view libtomcrypt/src/mac/xcbc/xcbc_memory.c @ 1715:3974f087d9c0

Disallow leading lines before the ident for server (#102) Per RFC4253 4.2 clients must be able to process other lines of data before the version string, server behavior is not defined neither with MUST/SHOULD nor with MAY. If server process up to 50 lines too - it may cause too long hanging session with invalid/evil client that consume host resources and potentially may lead to DDoS on poor embedded boxes. Let's require first line from client to be version string and fail early if it's not - matches both RFC and real OpenSSH behavior.
author Vladislav Grishenko <themiron@users.noreply.github.com>
date Mon, 15 Jun 2020 18:22:18 +0500
parents 6dba84798cd5
children
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/* 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 xcbc_process.c
  XCBC Support, XCBC-MAC a block of memory
*/

#ifdef LTC_XCBC

/** XCBC-MAC a block of memory
  @param cipher     Index of cipher to use
  @param key        [in]  Secret key
  @param keylen     Length of key in octets
  @param in         [in]  Message to MAC
  @param inlen      Length of input in octets
  @param out        [out] Destination for the MAC tag
  @param outlen     [in/out] Output size and final tag size
  Return CRYPT_OK on success.
*/
int xcbc_memory(int cipher,
               const unsigned char *key, unsigned long keylen,
               const unsigned char *in,  unsigned long inlen,
                     unsigned char *out, unsigned long *outlen)
{
   xcbc_state *xcbc;
   int         err;

   /* is the cipher valid? */
   if ((err = cipher_is_valid(cipher)) != CRYPT_OK) {
      return err;
   }

   /* Use accelerator if found */
   if (cipher_descriptor[cipher].xcbc_memory != NULL) {
      return cipher_descriptor[cipher].xcbc_memory(key, keylen, in, inlen, out, outlen);
   }

   xcbc = XCALLOC(1, sizeof(*xcbc));
   if (xcbc == NULL) {
      return CRYPT_MEM;
   }

   if ((err = xcbc_init(xcbc, cipher, key, keylen)) != CRYPT_OK) {
     goto done;
   }

   if ((err = xcbc_process(xcbc, in, inlen)) != CRYPT_OK) {
     goto done;
   }

   err = xcbc_done(xcbc, out, outlen);
done:
   XFREE(xcbc);
   return err;
}

#endif

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