version: 1.10

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:

  1. // CheckMAC reports whether messageMAC is a valid HMAC tag for message.
  2. func CheckMAC(message, messageMAC, key []byte) bool {
  3. mac := hmac.New(sha256.New, key)
  4. mac.Write(message)
  5. expectedMAC := mac.Sum(nil)
  6. return hmac.Equal(messageMAC, expectedMAC)
  7. }


Package files


func Equal

  1. func Equal(mac1, mac2 []byte) bool

Equal compares two MACs for equality without leaking timing information.

func New

  1. 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.