Added CCM and CCM_8 cipher suites.

[BoarSSL] / SSLTLS / RecordDecryptCCM.cs

diff --git a/SSLTLS/RecordDecryptCCM.cs b/SSLTLS/RecordDecryptCCM.cs
new file mode 100644 (file)
index 0000000..4a60e8d
--- /dev/null
+++ b/SSLTLS/RecordDecryptCCM.cs
@@ -0,0 +1,135 @@
+/*
+ * Copyright (c) 2018 Thomas Pornin <pornin@bolet.org>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining 
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be 
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+using System;
+using System.Text;
+
+using Crypto;
+
+namespace SSLTLS {
+
+internal class RecordDecryptCCM : RecordDecrypt {
+
+       IBlockCipher bc;
+       byte[] iv;
+       ulong seq;
+       byte[] tmp, tag, ctr, cbcmac;
+       bool ccm8;
+
+       internal RecordDecryptCCM(IBlockCipher bc, byte[] iv, bool ccm8)
+       {
+               this.bc = bc;
+               this.iv = new byte[12];
+               Array.Copy(iv, 0, this.iv, 0, 4);
+               seq = 0;
+               tag = new byte[16];
+               tmp = new byte[32];
+               ctr = new byte[16];
+               cbcmac = new byte[16];
+               this.ccm8 = ccm8;
+       }
+
+       internal override bool CheckLength(int len)
+       {
+               int tagLen = ccm8 ? 8 : 16;
+               return len >= (8 + tagLen) && len <= (16384 + 8 + tagLen);
+       }
+
+       internal override bool Decrypt(int recordType, int version,
+               byte[] data, ref int off, ref int len)
+       {
+               Array.Copy(data, off, iv, 4, 8);
+               off += 8;
+               len -= ccm8 ? 16 : 24;
+
+               /*
+                * Assemble block B0 and AAD.
+                */
+               tmp[0] = (byte)(0x40 | ((ccm8 ? 6 : 14) << 2) | 2);
+               Array.Copy(iv, 0, tmp, 1, 12);
+               tmp[13] = 0;
+               IO.Enc16be(len, tmp, 14);
+
+               tmp[16] = 0;
+               tmp[17] = 13;
+               IO.Enc64be(seq, tmp, 18);
+               IO.WriteHeader(recordType, version, len, tmp, 26);
+               tmp[31] = 0;
+               seq ++;
+
+               for (int i = 0; i < cbcmac.Length; i ++) {
+                       cbcmac[i] = 0;
+               }
+               bc.CBCMac(cbcmac, tmp, 0, 32);
+
+               /*
+                * Make initial counter value, and compute tag mask.
+                * Since the counter least significant byte has value 0,
+                * getting it to the next value is simple and requires
+                * no carry propagation.
+                */
+               ctr[0] = 2;
+               Array.Copy(iv, 0, ctr, 1, 12);
+               for (int i = 13; i < 16; i ++) {
+                       ctr[i] = 0;
+               }
+               Array.Copy(ctr, 0, tag, 0, 16);
+               bc.BlockEncrypt(tag);
+               ctr[15] = 1;
+
+               /*
+                * Perform CTR decryption, and compute CBC-MAC. Since
+                * CBC-MAC requires full blocks, we have to do the
+                * processing of the last partial block in a temporary
+                * buffer. The CBC-MAC is computed on the plaintext,
+                * padded with zeros in the last block.
+                */
+               int len1 = len & ~15;
+               int len2 = len - len1;
+               bc.CTRCBCRun(ctr, cbcmac, true, data, off, len1);
+               if (len2 > 0) {
+                       bc.BlockEncrypt(ctr);
+                       for (int i = 0; i < len2; i ++) {
+                               data[off + len1 + i] ^= ctr[i];
+                       }
+                       Array.Copy(data, off + len1, tmp, 0, len2);
+                       for (int i = len2; i < 16; i ++) {
+                               tmp[i] = 0;
+                       }
+                       bc.CBCMac(cbcmac, tmp, 0, 16);
+               }
+
+               /*
+                * Check that the record MAC matches the expected value
+                * (taking into account the tag mask).
+                */
+               int z = 0;
+               for (int i = 0; i < (ccm8 ? 8 : 16); i ++) {
+                       z |= cbcmac[i] ^ tag[i] ^ data[off + len + i];
+               }
+               return z == 0;
+       }
+}
+
+}