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278 lines
7.5 KiB
C++
278 lines
7.5 KiB
C++
// Copyright 2005-2017 The Mumble Developers. All rights reserved.
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// Use of this source code is governed by a BSD-style license
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// that can be found in the LICENSE file at the root of the
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// Mumble source tree or at <https://www.mumble.info/LICENSE>.
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/*
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* This code implements OCB-AES128.
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* In the US, OCB is covered by patents. The inventor has given a license
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* to all programs distributed under the GPL.
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* Mumble is BSD (revised) licensed, meaning you can use the code in a
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* closed-source program. If you do, you'll have to either replace
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* OCB with something else or get yourself a license.
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*/
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#include "murmur_pch.h"
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#include "CryptState.h"
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#include "Net.h"
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CryptState::CryptState() {
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for (int i=0;i<0x100;i++)
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decrypt_history[i] = 0;
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bInit = false;
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uiGood=uiLate=uiLost=uiResync=0;
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uiRemoteGood=uiRemoteLate=uiRemoteLost=uiRemoteResync=0;
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}
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bool CryptState::isValid() const {
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return bInit;
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}
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void CryptState::genKey() {
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RAND_bytes(raw_key, AES_BLOCK_SIZE);
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RAND_bytes(encrypt_iv, AES_BLOCK_SIZE);
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RAND_bytes(decrypt_iv, AES_BLOCK_SIZE);
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AES_set_encrypt_key(raw_key, 128, &encrypt_key);
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AES_set_decrypt_key(raw_key, 128, &decrypt_key);
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bInit = true;
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}
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void CryptState::setKey(const unsigned char *rkey, const unsigned char *eiv, const unsigned char *div) {
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memcpy(raw_key, rkey, AES_BLOCK_SIZE);
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memcpy(encrypt_iv, eiv, AES_BLOCK_SIZE);
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memcpy(decrypt_iv, div, AES_BLOCK_SIZE);
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AES_set_encrypt_key(raw_key, 128, &encrypt_key);
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AES_set_decrypt_key(raw_key, 128, &decrypt_key);
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bInit = true;
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}
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void CryptState::setDecryptIV(const unsigned char *iv) {
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memcpy(decrypt_iv, iv, AES_BLOCK_SIZE);
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}
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void CryptState::encrypt(const unsigned char *source, unsigned char *dst, unsigned int plain_length) {
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unsigned char tag[AES_BLOCK_SIZE];
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// First, increase our IV.
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for (int i=0;i<AES_BLOCK_SIZE;i++)
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if (++encrypt_iv[i])
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break;
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ocb_encrypt(source, dst+4, plain_length, encrypt_iv, tag);
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dst[0] = encrypt_iv[0];
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dst[1] = tag[0];
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dst[2] = tag[1];
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dst[3] = tag[2];
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}
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bool CryptState::decrypt(const unsigned char *source, unsigned char *dst, unsigned int crypted_length) {
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if (crypted_length < 4)
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return false;
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unsigned int plain_length = crypted_length - 4;
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unsigned char saveiv[AES_BLOCK_SIZE];
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unsigned char ivbyte = source[0];
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bool restore = false;
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unsigned char tag[AES_BLOCK_SIZE];
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int lost = 0;
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int late = 0;
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memcpy(saveiv, decrypt_iv, AES_BLOCK_SIZE);
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if (((decrypt_iv[0] + 1) & 0xFF) == ivbyte) {
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// In order as expected.
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if (ivbyte > decrypt_iv[0]) {
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decrypt_iv[0] = ivbyte;
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} else if (ivbyte < decrypt_iv[0]) {
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decrypt_iv[0] = ivbyte;
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for (int i=1;i<AES_BLOCK_SIZE;i++)
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if (++decrypt_iv[i])
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break;
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} else {
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return false;
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}
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} else {
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// This is either out of order or a repeat.
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int diff = ivbyte - decrypt_iv[0];
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if (diff > 128)
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diff = diff-256;
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else if (diff < -128)
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diff = diff+256;
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if ((ivbyte < decrypt_iv[0]) && (diff > -30) && (diff < 0)) {
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// Late packet, but no wraparound.
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late = 1;
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lost = -1;
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decrypt_iv[0] = ivbyte;
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restore = true;
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} else if ((ivbyte > decrypt_iv[0]) && (diff > -30) && (diff < 0)) {
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// Last was 0x02, here comes 0xff from last round
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late = 1;
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lost = -1;
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decrypt_iv[0] = ivbyte;
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for (int i=1;i<AES_BLOCK_SIZE;i++)
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if (decrypt_iv[i]--)
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break;
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restore = true;
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} else if ((ivbyte > decrypt_iv[0]) && (diff > 0)) {
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// Lost a few packets, but beyond that we're good.
