skein

README

Go implementation of Skein-512 hash function, MAC, and stream cipher.

Usage:
	
	$ go get github.com/dchest/skein

Import:

	import "github.com/dchest/skein"

Docs:

	http://go.pkgdoc.org/github.com/dchest/skein

Documentation

Overview

Package skein implements the Skein-512 hash function, MAC, and stream cipher as defined in "The Skein Hash Function Family, v1.3".

Index

• Constants
• func NewHash(outLen uint64) hash.Hash
• func NewMAC(outLen uint64, key []byte) hash.Hash
• func NewStream(key []byte, nonce []byte) cipher.Stream
• type Args
• type Hash
  • func New(outLen uint64, args *Args) *Hash
  • func (h *Hash) BlockSize() int
  • func (h *Hash) OutputReader() io.Reader
  • func (h *Hash) Reset()
  • func (h *Hash) Size() int
  • func (h0 *Hash) Sum(in []byte) []byte
  • func (h *Hash) Write(b []byte) (n int, err error)

Constants

const BlockSize = 64

BlockSize is the block size of Skein-512 in bytes.

Functions

func NewHash

func NewHash(outLen uint64) hash.Hash

NewHash returns hash.Hash calculating checksum of the given length in bytes (for example, to calculate 256-bit hash, outLen must be set to 32).

func NewMAC

func NewMAC(outLen uint64, key []byte) hash.Hash

NewMAC returns hash.Hash calculating Skein Message Authentication Code of the given length in bytes. A MAC is a cryptographic hash that uses a key to authenticate a message. The receiver verifies the hash by recomputing it using the same key.

func NewStream

func NewStream(key []byte, nonce []byte) cipher.Stream

NewStream returns a cipher.Stream for encrypting a message with the given key and nonce. The same key-nonce combination must not be used to encrypt more than one message. There are no limits on the length of key or nonce.

Types

type Args

type Args struct {
	// Key is a secret key for MAC, KDF, or stream cipher
	Key []byte
	// Person is a personalization string
	Person []byte
	// PublicKey is a public key for signature hashing
	PublicKey []byte
	// KeyId is a key identifier for KDF
	KeyId []byte
	// Nonce for stream cipher or randomized hashing
	Nonce []byte
	// NoMsg indicates whether message input is used by the function.
	//
	// If false (default), message input it used, and thus if zero-length
	// message is supplied to Write or if Write was not called, it will be
	// assumed that the message input is zero-length, and thus will be
	// processed as such (padded with zeroes). This is the normal way Skein
	// hash and MAC are used.
	//
	// If true, message input is not used, so any call to Write will
	// return an error. This is useful for constructions such as a
	// that skip message input, such as a stream cipher.
	//
	// The name is negative to preserve backward compatibility.
	NoMsg bool
}

Args can be used to configure hash function for different purposes. All fields are optional: if a field is nil, it will not be used.

type Hash

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

Hash represents a state of Skein hash function. It implements hash.Hash interface.

func New

func New(outLen uint64, args *Args) *Hash

New returns a new skein.Hash configured with the given arguments. The final output length of hash function in bytes is outLen (for example, 64 when calculating 512-bit hash). Configuration arguments may be nil.

func (*Hash) BlockSize

func (h *Hash) BlockSize() int

BlockSize returns the hash's underlying block size.

func (*Hash) OutputReader

func (h *Hash) OutputReader() io.Reader

OutputReader returns an io.Reader that can be used to read arbitrary-length output of the hash. Reading from it doesn't change the underlying hash state.

func (*Hash) Reset

func (h *Hash) Reset()

Reset resets hash to its state after initialization. If hash was initialized with arguments, such as key, these arguments are preserved.

func (*Hash) Size

func (h *Hash) Size() int

Size returns the number of bytes Sum will return. If the hash was created with output size greater than the maximum size of int, the result is undefined.

func (*Hash) Sum

func (h0 *Hash) Sum(in []byte) []byte

Sum appends the current hash to in and returns the resulting slice. It does not change the underlying hash state.

func (*Hash) Write

func (h *Hash) Write(b []byte) (n int, err error)

Write adds more data to the running hash. It never returns an error.