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merge all crypto functions to decoder

pull/15/head
Jean-Michel Friedt 2024-12-22 18:46:29 +01:00
parent d88782d9f0
commit 1bbd406e28
3 changed files with 114 additions and 9 deletions
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7
include/gnuradio/m17/m17_decoder.h
View File

@ -23,6 +23,13 @@ class M17_API m17_decoder : virtual public gr::block
{
public:
typedef std::shared_ptr<m17_decoder> sptr;
typedef enum
{
ENCR_NONE,
ENCR_SCRAM,
ENCR_AES,
ENCR_RES //reserved
} encr_t;
/*!
* \brief Return a shared_ptr to a new instance of m17::m17_decoder.

99
lib/m17_decoder_impl.cc
View File

@ -377,20 +377,68 @@ void m17_decoder_impl::parse_raw_key_string(uint8_t* dest, const char* inp)
//fwrite(&frame_data[3], 16, 1, stdout);
//if the stream is signed
if(_signed_str && fn<0x7FFC)
if(_signed_str==true && fn<0x7FFC)
{
//if thats the first frame (fn=0)
if(fn==0)
memcpy(digest, &frame_data[3], sizeof(digest));
memcpy(_digest, &frame_data[3], sizeof(_digest));
for(uint8_t i=0; i<sizeof(digest); i++)
digest[i]^=frame_data[3+i];
uint8_t tmp=digest[0];
for(uint8_t i=0; i<sizeof(digest)-1; i++)
digest[i]=digest[i+1];
digest[sizeof(digest)-1]=tmp;
for(uint8_t i=0; i<sizeof(_digest); i++)
_digest[i]^=frame_data[3+i];
uint8_t tmp=_digest[0];
for(uint8_t i=0; i<sizeof(_digest)-1; i++)
_digest[i]=_digest[i+1];
_digest[sizeof(_digest)-1]=tmp;
}
//NOTE: Don't attempt decryption when a signed stream is >= 0x7FFC
//The Signature is not encrypted
//AES
if(_encr_type==ENCR_AES)
{
memcpy(_iv, lsf+14, 14);
_iv[14] = frame_data[1] & 0x7F;
_iv[15] = frame_data[2] & 0xFF;
if(_signed_str==true && (fn % 0x8000)<0x7FFC) //signed stream
aes_ctr_bytewise_payload_crypt(_iv, _key, frame_data+3, AES128); //hardcoded for now
else if(_signed_str==false) //non-signed stream
aes_ctr_bytewise_payload_crypt(_iv, _key, frame_data+3, AES128); //hardcoded for now
}
//Scrambler
if(_encr_type==ENCR_SCRAM)
{
if(fn != 0 && (fn % 0x8000)!=_expected_next_fn) //frame skip, etc
scrambler_seed = scrambler_seed_calculation(scrambler_subtype, _scrambler_key, fn&0x7FFF);
else if(fn == 0) scrambler_seed = _scrambler_key; //reset back to key value
if(_signed_str==true && (fn % 0x8000)<0x7FFC) //signed stream
scrambler_sequence_generator();
else if(_signed_str==false) //non-signed stream
scrambler_sequence_generator();
for(uint8_t i=0; i<16; i++)
{
frame_data[i+3] ^= scr_bytes[i];
}
}
//dump data - first byte is empty
printf("FN: %04X PLD: ", fn);
for(uint8_t i=3; i<19; i++)
{
printf("%02X", frame_data[i]);
}
if (_debug_ctrl==true)
printf(" e=%1.1f\n", (float)e/0xFFFF);
printf("\n");
//send codec2 stream to stdout
//fwrite(&frame_data[3], 16, 1, stdout);
//extract LICH
for(uint16_t i=0; i<96; i++)
{
@ -480,6 +528,41 @@ void m17_decoder_impl::parse_raw_key_string(uint8_t* dest, const char* inp)
printf("\n");
}
}
//if the contents of the payload is now digital signature, not data/voice
if(fn>=0x7FFC && _signed_str==true)
{
memcpy(&_sig[((fn&0x7FFF)-0x7FFC)*16], &frame_data[3], 16);
if(fn==(0x7FFF|0x8000))
{
//dump data
/*printf("DEC-Digest: ");
for(uint8_t i=0; i<sizeof(digest); i++)
printf("%02X", digest[i]);
printf("\n");
printf("Key: ");
for(uint8_t i=0; i<sizeof(pub_key); i++)
printf("%02X", pub_key[i]);
printf("\n");
printf("Signature: ");
for(uint8_t i=0; i<sizeof(sig); i++)
printf("%02X", sig[i]);
printf("\n");*/
if(uECC_verify(_key, _digest, sizeof(_digest), _sig, _curve))
{
printf("Signature OK\n");
}
else
{
printf("Signature invalid\n");
}
}
}
_expected_next_fn = (fn + 1) % 0x8000;
}
else //lsf

17
lib/m17_decoder_impl.h
View File

@ -33,7 +33,21 @@ private:
float _threshold=0.9;
bool _callsign=false;
bool _signed_str=false;
uint8_t _key[32];
// uint8_t _key[32];
uint8_t _key[64]={0}; //public key
uint8_t _iv[16];
encr_t _encr_type=ENCR_NONE;
//used for signatures
uint8_t _digest[16]={0}; //16-byte field for the stream digest
uint8_t _sig[64]={0}; //ECDSA signature
uint32_t _scrambler_key=0; //keep set to initial value for seed calculation function
typedef enum
{
AES128,
AES192,
AES256
} aes_t;
float last[8] = {0}; //look-back buffer for finding syncwords
float pld[SYM_PER_PLD]; //raw frame symbols
@ -63,6 +77,7 @@ uint8_t scrambler_pn[128];
uint32_t scrambler_seed=0;
int8_t scrambler_subtype = -1;
#endif
const struct uECC_Curve_t* _curve = uECC_secp256r1();
public:
m17_decoder_impl(bool debug_data,bool debug_ctrl,float threshold,bool callsign, bool signed_str, std::string key);