chacha8

README

chacha8 - ChaCha8

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Henry (chocolatkey@gmail.com)

For those that dare go low...

Don't use this

Documentation

Overview

Package chacha8 implements the ChaCha8 stream cipher.

Index

• Constants
• Variables
• func HChaCha(key, nonce []byte, dst *[32]byte)
• type Cipher
  • func New(key, nonce []byte) (*Cipher, error)
  • func (c *Cipher) KeyStream(dst []byte)
  • func (c *Cipher) ReKey(key, nonce []byte) error
  • func (c *Cipher) Reset()
  • func (c *Cipher) Seek(blockCounter uint64) error
  • func (c *Cipher) XORKeyStream(dst, src []byte)

Constants

const (
	// KeySize is the ChaCha8 key size in bytes.
	KeySize = 32

	// NonceSize is the ChaCha8 nonce size in bytes.
	NonceSize = 8

	// INonceSize is the IETF ChaCha8 nonce size in bytes.
	INonceSize = 12

	// XNonceSize is the XChaCha8 nonce size in bytes.
	XNonceSize = 24

	// HNonceSize is the HChaCha8 nonce size in bytes.
	HNonceSize = 16
)

Variables

var (
	// ErrInvalidKey is the error returned when the key is invalid.
	ErrInvalidKey = errors.New("chacha8: key length must be KeySize bytes")

	// ErrInvalidNonce is the error returned when the nonce is invalid.
	ErrInvalidNonce = errors.New("chacha8: nonce length must be NonceSize/INonceSize/XNonceSize bytes")

	// ErrInvalidCounter is the error returned when the counter is invalid.
	ErrInvalidCounter = errors.New("chacha8: block counter is invalid (out of range)")
)

Functions

func HChaCha

func HChaCha(key, nonce []byte, dst *[32]byte)

HChaCha is the HChaCha8 hash function used to make XChaCha.

Types

type Cipher

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

Cipher is an instance of ChaCha8/XChaCha8 using a particular key and nonce.

func New

func New(key, nonce []byte) (*Cipher, error)

New returns a new ChaCha8/XChaCha8 instance.

func (*Cipher) KeyStream

func (c *Cipher) KeyStream(dst []byte)

KeyStream sets dst to the raw keystream.

func (*Cipher) ReKey

func (c *Cipher) ReKey(key, nonce []byte) error

ReKey reinitializes the ChaCha8/XChaCha8 instance with the provided key and nonce.

func (*Cipher) Reset

func (c *Cipher) Reset()

Reset zeros the key data so that it will no longer appear in the process's memory.

func (*Cipher) Seek

func (c *Cipher) Seek(blockCounter uint64) error

Seek sets the block counter to a given offset.

func (*Cipher) XORKeyStream

func (c *Cipher) XORKeyStream(dst, src []byte)

XORKeyStream sets dst to the result of XORing src with the key stream. Dst and src may be the same slice but otherwise should not overlap.