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.
This approach is described on
https://wiki.mozilla.org/WebAppSec/Secure_Coding_Guidelines#Password_Storage
go-hmaccrypt can be used safely by multiple goroutines.
== Installation
go get github.com/pmylund/go-hmaccrypt
== Documentation
go doc github.com/pmylund/go-hmaccrypt
or http://go.pkgdoc.org/github.com/pmylund/go-hmaccrypt
== Usage
import (
"crypto/sha512"
"github.com/pmylund/go-hmaccrypt"
)
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 := crypt.BcryptCompare(digest, password); err == nil {
// the password is a match
...
}
Returns a HmacCrypt using the specified hash (e.g. sha512.New) and pepper for
its HMAC function. The pepper should be stored separately from the returned
digests. If the digests are stored in a database, it is a good idea to store
the pepper on the disk, or as a constant in the application itself.
Generates a new bcrypt(HMAC-hash(password, pepper), salt(cost)) digest of a
password with a given bcrypt cost/work factor, e.g. 10 (bcrypt.DefaultCost).
Use BcryptCompare to compare a password to an existing digest.