options: Complete the transition to numeric toggles (`#if') For the sake of review, this commit alters only the code; the affiliated comments within the source files also need to be updated, but doing so now would obscure the operational changes that have been made here. * All on/off options have been switched to the numeric `#if' variant; that is the only way to make this `default_options.h.in' thing work in a reasonable manner. * There is now some very minor compile-time checking of the user's choice of options. * NO_FAST_EXPTMOD doesn't seem to be used, so it has been removed. * ENABLE_USER_ALGO_LIST was supposed to be renamed DROPBEAR_USER_ALGO_LIST, and this commit completes that work. * DROPBEAR_FUZZ seems to be a relatively new, as-yet undocumented option, which was added by the following commit: commit 6e0b539e9ca0b5628c6c5a3d118ad6a2e79e8039 Author: Matt Johnston <[email protected]> Date: Tue May 23 22:29:21 2017 +0800 split out checkpubkey_line() separately It has now been added to `sysoptions.h' and defined as `0' by default. * The configuration option `DROPBEAR_PASSWORD_ENV' is no longer listed in `default_options.h.in'; it is no longer meant to be set by the user, and is instead left to be defined in `sysoptions.h' (where it was already being defined) as merely the name of the environment variable in question: DROPBEAR_PASSWORD To enable or disable use of that environment variable, the user must now toggle `DROPBEAR_USE_DROPBEAR_PASSWORD'. * The sFTP support is now toggled by setting `DROPBEAR_SFTPSERVER', and the path of the sFTP server program is set independently through the usual SFTPSERVER_PATH.

/* LibTomCrypt, modular cryptographic library -- Tom St Denis
 *
 * LibTomCrypt is a library that provides various cryptographic
 * algorithms in a highly modular and flexible manner.
 *
 * The library is free for all purposes without any express
 * guarantee it works.
 */
#include "tomcrypt.h"

/**
  @file ofb_encrypt.c
  OFB implementation, encrypt data, Tom St Denis
*/

#ifdef LTC_OFB_MODE

/**
  OFB encrypt
  @param pt     Plaintext
  @param ct     [out] Ciphertext
  @param len    Length of plaintext (octets)
  @param ofb    OFB state
  @return CRYPT_OK if successful
*/
int ofb_encrypt(const unsigned char *pt, unsigned char *ct, unsigned long len, symmetric_OFB *ofb)
{
   int err;
   LTC_ARGCHK(pt != NULL);
   LTC_ARGCHK(ct != NULL);
   LTC_ARGCHK(ofb != NULL);
   if ((err = cipher_is_valid(ofb->cipher)) != CRYPT_OK) {
       return err;
   }

   /* is blocklen/padlen valid? */
   if (ofb->blocklen < 0 || ofb->blocklen > (int)sizeof(ofb->IV) ||
       ofb->padlen   < 0 || ofb->padlen   > (int)sizeof(ofb->IV)) {
      return CRYPT_INVALID_ARG;
   }

   while (len-- > 0) {
       if (ofb->padlen == ofb->blocklen) {
          if ((err = cipher_descriptor[ofb->cipher].ecb_encrypt(ofb->IV, ofb->IV, &ofb->key)) != CRYPT_OK) {
             return err;
          }
          ofb->padlen = 0;
       }
       *ct++ = *pt++ ^ ofb->IV[(ofb->padlen)++];
   }
   return CRYPT_OK;
}

#endif

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