Mercurial > dropbear
view libtomcrypt/src/encauth/ocb3/ocb3_done.c @ 1686:83d48276885b
fix typo
author | Matt Johnston <matt@ucc.asn.au> |
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date | Tue, 26 May 2020 20:15:00 +0800 |
parents | 6dba84798cd5 |
children |
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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_done.c OCB implementation, INTERNAL ONLY helper, by Tom St Denis */ #include "tomcrypt.h" #ifdef LTC_OCB3_MODE /** Finish OCB processing and compute the tag @param ocb The OCB state @param tag [out] The destination for the authentication tag @param taglen [in/out] The max size and resulting size of the authentication tag @return CRYPT_OK if successful */ int ocb3_done(ocb3_state *ocb, unsigned char *tag, unsigned long *taglen) { unsigned char tmp[MAXBLOCKSIZE]; int err, x; LTC_ARGCHK(ocb != NULL); LTC_ARGCHK(tag != NULL); LTC_ARGCHK(taglen != NULL); if ((err = cipher_is_valid(ocb->cipher)) != CRYPT_OK) { goto LBL_ERR; } /* check taglen */ if ((int)*taglen < ocb->tag_len) { *taglen = (unsigned long)ocb->tag_len; return CRYPT_BUFFER_OVERFLOW; } /* finalize AAD processing */ if (ocb->adata_buffer_bytes>0) { /* Offset_* = Offset_m xor L_* */ ocb3_int_xor_blocks(ocb->aOffset_current, ocb->aOffset_current, ocb->L_star, ocb->block_len); /* CipherInput = (A_* || 1 || zeros(127-bitlen(A_*))) xor Offset_* */ ocb3_int_xor_blocks(tmp, ocb->adata_buffer, ocb->aOffset_current, ocb->adata_buffer_bytes); for(x=ocb->adata_buffer_bytes; x<ocb->block_len; x++) { if (x == ocb->adata_buffer_bytes) { tmp[x] = 0x80 ^ ocb->aOffset_current[x]; } else { tmp[x] = 0x00 ^ ocb->aOffset_current[x]; } } /* Sum = Sum_m xor ENCIPHER(K, CipherInput) */ if ((err = cipher_descriptor[ocb->cipher].ecb_encrypt(tmp, tmp, &ocb->key)) != CRYPT_OK) { goto LBL_ERR; } ocb3_int_xor_blocks(ocb->aSum_current, ocb->aSum_current, tmp, ocb->block_len); } /* finalize TAG computing */ /* at this point ocb->aSum_current = HASH(K, A) */ /* tag = tag ^ HASH(K, A) */ ocb3_int_xor_blocks(tmp, ocb->tag_part, ocb->aSum_current, ocb->block_len); /* copy tag bytes */ for(x = 0; x < ocb->tag_len; x++) tag[x] = tmp[x]; *taglen = (unsigned long)ocb->tag_len; err = CRYPT_OK; LBL_ERR: #ifdef LTC_CLEAN_STACK zeromem(tmp, MAXBLOCKSIZE); zeromem(ocb, sizeof(*ocb)); #endif return err; } #endif /* ref: $Format:%D$ */ /* git commit: $Format:%H$ */ /* commit time: $Format:%ai$ */