code review 217116: Implementation of the symmetric block cipher Blowfish.

src/pkg/crypto/blowfish/block.go

 // 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
 
 func expandKey(key []byte, c *Cipher) {
-        copy(c.p[0:], p)
-        copy(c.s0[0:], s0)
-        copy(c.s1[0:], s1)
-        copy(c.s2[0:], s2)
-        copy(c.s3[0:], s3)
+        copy(&c.p, &p)
+        copy(&c.s0, &s0)
+        copy(&c.s1, &s1)
+        copy(&c.s2, &s2)
+        copy(&c.s3, &s3)
 
         j := 0
         for i := 0; i < 18; i++ {
                 var d uint32
                 for k := 0; k < 4; k++ {
                         d = d<<8 | uint32(key[j])&0x000000FF
                         j++
                         if j >= len(key) {
                                 j = 0
                         }
@@ skipping 18 matching lines @@
         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
         }
 }
 
-//func _F(ctx *Cipher, x uint32) uint32 {
-//      d := uint(x & 0xFF)
-//      c := uint(x >> 8 & 0xFF)
-//      b := uint(x >> 16 & 0xFF)
-//      a := uint(x >> 24 & 0xFF)
-//      result := ctx.s0[a] + ctx.s1[b]
-//      result ^= ctx.s2[c]
-//      result += ctx.s3[d]
-//      return result
-//}
-
 func encryptBlock(l, r uint32, c *Cipher) (uint32, uint32) {
         xl, xr := l, r
-        //      for i := 0; i < 16; i++ {
-        //              xl ^= c.p[i]
-        //              xr ^= _F(c, xl)
-        //              xl, xr = xr, xl
-        //      }
-        //      xl ^= c.p[16]
-        //      xr ^= c.p[17]
         xl ^= c.p[0]
-        //      xr ^= ((c.s0[byte(xl>>24)] + c.s1[byte(xl>>16&0xFF)]) ^ c.s2[byte(xl>>8&0xFF)]) + c.s3[byte(xl&0xFF)] ^ c.p[1]
-        //      xl ^= ((c.s0[byte(xr>>24)] + c.s1[byte(xr>>16&0xFF)]) ^ c.s2[byte(xr>>8&0xFF)]) + c.s3[byte(xr&0xFF)] ^ c.p[2]
-        //      xr ^= ((c.s0[byte(xl>>24)] + c.s1[byte(xl>>16&0xFF)]) ^ c.s2[byte(xl>>8&0xFF)]) + c.s3[byte(xl&0xFF)] ^ c.p[3]
-        //      xl ^= ((c.s0[byte(xr>>24)] + c.s1[byte(xr>>16&0xFF)]) ^ c.s2[byte(xr>>8&0xFF)]) + c.s3[byte(xr&0xFF)] ^ c.p[4]
-        //      xr ^= ((c.s0[byte(xl>>24)] + c.s1[byte(xl>>16&0xFF)]) ^ c.s2[byte(xl>>8&0xFF)]) + c.s3[byte(xl&0xFF)] ^ c.p[5]
-        //      xl ^= ((c.s0[byte(xr>>24)] + c.s1[byte(xr>>16&0xFF)]) ^ c.s2[byte(xr>>8&0xFF)]) + c.s3[byte(xr&0xFF)] ^ c.p[6]
