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