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crypto.go
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crypto.go
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package crypto
import (
"crypto/aes"
"crypto/cipher"
"crypto/rand"
"crypto/sha256"
"errors"
"io"
"golang.org/x/crypto/scrypt"
)
// KeyFromPassphrase generates 32 byte key from the passphrase
func KeyFromPassphrase(passphrase string) ([]byte, error) {
// salt is just a hash of a passphrase (effectively no salt)
salt := sha256.Sum256([]byte(passphrase))
// These defaults will consume approximately 16MB of memory (128 * r * N)
const N = 16384
const r = 8
return scrypt.Key([]byte(passphrase), salt[:], N, r, 1, 32)
}
// Encrypt encrypts the given data with the given passphrase.
func Encrypt(data []byte, key []byte) ([]byte, error) {
block, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
gcm, err := cipher.NewGCM(block)
if err != nil {
return nil, err
}
nonce := make([]byte, gcm.NonceSize())
if _, err = io.ReadFull(rand.Reader, nonce); err != nil {
return nil, err
}
ciphertext := gcm.Seal(nonce, nonce, data, nil)
return ciphertext, nil
}
// Decrypt decrypts the given data using the given passphrase.
func Decrypt(data []byte, key []byte) ([]byte, error) {
block, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
gcm, err := cipher.NewGCM(block)
if err != nil {
return nil, err
}
nonceSize := gcm.NonceSize()
if len(data) < nonceSize {
return nil, errors.New("data length is less than nonce size")
}
nonce, ciphertext := data[:nonceSize], data[nonceSize:]
plaintext, err := gcm.Open(nil, nonce, ciphertext, nil)
if err != nil {
return nil, err
}
return plaintext, nil
}