text: /*
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   * corecrypto Internal Use License Agreement
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   * EA1350 
   * 10/5/15
   */
  
  
  #include "ccmode_internal.h"
  
  void ccmode_cfb_decrypt(cccfb_ctx *key,
                          size_t nbytes, const void *in, void *out) {
      const struct ccmode_ecb *ecb = CCMODE_CFB_KEY_ECB(key);
      const ccecb_ctx *ecb_key = CCMODE_CFB_KEY_ECB_KEY(key);
      uint8_t *iv = (uint8_t *)CCMODE_CFB_KEY_IV(key);
      uint8_t *pad = (uint8_t *)CCMODE_CFB_KEY_PAD(key);
      cc_size pad_len = CCMODE_CFB_KEY_PAD_LEN(key);
      const uint8_t *ct = in;
      uint8_t *pt = out;
  
      while (nbytes-- != 0) {
          if (pad_len == ecb->block_size) {
              ecb->ecb(ecb_key, 1, iv, pad);
              pad_len = 0;
          }
  
          iv[pad_len] = *ct;
          *pt++ = *ct++ ^ pad[pad_len++];
      }
      CCMODE_CFB_KEY_PAD_LEN(key) = pad_len;
  }
  