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des_check_key.c

/*
 * Cryptographic API.
 *
 * Function for checking keys for the DES and Tripple DES Encryption
 * algorithms.
 *
 * Originally released as descore by Dana L. How <how@isl.stanford.edu>.
 * Modified by Raimar Falke <rf13@inf.tu-dresden.de> for the Linux-Kernel.
 * Derived from Cryptoapi and Nettle implementations, adapted for in-place
 * scatterlist interface.  Changed LGPL to GPL per section 3 of the LGPL.
 *
 * s390 Version:
 *   Copyright IBM Corp. 2003
 *   Author(s): Thomas Spatzier
 *          Jan Glauber (jan.glauber@de.ibm.com)
 *
 * Derived from "crypto/des.c"
 *   Copyright (c) 1992 Dana L. How.
 *   Copyright (c) Raimar Falke <rf13@inf.tu-dresden.de>
 *   Copyright (c) Gisle Sflensminde <gisle@ii.uib.no>
 *   Copyright (C) 2001 Niels Mvller.
 *   Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 */
#include <linux/init.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/crypto.h>
#include "crypto_des.h"

#define ROR(d,c,o)      ((d) = (d) >> (c) | (d) << (o))

static const u8 parity[] = {
      8,1,0,8,0,8,8,0,0,8,8,0,8,0,2,8,0,8,8,0,8,0,0,8,8,0,0,8,0,8,8,3,
      0,8,8,0,8,0,0,8,8,0,0,8,0,8,8,0,8,0,0,8,0,8,8,0,0,8,8,0,8,0,0,8,
      0,8,8,0,8,0,0,8,8,0,0,8,0,8,8,0,8,0,0,8,0,8,8,0,0,8,8,0,8,0,0,8,
      8,0,0,8,0,8,8,0,0,8,8,0,8,0,0,8,0,8,8,0,8,0,0,8,8,0,0,8,0,8,8,0,
      0,8,8,0,8,0,0,8,8,0,0,8,0,8,8,0,8,0,0,8,0,8,8,0,0,8,8,0,8,0,0,8,
      8,0,0,8,0,8,8,0,0,8,8,0,8,0,0,8,0,8,8,0,8,0,0,8,8,0,0,8,0,8,8,0,
      8,0,0,8,0,8,8,0,0,8,8,0,8,0,0,8,0,8,8,0,8,0,0,8,8,0,0,8,0,8,8,0,
      4,8,8,0,8,0,0,8,8,0,0,8,0,8,8,0,8,5,0,8,0,8,8,0,0,8,8,0,8,0,6,8,
};

/*
 * RFC2451: Weak key checks SHOULD be performed.
 */
int
crypto_des_check_key(const u8 *key, unsigned int keylen, u32 *flags)
{
      u32 n, w;

      n  = parity[key[0]]; n <<= 4;
      n |= parity[key[1]]; n <<= 4;
      n |= parity[key[2]]; n <<= 4;
      n |= parity[key[3]]; n <<= 4;
      n |= parity[key[4]]; n <<= 4;
      n |= parity[key[5]]; n <<= 4;
      n |= parity[key[6]]; n <<= 4;
      n |= parity[key[7]];
      w = 0x88888888L;

      if ((*flags & CRYPTO_TFM_REQ_WEAK_KEY)
          && !((n - (w >> 3)) & w)) {  /* 1 in 10^10 keys passes this test */
            if (n < 0x41415151) {
                  if (n < 0x31312121) {
                        if (n < 0x14141515) {
                              /* 01 01 01 01 01 01 01 01 */
                              if (n == 0x11111111) goto weak;
                              /* 01 1F 01 1F 01 0E 01 0E */
                              if (n == 0x13131212) goto weak;
                        } else {
                              /* 01 E0 01 E0 01 F1 01 F1 */
                              if (n == 0x14141515) goto weak;
                              /* 01 FE 01 FE 01 FE 01 FE */
                              if (n == 0x16161616) goto weak;
                        }
                  } else {
                        if (n < 0x34342525) {
                              /* 1F 01 1F 01 0E 01 0E 01 */
                              if (n == 0x31312121) goto weak;
                              /* 1F 1F 1F 1F 0E 0E 0E 0E (?) */
                              if (n == 0x33332222) goto weak;
                        } else {
                              /* 1F E0 1F E0 0E F1 0E F1 */
                              if (n == 0x34342525) goto weak;
                              /* 1F FE 1F FE 0E FE 0E FE */
                              if (n == 0x36362626) goto weak;
                        }
                  }
            } else {
                  if (n < 0x61616161) {
                        if (n < 0x44445555) {
                              /* E0 01 E0 01 F1 01 F1 01 */
                              if (n == 0x41415151) goto weak;
                              /* E0 1F E0 1F F1 0E F1 0E */
                              if (n == 0x43435252) goto weak;
                        } else {
                              /* E0 E0 E0 E0 F1 F1 F1 F1 (?) */
                              if (n == 0x44445555) goto weak;
                              /* E0 FE E0 FE F1 FE F1 FE */
                              if (n == 0x46465656) goto weak;
                        }
                  } else {
                        if (n < 0x64646565) {
                              /* FE 01 FE 01 FE 01 FE 01 */
                              if (n == 0x61616161) goto weak;
                              /* FE 1F FE 1F FE 0E FE 0E */
                              if (n == 0x63636262) goto weak;
                        } else {
                              /* FE E0 FE E0 FE F1 FE F1 */
                              if (n == 0x64646565) goto weak;
                              /* FE FE FE FE FE FE FE FE */
                              if (n == 0x66666666) goto weak;
                        }
                  }
            }
      }
      return 0;
weak:
      *flags |= CRYPTO_TFM_RES_WEAK_KEY;
      return -EINVAL;
}

EXPORT_SYMBOL(crypto_des_check_key);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Key Check function for DES &  DES3 Cipher Algorithms");

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