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lost = ivbyte - decrypt_iv[0] - 1;
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decrypt_iv[0] = ivbyte;
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} else if ((ivbyte < decrypt_iv[0]) && (diff > 0)) {
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// Lost a few packets, and wrapped around
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lost = 256 - decrypt_iv[0] + ivbyte - 1;
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decrypt_iv[0] = ivbyte;
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for (int i=1;i<AES_BLOCK_SIZE;i++)
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if (++decrypt_iv[i])
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break;
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} else {
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return false;
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}
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if (decrypt_history[decrypt_iv[0]] == decrypt_iv[1]) {
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memcpy(decrypt_iv, saveiv, AES_BLOCK_SIZE);
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return false;
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}
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}
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ocb_decrypt(source+4, dst, plain_length, decrypt_iv, tag);
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if (memcmp(tag, source+1, 3) != 0) {
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memcpy(decrypt_iv, saveiv, AES_BLOCK_SIZE);
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return false;
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}
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decrypt_history[decrypt_iv[0]] = decrypt_iv[1];
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if (restore)
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memcpy(decrypt_iv, saveiv, AES_BLOCK_SIZE);
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uiGood++;
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uiLate += late;
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uiLost += lost;
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tLastGood.restart();
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return true;
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}
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#if defined(__LP64__)
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#define BLOCKSIZE 2
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#define SHIFTBITS 63
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typedef quint64 subblock;
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#define SWAPPED(x) SWAP64(x)
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#else
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#define BLOCKSIZE 4
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#define SHIFTBITS 31
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typedef quint32 subblock;
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#define SWAPPED(x) htonl(x)
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#endif
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typedef subblock keyblock[BLOCKSIZE];
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#define HIGHBIT (1<<SHIFTBITS);
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static void inline XOR(subblock *dst, const subblock *a, const subblock *b) {
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for (int i=0;i<BLOCKSIZE;i++) {
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dst[i] = a[i] ^ b[i];
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}
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}
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static void inline S2(subblock *block) {
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subblock carry = SWAPPED(block[0]) >> SHIFTBITS;
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for (int i=0;i<BLOCKSIZE-1;i++)
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block[i] = SWAPPED((SWAPPED(block[i]) << 1) | (SWAPPED(block[i+1]) >> SHIFTBITS));
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block[BLOCKSIZE-1] = SWAPPED((SWAPPED(block[BLOCKSIZE-1]) << 1) ^(carry * 0x87));
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}
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static void inline S3(subblock *block) {
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subblock carry = SWAPPED(block[0]) >> SHIFTBITS;
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for (int i=0;i<BLOCKSIZE-1;i++)
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block[i] ^= SWAPPED((SWAPPED(block[i]) << 1) | (SWAPPED(block[i+1]) >> SHIFTBITS));
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block[BLOCKSIZE-1] ^= SWAPPED((SWAPPED(block[BLOCKSIZE-1]) << 1) ^(carry * 0x87));
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}
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static void inline ZERO(keyblock &block) {
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for (int i=0;i<BLOCKSIZE;i++)
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block[i]=0;
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}
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#define AESencrypt(src,dst,key) AES_encrypt(reinterpret_cast<const unsigned char *>(src),reinterpret_cast<unsigned char *>(dst), key);
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#define AESdecrypt(src,dst,key) AES_decrypt(reinterpret_cast<const unsigned char *>(src),reinterpret_cast<unsigned char *>(dst), key);
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void CryptState::ocb_encrypt(const unsigned char *plain, unsigned char *encrypted, unsigned int len, const unsigned char *nonce, unsigned char *tag) {
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keyblock checksum, delta, tmp, pad;
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// Initialize
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AESencrypt(nonce, delta, &encrypt_key);
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ZERO(checksum);
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while (len > AES_BLOCK_SIZE) {
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S2(delta);
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XOR(tmp, delta, reinterpret_cast<const subblock *>(plain));
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AESencrypt(tmp, tmp, &encrypt_key);
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XOR(reinterpret_cast<subblock *>(encrypted), delta, tmp);
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XOR(checksum, checksum, reinterpret_cast<const subblock *>(plain));
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len -= AES_BLOCK_SIZE;
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plain += AES_BLOCK_SIZE;
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encrypted += AES_BLOCK_SIZE;
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}
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S2(delta);
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ZERO(tmp);
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tmp[BLOCKSIZE - 1] = SWAPPED(len * 8);
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XOR(tmp, tmp, delta);
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AESencrypt(tmp, pad, &encrypt_key);
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memcpy(tmp, plain, len);
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memcpy(reinterpret_cast<unsigned char *>(tmp)+len, reinterpret_cast<const unsigned char *>(pad)+len, AES_BLOCK_SIZE - len);
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XOR(checksum, checksum, tmp);
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XOR(tmp, pad, tmp);
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memcpy(encrypted, tmp, len);
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S3(delta);
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XOR(tmp, delta, checksum);
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AESencrypt(tmp, tag, &encrypt_key);
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}
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void CryptState::ocb_decrypt(const unsigned char *encrypted, unsigned char *plain, unsigned int len, const unsigned char *nonce, unsigned char *tag) {
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keyblock checksum, delta, tmp, pad;
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// Initialize
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AESencrypt(nonce, delta, &encrypt_key);
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ZERO(checksum);
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while (len > AES_BLOCK_SIZE) {
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S2(delta);
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XOR(tmp, delta, reinterpret_cast<const subblock *>(encrypted));
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AESdecrypt(tmp, tmp, &decrypt_key);
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XOR(reinterpret_cast<subblock *>(plain), delta, tmp);
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XOR(checksum, checksum, reinterpret_cast<const subblock *>(plain));
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len -= AES_BLOCK_SIZE;
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plain += AES_BLOCK_SIZE;
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encrypted += AES_BLOCK_SIZE;
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}
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S2(delta);
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ZERO(tmp);
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tmp[BLOCKSIZE - 1] = SWAPPED(len * 8);
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XOR(tmp, tmp, delta);
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AESencrypt(tmp, pad, &encrypt_key);
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memset(tmp, 0, AES_BLOCK_SIZE);
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memcpy(tmp, encrypted, len);
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XOR(tmp, tmp, pad);
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XOR(checksum, checksum, tmp);
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memcpy(plain, tmp, len);
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S3(delta);
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XOR(tmp, delta, checksum);
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AESencrypt(tmp, tag, &encrypt_key);
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}
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