/**
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 && XMEM_NEQ(tagbuf, tag, taglen) == 0) {
*stat = 1;
}
err = CRYPT_OK;
LBL_ERR:
#ifdef LTC_CLEAN_STACK
zeromem(tagbuf, MAXBLOCKSIZE);
#endif
XFREE(tagbuf);
return err;
}
/**
Decrypt a block of memory and verify the provided MAC tag with EAX
@param cipher The index of the cipher desired
@param key The secret key
@param keylen The length of the key (octets)
@param nonce The nonce data (use once) for the session
@param noncelen The length of the nonce data.
@param header The session header data
@param headerlen The length of the header (octets)
@param ct The ciphertext
@param ctlen The length of the ciphertext (octets)
@param pt [out] The plaintext
@param tag The authentication tag provided by the encoder
@param taglen [in/out] The length of the tag (octets)
@param stat [out] The result of the decryption (1==valid tag, 0==invalid)
@return CRYPT_OK if successful regardless of the resulting tag comparison
*/
int eax_decrypt_verify_memory(int cipher,
const unsigned char *key, unsigned long keylen,
const unsigned char *nonce, unsigned long noncelen,
const unsigned char *header, unsigned long headerlen,
const unsigned char *ct, unsigned long ctlen,
unsigned char *pt,
unsigned char *tag, unsigned long taglen,
int *stat)
{
int err;
eax_state *eax;
unsigned char *buf;
unsigned long buflen;
LTC_ARGCHK(stat != NULL);
LTC_ARGCHK(key != NULL);
LTC_ARGCHK(pt != NULL);
LTC_ARGCHK(ct != NULL);
LTC_ARGCHK(tag != NULL);
/* default to zero */
*stat = 0;
/* limit taglen */
taglen = MIN(taglen, MAXBLOCKSIZE);
/* allocate ram */
buf = XMALLOC(taglen);
eax = XMALLOC(sizeof(*eax));
if (eax == NULL || buf == NULL) {
if (eax != NULL) {
XFREE(eax);
}
if (buf != NULL) {
XFREE(buf);
}
return CRYPT_MEM;
}
if ((err = eax_init(eax, cipher, key, keylen, nonce, noncelen, header, headerlen)) != CRYPT_OK) {
goto LBL_ERR;
}
if ((err = eax_decrypt(eax, ct, pt, ctlen)) != CRYPT_OK) {
goto LBL_ERR;
}
buflen = taglen;
if ((err = eax_done(eax, buf, &buflen)) != CRYPT_OK) {
goto LBL_ERR;
}
/* compare tags */
if (buflen >= taglen && XMEM_NEQ(buf, tag, taglen) == 0) {
*stat = 1;
}
err = CRYPT_OK;
LBL_ERR:
#ifdef LTC_CLEAN_STACK
zeromem(buf, taglen);
zeromem(eax, sizeof(*eax));
#endif
XFREE(eax);
XFREE(buf);
return err;
}
int ecc_dp_set_by_oid(ltc_ecc_set_type *dp, unsigned long *oid, unsigned long oidsize)
{
int i;
unsigned long len;
for(i=0; ltc_ecc_sets[i].size != 0; i++) {
if ((oidsize == ltc_ecc_sets[i].oid.OIDlen) &&
(XMEM_NEQ(oid, ltc_ecc_sets[i].oid.OID, sizeof(unsigned long) * ltc_ecc_sets[i].oid.OIDlen) == 0)) {
break;
}
}
if (ltc_ecc_sets[i].size == 0) return CRYPT_INVALID_ARG; /* not found */
/* a */
len = (unsigned long)strlen(ltc_ecc_sets[i].A);
if ((dp->A = XMALLOC(1+len)) == NULL) goto cleanup1;
strncpy(dp->A, ltc_ecc_sets[i].A, 1+len);
/* b */
len = (unsigned long)strlen(ltc_ecc_sets[i].B);
if ((dp->B = XMALLOC(1+len)) == NULL) goto cleanup2;
strncpy(dp->B, ltc_ecc_sets[i].B, 1+len);
/* order */
len = (unsigned long)strlen(ltc_ecc_sets[i].order);
if ((dp->order = XMALLOC(1+len)) == NULL) goto cleanup3;
strncpy(dp->order, ltc_ecc_sets[i].order, 1+len);
