108 lines
2.8 KiB
Go
108 lines
2.8 KiB
Go
package crypto
|
|
|
|
import (
|
|
"crypto/aes"
|
|
"crypto/cipher"
|
|
"crypto/rand"
|
|
"encoding/base64"
|
|
"errors"
|
|
"fmt"
|
|
"io"
|
|
|
|
"golang.org/x/crypto/argon2"
|
|
)
|
|
|
|
// Params holds Argon2id parameters and the salt used for key derivation.
|
|
type Params struct {
|
|
Salt []byte
|
|
Time uint32
|
|
Memory uint32
|
|
Threads uint8
|
|
}
|
|
|
|
// DefaultParams generates new Params with a random 16-byte salt and
|
|
// reasonable Argon2id defaults.
|
|
func DefaultParams() (*Params, error) {
|
|
salt := make([]byte, 16)
|
|
if _, err := io.ReadFull(rand.Reader, salt); err != nil {
|
|
return nil, fmt.Errorf("generate salt: %w", err)
|
|
}
|
|
return &Params{
|
|
Salt: salt,
|
|
Time: 3,
|
|
Memory: 64 * 1024,
|
|
Threads: 4,
|
|
}, nil
|
|
}
|
|
|
|
// DeriveKey derives a 32-byte AES-256 key from a passphrase using Argon2id.
|
|
func DeriveKey(passphrase string, p *Params) []byte {
|
|
return argon2.IDKey([]byte(passphrase), p.Salt, p.Time, p.Memory, p.Threads, 32)
|
|
}
|
|
|
|
// Encryptor provides AES-256-GCM encryption and decryption.
|
|
type Encryptor struct {
|
|
aead cipher.AEAD
|
|
}
|
|
|
|
// NewEncryptor creates an Encryptor from a 32-byte key.
|
|
func NewEncryptor(key []byte) (*Encryptor, error) {
|
|
if len(key) != 32 {
|
|
return nil, errors.New("key must be 32 bytes")
|
|
}
|
|
block, err := aes.NewCipher(key)
|
|
if err != nil {
|
|
return nil, fmt.Errorf("new cipher: %w", err)
|
|
}
|
|
aead, err := cipher.NewGCM(block)
|
|
if err != nil {
|
|
return nil, fmt.Errorf("new gcm: %w", err)
|
|
}
|
|
return &Encryptor{aead: aead}, nil
|
|
}
|
|
|
|
// Encrypt encrypts plaintext. The returned ciphertext has the nonce prepended.
|
|
func (e *Encryptor) Encrypt(plaintext []byte) ([]byte, error) {
|
|
nonce := make([]byte, e.aead.NonceSize())
|
|
if _, err := io.ReadFull(rand.Reader, nonce); err != nil {
|
|
return nil, fmt.Errorf("generate nonce: %w", err)
|
|
}
|
|
return e.aead.Seal(nonce, nonce, plaintext, nil), nil
|
|
}
|
|
|
|
// Decrypt decrypts ciphertext produced by Encrypt.
|
|
func (e *Encryptor) Decrypt(ciphertext []byte) ([]byte, error) {
|
|
nonceSize := e.aead.NonceSize()
|
|
if len(ciphertext) < nonceSize {
|
|
return nil, errors.New("ciphertext too short")
|
|
}
|
|
nonce, ct := ciphertext[:nonceSize], ciphertext[nonceSize:]
|
|
plaintext, err := e.aead.Open(nil, nonce, ct, nil)
|
|
if err != nil {
|
|
return nil, fmt.Errorf("decrypt: %w", err)
|
|
}
|
|
return plaintext, nil
|
|
}
|
|
|
|
// EncryptString encrypts a string and returns base64-encoded ciphertext.
|
|
func (e *Encryptor) EncryptString(plaintext string) (string, error) {
|
|
ct, err := e.Encrypt([]byte(plaintext))
|
|
if err != nil {
|
|
return "", err
|
|
}
|
|
return base64.StdEncoding.EncodeToString(ct), nil
|
|
}
|
|
|
|
// DecryptString decodes base64 ciphertext and returns the decrypted string.
|
|
func (e *Encryptor) DecryptString(encoded string) (string, error) {
|
|
ct, err := base64.StdEncoding.DecodeString(encoded)
|
|
if err != nil {
|
|
return "", fmt.Errorf("decode base64: %w", err)
|
|
}
|
|
pt, err := e.Decrypt(ct)
|
|
if err != nil {
|
|
return "", err
|
|
}
|
|
return string(pt), nil
|
|
}
|