crypto

Documentation

Index

• Constants
• Variables
• type AESGCM
  • func NewAESGCM() *AESGCM
  • func (a *AESGCM) Decrypt(ciphertext []byte, key []byte) ([]byte, error)
  • func (a *AESGCM) Encrypt(plaintext []byte, key []byte) ([]byte, error)
  • func (a *AESGCM) GenerateNonce() ([]byte, error)
• type Argon2idDeriver
  • func NewArgon2idDeriver() *Argon2idDeriver
  • func (d *Argon2idDeriver) DeriveKey(password, salt []byte) []byte
  • func (d *Argon2idDeriver) GenerateSalt() ([]byte, error)
  • func (d *Argon2idDeriver) GetKeyLength() uint32
  • func (d *Argon2idDeriver) GetSaltLength() int
  • func (d *Argon2idDeriver) Verify(password []byte, key []byte) bool
  • func (d *Argon2idDeriver) VerifyWithSalt(password, salt, expectedKey []byte) bool
• type Cipher
• type KeyDerivationFunc

Constants

const (
	// KeySize is the required key size for AES-256 (32 bytes)
	KeySize = 32
	// NonceSize is the standard nonce size for GCM (12 bytes)
	NonceSize = 12
)

const (
	Argon2idMemory      = 64 * 1024 // 64 MiB
	Argon2idIterations  = 3
	Argon2idParallelism = 1
	Argon2idKeyLength   = 32 // 256 bits for AES-256
	Argon2idSaltLength  = 16 // 128 bits
)

Argon2id parameters following OWASP recommendations

Variables

var (
	ErrInvalidKeySize    = errors.New("key must be 32 bytes for AES-256")
	ErrInvalidCiphertext = errors.New("ciphertext too short")
)

var (
	ErrInvalidKey       = errors.New("invalid key")
	ErrDecryptionFailed = errors.New("decryption failed")
	ErrInvalidNonce     = errors.New("invalid nonce")
	ErrKeyNotFound      = errors.New("key not found")
)

Types

type AESGCM

type AESGCM struct{}

AESGCM implements the Cipher interface using AES-256-GCM. This provides both confidentiality and authenticity for encrypted data.

func NewAESGCM

func NewAESGCM() *AESGCM

NewAESGCM creates a new AES-256-GCM cipher instance.

func (*AESGCM) Decrypt

func (a *AESGCM) Decrypt(ciphertext []byte, key []byte) ([]byte, error)

Decrypt decrypts ciphertext that was encrypted with AES-256-GCM. Expects the ciphertext to be in format: nonce || ciphertext (12-byte nonce prepended). Verifies the authentication tag during decryption - will fail if ciphertext was tampered.

func (*AESGCM) Encrypt

func (a *AESGCM) Encrypt(plaintext []byte, key []byte) ([]byte, error)

Encrypt encrypts plaintext using AES-256-GCM with the provided key. The key must be exactly 32 bytes for AES-256. Returns nonce || ciphertext, where nonce is 12 bytes prepended to the ciphertext. A new random nonce is generated for each encryption to ensure uniqueness.

func (*AESGCM) GenerateNonce

func (a *AESGCM) GenerateNonce() ([]byte, error)

GenerateNonce generates a cryptographically secure random 12-byte nonce. This should be called for each encryption operation to ensure nonce uniqueness.

type Argon2idDeriver

type Argon2idDeriver struct {
	// contains filtered or unexported fields
}

Argon2idDeriver implements KeyDerivationFunc using Argon2id. Argon2id is the recommended algorithm for password hashing and key derivation, providing resistance against GPU and side-channel attacks.

func NewArgon2idDeriver

func NewArgon2idDeriver() *Argon2idDeriver

NewArgon2idDeriver creates a new Argon2idDeriver with secure default parameters.

func (*Argon2idDeriver) DeriveKey

func (d *Argon2idDeriver) DeriveKey(password, salt []byte) []byte

DeriveKey derives a cryptographic key from the given password and salt using Argon2id. The same password and salt will always produce the same key.

func (*Argon2idDeriver) GenerateSalt

func (d *Argon2idDeriver) GenerateSalt() ([]byte, error)

GenerateSalt generates a cryptographically secure random salt. The salt is used to ensure unique keys even for the same password.

func (*Argon2idDeriver) GetKeyLength

func (d *Argon2idDeriver) GetKeyLength() uint32

GetKeyLength returns the configured key length in bytes.

func (*Argon2idDeriver) GetSaltLength

func (d *Argon2idDeriver) GetSaltLength() int

GetSaltLength returns the configured salt length in bytes.

func (*Argon2idDeriver) Verify

func (d *Argon2idDeriver) Verify(password []byte, key []byte) bool

Verify performs constant-time comparison to prevent timing attacks.

func (*Argon2idDeriver) VerifyWithSalt

func (d *Argon2idDeriver) VerifyWithSalt(password, salt, expectedKey []byte) bool

VerifyWithSalt derives a key from password+salt and compares it to the expected key. This is the proper way to verify a password when you have the stored salt.

type Cipher

type Cipher interface {
	Encrypt(plaintext []byte, key []byte) ([]byte, error)
	Decrypt(ciphertext []byte, key []byte) ([]byte, error)
	GenerateNonce() ([]byte, error)
}

type KeyDerivationFunc

type KeyDerivationFunc interface {
	DeriveKey(password, salt []byte) []byte
	Verify(password []byte, key []byte) bool
	GenerateSalt() ([]byte, error)
}