Documentation

Overview

Package hmac implements the Keyed-Hash Message Authentication Code (HMAC) as defined in U.S. Federal Information Processing Standards Publication 198. An HMAC is a cryptographic hash that uses a key to sign a message. The receiver verifies the hash by recomputing it using the same key.

Receivers should be careful to use Equal to compare MACs in order to avoid timing side-channels:

// ValidMAC reports whether messageMAC is a valid HMAC tag for message.
func ValidMAC(message, messageMAC, key []byte) bool {
	mac := hmac.New(sha256.New, key)
	mac.Write(message)
	expectedMAC := mac.Sum(nil)
	return hmac.Equal(messageMAC, expectedMAC)
}

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

func Equal

func Equal(mac1, mac2 []byte) bool

Equal compares two MACs for equality without leaking timing information.

func New

func New(h func() hash.Hash, key []byte) hash.Hash

New returns a new HMAC hash using the given hash.Hash type and key. Note that unlike other hash implementations in the standard library, the returned Hash does not implement encoding.BinaryMarshaler or encoding.BinaryUnmarshaler.

Types

This section is empty.

Source Files