-        //      xr ^= ((c.s0[byte(xl>>24)] + c.s1[byte(xl>>16&0xFF)]) ^ c.s2[byte(xl>>8&0xFF)]) + c.s3[byte(xl&0xFF)] ^ c.p[7]
-        //      xl ^= ((c.s0[byte(xr>>24)] + c.s1[byte(xr>>16&0xFF)]) ^ c.s2[byte(xr>>8&0xFF)]) + c.s3[byte(xr&0xFF)] ^ c.p[8]
-        //      xr ^= ((c.s0[byte(xl>>24)] + c.s1[byte(xl>>16&0xFF)]) ^ c.s2[byte(xl>>8&0xFF)]) + c.s3[byte(xl&0xFF)] ^ c.p[9]
-        //      xl ^= ((c.s0[byte(xr>>24)] + c.s1[byte(xr>>16&0xFF)]) ^ c.s2[byte(xr>>8&0xFF)]) + c.s3[byte(xr&0xFF)] ^ c.p[10]
-        //      xr ^= ((c.s0[byte(xl>>24)] + c.s1[byte(xl>>16&0xFF)]) ^ c.s2[byte(xl>>8&0xFF)]) + c.s3[byte(xl&0xFF)] ^ c.p[11]
-        //      xl ^= ((c.s0[byte(xr>>24)] + c.s1[byte(xr>>16&0xFF)]) ^ c.s2[byte(xr>>8&0xFF)]) + c.s3[byte(xr&0xFF)] ^ c.p[12]
-        //      xr ^= ((c.s0[byte(xl>>24)] + c.s1[byte(xl>>16&0xFF)]) ^ c.s2[byte(xl>>8&0xFF)]) + c.s3[byte(xl&0xFF)] ^ c.p[13]
-        //      xl ^= ((c.s0[byte(xr>>24)] + c.s1[byte(xr>>16&0xFF)]) ^ c.s2[byte(xr>>8&0xFF)]) + c.s3[byte(xr&0xFF)] ^ c.p[14]
-        //      xr ^= ((c.s0[byte(xl>>24)] + c.s1[byte(xl>>16&0xFF)]) ^ c.s2[byte(xl>>8&0xFF)]) + c.s3[byte(xl&0xFF)] ^ c.p[15]
-        //      xl ^= ((c.s0[byte(xr>>24)] + c.s1[byte(xr>>16&0xFF)]) ^ c.s2[byte(xr>>8&0xFF)]) + c.s3[byte(xr&0xFF)] ^ c.p[16]
-        xr ^= ((c.s0[xl>>24] + c.s1[xl>>16&0xFF]) ^ c.s2[xl>>8&0xFF]) + c.s3[xl&0xFF] ^ c.p[1]
-        xl ^= ((c.s0[xr>>24] + c.s1[xr>>16&0xFF]) ^ c.s2[xr>>8&0xFF]) + c.s3[xr&0xFF] ^ c.p[2]
-        xr ^= ((c.s0[xl>>24] + c.s1[xl>>16&0xFF]) ^ c.s2[xl>>8&0xFF]) + c.s3[xl&0xFF] ^ c.p[3]
-        xl ^= ((c.s0[xr>>24] + c.s1[xr>>16&0xFF]) ^ c.s2[xr>>8&0xFF]) + c.s3[xr&0xFF] ^ c.p[4]
-        xr ^= ((c.s0[xl>>24] + c.s1[xl>>16&0xFF]) ^ c.s2[xl>>8&0xFF]) + c.s3[xl&0xFF] ^ c.p[5]
-        xl ^= ((c.s0[xr>>24] + c.s1[xr>>16&0xFF]) ^ c.s2[xr>>8&0xFF]) + c.s3[xr&0xFF] ^ c.p[6]
-        xr ^= ((c.s0[xl>>24] + c.s1[xl>>16&0xFF]) ^ c.s2[xl>>8&0xFF]) + c.s3[xl&0xFF] ^ c.p[7]
-        xl ^= ((c.s0[xr>>24] + c.s1[xr>>16&0xFF]) ^ c.s2[xr>>8&0xFF]) + c.s3[xr&0xFF] ^ c.p[8]
-        xr ^= ((c.s0[xl>>24] + c.s1[xl>>16&0xFF]) ^ c.s2[xl>>8&0xFF]) + c.s3[xl&0xFF] ^ c.p[9]
-        xl ^= ((c.s0[xr>>24] + c.s1[xr>>16&0xFF]) ^ c.s2[xr>>8&0xFF]) + c.s3[xr&0xFF] ^ c.p[10]
