1// Package bcrypt_pbkdf implements OpenBSD's bcrypt_pbkdf(3) 2package bcrypt_pbkdf 3 4import ( 5 "crypto/sha512" 6 "github.com/ebfe/bcrypt_pbkdf/blowfish" 7) 8 9// derived from /usr/src/lib/libutil/bcrypt_pbkdf.c 10/* 11 $OpenBSD: bcrypt_pbkdf.c,v 1.6 2014/01/31 16:56:32 tedu Exp $ 12 13 Copyright (c) 2013 Ted Unangst <tedu@openbsd.org> 14 15 Permission to use, copy, modify, and distribute this software for any 16 purpose with or without fee is hereby granted, provided that the above 17 copyright notice and this permission notice appear in all copies. 18 19 THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 20 WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 21 MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 22 ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 23 WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 24 ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 25 OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 26*/ 27 28const ( 29 bcryptBlocks = 8 30 bcryptHashSize = 4 * bcryptBlocks 31 magic = "OxychromaticBlowfishSwatDynamite" 32) 33 34func bcryptHash(bf *blowfish.Cipher, hpass, hsalt, out []byte) { 35 err := bf.InitSaltedCipher(hpass, hsalt) 36 if err != nil { 37 panic(err) 38 } 39 40 for i := 0; i < 64; i++ { 41 blowfish.ExpandKey(hsalt, bf) 42 blowfish.ExpandKey(hpass, bf) 43 } 44 45 copy(out, magic) 46 47 for i := 0; i < 64; i++ { 48 for j := 0; j < bcryptHashSize/blowfish.BlockSize; j++ { 49 bf.Encrypt(out[j*blowfish.BlockSize:], out[j*blowfish.BlockSize:]) 50 } 51 } 52 53 for i := 0; i < len(out); i += 4 { 54 out[i+0], out[i+1], out[i+2], out[i+3] = out[i+3], out[i+2], out[i+1], out[i+0] 55 } 56} 57 58func bcryptPBKDF(password, salt []byte, rounds, keyLen int) []byte { 59 countsalt := make([]byte, 4) 60 hpass := make([]byte, sha512.Size) 61 hsalt := make([]byte, sha512.Size) 62 out := make([]byte, bcryptHashSize) 63 tmp := make([]byte, bcryptHashSize) 64 key := make([]byte, keyLen) 65 cipher := &blowfish.Cipher{} 66 67 stride := (keyLen + bcryptHashSize - 1) / bcryptHashSize 68 amt := (keyLen + stride - 1) / stride 69 70 sha := sha512.New() 71 sha.Write(password) 72 hpass = sha.Sum(hpass[:0]) 73 74 for count := uint32(1); keyLen > 0; count++ { 75 sha.Reset() 76 sha.Write(salt) 77 countsalt[0] = byte(count >> 24) 78 countsalt[1] = byte(count >> 16) 79 countsalt[2] = byte(count >> 8) 80 countsalt[3] = byte(count) 81 sha.Write(countsalt) 82 hsalt = sha.Sum(hsalt[:0]) 83 84 bcryptHash(cipher, hpass, hsalt, tmp) 85 copy(out, tmp) 86 87 for i := 1; i < rounds; i++ { 88 sha.Reset() 89 sha.Write(tmp) 90 hsalt = sha.Sum(hsalt[:0]) 91 bcryptHash(cipher, hpass, hsalt, tmp) 92 for i := range out { 93 out[i] ^= tmp[i] 94 } 95 } 96 97 if amt > keyLen { 98 amt = keyLen 99 } 100 101 for i := 0; i < amt; i++ { 102 key[i*stride+(int(count)-1)] = out[i] 103 } 104 keyLen -= amt 105 } 106 107 return key 108} 109 110func Key(password, salt []byte, rounds, keyLen int) []byte { 111 return bcryptPBKDF(password, salt, rounds, keyLen) 112} 113