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DSMR with encrypted payload

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This commit is contained in:
Gunnar Skjold
2024-12-14 10:54:02 +01:00
parent 42e0ca963c
commit 61d4728ffa
16 changed files with 224 additions and 184 deletions
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23
lib/AmsDecoder/src/GcmParser.cpp
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@@ -17,25 +17,34 @@ GCMParser::GCMParser(uint8_t *encryption_key, uint8_t *authentication_key) {
memcpy(this->authentication_key, authentication_key, 16);
}
int8_t GCMParser::parse(uint8_t *d, DataParserContext &ctx) {
int8_t GCMParser::parse(uint8_t *d, DataParserContext &ctx, bool hastag) {
if(ctx.length < 12) return DATA_PARSE_INCOMPLETE;
uint32_t headersize = 0;
uint8_t* ptr = (uint8_t*) d;
if(*ptr != GCM_TAG) return DATA_PARSE_BOUNDRY_FLAG_MISSING;
ptr++;
if(hastag) {
if(*ptr != GCM_TAG) return DATA_PARSE_BOUNDRY_FLAG_MISSING;
ptr++;
headersize++;
}
// Encrypted APDU
// http://www.weigu.lu/tutorials/sensors2bus/04_encryption/index.html
uint8_t systemTitleLength = *ptr;
ptr++;
headersize++;
uint8_t initialization_vector[12];
memcpy(ctx.system_title, ptr, systemTitleLength);
memcpy(initialization_vector, ctx.system_title, systemTitleLength);
memset(ctx.system_title, 0, 8);
memset(initialization_vector, 0, 12);
if(systemTitleLength > 0) {
memcpy(ctx.system_title, ptr, systemTitleLength);
memcpy(initialization_vector, ctx.system_title, systemTitleLength);
ptr += systemTitleLength;
headersize += systemTitleLength;
}
uint32_t len = 0;
uint32_t headersize = 2 + systemTitleLength;
ptr += systemTitleLength;
if(((*ptr) & 0xFF) == 0x81) {
// 1-byte payload length
ptr++;