CHG: Crapto1 v3.3 now with comments, and I've tried to unnest some loops.

[proxmark3-svn] / tools / nonce2key / crapto1.c

diff --git a/tools/nonce2key/crapto1.c b/tools/nonce2key/crapto1.c
index 8d514a0cdd8ea6d79b92d69d63546c5f9870be28..10dedcb5177a4989a0df3a3001aab7acfb81fac9 100644 (file)
--- a/tools/nonce2key/crapto1.c
+++ b/tools/nonce2key/crapto1.c
@@ -184,6 +184,7 @@ struct Crypto1State* lfsr_recovery32(uint32_t ks2, uint32_t in)
        uint32_t *even_head = 0, *even_tail = 0, eks = 0;\r
        int i;\r
 \r
+       // split the keystream into an odd and even part\r
        for(i = 31; i >= 0; i -= 2)\r
                oks = oks << 1 | BEBIT(ks2, i);\r
        for(i = 30; i >= 0; i -= 2)\r
@@ -200,6 +201,7 @@ struct Crypto1State* lfsr_recovery32(uint32_t ks2, uint32_t in)
 \r
        statelist->odd = statelist->even = 0;\r
 \r
+       // initialize statelists: add all possible states which would result into the rightmost 2 bits of the keystream\r
        for(i = 1 << 20; i >= 0; --i) {\r
                if(filter(i) == (oks & 1))\r
                        *++odd_tail = i;\r
@@ -207,11 +209,15 @@ struct Crypto1State* lfsr_recovery32(uint32_t ks2, uint32_t in)
                        *++even_tail = i;\r
        }\r
 \r
+       // extend the statelists. Look at the next 8 Bits of the keystream (4 Bit each odd and even):\r
        for(i = 0; i < 4; i++) {\r
                extend_table_simple(odd_head,  &odd_tail, (oks >>= 1) & 1);\r
                extend_table_simple(even_head, &even_tail, (eks >>= 1) & 1);\r
        }\r
 \r
+       // the statelists now contain all states which could have generated the last 10 Bits of the keystream.\r
+       // 22 bits to go to recover 32 bits in total. From now on, we need to take the "in"\r
+       // parameter into account.\r
        in = (in >> 16 & 0xff) | (in << 16) | (in & 0xff00);\r
        recover(odd_head, odd_tail, oks,\r
                even_head, even_tail, eks, 11, statelist, in << 1);\r
@@ -338,9 +344,21 @@ uint8_t lfsr_rollback_bit(struct Crypto1State *s, uint32_t in, int fb)
  */\r
 uint8_t lfsr_rollback_byte(struct Crypto1State *s, uint32_t in, int fb)\r
 {\r
+       /*\r
        int i, ret = 0;\r
        for (i = 7; i >= 0; --i)\r
                ret |= lfsr_rollback_bit(s, BIT(in, i), fb) << i;\r
+*/\r
+\r
+       uint8_t ret = 0;\r
+       ret |= lfsr_rollback_bit(s, BIT(in, 7), fb) << 7;\r
+       ret |= lfsr_rollback_bit(s, BIT(in, 6), fb) << 6;\r
+       ret |= lfsr_rollback_bit(s, BIT(in, 5), fb) << 5;\r
+       ret |= lfsr_rollback_bit(s, BIT(in, 4), fb) << 4;\r
+       ret |= lfsr_rollback_bit(s, BIT(in, 3), fb) << 3;\r
+       ret |= lfsr_rollback_bit(s, BIT(in, 2), fb) << 2;\r
+       ret |= lfsr_rollback_bit(s, BIT(in, 1), fb) << 1;\r
+       ret |= lfsr_rollback_bit(s, BIT(in, 0), fb) << 0;\r
        return ret;\r
 }\r
 /** lfsr_rollback_word\r
@@ -348,10 +366,50 @@ uint8_t lfsr_rollback_byte(struct Crypto1State *s, uint32_t in, int fb)
  */\r
 uint32_t lfsr_rollback_word(struct Crypto1State *s, uint32_t in, int fb)\r
 {\r
+       /*\r
        int i;\r
        uint32_t ret = 0;\r
