mirror of
https://github.com/rocky-linux/peridot.git
synced 2024-11-14 17:51:25 +00:00
78 lines
2.4 KiB
Go
78 lines
2.4 KiB
Go
// Copyright 2012 The Go Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
/*
|
|
Package pbkdf2 implements the key derivation function PBKDF2 as defined in RFC
|
|
2898 / PKCS #5 v2.0.
|
|
|
|
A key derivation function is useful when encrypting data based on a password
|
|
or any other not-fully-random data. It uses a pseudorandom function to derive
|
|
a secure encryption key based on the password.
|
|
|
|
While v2.0 of the standard defines only one pseudorandom function to use,
|
|
HMAC-SHA1, the drafted v2.1 specification allows use of all five FIPS Approved
|
|
Hash Functions SHA-1, SHA-224, SHA-256, SHA-384 and SHA-512 for HMAC. To
|
|
choose, you can pass the `New` functions from the different SHA packages to
|
|
pbkdf2.Key.
|
|
*/
|
|
package pbkdf2 // import "golang.org/x/crypto/pbkdf2"
|
|
|
|
import (
|
|
"crypto/hmac"
|
|
"hash"
|
|
)
|
|
|
|
// Key derives a key from the password, salt and iteration count, returning a
|
|
// []byte of length keylen that can be used as cryptographic key. The key is
|
|
// derived based on the method described as PBKDF2 with the HMAC variant using
|
|
// the supplied hash function.
|
|
//
|
|
// For example, to use a HMAC-SHA-1 based PBKDF2 key derivation function, you
|
|
// can get a derived key for e.g. AES-256 (which needs a 32-byte key) by
|
|
// doing:
|
|
//
|
|
// dk := pbkdf2.Key([]byte("some password"), salt, 4096, 32, sha1.New)
|
|
//
|
|
// Remember to get a good random salt. At least 8 bytes is recommended by the
|
|
// RFC.
|
|
//
|
|
// Using a higher iteration count will increase the cost of an exhaustive
|
|
// search but will also make derivation proportionally slower.
|
|
func Key(password, salt []byte, iter, keyLen int, h func() hash.Hash) []byte {
|
|
prf := hmac.New(h, password)
|
|
hashLen := prf.Size()
|
|
numBlocks := (keyLen + hashLen - 1) / hashLen
|
|
|
|
var buf [4]byte
|
|
dk := make([]byte, 0, numBlocks*hashLen)
|
|
U := make([]byte, hashLen)
|
|
for block := 1; block <= numBlocks; block++ {
|
|
// N.B.: || means concatenation, ^ means XOR
|
|
// for each block T_i = U_1 ^ U_2 ^ ... ^ U_iter
|
|
// U_1 = PRF(password, salt || uint(i))
|
|
prf.Reset()
|
|
prf.Write(salt)
|
|
buf[0] = byte(block >> 24)
|
|
buf[1] = byte(block >> 16)
|
|
buf[2] = byte(block >> 8)
|
|
buf[3] = byte(block)
|
|
prf.Write(buf[:4])
|
|
dk = prf.Sum(dk)
|
|
T := dk[len(dk)-hashLen:]
|
|
copy(U, T)
|
|
|
|
// U_n = PRF(password, U_(n-1))
|
|
for n := 2; n <= iter; n++ {
|
|
prf.Reset()
|
|
prf.Write(U)
|
|
U = U[:0]
|
|
U = prf.Sum(U)
|
|
for x := range U {
|
|
T[x] ^= U[x]
|
|
}
|
|
}
|
|
}
|
|
return dk[:keyLen]
|
|
}
|