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107 lines
2.9 KiB
C
107 lines
2.9 KiB
C
/* LibTomCrypt, modular cryptographic library -- Tom St Denis
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*
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* LibTomCrypt is a library that provides various cryptographic
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* algorithms in a highly modular and flexible manner.
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*
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* The library is free for all purposes without any express
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* guarantee it works.
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*/
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/**
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@file ocb3_add_aad.c
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OCB implementation, add AAD data, by Karel Miko
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*/
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#include "tomcrypt.h"
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#ifdef LTC_OCB3_MODE
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/**
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Add one block of AAD data (internal function)
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@param ocb The OCB state
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@param aad_block [in] AAD data (block_len size)
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@return CRYPT_OK if successful
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*/
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static int _ocb3_int_aad_add_block(ocb3_state *ocb, const unsigned char *aad_block)
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{
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unsigned char tmp[MAXBLOCKSIZE];
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int err;
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/* Offset_i = Offset_{i-1} xor L_{ntz(i)} */
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ocb3_int_xor_blocks(ocb->aOffset_current, ocb->aOffset_current, ocb->L_[ocb3_int_ntz(ocb->ablock_index)], ocb->block_len);
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/* Sum_i = Sum_{i-1} xor ENCIPHER(K, A_i xor Offset_i) */
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ocb3_int_xor_blocks(tmp, aad_block, ocb->aOffset_current, ocb->block_len);
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if ((err = cipher_descriptor[ocb->cipher].ecb_encrypt(tmp, tmp, &ocb->key)) != CRYPT_OK) {
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return err;
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}
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ocb3_int_xor_blocks(ocb->aSum_current, ocb->aSum_current, tmp, ocb->block_len);
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ocb->ablock_index++;
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return CRYPT_OK;
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}
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/**
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Add AAD - additional associated data
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@param ocb The OCB state
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@param aad The AAD data
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@param aadlen The size of AAD data (octets)
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@return CRYPT_OK if successful
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*/
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int ocb3_add_aad(ocb3_state *ocb, const unsigned char *aad, unsigned long aadlen)
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{
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int err, x, full_blocks, full_blocks_len, last_block_len;
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unsigned char *data;
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unsigned long datalen, l;
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LTC_ARGCHK(ocb != NULL);
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if (aadlen == 0) return CRYPT_OK;
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LTC_ARGCHK(aad != NULL);
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if (ocb->adata_buffer_bytes > 0) {
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l = ocb->block_len - ocb->adata_buffer_bytes;
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if (l > aadlen) l = aadlen;
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XMEMCPY(ocb->adata_buffer+ocb->adata_buffer_bytes, aad, l);
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ocb->adata_buffer_bytes += l;
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if (ocb->adata_buffer_bytes == ocb->block_len) {
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if ((err = _ocb3_int_aad_add_block(ocb, ocb->adata_buffer)) != CRYPT_OK) {
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return err;
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}
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ocb->adata_buffer_bytes = 0;
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}
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data = (unsigned char *)aad + l;
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datalen = aadlen - l;
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}
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else {
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data = (unsigned char *)aad;
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datalen = aadlen;
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}
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if (datalen == 0) return CRYPT_OK;
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full_blocks = datalen/ocb->block_len;
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full_blocks_len = full_blocks * ocb->block_len;
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last_block_len = datalen - full_blocks_len;
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for (x=0; x<full_blocks; x++) {
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if ((err = _ocb3_int_aad_add_block(ocb, data+x*ocb->block_len)) != CRYPT_OK) {
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return err;
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}
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}
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if (last_block_len>0) {
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XMEMCPY(ocb->adata_buffer, data+full_blocks_len, last_block_len);
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ocb->adata_buffer_bytes = last_block_len;
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}
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return CRYPT_OK;
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}
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#endif
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/* ref: HEAD -> master, tag: v1.18.2 */
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/* git commit: 7e7eb695d581782f04b24dc444cbfde86af59853 */
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/* commit time: 2018-07-01 22:49:01 +0200 */
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