view libtomcrypt/src/hashes/md4.c @ 1790:42745af83b7d

Introduce extra delay before closing unauthenticated sessions To make it harder for attackers, introduce a delay to keep an unauthenticated session open a bit longer, thus blocking a connection slot until after the delay. Without this, while there is a limit on the amount of attempts an attacker can make at the same time (MAX_UNAUTH_PER_IP), the time taken by dropbear to handle one attempt is still short and thus for each of the allowed parallel attempts many attempts can be chained one after the other. The attempt rate is then: "MAX_UNAUTH_PER_IP / <process time of one attempt>". With the delay, this rate becomes: "MAX_UNAUTH_PER_IP / UNAUTH_CLOSE_DELAY".
author Thomas De Schampheleire <thomas.de_schampheleire@nokia.com>
date Wed, 15 Feb 2017 13:53:04 +0100
parents 6dba84798cd5
children
line wrap: on
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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"

/**
   @param md4.c
   Submitted by Dobes Vandermeer  ([email protected])
*/

#ifdef LTC_MD4

const struct ltc_hash_descriptor md4_desc =
{
    "md4",
    6,
    16,
    64,

    /* OID */
   { 1, 2, 840, 113549, 2, 4,  },
   6,

    &md4_init,
    &md4_process,
    &md4_done,
    &md4_test,
    NULL
};

#define S11 3
#define S12 7
#define S13 11
#define S14 19
#define S21 3
#define S22 5
#define S23 9
#define S24 13
#define S31 3
#define S32 9
#define S33 11
#define S34 15

/* F, G and H are basic LTC_MD4 functions. */
#define F(x, y, z) (z ^ (x & (y ^ z)))
#define G(x, y, z) ((x & y) | (z & (x | y)))
#define H(x, y, z) ((x) ^ (y) ^ (z))

/* ROTATE_LEFT rotates x left n bits. */
#define ROTATE_LEFT(x, n) ROLc(x, n)

/* FF, GG and HH are transformations for rounds 1, 2 and 3 */
/* Rotation is separate from addition to prevent recomputation */

#define FF(a, b, c, d, x, s) { \
    (a) += F ((b), (c), (d)) + (x); \
    (a) = ROTATE_LEFT ((a), (s)); \
  }
#define GG(a, b, c, d, x, s) { \
    (a) += G ((b), (c), (d)) + (x) + 0x5a827999UL; \
    (a) = ROTATE_LEFT ((a), (s)); \
  }
#define HH(a, b, c, d, x, s) { \
    (a) += H ((b), (c), (d)) + (x) + 0x6ed9eba1UL; \
    (a) = ROTATE_LEFT ((a), (s)); \
  }

#ifdef LTC_CLEAN_STACK
static int _md4_compress(hash_state *md, unsigned char *buf)
#else
static int  md4_compress(hash_state *md, unsigned char *buf)
#endif
{
    ulong32 x[16], a, b, c, d;
    int i;

    /* copy state */
    a = md->md4.state[0];
    b = md->md4.state[1];
    c = md->md4.state[2];
    d = md->md4.state[3];

    /* copy the state into 512-bits into W[0..15] */
    for (i = 0; i < 16; i++) {
        LOAD32L(x[i], buf + (4*i));
    }

    /* Round 1 */
    FF (a, b, c, d, x[ 0], S11); /* 1 */
    FF (d, a, b, c, x[ 1], S12); /* 2 */
    FF (c, d, a, b, x[ 2], S13); /* 3 */
    FF (b, c, d, a, x[ 3], S14); /* 4 */
    FF (a, b, c, d, x[ 4], S11); /* 5 */
    FF (d, a, b, c, x[ 5], S12); /* 6 */
    FF (c, d, a, b, x[ 6], S13); /* 7 */
    FF (b, c, d, a, x[ 7], S14); /* 8 */
    FF (a, b, c, d, x[ 8], S11); /* 9 */
    FF (d, a, b, c, x[ 9], S12); /* 10 */
    FF (c, d, a, b, x[10], S13); /* 11 */
    FF (b, c, d, a, x[11], S14); /* 12 */
    FF (a, b, c, d, x[12], S11); /* 13 */
    FF (d, a, b, c, x[13], S12); /* 14 */
    FF (c, d, a, b, x[14], S13); /* 15 */
    FF (b, c, d, a, x[15], S14); /* 16 */

