Mercurial > dropbear
view libtomcrypt/src/modes/lrw/lrw_process.c @ 505:805e557fdff7
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author | Matt Johnston <matt@ucc.asn.au> |
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date | Sun, 02 Nov 2008 12:25:08 +0000 |
parents | 0cbe8f6dbf9e |
children | f849a5ca2efc |
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/* LibTomCrypt, modular cryptographic library -- Tom St Denis * * LibTomCrypt is a library that provides various cryptographic * algorithms in a highly modular and flexible manner. * * The library is free for all purposes without any express * guarantee it works. * * Tom St Denis, [email protected], http://libtomcrypt.com */ #include "tomcrypt.h" /** @file lrw_process.c LRW_MODE implementation, Encrypt/decrypt blocks, Tom St Denis */ #ifdef LTC_LRW_MODE /** Process blocks with LRW, since decrypt/encrypt are largely the same they share this code. @param pt The "input" data @param ct [out] The "output" data @param len The length of the input, must be a multiple of 128-bits (16 octets) @param mode LRW_ENCRYPT or LRW_DECRYPT @param lrw The LRW state @return CRYPT_OK if successful */ int lrw_process(const unsigned char *pt, unsigned char *ct, unsigned long len, int mode, symmetric_LRW *lrw) { unsigned char prod[16]; int x, err; #ifdef LRW_TABLES int y; #endif LTC_ARGCHK(pt != NULL); LTC_ARGCHK(ct != NULL); LTC_ARGCHK(lrw != NULL); if (len & 15) { return CRYPT_INVALID_ARG; } while (len) { /* copy pad */ XMEMCPY(prod, lrw->pad, 16); /* increment IV */ for (x = 15; x >= 0; x--) { lrw->IV[x] = (lrw->IV[x] + 1) & 255; if (lrw->IV[x]) { break; } } /* update pad */ #ifdef LRW_TABLES /* for each byte changed we undo it's affect on the pad then add the new product */ for (; x < 16; x++) { #ifdef LTC_FAST for (y = 0; y < 16; y += sizeof(LTC_FAST_TYPE)) { *((LTC_FAST_TYPE *)(lrw->pad + y)) ^= *((LTC_FAST_TYPE *)(&lrw->PC[x][lrw->IV[x]][y])) ^ *((LTC_FAST_TYPE *)(&lrw->PC[x][(lrw->IV[x]-1)&255][y])); } #else for (y = 0; y < 16; y++) { lrw->pad[y] ^= lrw->PC[x][lrw->IV[x]][y] ^ lrw->PC[x][(lrw->IV[x]-1)&255][y]; } #endif } #else gcm_gf_mult(lrw->tweak, lrw->IV, lrw->pad); #endif /* xor prod */ #ifdef LTC_FAST for (x = 0; x < 16; x += sizeof(LTC_FAST_TYPE)) { *((LTC_FAST_TYPE *)(ct + x)) = *((LTC_FAST_TYPE *)(pt + x)) ^ *((LTC_FAST_TYPE *)(prod + x)); } #else for (x = 0; x < 16; x++) { ct[x] = pt[x] ^ prod[x]; } #endif /* send through cipher */ if (mode == LRW_ENCRYPT) { if ((err = cipher_descriptor[lrw->cipher].ecb_encrypt(ct, ct, &lrw->key)) != CRYPT_OK) { return err; } } else { if ((err = cipher_descriptor[lrw->cipher].ecb_decrypt(ct, ct, &lrw->key)) != CRYPT_OK) { return err; } } /* xor prod */ #ifdef LTC_FAST for (x = 0; x < 16; x += sizeof(LTC_FAST_TYPE)) { *((LTC_FAST_TYPE *)(ct + x)) = *((LTC_FAST_TYPE *)(ct + x)) ^ *((LTC_FAST_TYPE *)(prod + x)); } #else for (x = 0; x < 16; x++) { ct[x] = ct[x] ^ prod[x]; } #endif /* move to next */ pt += 16; ct += 16; len -= 16; } return CRYPT_OK; } #endif /* $Source: /cvs/libtom/libtomcrypt/src/modes/lrw/lrw_process.c,v $ */ /* $Revision: 1.10 $ */ /* $Date: 2006/06/29 01:53:13 $ */