/
block.go
159 lines (146 loc) · 6.02 KB
/
block.go
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// Copyright 2010 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 blowfish
// getNextWord returns the next big-endian uint32 value from the byte slice
// at the given position in a circular manner, updating the position.
func getNextWord(b []byte, pos *int) uint32 {
var w uint32
j := *pos
for i := 0; i < 4; i++ {
w = w<<8 | uint32(b[j])
j++
if j >= len(b) {
j = 0
}
}
*pos = j
return w
}
// ExpandKey performs a key expansion on the given *Cipher. Specifically, it
// performs the Blowfish algorithm's key schedule which sets up the *Cipher's
// pi and substitution tables for calls to Encrypt. This is used, primarily,
// by the bcrypt package to reuse the Blowfish key schedule during its
// set up. It's unlikely that you need to use this directly.
func ExpandKey(key []byte, c *Cipher) {
j := 0
for i := 0; i < 18; i++ {
// Using inlined getNextWord for performance.
var d uint32
for k := 0; k < 4; k++ {
d = d<<8 | uint32(key[j])
j++
if j >= len(key) {
j = 0
}
}
c.p[i] ^= d
}
var l, r uint32
for i := 0; i < 18; i += 2 {
l, r = encryptBlock(l, r, c)
c.p[i], c.p[i+1] = l, r
}
for i := 0; i < 256; i += 2 {
l, r = encryptBlock(l, r, c)
c.s0[i], c.s0[i+1] = l, r
}
for i := 0; i < 256; i += 2 {
l, r = encryptBlock(l, r, c)
c.s1[i], c.s1[i+1] = l, r
}
for i := 0; i < 256; i += 2 {
l, r = encryptBlock(l, r, c)
c.s2[i], c.s2[i+1] = l, r
}
for i := 0; i < 256; i += 2 {
l, r = encryptBlock(l, r, c)
c.s3[i], c.s3[i+1] = l, r
}
}
// This is similar to ExpandKey, but folds the salt during the key
// schedule. While ExpandKey is essentially expandKeyWithSalt with an all-zero
// salt passed in, reusing ExpandKey turns out to be a place of inefficiency
// and specializing it here is useful.
func expandKeyWithSalt(key []byte, salt []byte, c *Cipher) {
j := 0
for i := 0; i < 18; i++ {
c.p[i] ^= getNextWord(key, &j)
}
j = 0
var l, r uint32
for i := 0; i < 18; i += 2 {
l ^= getNextWord(salt, &j)
r ^= getNextWord(salt, &j)
l, r = encryptBlock(l, r, c)
c.p[i], c.p[i+1] = l, r
}
for i := 0; i < 256; i += 2 {
l ^= getNextWord(salt, &j)
r ^= getNextWord(salt, &j)
l, r = encryptBlock(l, r, c)
c.s0[i], c.s0[i+1] = l, r
}
for i := 0; i < 256; i += 2 {
l ^= getNextWord(salt, &j)
r ^= getNextWord(salt, &j)
l, r = encryptBlock(l, r, c)
c.s1[i], c.s1[i+1] = l, r
}
for i := 0; i < 256; i += 2 {
l ^= getNextWord(salt, &j)
r ^= getNextWord(salt, &j)
l, r = encryptBlock(l, r, c)
c.s2[i], c.s2[i+1] = l, r
}
for i := 0; i < 256; i += 2 {
l ^= getNextWord(salt, &j)
r ^= getNextWord(salt, &j)
l, r = encryptBlock(l, r, c)
c.s3[i], c.s3[i+1] = l, r
}
}
func encryptBlock(l, r uint32, c *Cipher) (uint32, uint32) {
xl, xr := l, r
xl ^= c.p[0]
xr ^= ((c.s0[byte(xl>>24)] + c.s1[byte(xl>>16)]) ^ c.s2[byte(xl>>8)]) + c.s3[byte(xl)] ^ c.p[1]
xl ^= ((c.s0[byte(xr>>24)] + c.s1[byte(xr>>16)]) ^ c.s2[byte(xr>>8)]) + c.s3[byte(xr)] ^ c.p[2]
xr ^= ((c.s0[byte(xl>>24)] + c.s1[byte(xl>>16)]) ^ c.s2[byte(xl>>8)]) + c.s3[byte(xl)] ^ c.p[3]
