diff options
Diffstat (limited to 'src/modes/ctr/ctr_start.c')
| -rw-r--r-- | src/modes/ctr/ctr_start.c | 35 |
1 files changed, 28 insertions, 7 deletions
diff --git a/src/modes/ctr/ctr_start.c b/src/modes/ctr/ctr_start.c index 7c7eebb..895c8a4 100644 --- a/src/modes/ctr/ctr_start.c +++ b/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.org + * Tom St Denis, tomstdenis@gmail.com, http://libtomcrypt.com */ #include "tomcrypt.h" @@ -16,7 +16,7 @@ */ -#ifdef CTR +#ifdef LTC_CTR_MODE /** Initialize a CTR context @@ -55,16 +55,37 @@ int ctr_start( int cipher, ctr->blocklen = cipher_descriptor[cipher].block_length; ctr->cipher = cipher; ctr->padlen = 0; - ctr->mode = ctr_mode; + ctr->mode = ctr_mode & 1; for (x = 0; x < ctr->blocklen; x++) { ctr->ctr[x] = IV[x]; } - cipher_descriptor[ctr->cipher].ecb_encrypt(ctr->ctr, ctr->pad, &ctr->key); - return CRYPT_OK; + + if (ctr_mode & LTC_CTR_RFC3686) { + /* increment the IV as per RFC 3686 */ + if (ctr->mode == CTR_COUNTER_LITTLE_ENDIAN) { + /* little-endian */ + for (x = 0; x < ctr->blocklen; x++) { + ctr->ctr[x] = (ctr->ctr[x] + (unsigned char)1) & (unsigned char)255; + if (ctr->ctr[x] != (unsigned char)0) { + break; + } + } + } else { + /* big-endian */ + for (x = ctr->blocklen-1; x >= 0; x--) { + ctr->ctr[x] = (ctr->ctr[x] + (unsigned char)1) & (unsigned char)255; + if (ctr->ctr[x] != (unsigned char)0) { + break; + } + } + } + } + + return cipher_descriptor[ctr->cipher].ecb_encrypt(ctr->ctr, ctr->pad, &ctr->key); } #endif /* $Source: /cvs/libtom/libtomcrypt/src/modes/ctr/ctr_start.c,v $ */ -/* $Revision: 1.6 $ */ -/* $Date: 2005/05/05 14:35:59 $ */ +/* $Revision: 1.11 $ */ +/* $Date: 2006/11/05 01:46:35 $ */ |