Documentation
¶
Overview ¶
Package cipher implements standard block cipher modes that can be wrapped around low-level block cipher implementations. See https://csrc.nist.gov/groups/ST/toolkit/BCM/current_modes.html and NIST Special Publication 800-38A.
Index ¶
Examples ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type AEAD ¶ added in go1.2
type AEAD interface {
// NonceSize returns the size of the nonce that must be passed to Seal
// and Open.
NonceSize() int
// Overhead returns the maximum difference between the lengths of a
// plaintext and its ciphertext.
Overhead() int
// Seal encrypts and authenticates plaintext, authenticates the
// additional data and appends the result to dst, returning the updated
// slice. The nonce must be NonceSize() bytes long and unique for all
// time, for a given key.
//
// To reuse plaintext's storage for the encrypted output, use plaintext[:0]
// as dst. Otherwise, the remaining capacity of dst must not overlap plaintext.
// dst and additionalData may not overlap.
Seal(dst, nonce, plaintext, additionalData []byte) []byte
// Open decrypts and authenticates ciphertext, authenticates the
// additional data and, if successful, appends the resulting plaintext
// to dst, returning the updated slice. The nonce must be NonceSize()
// bytes long and both it and the additional data must match the
// value passed to Seal.
//
// To reuse ciphertext's storage for the decrypted output, use ciphertext[:0]
// as dst. Otherwise, the remaining capacity of dst must not overlap ciphertext.
// dst and additionalData may not overlap.
//
// Even if the function fails, the contents of dst, up to its capacity,
// may be overwritten.
Open(dst, nonce, ciphertext, additionalData []byte) ([]byte, error)
}
AEAD is a cipher mode providing authenticated encryption with associated data. For a description of the methodology, see https://en.wikipedia.org/wiki/Authenticated_encryption.
func NewGCM ¶ added in go1.2
NewGCM returns the given 128-bit, block cipher wrapped in Galois Counter Mode with the standard nonce length.
Example (Decrypt) ¶
package main
import (
"crypto/aes"
"crypto/cipher"
"encoding/hex"
"fmt"
)
func main() {
// Load your secret key from a safe place and reuse it across multiple
// Seal/Open calls. (Obviously don't use this example key for anything
// real.) If you want to convert a passphrase to a key, use a suitable
// package like bcrypt or scrypt.
// When decoded the key should be 16 bytes (AES-128) or 32 (AES-256).
key, _ := hex.DecodeString("6368616e676520746869732070617373776f726420746f206120736563726574")
ciphertext, _ := hex.DecodeString("c3aaa29f002ca75870806e44086700f62ce4d43e902b3888e23ceff797a7a471")
nonce, _ := hex.DecodeString("64a9433eae7ccceee2fc0eda")
block, err := aes.NewCipher(key)
if err != nil {
panic(err.Error())
}
aesgcm, err := cipher.NewGCM(block)
if err != nil {
panic(err.Error())
}
plaintext, err := aesgcm.Open(nil, nonce, ciphertext, nil)
if err != nil {
panic(err.Error())
}
fmt.Printf("%s\n", plaintext)
}
Output: exampleplaintext