/* prime */
len = (unsigned long)strlen(ltc_ecc_sets[i].prime);
if ((dp->prime = XMALLOC(1+len)) == NULL) goto cleanup4;
strncpy(dp->prime, ltc_ecc_sets[i].prime, 1+len);
/* gx */
len = (unsigned long)strlen(ltc_ecc_sets[i].Gx);
if ((dp->Gx = XMALLOC(1+len)) == NULL) goto cleanup5;
strncpy(dp->Gx, ltc_ecc_sets[i].Gx, 1+len);
/* gy */
len = (unsigned long)strlen(ltc_ecc_sets[i].Gy);
if ((dp->Gy = XMALLOC(1+len)) == NULL) goto cleanup6;
strncpy(dp->Gy, ltc_ecc_sets[i].Gy, 1+len);
/* cofactor & size */
dp->cofactor = ltc_ecc_sets[i].cofactor;
dp->size = ltc_ecc_sets[i].size;
/* name */
len = (unsigned long)strlen(ltc_ecc_sets[i].name);
if ((dp->name = XMALLOC(1+len)) == NULL) goto cleanup7;
strncpy(dp->name, ltc_ecc_sets[i].name, 1+len);
/* oid */
dp->oid.OIDlen = ltc_ecc_sets[i].oid.OIDlen;
XMEMCPY(dp->oid.OID, ltc_ecc_sets[i].oid.OID, dp->oid.OIDlen * sizeof(dp->oid.OID[0]));
/* done - success */
return CRYPT_OK;
cleanup7:
XFREE(dp->Gy);
cleanup6:
XFREE(dp->Gx);
cleanup5:
XFREE(dp->prime);
cleanup4:
XFREE(dp->order);
cleanup3:
XFREE(dp->B);
cleanup2:
XFREE(dp->A);
cleanup1:
return CRYPT_MEM;
}
/**
Decrypt and compare the tag with OCB
@param cipher The index of the cipher desired
@param key The secret key
@param keylen The length of the secret key (octets)
@param nonce The session nonce (length of the block size of the block cipher)
@param noncelen The length of the nonce (octets)
@param adata The AAD - additional associated data
@param adatalen The length of AAD (octets)
@param ct The ciphertext
@param ctlen The length of the ciphertext (octets)
@param pt [out] The plaintext
@param tag The tag to compare against
@param taglen The length of the tag (octets)
@param stat [out] The result of the tag comparison (1==valid, 0==invalid)
@return CRYPT_OK if successful regardless of the tag comparison
*/
int ocb3_decrypt_verify_memory(int cipher,
const unsigned char *key, unsigned long keylen,
const unsigned char *nonce, unsigned long noncelen,
const unsigned char *adata, unsigned long adatalen,
const unsigned char *ct, unsigned long ctlen,
unsigned char *pt,
const unsigned char *tag, unsigned long taglen,
int *stat)
{
int err;
ocb3_state *ocb;
unsigned char *buf;
unsigned long buflen;
LTC_ARGCHK(stat != NULL);
/* default to zero */
*stat = 0;
/* limit taglen */
taglen = MIN(taglen, MAXBLOCKSIZE);
/* allocate memory */
buf = XMALLOC(taglen);
ocb = XMALLOC(sizeof(ocb3_state));
if (ocb == NULL || buf == NULL) {
if (ocb != NULL) {
XFREE(ocb);
}
if (buf != NULL) {
XFREE(buf);
}
return CRYPT_MEM;
}
if ((err = ocb3_init(ocb, cipher, key, keylen, nonce, noncelen, taglen)) != CRYPT_OK) {
goto LBL_ERR;
}
if (adata != NULL || adatalen != 0) {
if ((err = ocb3_add_aad(ocb, adata, adatalen)) != CRYPT_OK) {
goto LBL_ERR;
}
}
if ((err = ocb3_decrypt_last(ocb, ct, ctlen, pt)) != CRYPT_OK) {
goto LBL_ERR;
}
buflen = taglen;
if ((err = ocb3_done(ocb, buf, &buflen)) != CRYPT_OK) {
goto LBL_ERR;
}
/* compare tags */
if (buflen >= taglen && XMEM_NEQ(buf, tag, taglen) == 0) {
*stat = 1;
}
err = CRYPT_OK;
LBL_ERR:
#ifdef LTC_CLEAN_STACK
zeromem(ocb, sizeof(ocb3_state));
#endif
XFREE(ocb);
XFREE(buf);
return err;
}