/**
Terminate an encryption OCB state
@param ocb The OCB state
@param pt Remaining plaintext (if any)
@param ptlen The length of the plaintext (octets)
@param ct [out] The ciphertext (if any)
@param tag [out] The tag for the OCB stream
@param taglen [in/out] The max size and resulting size of the tag
@return CRYPT_OK if successful
*/
int ocb_done_encrypt(ocb_state *ocb, const unsigned char *pt, unsigned long ptlen,
unsigned char *ct, unsigned char *tag, unsigned long *taglen)
{
LTC_ARGCHK(ocb != NULL);
LTC_ARGCHK(pt != NULL);
LTC_ARGCHK(ct != NULL);
LTC_ARGCHK(tag != NULL);
LTC_ARGCHK(taglen != NULL);
return s_ocb_done(ocb, pt, ptlen, ct, tag, taglen, 0);
}
/**
Terminate a decrypting OCB state
@param ocb The OCB state
@param ct The ciphertext (if any)
@param ctlen The length of the ciphertext (octets)
@param pt [out] The plaintext
@param tag The authentication tag (to compare against)
@param taglen The length of the authentication tag provided
@param stat [out] The result of the tag comparison
@return CRYPT_OK if the process was successful regardless if the tag is valid
*/
int ocb_done_decrypt(ocb_state *ocb,
const unsigned char *ct, unsigned long ctlen,
unsigned char *pt,
const unsigned char *tag, unsigned long taglen, int *stat)
{
int err;
unsigned char *tagbuf;
unsigned long tagbuflen;
LTC_ARGCHK(ocb != NULL);
LTC_ARGCHK(pt != NULL);
LTC_ARGCHK(ct != NULL);
LTC_ARGCHK(tag != NULL);
LTC_ARGCHK(stat != NULL);
/* default to failed */
*stat = 0;
/* allocate memory */
tagbuf = XMALLOC(MAXBLOCKSIZE);
if (tagbuf == NULL) {
return CRYPT_MEM;
}
tagbuflen = MAXBLOCKSIZE;
if ((err = s_ocb_done(ocb, ct, ctlen, pt, tagbuf, &tagbuflen, 1)) != CRYPT_OK) {
goto LBL_ERR;
}
if (taglen <= tagbuflen && XMEMCMP(tagbuf, tag, taglen) == 0) {
*stat = 1;
}
err = CRYPT_OK;
LBL_ERR:
#ifdef LTC_CLEAN_STACK
zeromem(tagbuf, MAXBLOCKSIZE);
#endif
XFREE(tagbuf);
return err;
}