go-hmaccrypt provides very strong password digests using a combination of a peppered hash-based message authentication code (HMAC) and a salted adaptive key derivation function like bcrypt.

A digest of each password is generated using e.g. HMAC-SHA512 with a pepper—a value stored separately from the final digests—after which a bcrypt digest of the HMAC digest is generated. The bcrypt digest is saved in e.g. a database.

With this approach, you can ensure the safety of user passwords even if an SQL injection compromises the contents of your database’s users table, or if a weakness is found in e.g. bcrypt. The approach is described here.

go-hmaccrypt can be used safely by multiple goroutines.


go get github.com/patrickmn/go-hmaccrypt


godoc github.com/patrickmn/go-hmaccrypt
or https://godoc.org/github.com/patrickmn/go-hmaccrypt


import (

pepper := []byte("randomly generated sequence stored on disk or in the source")
crypt := hmaccrypt.New(sha512.New, pepper)

password := []byte("f00b4r!")
digest, err := crypt.Bcrypt(password, 10)
if err != nil {
// save the bcrypt digest in the database

if err := c.BcryptCompare(digest, password); err == nil {
	// the password is a match