-        xr ^= ((c.s0[xl>>24] + c.s1[xl>>16&0xFF]) ^ c.s2[xl>>8&0xFF]) + c.s3[xl&0xFF] ^ c.p[11]
-        xl ^= ((c.s0[xr>>24] + c.s1[xr>>16&0xFF]) ^ c.s2[xr>>8&0xFF]) + c.s3[xr&0xFF] ^ c.p[12]
-        xr ^= ((c.s0[xl>>24] + c.s1[xl>>16&0xFF]) ^ c.s2[xl>>8&0xFF]) + c.s3[xl&0xFF] ^ c.p[13]
-        xl ^= ((c.s0[xr>>24] + c.s1[xr>>16&0xFF]) ^ c.s2[xr>>8&0xFF]) + c.s3[xr&0xFF] ^ c.p[14]
-        xr ^= ((c.s0[xl>>24] + c.s1[xl>>16&0xFF]) ^ c.s2[xl>>8&0xFF]) + c.s3[xl&0xFF] ^ c.p[15]
-        xl ^= ((c.s0[xr>>24] + c.s1[xr>>16&0xFF]) ^ c.s2[xr>>8&0xFF]) + c.s3[xr&0xFF] ^ c.p[16]
+        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
-        //      for i := 17; i > 1; i-- {
-        //              xl ^= c.p[i]
-        //              xr ^= _F(c, xl)
-        //              xl, xr = xr, xl
-        //      }
-        //      xl ^= c.p[1]
-        //      xr ^= c.p[0]
         xl ^= c.p[17]
-        //      xr ^= ((c.s0[byte(xl>>24)] + c.s1[byte(xl>>16&0xFF)]) ^ c.s2[byte(xl>>8&0xFF)]) + c.s3[byte(xl&0xFF)] ^ c.p[16]
-        //      xl ^= ((c.s0[byte(xr>>24)] + c.s1[byte(xr>>16&0xFF)]) ^ c.s2[byte(xr>>8&0xFF)]) + c.s3[byte(xr&0xFF)] ^ c.p[15]
-        //      xr ^= ((c.s0[byte(xl>>24)] + c.s1[byte(xl>>16&0xFF)]) ^ c.s2[byte(xl>>8&0xFF)]) + c.s3[byte(xl&0xFF)] ^ c.p[14]
-        //      xl ^= ((c.s0[byte(xr>>24)] + c.s1[byte(xr>>16&0xFF)]) ^ c.s2[byte(xr>>8&0xFF)]) + c.s3[byte(xr&0xFF)] ^ c.p[13]
-        //      xr ^= ((c.s0[byte(xl>>24)] + c.s1[byte(xl>>16&0xFF)]) ^ c.s2[byte(xl>>8&0xFF)]) + c.s3[byte(xl&0xFF)] ^ c.p[12]
-        //      xl ^= ((c.s0[byte(xr>>24)] + c.s1[byte(xr>>16&0xFF)]) ^ c.s2[byte(xr>>8&0xFF)]) + c.s3[byte(xr&0xFF)] ^ c.p[11]
-        //      xr ^= ((c.s0[byte(xl>>24)] + c.s1[byte(xl>>16&0xFF)]) ^ c.s2[byte(xl>>8&0xFF)]) + c.s3[byte(xl&0xFF)] ^ c.p[10]
-        //      xl ^= ((c.s0[byte(xr>>24)] + c.s1[byte(xr>>16&0xFF)]) ^ c.s2[byte(xr>>8&0xFF)]) + c.s3[byte(xr&0xFF)] ^ c.p[9]
-        //      xr ^= ((c.s0[byte(xl>>24)] + c.s1[byte(xl>>16&0xFF)]) ^ c.s2[byte(xl>>8&0xFF)]) + c.s3[byte(xl&0xFF)] ^ c.p[8]
-        //      xl ^= ((c.s0[byte(xr>>24)] + c.s1[byte(xr>>16&0xFF)]) ^ c.s2[byte(xr>>8&0xFF)]) + c.s3[byte(xr&0xFF)] ^ c.p[7]
-        //      xr ^= ((c.s0[byte(xl>>24)] + c.s1[byte(xl>>16&0xFF)]) ^ c.s2[byte(xl>>8&0xFF)]) + c.s3[byte(xl&0xFF)] ^ c.p[6]