    /* Round 2 */
    GG (a, b, c, d, x[ 0], S21); /* 17 */
    GG (d, a, b, c, x[ 4], S22); /* 18 */
    GG (c, d, a, b, x[ 8], S23); /* 19 */
    GG (b, c, d, a, x[12], S24); /* 20 */
    GG (a, b, c, d, x[ 1], S21); /* 21 */
    GG (d, a, b, c, x[ 5], S22); /* 22 */
    GG (c, d, a, b, x[ 9], S23); /* 23 */
    GG (b, c, d, a, x[13], S24); /* 24 */
    GG (a, b, c, d, x[ 2], S21); /* 25 */
    GG (d, a, b, c, x[ 6], S22); /* 26 */
    GG (c, d, a, b, x[10], S23); /* 27 */
    GG (b, c, d, a, x[14], S24); /* 28 */
    GG (a, b, c, d, x[ 3], S21); /* 29 */
    GG (d, a, b, c, x[ 7], S22); /* 30 */
    GG (c, d, a, b, x[11], S23); /* 31 */
    GG (b, c, d, a, x[15], S24); /* 32 */

    /* Round 3 */
    HH (a, b, c, d, x[ 0], S31); /* 33 */
    HH (d, a, b, c, x[ 8], S32); /* 34 */
    HH (c, d, a, b, x[ 4], S33); /* 35 */
    HH (b, c, d, a, x[12], S34); /* 36 */
    HH (a, b, c, d, x[ 2], S31); /* 37 */
    HH (d, a, b, c, x[10], S32); /* 38 */
    HH (c, d, a, b, x[ 6], S33); /* 39 */
    HH (b, c, d, a, x[14], S34); /* 40 */
    HH (a, b, c, d, x[ 1], S31); /* 41 */
    HH (d, a, b, c, x[ 9], S32); /* 42 */
    HH (c, d, a, b, x[ 5], S33); /* 43 */
    HH (b, c, d, a, x[13], S34); /* 44 */
    HH (a, b, c, d, x[ 3], S31); /* 45 */
    HH (d, a, b, c, x[11], S32); /* 46 */
    HH (c, d, a, b, x[ 7], S33); /* 47 */
    HH (b, c, d, a, x[15], S34); /* 48 */


    /* Update our state */
    md->md4.state[0] = md->md4.state[0] + a;
    md->md4.state[1] = md->md4.state[1] + b;
    md->md4.state[2] = md->md4.state[2] + c;
    md->md4.state[3] = md->md4.state[3] + d;

    return CRYPT_OK;
}

#ifdef LTC_CLEAN_STACK
static int md4_compress(hash_state *md, unsigned char *buf)
{
   int err;
   err = _md4_compress(md, buf);
   burn_stack(sizeof(ulong32) * 20 + sizeof(int));
   return err;
}
#endif

/**
   Initialize the hash state
   @param md   The hash state you wish to initialize
   @return CRYPT_OK if successful
*/
int md4_init(hash_state * md)
{
   LTC_ARGCHK(md != NULL);
   md->md4.state[0] = 0x67452301UL;
   md->md4.state[1] = 0xefcdab89UL;
   md->md4.state[2] = 0x98badcfeUL;
   md->md4.state[3] = 0x10325476UL;
   md->md4.length  = 0;
   md->md4.curlen  = 0;
   return CRYPT_OK;
}

/**
   Process a block of memory though the hash
   @param md     The hash state
   @param in     The data to hash
   @param inlen  The length of the data (octets)
   @return CRYPT_OK if successful
*/
HASH_PROCESS(md4_process, md4_compress, md4, 64)

/**
   Terminate the hash to get the digest
   @param md  The hash state
   @param out [out] The destination of the hash (16 bytes)
   @return CRYPT_OK if successful
*/
int md4_done(hash_state * md, unsigned char *out)
{
    int i;

