kopia lustrzana https://github.com/weetmuts/wmbusmeters
266 wiersze
8.7 KiB
C++
266 wiersze
8.7 KiB
C++
/*
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Copyright (C) 2018-2020 Fredrik Öhrström (gpl-3.0-or-later)
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include"aes.h"
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#include"util.h"
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#include"wmbus.h"
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#include<assert.h>
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#include<memory.h>
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bool decrypt_ELL_AES_CTR(Telegram *t, vector<uchar> &frame, vector<uchar>::iterator &pos, vector<uchar> &aeskey)
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{
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if (aeskey.size() == 0) return true;
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vector<uchar> encrypted_bytes;
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vector<uchar> decrypted_bytes;
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encrypted_bytes.insert(encrypted_bytes.end(), pos, frame.end());
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debugPayload("(ELL) decrypting", encrypted_bytes);
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uchar iv[16];
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int i=0;
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// M-field
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iv[i++] = t->dll_mfct_b[0]; iv[i++] = t->dll_mfct_b[1];
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// A-field
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for (int j=0; j<6; ++j) { iv[i++] = t->dll_a[j]; }
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// CC-field
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iv[i++] = t->ell_cc;
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// SN-field
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for (int j=0; j<4; ++j) { iv[i++] = t->ell_sn_b[j]; }
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// FN
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iv[i++] = 0; iv[i++] = 0;
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// BC
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iv[i++] = 0;
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vector<uchar> ivv(iv, iv+16);
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string s = bin2hex(ivv);
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debug("(ELL) IV %s\n", s.c_str());
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int block = 0;
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for (size_t offset = 0; offset < encrypted_bytes.size(); offset += 16)
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{
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size_t block_size = 16;
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if (offset + block_size > encrypted_bytes.size())
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{
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block_size = encrypted_bytes.size() - offset;
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}
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assert(block_size > 0 && block_size <= 16);
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// Generate the pseudo-random bits from the IV and the key.
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uchar xordata[16];
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AES_ECB_encrypt(iv, safeButUnsafeVectorPtr(aeskey), xordata, 16);
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// Xor the data with the pseudo-random bits to decrypt into tmp.
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uchar tmp[block_size];
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xorit(xordata, &encrypted_bytes[offset], tmp, block_size);
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debug("(ELL) block %d block_size %d offset %zu\n", block, block_size, offset);
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block++;
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vector<uchar> tmpv(tmp, tmp+block_size);
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debugPayload("(ELL) decrypted", tmpv);
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decrypted_bytes.insert(decrypted_bytes.end(), tmpv.begin(), tmpv.end());
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incrementIV(iv, sizeof(iv));
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}
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debugPayload("(ELL) decrypted", decrypted_bytes);
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// Remove the encrypted bytes.
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frame.erase(pos, frame.end());
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// Insert the decrypted bytes.
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frame.insert(frame.end(), decrypted_bytes.begin(), decrypted_bytes.end());
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return true;
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}
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string frameTypeKamstrupC1(int ft) {
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if (ft == 0x78) return "long frame";
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if (ft == 0x79) return "short frame";
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return "?";
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}
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bool decrypt_TPL_AES_CBC_IV(Telegram *t,
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vector<uchar> &frame,
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vector<uchar>::iterator &pos,
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vector<uchar> &aeskey,
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int *num_encrypted_bytes,
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int *num_not_encrypted_at_end)
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{
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vector<uchar> buffer;
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buffer.insert(buffer.end(), pos, frame.end());
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size_t num_bytes_to_decrypt = frame.end()-pos;
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if (t->tpl_num_encr_blocks)
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{
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num_bytes_to_decrypt = t->tpl_num_encr_blocks*16;
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}
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*num_encrypted_bytes = num_bytes_to_decrypt;
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*num_not_encrypted_at_end = buffer.size()-num_bytes_to_decrypt;
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debug("(TPL) num encrypted blocks %zu (%d bytes and remaining unencrypted %zu bytes)\n",
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t->tpl_num_encr_blocks, num_bytes_to_decrypt, buffer.size()-num_bytes_to_decrypt);
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if (aeskey.size() == 0) return false;
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debugPayload("(TPL) AES CBC IV decrypting", buffer);
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if (buffer.size() < num_bytes_to_decrypt)
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{
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warning("(TPL) warning: decryption received less bytes than expected for decryption! "
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"Got %zu bytes but expected at least %zu bytes since num encr blocks was %d.\n",
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buffer.size(), num_bytes_to_decrypt,
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t->tpl_num_encr_blocks);
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num_bytes_to_decrypt = buffer.size();
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}
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// The content should be a multiple of 16 since we are using AES CBC mode.
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if (num_bytes_to_decrypt % 16 != 0)
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{
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warning("(TPL) warning: decryption received non-multiple of 16 bytes! "
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"Got %zu bytes shrinking message to %zu bytes.\n",
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num_bytes_to_decrypt, num_bytes_to_decrypt - num_bytes_to_decrypt % 16);
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num_bytes_to_decrypt -= num_bytes_to_decrypt % 16;
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assert (num_bytes_to_decrypt % 16 == 0);
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}
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uchar iv[16];
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int i=0;
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// If there is a tpl_id, then use it, else use ddl_id.