-        //      xl ^= ((c.s0[byte(xr>>24)] + c.s1[byte(xr>>16&0xFF)]) ^ c.s2[byte(xr>>8&0xFF)]) + c.s3[byte(xr&0xFF)] ^ c.p[5]
-        //      xr ^= ((c.s0[byte(xl>>24)] + c.s1[byte(xl>>16&0xFF)]) ^ c.s2[byte(xl>>8&0xFF)]) + c.s3[byte(xl&0xFF)] ^ c.p[4]
-        //      xl ^= ((c.s0[byte(xr>>24)] + c.s1[byte(xr>>16&0xFF)]) ^ c.s2[byte(xr>>8&0xFF)]) + c.s3[byte(xr&0xFF)] ^ c.p[3]
-        //      xr ^= ((c.s0[byte(xl>>24)] + c.s1[byte(xl>>16&0xFF)]) ^ c.s2[byte(xl>>8&0xFF)]) + c.s3[byte(xl&0xFF)] ^ c.p[2]
-        //      xl ^= ((c.s0[byte(xr>>24)] + c.s1[byte(xr>>16&0xFF)]) ^ c.s2[byte(xr>>8&0xFF)]) + c.s3[byte(xr&0xFF)] ^ c.p[1]
-        xr ^= ((c.s0[xl>>24] + c.s1[xl>>16&0xFF]) ^ c.s2[xl>>8&0xFF]) + c.s3[xl&0xFF] ^ c.p[16]
-        xl ^= ((c.s0[xr>>24] + c.s1[xr>>16&0xFF]) ^ c.s2[xr>>8&0xFF]) + c.s3[xr&0xFF] ^ c.p[15]
-        xr ^= ((c.s0[xl>>24] + c.s1[xl>>16&0xFF]) ^ c.s2[xl>>8&0xFF]) + c.s3[xl&0xFF] ^ c.p[14]
-        xl ^= ((c.s0[xr>>24] + c.s1[xr>>16&0xFF]) ^ c.s2[xr>>8&0xFF]) + c.s3[xr&0xFF] ^ c.p[13]
-        xr ^= ((c.s0[xl>>24] + c.s1[xl>>16&0xFF]) ^ c.s2[xl>>8&0xFF]) + c.s3[xl&0xFF] ^ c.p[12]
-        xl ^= ((c.s0[xr>>24] + c.s1[xr>>16&0xFF]) ^ c.s2[xr>>8&0xFF]) + c.s3[xr&0xFF] ^ c.p[11]
-        xr ^= ((c.s0[xl>>24] + c.s1[xl>>16&0xFF]) ^ c.s2[xl>>8&0xFF]) + c.s3[xl&0xFF] ^ c.p[10]
-        xl ^= ((c.s0[xr>>24] + c.s1[xr>>16&0xFF]) ^ c.s2[xr>>8&0xFF]) + c.s3[xr&0xFF] ^ c.p[9]
-        xr ^= ((c.s0[xl>>24] + c.s1[xl>>16&0xFF]) ^ c.s2[xl>>8&0xFF]) + c.s3[xl&0xFF] ^ c.p[8]
-        xl ^= ((c.s0[xr>>24] + c.s1[xr>>16&0xFF]) ^ c.s2[xr>>8&0xFF]) + c.s3[xr&0xFF] ^ c.p[7]
-        xr ^= ((c.s0[xl>>24] + c.s1[xl>>16&0xFF]) ^ c.s2[xl>>8&0xFF]) + c.s3[xl&0xFF] ^ c.p[6]
-        xl ^= ((c.s0[xr>>24] + c.s1[xr>>16&0xFF]) ^ c.s2[xr>>8&0xFF]) + c.s3[xr&0xFF] ^ c.p[5]
-        xr ^= ((c.s0[xl>>24] + c.s1[xl>>16&0xFF]) ^ c.s2[xl>>8&0xFF]) + c.s3[xl&0xFF] ^ c.p[4]
-        xl ^= ((c.s0[xr>>24] + c.s1[xr>>16&0xFF]) ^ c.s2[xr>>8&0xFF]) + c.s3[xr&0xFF] ^ c.p[3]
-        xr ^= ((c.s0[xl>>24] + c.s1[xl>>16&0xFF]) ^ c.s2[xl>>8&0xFF]) + c.s3[xl&0xFF] ^ c.p[2]
-        xl ^= ((c.s0[xr>>24] + c.s1[xr>>16&0xFF]) ^ c.s2[xr>>8&0xFF]) + c.s3[xr&0xFF] ^ c.p[1]
+        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
 }
 
 func zero(x []uint32) {
         for i := range x {
                 x[i] = 0
         }
 }