    LTC_ARGCHK(md  != NULL);
    LTC_ARGCHK(out != NULL);

    if (md->md4.curlen >= sizeof(md->md4.buf)) {
       return CRYPT_INVALID_ARG;
    }

    /* increase the length of the message */
    md->md4.length += md->md4.curlen * 8;

    /* append the '1' bit */
    md->md4.buf[md->md4.curlen++] = (unsigned char)0x80;

    /* if the length is currently above 56 bytes we append zeros
     * then compress.  Then we can fall back to padding zeros and length
     * encoding like normal.
     */
    if (md->md4.curlen > 56) {
        while (md->md4.curlen < 64) {
            md->md4.buf[md->md4.curlen++] = (unsigned char)0;
        }
        md4_compress(md, md->md4.buf);
        md->md4.curlen = 0;
    }

    /* pad upto 56 bytes of zeroes */
    while (md->md4.curlen < 56) {
        md->md4.buf[md->md4.curlen++] = (unsigned char)0;
    }

    /* store length */
    STORE64L(md->md4.length, md->md4.buf+56);
    md4_compress(md, md->md4.buf);

    /* copy output */
    for (i = 0; i < 4; i++) {
        STORE32L(md->md4.state[i], out+(4*i));
    }
#ifdef LTC_CLEAN_STACK
    zeromem(md, sizeof(hash_state));
#endif
    return CRYPT_OK;
}

/**
  Self-test the hash
  @return CRYPT_OK if successful, CRYPT_NOP if self-tests have been disabled
*/
int md4_test(void)
{
 #ifndef LTC_TEST
    return CRYPT_NOP;
 #else
    static const struct md4_test_case {
        const char *input;
        unsigned char hash[16];
    } tests[] = {
        { "",
          {0x31, 0xd6, 0xcf, 0xe0, 0xd1, 0x6a, 0xe9, 0x31,
           0xb7, 0x3c, 0x59, 0xd7, 0xe0, 0xc0, 0x89, 0xc0} },
        { "a",
          {0xbd, 0xe5, 0x2c, 0xb3, 0x1d, 0xe3, 0x3e, 0x46,
           0x24, 0x5e, 0x05, 0xfb, 0xdb, 0xd6, 0xfb, 0x24} },
        { "abc",
          {0xa4, 0x48, 0x01, 0x7a, 0xaf, 0x21, 0xd8, 0x52,
           0x5f, 0xc1, 0x0a, 0xe8, 0x7a, 0xa6, 0x72, 0x9d} },
        { "message digest",
          {0xd9, 0x13, 0x0a, 0x81, 0x64, 0x54, 0x9f, 0xe8,
           0x18, 0x87, 0x48, 0x06, 0xe1, 0xc7, 0x01, 0x4b} },
        { "abcdefghijklmnopqrstuvwxyz",
          {0xd7, 0x9e, 0x1c, 0x30, 0x8a, 0xa5, 0xbb, 0xcd,
           0xee, 0xa8, 0xed, 0x63, 0xdf, 0x41, 0x2d, 0xa9} },
        { "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789",
          {0x04, 0x3f, 0x85, 0x82, 0xf2, 0x41, 0xdb, 0x35,
           0x1c, 0xe6, 0x27, 0xe1, 0x53, 0xe7, 0xf0, 0xe4} },
        { "12345678901234567890123456789012345678901234567890123456789012345678901234567890",
          {0xe3, 0x3b, 0x4d, 0xdc, 0x9c, 0x38, 0xf2, 0x19,
           0x9c, 0x3e, 0x7b, 0x16, 0x4f, 0xcc, 0x05, 0x36} },
    };

    int i;
    unsigned char tmp[16];
    hash_state md;

    for(i = 0; i < (int)(sizeof(tests) / sizeof(tests[0])); i++) {
        md4_init(&md);
        md4_process(&md, (unsigned char *)tests[i].input, (unsigned long)strlen(tests[i].input));
        md4_done(&md, tmp);
        if (compare_testvector(tmp, sizeof(tmp), tests[i].hash, sizeof(tests[i].hash), "MD4", i)) {
           return CRYPT_FAIL_TESTVECTOR;
        }

    }
    return CRYPT_OK;
  #endif
}

#endif



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