kopia lustrzana https://github.com/weetmuts/wmbusmeters
98 wiersze
3.3 KiB
C++
98 wiersze
3.3 KiB
C++
// Copyright (c) 2018 Fredrik Öhrström
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in all
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// copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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// SOFTWARE.
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#ifndef WMBUS_UTILS_H
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#define WMBUS_UTILS_H
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#include"aes.h"
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#include"wmbus.h"
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void decryptKamstrupC1(Telegram *t, vector<uchar> &aeskey)
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{
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vector<uchar> content;
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content.insert(content.end(), t->payload.begin(), t->payload.end());
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size_t remaining = content.size();
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if (remaining > 16) remaining = 16;
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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->m_field&255; iv[i++] = t->m_field>>8;
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// A-field
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for (int j=0; j<6; ++j) { iv[i++] = t->a_field[j]; }
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// CC-field
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iv[i++] = t->cc_field;
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// SN-field
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for (int j=0; j<4; ++j) { iv[i++] = t->sn[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("(multical21) IV %s\n", s.c_str());
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uchar xordata[16];
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AES_ECB_encrypt(iv, &aeskey[0], xordata, 16);
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uchar decrypt[16];
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xorit(xordata, &content[0], decrypt, remaining);
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vector<uchar> dec(decrypt, decrypt+remaining);
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debugPayload("(multical21) decrypted", dec);
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if (content.size() > 22) {
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warning("(multical21) warning: Received too many bytes of content! "
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"Got %zu bytes, expected at most 22.\n", content.size());
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}
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if (content.size() > 16) {
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// Yay! Lets decrypt a second block. Full frame content is 22 bytes.
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// So a second block should enough for everyone!
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remaining = content.size()-16;
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if (remaining > 16) remaining = 16; // Should not happen.
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incrementIV(iv, sizeof(iv));
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vector<uchar> ivv2(iv, iv+16);
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string s2 = bin2hex(ivv2);
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debug("(multical21) IV+1 %s\n", s2.c_str());
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AES_ECB_encrypt(iv, &aeskey[0], xordata, 16);
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xorit(xordata, &content[16], decrypt, remaining);
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vector<uchar> dec2(decrypt, decrypt+remaining);
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debugPayload("(multical21) decrypted", dec2);
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// Append the second decrypted block to the first.
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dec.insert(dec.end(), dec2.begin(), dec2.end());
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}
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t->content.clear();
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t->content.insert(t->content.end(), dec.begin(), dec.end());
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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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#endif
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