1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis 2 * 3 * LibTomCrypt is a library that provides various cryptographic 4 * algorithms in a highly modular and flexible manner. 5 * 6 * The library is free for all purposes without any express 7 * guarantee it works. 8 * 9 * Tom St Denis, tomstdenis (at) gmail.com, http://libtomcrypt.com 10 */ 11 12 /** 13 @file ocb_encrypt.c 14 OCB implementation, encrypt data, by Tom St Denis 15 */ 16 #include "tomcrypt.h" 17 18 #ifdef OCB_MODE 19 20 /** 21 Encrypt a block of data with OCB. 22 @param ocb The OCB state 23 @param pt The plaintext (length of the block size of the block cipher) 24 @param ct [out] The ciphertext (same size as the pt) 25 @return CRYPT_OK if successful 26 */ 27 int ocb_encrypt(ocb_state *ocb, const unsigned char *pt, unsigned char *ct) 28 { 29 unsigned char Z[MAXBLOCKSIZE], tmp[MAXBLOCKSIZE]; 30 int err, x; 31 32 LTC_ARGCHK(ocb != NULL); 33 LTC_ARGCHK(pt != NULL); 34 LTC_ARGCHK(ct != NULL); 35 if ((err = cipher_is_valid(ocb->cipher)) != CRYPT_OK) { 36 return err; 37 } 38 if (ocb->block_len != cipher_descriptor[ocb->cipher].block_length) { 39 return CRYPT_INVALID_ARG; 40 } 41 42 /* compute checksum */ 43 for (x = 0; x < ocb->block_len; x++) { 44 ocb->checksum[x] ^= pt[x]; 45 } 46 47 /* Get Z[i] value */ 48 ocb_shift_xor(ocb, Z); 49 50 /* xor pt in, encrypt, xor Z out */ 51 for (x = 0; x < ocb->block_len; x++) { 52 tmp[x] = pt[x] ^ Z[x]; 53 } 54 if ((err = cipher_descriptor[ocb->cipher].ecb_encrypt(tmp, ct, &ocb->key)) != CRYPT_OK) { 55 return err; 56 } 57 for (x = 0; x < ocb->block_len; x++) { 58 ct[x] ^= Z[x]; 59 } 60 61 #ifdef LTC_CLEAN_STACK 62 zeromem(Z, sizeof(Z)); 63 zeromem(tmp, sizeof(tmp)); 64 #endif 65 return CRYPT_OK; 66 } 67 68 #endif 69 70 /* $Source: /cvs/libtom/libtomcrypt/src/encauth/ocb/ocb_encrypt.c,v $ */ 71 /* $Revision: 1.5 $ */ 72 /* $Date: 2006/03/31 14:15:35 $ */ 73
