code review 2687042: Additional crypto library: Schneier's Twofish

src/pkg/crypto/twofish/twofish_test.go

 // Copyright 2011 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 twofish
 
 import (
         "bytes"
         "testing"
 )
@@ skipping 18 matching lines @@
         a0, b0 := x/16, x%16
         for i := 0; i < 2; i++ {
                 a1 := a0 ^ b0
                 b1 := (a0 ^ ((b0 << 3) | (b0 >> 1)) ^ (a0 << 3)) & 15
                 a0 = qbox[qi][2*i][a1]
                 b0 = qbox[qi][2*i+1][b1]
         }
         return (b0 << 4) + a0
 }
 
+// Test if the sbox saved as variable contains the values as defined by its function
 func TestSbox(t *testing.T) {
-        for n := 0; n < 2; n++ {
-                for m := 0; m < 256; m++ {
+        for n := range sbox {
+                for m := range sbox[n] {
                         if genSbox(n, byte(m)) != sbox[n][m] {
                                 t.Errorf("#%d|%d: sbox value = %d want %d", n, m, sbox[n][m], genSbox(n, byte(m)))
                         }
                 }
         }
 }
 
+// All tests are designed for direct encryption
+// please note that this ist not the recommended way for data bigger than the blocksize
 var testVectors = []struct {
         key []byte
         dec []byte
         enc []byte
 }{
         // These tests are extracted from LibTom
         {
                 []byte{0x9F, 0x58, 0x9F, 0x5C, 0xF6, 0x12, 0x2C, 0x32, 0xB6, 0xBF, 0xEC, 0x2F, 0x2A, 0xE8, 0xC3, 0x5A},
                 []byte{0xD4, 0x91, 0xDB, 0x16, 0xE7, 0xB1, 0xC3, 0x9E, 0x86, 0xCB, 0x08, 0x6B, 0x78, 0x9F, 0x54, 0x19},
                 []byte{0x01, 0x9F, 0x98, 0x09, 0xDE, 0x17, 0x11, 0x85, 0x8F, 0xAA, 0xC3, 0xA3, 0xBA, 0x20, 0xFB, 0xC3},
@@ skipping 27 matching lines @@
                 []byte{0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF, 0xFE, 0xDC, 0xBA, 0x98, 0x76, 0x54, 0x32, 0x10,
                         0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 0x88, 0x99, 0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF,
                 },
                 []byte{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
                 []byte{0x37, 0x52, 0x7B, 0xE0, 0x05, 0x23, 0x34, 0xB8, 0x9F, 0x0C, 0xFC, 0xCA, 0xE8, 0x7C, 0xFA, 0x20},
         },
 }
 
 func TestCipher(t *testing.T) {
         for n, tt := range testVectors {
-                // Test if the plaintext (dec) is encrypts to the given
-                // ciphertext (enc) using the given key. Test also if enc can
-                // be decrypted again into dec.
+                // Test if the known plaintext (dec) is encrypted into the known crypttext (enc)
+                // using the known key. Test also if enc can be decrypted again into dec.
                 c, err := NewCipher(tt.key)
                 if err != nil {
                         t.Errorf("#%d: NewCipher: %v", n, err)
                         return
                 }
 
                 buf := make([]byte, 16)
                 c.Encrypt(buf, tt.dec)
                 if !bytes.Equal(buf, tt.enc) {
                         t.Errorf("#%d: encrypt = %x want %x", n, buf, tt.enc)
                 }
                 c.Decrypt(buf, tt.enc)
                 if !bytes.Equal(buf, tt.dec) {
                         t.Errorf("#%d: decrypt = %x want %x", n, buf, tt.dec)
                 }
 
-                // Test that 16 zero bytes, encrypted 1000 times then decrypted
-                // 1000 times results in zero bytes again.
+                // Test if 16 zero bytes can  be encrypt 1000 times, decrypted and come
+                // back where we started using all different test keys
                 zero := make([]byte, 16)
                 buf = make([]byte, 16)
                 for i := 0; i < 1000; i++ {
                         c.Encrypt(buf, buf)
                 }
                 for i := 0; i < 1000; i++ {
                         c.Decrypt(buf, buf)
                 }
                 if !bytes.Equal(buf, zero) {
                         t.Errorf("#%d: encrypt/decrypt 1000: have %x want %x", n, buf, zero)
                 }
         }
 }