_ Git - BoarSSL/blob - Tests/Poly1305Ref.cs

   1 /*
   2  * Copyright (c) 2017 Thomas Pornin <pornin@bolet.org>
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining
   5  * a copy of this software and associated documentation files (the
   6  * "Software"), to deal in the Software without restriction, including
   7  * without limitation the rights to use, copy, modify, merge, publish,
   8  * distribute, sublicense, and/or sell copies of the Software, and to
   9  * permit persons to whom the Software is furnished to do so, subject to
  10  * the following conditions:
  11  *
  12  * The above copyright notice and this permission notice shall be
  13  * included in all copies or substantial portions of the Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  16  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  17  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  18  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  19  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  20  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  21  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  22  * SOFTWARE.
  23  */
  24
  25 using System;
  26
  27 using Crypto;
  28
  29 /*
  30  * This is a "reference" implementation of Poly1305 that uses the
  31  * generic ZInt code for computations. It is not constant-time, and
  32  * it is very slow; it is meant to test other implementations.
  33  *
  34  * API is identical to the Poly1305 class.
  35  */
  36
  37 public class Poly1305Ref {
  38
  39         public ChaCha20 ChaCha {
  40                 get; set;
  41         }
  42
  43         public Poly1305Ref()
  44         {
  45         }
  46
  47         static ZInt p = ((ZInt)1 << 130) - (ZInt)5;
  48         static ZInt rmask = ((ZInt)1 << 124) - (ZInt)1
  49                 - ((ZInt)15 << 28) - ((ZInt)15 << 60) - ((ZInt)15 << 92)
  50                 - ((ZInt)3 << 32) - ((ZInt)3 << 64) - ((ZInt)3 << 96);
  51
  52         public void Run(byte[] iv,
  53                 byte[] data, int off, int len,
  54                 byte[] aad, int offAAD, int lenAAD,
  55                 byte[] tag, bool encrypt)
  56         {
  57                 byte[] pkey = new byte[32];
  58                 ChaCha.Run(iv, 0, pkey);
  59                 if (encrypt) {
  60                         ChaCha.Run(iv, 1, data, off, len);
  61                 }
  62
  63                 ByteSwap(pkey, 0, 16);
  64                 ZInt r = ZInt.DecodeUnsignedBE(pkey, 0, 16);
  65                 r &= rmask;
  66                 ZInt a = (ZInt)0;
  67
  68                 a = RunInner(a, r, aad, offAAD, lenAAD);
  69                 a = RunInner(a, r, data, off, len);
  70                 byte[] foot = new byte[16];
  71                 foot[ 0] = (byte)lenAAD;
  72                 foot[ 1] = (byte)(lenAAD >> 8);
  73                 foot[ 2] = (byte)(lenAAD >> 16);
  74                 foot[ 3] = (byte)(lenAAD >> 24);
  75                 foot[ 8] = (byte)len;
  76                 foot[ 9] = (byte)(len >> 8);
  77                 foot[10] = (byte)(len >> 16);
  78                 foot[11] = (byte)(len >> 24);
  79                 a = RunInner(a, r, foot, 0, 16);
  80
  81                 ByteSwap(pkey, 16, 16);
  82                 ZInt s = ZInt.DecodeUnsignedBE(pkey, 16, 16);
  83                 a += s;
  84                 a.ToBytesLE(tag, 0, 16);
  85
  86                 if (!encrypt) {
  87                         ChaCha.Run(iv, 1, data, off, len);
  88                 }
  89         }
  90
  91         ZInt RunInner(ZInt a, ZInt r, byte[] data, int off, int len)
  92         {
  93                 byte[] tmp = new byte[16];
  94                 while (len > 0) {
  95                         if (len >= 16) {
  96                                 Array.Copy(data, off, tmp, 0, 16);
  97                         } else {
  98                                 Array.Copy(data, off, tmp, 0, len);
  99                                 for (int i = len; i < 16; i ++) {
 100                                         tmp[i] = 0;
 101                                 }
 102                         }
 103                         ByteSwap(tmp, 0, 16);
 104                         ZInt v = ZInt.DecodeUnsignedBE(tmp) | ((ZInt)1 << 128);
 105                         a = ((a + v) * r) % p;
 106                         off += 16;
 107                         len -= 16;
 108                 }
 109                 return a;
 110         }
 111
 112         static void ByteSwap(byte[] buf, int off, int len)
 113         {
 114                 for (int i = 0; (i + i) < len; i ++) {
 115                         byte t = buf[off + i];
 116                         buf[off + i] = buf[off + len - 1 - i];
 117                         buf[off + len - 1 - i] = t;
 118                 }
 119         }
 120 }