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Import code from previous AssetBuilder version

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Jan
2019-09-24 10:45:09 +02:00
parent 5609557516
commit 0d8432d4f7
919 changed files with 154412 additions and 26 deletions
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110
thirdparty/libtomcrypt/encauth/ocb3/ocb3_decrypt_last.c vendored Normal file
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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.
*/
/**
@file ocb3_decrypt_last.c
OCB implementation, internal helper, by Karel Miko
*/
#include "tomcrypt.h"
#ifdef LTC_OCB3_MODE
/**
Finish an OCB (decryption) stream
@param ocb The OCB state
@param ct The remaining ciphertext
@param ctlen The length of the ciphertext (octets)
@param pt [out] The output buffer
@return CRYPT_OK if successful
*/
int ocb3_decrypt_last(ocb3_state *ocb, const unsigned char *ct, unsigned long ctlen, unsigned char *pt)
{
unsigned char iOffset_star[MAXBLOCKSIZE];
unsigned char iPad[MAXBLOCKSIZE];
int err, x, full_blocks, full_blocks_len, last_block_len;
LTC_ARGCHK(ocb != NULL);
if (ct == NULL) LTC_ARGCHK(ctlen == 0);
if (ctlen != 0) {
LTC_ARGCHK(ct != NULL);
LTC_ARGCHK(pt != NULL);
}
if ((err = cipher_is_valid(ocb->cipher)) != CRYPT_OK) {
goto LBL_ERR;
}
full_blocks = ctlen/ocb->block_len;
full_blocks_len = full_blocks * ocb->block_len;
last_block_len = ctlen - full_blocks_len;
/* process full blocks first */
if (full_blocks>0) {
if ((err = ocb3_decrypt(ocb, ct, full_blocks_len, pt)) != CRYPT_OK) {
goto LBL_ERR;
}
}
if (last_block_len>0) {
/* Offset_* = Offset_m xor L_* */
ocb3_int_xor_blocks(iOffset_star, ocb->Offset_current, ocb->L_star, ocb->block_len);
/* Pad = ENCIPHER(K, Offset_*) */
if ((err = cipher_descriptor[ocb->cipher].ecb_encrypt(iOffset_star, iPad, &ocb->key)) != CRYPT_OK) {
goto LBL_ERR;
}
/* P_* = C_* xor Pad[1..bitlen(C_*)] */
ocb3_int_xor_blocks(pt+full_blocks_len, (unsigned char *)ct+full_blocks_len, iPad, last_block_len);
/* Checksum_* = Checksum_m xor (P_* || 1 || zeros(127-bitlen(P_*))) */
ocb3_int_xor_blocks(ocb->checksum, ocb->checksum, pt+full_blocks_len, last_block_len);
for(x=last_block_len; x<ocb->block_len; x++) {
if (x == last_block_len)
ocb->checksum[x] ^= 0x80;
else
ocb->checksum[x] ^= 0x00;
}
/* Tag = ENCIPHER(K, Checksum_* xor Offset_* xor L_$) xor HASH(K,A) */
/* at this point we calculate only: Tag_part = ENCIPHER(K, Checksum_* xor Offset_* xor L_$) */
for(x=0; x<ocb->block_len; x++) {
ocb->tag_part[x] = (ocb->checksum[x] ^ iOffset_star[x]) ^ ocb->L_dollar[x];
}
if ((err = cipher_descriptor[ocb->cipher].ecb_encrypt(ocb->tag_part, ocb->tag_part, &ocb->key)) != CRYPT_OK) {
goto LBL_ERR;
}
}
else {
/* Tag = ENCIPHER(K, Checksum_m xor Offset_m xor L_$) xor HASH(K,A) */
/* at this point we calculate only: Tag_part = ENCIPHER(K, Checksum_m xor Offset_m xor L_$) */
for(x=0; x<ocb->block_len; x++) {
ocb->tag_part[x] = (ocb->checksum[x] ^ ocb->Offset_current[x]) ^ ocb->L_dollar[x];
}
if ((err = cipher_descriptor[ocb->cipher].ecb_encrypt(ocb->tag_part, ocb->tag_part, &ocb->key)) != CRYPT_OK) {
goto LBL_ERR;
}
}
err = CRYPT_OK;
LBL_ERR:
#ifdef LTC_CLEAN_STACK
zeromem(iOffset_star, MAXBLOCKSIZE);
zeromem(iPad, MAXBLOCKSIZE);
#endif
return err;
}
#endif
/* ref: HEAD -> master, tag: v1.18.2 */
/* git commit: 7e7eb695d581782f04b24dc444cbfde86af59853 */
/* commit time: 2018-07-01 22:49:01 +0200 */