int ccmode_ctr_init(const struct ccmode_ctr *ctr, ccctr_ctx *key, size_t rawkey_len, const void *rawkey, const void *iv) { int rc; const struct ccmode_ecb *ecb = ctr->custom; CCMODE_CTR_KEY_ECB(key) = ecb; rc = ecb->init(ecb, CCMODE_CTR_KEY_ECB_KEY(key), rawkey_len, rawkey); ccctr_setctr(ctr, key, iv); return rc; }
void ccmode_ctr_crypt(ccctr_ctx *key, size_t nbytes, const void *in, void *out) { const struct ccmode_ecb *ecb = CCMODE_CTR_KEY_ECB(key); const ccecb_ctx *ecb_key = CCMODE_CTR_KEY_ECB_KEY(key); uint8_t *ctr = (uint8_t *)CCMODE_CTR_KEY_CTR(key); uint8_t *pad = (uint8_t *)CCMODE_CTR_KEY_PAD(key); cc_size pad_len = CCMODE_CTR_KEY_PAD_LEN(key); const uint8_t *pt = in; // Counter is 64bit wide for cipher with block size of 64bit or more // This is to match the assembly const size_t counter_size=(CC_MIN(ecb->block_size,(typeof(ecb->block_size))8)); uint8_t *ct = out; while (nbytes) { if (pad_len == ecb->block_size) { ecb->ecb(ecb_key, 1, ctr, pad); pad_len = 0; /* increment the big endian counter */ for (size_t x = ecb->block_size; x-- > (ecb->block_size-counter_size);) { ctr[x] = (ctr[x] + (unsigned char)1) & (unsigned char)255; if (ctr[x] != (unsigned char)0) { break; } } if (nbytes==0) break; } /* TODO: Make sure this works. If pt and ct aren't aligned this might not work right. */ #if 0 if (pad_len == 0 && nbytes >= ecb->block_size) { ccn_xor(ecb->block_size / CCN_UNIT_SIZE, ct, pt, pad); pad_len = ecb->block_size; pt += pad_len; ct += pad_len; nbytes -= pad_len; } #endif do { *ct++ = *pt++ ^ pad[pad_len++]; --nbytes; } while ((nbytes>0)&&(pad_len<ecb->block_size)); } CCMODE_CTR_KEY_PAD_LEN(key) = pad_len; }