poly

README

Polynomial authentication schemes

A polynomial authenticator is basically a message authentication scheme. Therefore the polynomial authenticator takes a secret key and a message of arbitrary size and computes a fixed size authentication tag.

It is critical for the security of the authenticator that the one key is never used for more than one message - so never reuse a key. Authenticating two different messages with the same key allows an attacker to forge messages at will.

This package provides a general interface for polynomial authenticators and natively supports two commonly used polynomials:

• GHASH used by the AES-GCM AEAD construction
• Poly1305 used by the ChaCha20Poly1305 AEAD construction

Those both polynomial authenticators are used in TLS.

Install

Install in your GOPATH: go get github.com/aead/poly

Performance

For GHASH benchmarks see: GHASH implementation
For Poly1305 benchmarks see: Poly1305 implementation

Documentation

Index

• type Hash
  • func NewPoly1305(key [32]byte) Hash

Types

type Hash

type Hash interface {
	// Write adds more data to the running authenticator.
	// This function should return a non-nil error if a call
	// to Write happens after a call to Sum. So it is not possible
	// to compute the checksum and than add more data.
	io.Writer

	// Size returns the number of bytes Sum will append.
	Size() int

	// Sum computes and appends the hash to b and returns the resulting slice.
	// It is safe to call this function multiple times.
	Sum(b []byte) []byte
}

Hash defines a common interface for polynomial authenticators.

func NewPoly1305

func NewPoly1305(key [32]byte) Hash

NewPoly1305 returns a new Hash computing a poly1305 authenticator.