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authorAmaury Pouly <amaury.pouly@gmail.com>2017-09-19 15:30:37 +0200
committerAmaury Pouly <amaury.pouly@gmail.com>2017-09-19 15:30:37 +0200
commit99cc8f88026f930c08e2e32439fe8f0d22e5e5a8 (patch)
tree453139f31650f93fb1515d4098e7957423a4a503
parent048aecd82a1dbf73dec9b6ca903f71c4b457dc9a (diff)
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upgtools: fix bug in brute force search
DES ignores the parity bit of each byte (making the 64-bit key really 56-bit), but the current code skipped the parity bit of each half-byte, thus missing some keys. Change-Id: Ia523ebb944e458905b7de1742df151df22166150
-rw-r--r--utils/nwztools/upgtools/keysig_search.c14
1 files changed, 8 insertions, 6 deletions
diff --git a/utils/nwztools/upgtools/keysig_search.c b/utils/nwztools/upgtools/keysig_search.c
index 51a04bb6f9..2f234d6358 100644
--- a/utils/nwztools/upgtools/keysig_search.c
+++ b/utils/nwztools/upgtools/keysig_search.c
@@ -266,11 +266,12 @@ static bool hex_rec(bool producer, struct hex_chunk_t *ch)
* significant bit of each byte is an (unused) parity bit. We thus only
* generate keys where the least significant bit is 0. */
int p = ch->pos++;
+ int step = (p % 2) ? 2 : 1; // skip significant bit at positions 1, 3, 5 and 7
if(ch->rem_digits > 0)
{
ch->rem_digits--;
/* NOTE (42) */
- for(int i = '0'; i <= '9'; i += 2)
+ for(int i = '0'; i <= '9'; i += step)
{
ch->key[p] = i;
if(hex_rec(producer, ch))
@@ -282,7 +283,7 @@ static bool hex_rec(bool producer, struct hex_chunk_t *ch)
{
ch->rem_letters--;
/* NOTE (42) */
- for(int i = 'a'; i <= 'f'; i += 2)
+ for(int i = 'a'; i <= 'f'; i += step)
{
ch->key[p] = i;
if(hex_rec(producer, ch))
@@ -290,7 +291,7 @@ static bool hex_rec(bool producer, struct hex_chunk_t *ch)
}
if(ch->upper_case)
{
- for(int i = 'A'; i <= 'F'; i += 2)
+ for(int i = 'A'; i <= 'F'; i += step)
{
ch->key[p] = i;
if(hex_rec(producer, ch))
@@ -379,7 +380,7 @@ static bool alnum_rec(bool producer, struct alnum_chunk_t *ch)
/* we list the first 5 pos in generator, and remaining 3 in workers */
if(producer && ch->pos == 4)
{
- printf("yield(%.8s,%d)\n", ch->key, ch->pos);
+ //printf("yield(%.8s,%d)\n", ch->key, ch->pos);
return producer_yield(ch, sizeof(struct alnum_chunk_t));
}
/* filled the key ? */
@@ -392,14 +393,15 @@ static bool alnum_rec(bool producer, struct alnum_chunk_t *ch)
* generate keys where the least significant bit is 0. */
int p = ch->pos++;
/* NOTE (42) */
- for(int i = '0'; i <= '9'; i += 2)
+ int step = (p % 2) ? 2 : 1; // skip significant bit at positions 1, 3, 5 and 7
+ for(int i = '0'; i <= '9'; i += step)
{
ch->key[p] = i;
if(alnum_rec(producer, ch))
return true;
}
/* NOTE (42) */
- for(int i = 'a'; i <= 'z'; i += 2)
+ for(int i = 'a'; i <= 'z'; i += step)
{
ch->key[p] = i;
if(alnum_rec(producer, ch))