        for (i = 31; i >= 0; --i)\r
                ret |= lfsr_rollback_bit(s, BEBIT(in, i), fb) << (i ^ 24);\r
+*/\r
+       \r
+       uint32_t ret = 0;\r
+       ret |= lfsr_rollback_bit(s, BEBIT(in, 31), fb) << (31 ^ 24);\r
+       ret |= lfsr_rollback_bit(s, BEBIT(in, 30), fb) << (30 ^ 24);\r
+       ret |= lfsr_rollback_bit(s, BEBIT(in, 29), fb) << (29 ^ 24);\r
+       ret |= lfsr_rollback_bit(s, BEBIT(in, 28), fb) << (28 ^ 24);\r
+       ret |= lfsr_rollback_bit(s, BEBIT(in, 27), fb) << (27 ^ 24);\r
+       ret |= lfsr_rollback_bit(s, BEBIT(in, 26), fb) << (26 ^ 24);\r
+       ret |= lfsr_rollback_bit(s, BEBIT(in, 25), fb) << (25 ^ 24);\r
+       ret |= lfsr_rollback_bit(s, BEBIT(in, 24), fb) << (24 ^ 24);\r
+\r
+       ret |= lfsr_rollback_bit(s, BEBIT(in, 23), fb) << (23 ^ 24);\r
+       ret |= lfsr_rollback_bit(s, BEBIT(in, 22), fb) << (22 ^ 24);\r
+       ret |= lfsr_rollback_bit(s, BEBIT(in, 21), fb) << (21 ^ 24);\r
+       ret |= lfsr_rollback_bit(s, BEBIT(in, 20), fb) << (20 ^ 24);\r
+       ret |= lfsr_rollback_bit(s, BEBIT(in, 19), fb) << (19 ^ 24);\r
+       ret |= lfsr_rollback_bit(s, BEBIT(in, 18), fb) << (18 ^ 24);\r
+       ret |= lfsr_rollback_bit(s, BEBIT(in, 17), fb) << (17 ^ 24);\r
+       ret |= lfsr_rollback_bit(s, BEBIT(in, 16), fb) << (16 ^ 24);\r
+       \r
+       ret |= lfsr_rollback_bit(s, BEBIT(in, 15), fb) << (15 ^ 24);\r
+       ret |= lfsr_rollback_bit(s, BEBIT(in, 14), fb) << (14 ^ 24);\r
+       ret |= lfsr_rollback_bit(s, BEBIT(in, 13), fb) << (13 ^ 24);\r
+       ret |= lfsr_rollback_bit(s, BEBIT(in, 12), fb) << (12 ^ 24);\r
+       ret |= lfsr_rollback_bit(s, BEBIT(in, 11), fb) << (11 ^ 24);\r
+       ret |= lfsr_rollback_bit(s, BEBIT(in, 10), fb) << (10 ^ 24);\r
+       ret |= lfsr_rollback_bit(s, BEBIT(in, 9), fb) << (9 ^ 24);\r
+       ret |= lfsr_rollback_bit(s, BEBIT(in, 8), fb) << (8 ^ 24);\r
+       \r
+       ret |= lfsr_rollback_bit(s, BEBIT(in, 7), fb) << (7 ^ 24);\r
+       ret |= lfsr_rollback_bit(s, BEBIT(in, 6), fb) << (6 ^ 24);\r
+       ret |= lfsr_rollback_bit(s, BEBIT(in, 5), fb) << (5 ^ 24);\r
+       ret |= lfsr_rollback_bit(s, BEBIT(in, 4), fb) << (4 ^ 24);\r
+       ret |= lfsr_rollback_bit(s, BEBIT(in, 3), fb) << (3 ^ 24);\r
+       ret |= lfsr_rollback_bit(s, BEBIT(in, 2), fb) << (2 ^ 24);\r
+       ret |= lfsr_rollback_bit(s, BEBIT(in, 1), fb) << (1 ^ 24);\r
+       ret |= lfsr_rollback_bit(s, BEBIT(in, 0), fb) << (0 ^ 24);\r
+       \r
        return ret;\r
 }\r
 \r
@@ -391,8 +449,9 @@ static uint32_t fastfwd[2][8] = {
  */\r
 uint32_t *lfsr_prefix_ks(uint8_t ks[8], int isodd)\r
 {\r
-       uint32_t c, entry, *candidates = malloc(4 << 10);\r
-       int i, size = 0, good;\r
+       uint32_t *candidates = malloc(4 << 10);\r
+       uint32_t c,  entry;\r
+       int size = 0, i, good;\r
 \r
        if(!candidates)\r
                return 0;\r
@@ -479,5 +538,8 @@ struct Crypto1State* lfsr_common_prefix(uint32_t pfx, uint32_t rr, uint8_t ks[8]
 \r
        s->odd = s->even = 0;\r
 \r
+       free(odd);\r
+       free(even);\r
+\r
        return statelist;\r
 }\r