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TYT EP: Fix User Key to Input Register; #302

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Bytes used as input register for TYT EP are loaded by byte reverse order, was undetected on some key patterns like all F's or all A's, but found out on 1234... patterns;
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lwvmobile
2025-08-17 15:24:22 -04:00
parent 4dd68f2221
commit a5b9984d78
1 changed files with 24 additions and 13 deletions
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37
src/dsd_main.c
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@@ -2011,31 +2011,42 @@
opts.szNumbers[1023] = '\0';
unsigned long long int K1 = strtoull (opts.szNumbers, &pEnd, 16);
unsigned long long int K2 = strtoull (pEnd, &pEnd, 16);
uint8_t key[32];
memset(key, 0, sizeof(key));
uint8_t static_key[32];
memset(static_key, 0, sizeof(static_key));
//static key value
key[0]=0x6e; key[1]=0x02; key[2]=0x8d; key[3]=0x8a;
key[4]=0xca; key[5]=0xeb; key[6]=0x9b; key[7]=0xbe;
key[8]=0x42; key[9]=0x72; key[10]=0xfb; key[11]=0x82;
key[12]=0x64; key[13]=0x56; key[14]=0x31; key[15]=0xfa;
static_key[0]=0x6e; static_key[1]=0x02; static_key[2]=0x8d; static_key[3]=0x8a;
static_key[4]=0xca; static_key[5]=0xeb; static_key[6]=0x9b; static_key[7]=0xbe;
static_key[8]=0x42; static_key[9]=0x72; static_key[10]=0xfb; static_key[11]=0x82;
static_key[12]=0x64; static_key[13]=0x56; static_key[14]=0x31; static_key[15]=0xfa;
//iv or input register is the key value provided by user
uint8_t iv[16];
memset(iv, 0, sizeof(iv));
//the key value provided by user
uint8_t user_key[16];
memset(user_key, 0, sizeof(user_key));
//Load user key into iv / input register
//Load user key into array to manipulate
for (int i = 0; i < 8; i++)
{
iv[i+0] = (K1 >> (56-(i*8))) & 0xFF;
iv[i+8] = (K2 >> (56-(i*8))) & 0xFF;
user_key[i+0] = (K1 >> (56-(i*8))) & 0xFF;
user_key[i+8] = (K2 >> (56-(i*8))) & 0xFF;
}
uint8_t input_register[16];
memset(input_register, 0, sizeof(input_register));
//manipulate user provided key by loading bytes in reverse order into the input_register
for (int i = 0; i < 16; i++)
input_register[15-i] = user_key[i];
uint8_t ks_bytes[16];
memset(ks_bytes, 0, sizeof(ks_bytes));
//NOTE: To clarify, TYT EP uses ECB mode with the user key as input_register and the static key in the
//forward (encryption) direction, but we are calling OFB mode because the first round is the
//same concept and we only need the first round output, OFB is easier to use anyways.
//create keystream
aes_ofb_keystream_output(iv, key, ks_bytes, 0, 1);
aes_ofb_keystream_output(input_register, static_key, ks_bytes, 0, 1);
uint8_t ks_bits[128];
memset(ks_bits, 0, sizeof(ks_bits));
unpack_byte_array_into_bit_array(ks_bytes, ks_bits, 16);