package hmac

import "crypto/hmac"

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:

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

Index ¶

• func Equal(mac1, mac2 []byte) bool
• func New(h func() hash.Hash, key []byte) hash.Hash

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.

Source Files ¶

hmac.go