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if (t->tpl_id_found)
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{
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// M-field
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iv[i++] = t->tpl_mfct_b[0]; iv[i++] = t->tpl_mfct_b[1];
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// A-field
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for (int j=0; j<6; ++j) { iv[i++] = t->tpl_a[j]; }
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}
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else
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{
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// M-field
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iv[i++] = t->dll_mfct_b[0]; iv[i++] = t->dll_mfct_b[1];
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// A-field
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for (int j=0; j<6; ++j) { iv[i++] = t->dll_a[j]; }
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}
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// ACC
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for (int j=0; j<8; ++j) { iv[i++] = t->tpl_acc; }
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vector<uchar> ivv(iv, iv+16);
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string s = bin2hex(ivv);
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debug("(TPL) IV %s\n", s.c_str());
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uchar buffer_data[num_bytes_to_decrypt];
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memcpy(buffer_data, safeButUnsafeVectorPtr(buffer), num_bytes_to_decrypt);
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uchar decrypted_data[num_bytes_to_decrypt];
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AES_CBC_decrypt_buffer(decrypted_data, buffer_data, num_bytes_to_decrypt, safeButUnsafeVectorPtr(aeskey), iv);
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// Remove the encrypted bytes.
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frame.erase(pos, frame.end());
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// Insert the decrypted bytes.
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frame.insert(frame.end(), decrypted_data, decrypted_data+num_bytes_to_decrypt);
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debugPayload("(TPL) decrypted ", frame, pos);
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if (num_bytes_to_decrypt < buffer.size())
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{
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frame.insert(frame.end(), buffer.begin()+num_bytes_to_decrypt, buffer.end());
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debugPayload("(TPL) appended ", frame, pos);
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}
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return true;
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}
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bool decrypt_TPL_AES_CBC_NO_IV(Telegram *t, vector<uchar> &frame, vector<uchar>::iterator &pos, vector<uchar> &aeskey,
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int *num_encrypted_bytes,
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int *num_not_encrypted_at_end)
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{
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if (aeskey.size() == 0) return true;
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vector<uchar> buffer;
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buffer.insert(buffer.end(), pos, frame.end());
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size_t num_bytes_to_decrypt = buffer.size();
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if (t->tpl_num_encr_blocks)
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{
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num_bytes_to_decrypt = t->tpl_num_encr_blocks*16;
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}
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*num_encrypted_bytes = num_bytes_to_decrypt;
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*num_not_encrypted_at_end = buffer.size()-num_bytes_to_decrypt;
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debug("(TPL) num encrypted blocks %d (%d bytes and remaining unencrypted %d bytes)\n",
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t->tpl_num_encr_blocks, num_bytes_to_decrypt, buffer.size()-num_bytes_to_decrypt);
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if (aeskey.size() == 0) return false;
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if (buffer.size() < num_bytes_to_decrypt)
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{
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warning("(TPL) warning: decryption received less bytes than expected for decryption! "
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"Got %zu bytes but expected at least %zu bytes since num encr blocks was %d.\n",
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buffer.size(), num_bytes_to_decrypt,
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t->tpl_num_encr_blocks);
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num_bytes_to_decrypt = buffer.size();
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}
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// The content should be a multiple of 16 since we are using AES CBC mode.
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if (num_bytes_to_decrypt % 16 != 0)
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{
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warning("(TPL) warning: decryption received non-multiple of 16 bytes! "
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"Got %zu bytes shrinking message to %zu bytes.\n",
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num_bytes_to_decrypt, num_bytes_to_decrypt - num_bytes_to_decrypt % 16);
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num_bytes_to_decrypt -= num_bytes_to_decrypt % 16;
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assert (num_bytes_to_decrypt % 16 == 0);
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}
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uchar iv[16];
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memset(iv, 0, sizeof(iv));
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vector<uchar> ivv(iv, iv+16);
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string s = bin2hex(ivv);
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debug("(TPL) IV %s\n", s.c_str());
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uchar buffer_data[num_bytes_to_decrypt];
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memcpy(buffer_data, safeButUnsafeVectorPtr(buffer), num_bytes_to_decrypt);
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uchar decrypted_data[num_bytes_to_decrypt];
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AES_CBC_decrypt_buffer(decrypted_data, buffer_data, num_bytes_to_decrypt, safeButUnsafeVectorPtr(aeskey), iv);
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// Remove the encrypted bytes and any potentially not decryptes bytes after.
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frame.erase(pos, frame.end());
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// Insert the decrypted bytes.
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frame.insert(frame.end(), decrypted_data, decrypted_data+num_bytes_to_decrypt);
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debugPayload("(TPL) decrypted ", frame, pos);
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if (num_bytes_to_decrypt < buffer.size())
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{
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frame.insert(frame.end(), buffer.begin()+num_bytes_to_decrypt, buffer.end());
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debugPayload("(TPL) appended ", frame, pos);
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}
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return true;
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}
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