte) (Cipher, error), secret []byte) (Ci
return &Base64Cipher{Cipher: c}, nil
}
// Encrypt encrypts a value with AES CFB & Base64 encodes it
// Encrypt encrypts a value with the embedded Cipher & Base64 encodes it
func (c *Base64Cipher) Encrypt(value []byte) ([]byte, error) {
encrypted, err := c.Cipher.Encrypt([]byte(value))
if err != nil {
@@ -60,7 +60,7 @@ func (c *Base64Cipher) Encrypt(value []byte) ([]byte, error) {
return []byte(base64.StdEncoding.EncodeToString(encrypted)), nil
}
// Decrypt Base64 decodes a value & decrypts it with AES CFB
// Decrypt Base64 decodes a value & decrypts it with the embedded Cipher
func (c *Base64Cipher) Decrypt(ciphertext []byte) ([]byte, error) {
encrypted, err := base64.StdEncoding.DecodeString(string(ciphertext))
if err != nil {
@@ -103,12 +103,12 @@ func (c *CFBCipher) Decrypt(ciphertext []byte) ([]byte, error) {
return nil, fmt.Errorf("encrypted value should be at least %d bytes, but is only %d bytes", aes.BlockSize, len(ciphertext))
}
iv := ciphertext[:aes.BlockSize]
ciphertext = ciphertext[aes.BlockSize:]
iv, ciphertext := ciphertext[:aes.BlockSize], ciphertext[aes.BlockSize:]
plaintext := make([]byte, len(ciphertext))
stream := cipher.NewCFBDecrypter(c.Block, iv)
stream.XORKeyStream(ciphertext, ciphertext)
stream.XORKeyStream(plaintext, ciphertext)
return ciphertext, nil
return plaintext, nil
}
type GCMCipher struct {
@@ -135,6 +135,8 @@ func (c *GCMCipher) Encrypt(value []byte) ([]byte, error) {
if _, err = io.ReadFull(rand.Reader, nonce); err != nil {
return nil, err
}
// Using nonce as Seal's dst argument results in it being the first
// chunk of bytes in the ciphertext. Decrypt retrieves the nonce/IV from this.
ciphertext := gcm.Seal(nonce, nonce, value, nil)
return ciphertext, nil
}