chacha20poly1305

Documentation

Overview

Package chacha20poly1305 implements the ChaCha20-Poly1305 AEAD and its extended nonce variant XChaCha20-Poly1305, as specified in RFC 8439 and draft-irtf-cfrg-xchacha-01.

Index

• Constants
• func New(key []byte) (cipher.AEAD, error)
• func NewX(key []byte) (cipher.AEAD, error)

Constants

const (
	// KeySize is the size of the key used by this AEAD, in bytes.
	KeySize = 32

	// NonceSize is the size of the nonce used with the standard variant of this
	// AEAD, in bytes.
	//
	// Note that this is too short to be safely generated at random if the same
	// key is reused more than 2³² times.
	NonceSize = 12

	// NonceSizeX is the size of the nonce used with the XChaCha20-Poly1305
	// variant of this AEAD, in bytes.
	NonceSizeX = 24

	// Overhead is the size of the Poly1305 authentication tag, and the
	// difference between a ciphertext length and its plaintext.
	Overhead = 16
)

Functions

func New

func New(key []byte) (cipher.AEAD, error)

New returns a ChaCha20-Poly1305 AEAD that uses the given 256-bit key.

func NewX

func NewX(key []byte) (cipher.AEAD, error)

NewX returns a XChaCha20-Poly1305 AEAD that uses the given 256-bit key.

XChaCha20-Poly1305 is a ChaCha20-Poly1305 variant that takes a longer nonce, suitable to be generated randomly without risk of collisions. It should be preferred when nonce uniqueness cannot be trivially ensured, or whenever nonces are randomly generated.