xl ^= ((c.s0[byte(xr>>24)] + c.s1[byte(xr>>16)]) ^ c.s2[byte(xr>>8)]) + c.s3[byte(xr)] ^ c.p[4]
xr ^= ((c.s0[byte(xl>>24)] + c.s1[byte(xl>>16)]) ^ c.s2[byte(xl>>8)]) + c.s3[byte(xl)] ^ c.p[5]
xl ^= ((c.s0[byte(xr>>24)] + c.s1[byte(xr>>16)]) ^ c.s2[byte(xr>>8)]) + c.s3[byte(xr)] ^ c.p[6]
xr ^= ((c.s0[byte(xl>>24)] + c.s1[byte(xl>>16)]) ^ c.s2[byte(xl>>8)]) + c.s3[byte(xl)] ^ c.p[7]
xl ^= ((c.s0[byte(xr>>24)] + c.s1[byte(xr>>16)]) ^ c.s2[byte(xr>>8)]) + c.s3[byte(xr)] ^ c.p[8]
xr ^= ((c.s0[byte(xl>>24)] + c.s1[byte(xl>>16)]) ^ c.s2[byte(xl>>8)]) + c.s3[byte(xl)] ^ c.p[9]
xl ^= ((c.s0[byte(xr>>24)] + c.s1[byte(xr>>16)]) ^ c.s2[byte(xr>>8)]) + c.s3[byte(xr)] ^ c.p[10]
xr ^= ((c.s0[byte(xl>>24)] + c.s1[byte(xl>>16)]) ^ c.s2[byte(xl>>8)]) + c.s3[byte(xl)] ^ c.p[11]
xl ^= ((c.s0[byte(xr>>24)] + c.s1[byte(xr>>16)]) ^ c.s2[byte(xr>>8)]) + c.s3[byte(xr)] ^ c.p[12]
xr ^= ((c.s0[byte(xl>>24)] + c.s1[byte(xl>>16)]) ^ c.s2[byte(xl>>8)]) + c.s3[byte(xl)] ^ c.p[13]
xl ^= ((c.s0[byte(xr>>24)] + c.s1[byte(xr>>16)]) ^ c.s2[byte(xr>>8)]) + c.s3[byte(xr)] ^ c.p[14]
xr ^= ((c.s0[byte(xl>>24)] + c.s1[byte(xl>>16)]) ^ c.s2[byte(xl>>8)]) + c.s3[byte(xl)] ^ c.p[15]
xl ^= ((c.s0[byte(xr>>24)] + c.s1[byte(xr>>16)]) ^ c.s2[byte(xr>>8)]) + c.s3[byte(xr)] ^ c.p[16]
xr ^= c.p[17]
return xr, xl
}
func decryptBlock(l, r uint32, c *Cipher) (uint32, uint32) {
xl, xr := l, r
xl ^= c.p[17]
xr ^= ((c.s0[byte(xl>>24)] + c.s1[byte(xl>>16)]) ^ c.s2[byte(xl>>8)]) + c.s3[byte(xl)] ^ c.p[16]
xl ^= ((c.s0[byte(xr>>24)] + c.s1[byte(xr>>16)]) ^ c.s2[byte(xr>>8)]) + c.s3[byte(xr)] ^ c.p[15]
xr ^= ((c.s0[byte(xl>>24)] + c.s1[byte(xl>>16)]) ^ c.s2[byte(xl>>8)]) + c.s3[byte(xl)] ^ c.p[14]
xl ^= ((c.s0[byte(xr>>24)] + c.s1[byte(xr>>16)]) ^ c.s2[byte(xr>>8)]) + c.s3[byte(xr)] ^ c.p[13]
xr ^= ((c.s0[byte(xl>>24)] + c.s1[byte(xl>>16)]) ^ c.s2[byte(xl>>8)]) + c.s3[byte(xl)] ^ c.p[12]
xl ^= ((c.s0[byte(xr>>24)] + c.s1[byte(xr>>16)]) ^ c.s2[byte(xr>>8)]) + c.s3[byte(xr)] ^ c.p[11]
xr ^= ((c.s0[byte(xl>>24)] + c.s1[byte(xl>>16)]) ^ c.s2[byte(xl>>8)]) + c.s3[byte(xl)] ^ c.p[10]
xl ^= ((c.s0[byte(xr>>24)] + c.s1[byte(xr>>16)]) ^ c.s2[byte(xr>>8)]) + c.s3[byte(xr)] ^ c.p[9]
xr ^= ((c.s0[byte(xl>>24)] + c.s1[byte(xl>>16)]) ^ c.s2[byte(xl>>8)]) + c.s3[byte(xl)] ^ c.p[8]
xl ^= ((c.s0[byte(xr>>24)] + c.s1[byte(xr>>16)]) ^ c.s2[byte(xr>>8)]) + c.s3[byte(xr)] ^ c.p[7]
xr ^= ((c.s0[byte(xl>>24)] + c.s1[byte(xl>>16)]) ^ c.s2[byte(xl>>8)]) + c.s3[byte(xl)] ^ c.p[6]
xl ^= ((c.s0[byte(xr>>24)] + c.s1[byte(xr>>16)]) ^ c.s2[byte(xr>>8)]) + c.s3[byte(xr)] ^ c.p[5]
xr ^= ((c.s0[byte(xl>>24)] + c.s1[byte(xl>>16)]) ^ c.s2[byte(xl>>8)]) + c.s3[byte(xl)] ^ c.p[4]
xl ^= ((c.s0[byte(xr>>24)] + c.s1[byte(xr>>16)]) ^ c.s2[byte(xr>>8)]) + c.s3[byte(xr)] ^ c.p[3]
xr ^= ((c.s0[byte(xl>>24)] + c.s1[byte(xl>>16)]) ^ c.s2[byte(xl>>8)]) + c.s3[byte(xl)] ^ c.p[2]
xl ^= ((c.s0[byte(xr>>24)] + c.s1[byte(xr>>16)]) ^ c.s2[byte(xr>>8)]) + c.s3[byte(xr)] ^ c.p[1]
xr ^= c.p[0]
return xr, xl
}