diff options
Diffstat (limited to 'lib/nfc/protocols/crypto1.c')
-rw-r--r-- | lib/nfc/protocols/crypto1.c | 75 |
1 files changed, 75 insertions, 0 deletions
diff --git a/lib/nfc/protocols/crypto1.c b/lib/nfc/protocols/crypto1.c new file mode 100644 index 00000000..f08164ba --- /dev/null +++ b/lib/nfc/protocols/crypto1.c @@ -0,0 +1,75 @@ +#include "crypto1.h" +#include "nfc_util.h" +#include <furi.h> + +// Algorithm from https://github.com/RfidResearchGroup/proxmark3.git + +#define SWAPENDIAN(x) (x = (x >> 8 & 0xff00ff) | (x & 0xff00ff) << 8, x = x >> 16 | x << 16) +#define LF_POLY_ODD (0x29CE5C) +#define LF_POLY_EVEN (0x870804) + +#define BEBIT(x, n) FURI_BIT(x, (n) ^ 24) + +void crypto1_reset(Crypto1* crypto1) { + furi_assert(crypto1); + crypto1->even = 0; + crypto1->odd = 0; +} + +void crypto1_init(Crypto1* crypto1, uint64_t key) { + furi_assert(crypto1); + crypto1->even = 0; + crypto1->odd = 0; + for(int8_t i = 47; i > 0; i -= 2) { + crypto1->odd = crypto1->odd << 1 | FURI_BIT(key, (i - 1) ^ 7); + crypto1->even = crypto1->even << 1 | FURI_BIT(key, i ^ 7); + } +} + +uint32_t crypto1_filter(uint32_t in) { + uint32_t out = 0; + out = 0xf22c0 >> (in & 0xf) & 16; + out |= 0x6c9c0 >> (in >> 4 & 0xf) & 8; + out |= 0x3c8b0 >> (in >> 8 & 0xf) & 4; + out |= 0x1e458 >> (in >> 12 & 0xf) & 2; + out |= 0x0d938 >> (in >> 16 & 0xf) & 1; + return FURI_BIT(0xEC57E80A, out); +} + +uint8_t crypto1_bit(Crypto1* crypto1, uint8_t in, int is_encrypted) { + furi_assert(crypto1); + uint8_t out = crypto1_filter(crypto1->odd); + uint32_t feed = out & (!!is_encrypted); + feed ^= !!in; + feed ^= LF_POLY_ODD & crypto1->odd; + feed ^= LF_POLY_EVEN & crypto1->even; + crypto1->even = crypto1->even << 1 | (nfc_util_even_parity32(feed)); + + FURI_SWAP(crypto1->odd, crypto1->even); + return out; +} + +uint8_t crypto1_byte(Crypto1* crypto1, uint8_t in, int is_encrypted) { + furi_assert(crypto1); + uint8_t out = 0; + for(uint8_t i = 0; i < 8; i++) { + out |= crypto1_bit(crypto1, FURI_BIT(in, i), is_encrypted) << i; + } + return out; +} + +uint32_t crypto1_word(Crypto1* crypto1, uint32_t in, int is_encrypted) { + furi_assert(crypto1); + uint32_t out = 0; + for(uint8_t i = 0; i < 32; i++) { + out |= crypto1_bit(crypto1, BEBIT(in, i), is_encrypted) << (24 ^ i); + } + return out; +} + +uint32_t prng_successor(uint32_t x, uint32_t n) { + SWAPENDIAN(x); + while(n--) x = x >> 1 | (x >> 16 ^ x >> 18 ^ x >> 19 ^ x >> 21) << 31; + + return SWAPENDIAN(x); +} |