diff options
Diffstat (limited to 'libtomcrypt/src/modes/ctr/ctr_start.c')
| -rw-r--r-- | libtomcrypt/src/modes/ctr/ctr_start.c | 24 |
1 files changed, 17 insertions, 7 deletions
diff --git a/libtomcrypt/src/modes/ctr/ctr_start.c b/libtomcrypt/src/modes/ctr/ctr_start.c index 895c8a4..b27bed0 100644 --- a/libtomcrypt/src/modes/ctr/ctr_start.c +++ b/libtomcrypt/src/modes/ctr/ctr_start.c @@ -6,7 +6,7 @@ * The library is free for all purposes without any express * guarantee it works. * - * Tom St Denis, tomstdenis@gmail.com, http://libtomcrypt.com + * Tom St Denis, tomstdenis@gmail.com, http://libtom.org */ #include "tomcrypt.h" @@ -46,6 +46,16 @@ int ctr_start( int cipher, return err; } + /* ctrlen == counter width */ + ctr->ctrlen = (ctr_mode & 255) ? (ctr_mode & 255) : cipher_descriptor[cipher].block_length; + if (ctr->ctrlen > cipher_descriptor[cipher].block_length) { + return CRYPT_INVALID_ARG; + } + + if ((ctr_mode & 0x1000) == CTR_COUNTER_BIG_ENDIAN) { + ctr->ctrlen = cipher_descriptor[cipher].block_length - ctr->ctrlen; + } + /* setup cipher */ if ((err = cipher_descriptor[cipher].setup(key, keylen, num_rounds, &ctr->key)) != CRYPT_OK) { return err; @@ -55,7 +65,7 @@ int ctr_start( int cipher, ctr->blocklen = cipher_descriptor[cipher].block_length; ctr->cipher = cipher; ctr->padlen = 0; - ctr->mode = ctr_mode & 1; + ctr->mode = ctr_mode & 0x1000; for (x = 0; x < ctr->blocklen; x++) { ctr->ctr[x] = IV[x]; } @@ -64,7 +74,7 @@ int ctr_start( int cipher, /* increment the IV as per RFC 3686 */ if (ctr->mode == CTR_COUNTER_LITTLE_ENDIAN) { /* little-endian */ - for (x = 0; x < ctr->blocklen; x++) { + for (x = 0; x < ctr->ctrlen; x++) { ctr->ctr[x] = (ctr->ctr[x] + (unsigned char)1) & (unsigned char)255; if (ctr->ctr[x] != (unsigned char)0) { break; @@ -72,7 +82,7 @@ int ctr_start( int cipher, } } else { /* big-endian */ - for (x = ctr->blocklen-1; x >= 0; x--) { + for (x = ctr->blocklen-1; x >= ctr->ctrlen; x--) { ctr->ctr[x] = (ctr->ctr[x] + (unsigned char)1) & (unsigned char)255; if (ctr->ctr[x] != (unsigned char)0) { break; @@ -86,6 +96,6 @@ int ctr_start( int cipher, #endif -/* $Source: /cvs/libtom/libtomcrypt/src/modes/ctr/ctr_start.c,v $ */ -/* $Revision: 1.11 $ */ -/* $Date: 2006/11/05 01:46:35 $ */ +/* $Source$ */ +/* $Revision$ */ +/* $Date$ */ |