5 int ofb_start(int cipher, const unsigned char *IV, const unsigned char *key,
6 int keylen, int num_rounds, symmetric_OFB *ofb)
14 if ((err = cipher_is_valid(cipher)) != CRYPT_OK) {
20 ofb->blocklen = cipher_descriptor[cipher].block_length;
21 for (x = 0; x < ofb->blocklen; x++) {
26 ofb->padlen = ofb->blocklen;
27 return cipher_descriptor[cipher].setup(key, keylen, num_rounds, &ofb->key);
30 int ofb_encrypt(const unsigned char *pt, unsigned char *ct, unsigned long len, symmetric_OFB *ofb)
36 if ((err = cipher_is_valid(ofb->cipher)) != CRYPT_OK) {
40 /* is blocklen/padlen valid? */
41 if (ofb->blocklen < 0 || ofb->blocklen > (int)sizeof(ofb->IV) ||
42 ofb->padlen < 0 || ofb->padlen > (int)sizeof(ofb->IV)) {
43 return CRYPT_INVALID_ARG;
47 if (ofb->padlen == ofb->blocklen) {
48 cipher_descriptor[ofb->cipher].ecb_encrypt(ofb->IV, ofb->IV, &ofb->key);
51 *ct++ = *pt++ ^ ofb->IV[ofb->padlen++];
56 int ofb_decrypt(const unsigned char *ct, unsigned char *pt, unsigned long len, symmetric_OFB *ofb)
61 return ofb_encrypt(ct, pt, len, ofb);