Mercurial > dropbear
view libtomcrypt/src/pk/dh/dh.c @ 397:2908122e9eed channel-fix
disapproval of revision '1250b8af44b62d8f4fe0f8d9fc7e7a1cc34e7e1c'
author | Matt Johnston <matt@ucc.asn.au> |
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date | Sat, 03 Feb 2007 08:10:09 +0000 |
parents | 1b9e69c058d2 |
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. * * Tom St Denis, [email protected], http://libtomcrypt.org */ #include "tomcrypt.h" /** @file dh.c DH crypto, Tom St Denis */ #ifdef MDH /* max export size we'll encounter (smaller than this but lets round up a bit) */ #define DH_BUF_SIZE 1200 /* This holds the key settings. ***MUST*** be organized by size from smallest to largest. */ static const struct { int size; char *name, *base, *prime; } sets[] = { #ifdef DH768 { 96, "DH-768", "4", "F///////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "//////m3wvV" }, #endif #ifdef DH1024 { 128, "DH-1024", "4", "F///////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "////////////////////////////////////////////////m3C47" }, #endif #ifdef DH1280 { 160, "DH-1280", "4", "F///////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "//////////////////////////////m4kSN" }, #endif #ifdef DH1536 { 192, "DH-1536", "4", "F///////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "////////////m5uqd" }, #endif #ifdef DH1792 { 224, "DH-1792", "4", "F///////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "//////////////////////////////////////////////////////mT/sd" }, #endif #ifdef DH2048 { 256, "DH-2048", "4", "3///////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "/////////////////////////////////////////m8MPh" }, #endif #ifdef DH2560 { 320, "DH-2560", "4", "3///////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "/////mKFpF" }, #endif #ifdef DH3072 { 384, "DH-3072", "4", "3///////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "/////////////////////////////m32nN" }, #endif #ifdef DH4096 { 512, "DH-4096", "4", "////////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "////////////////////////////////////////////////////////////" "/////////////////////m8pOF" }, #endif { 0, NULL, NULL, NULL } }; static int is_valid_idx(int n) { int x; for (x = 0; sets[x].size; x++); if ((n < 0) || (n >= x)) { return 0; } return 1; } /** Test the DH sub-system (can take a while) @return CRYPT_OK if successful */ int dh_test(void) { mp_int p, g, tmp; int x, err, primality; if ((err = mp_init_multi(&p, &g, &tmp, NULL)) != MP_OKAY) { goto error; } for (x = 0; sets[x].size != 0; x++) { #if 0 printf("dh_test():testing size %d-bits\n", sets[x].size * 8); #endif if ((err = mp_read_radix(&g,(char *)sets[x].base, 64)) != MP_OKAY) { goto error; } if ((err = mp_read_radix(&p,(char *)sets[x].prime, 64)) != MP_OKAY) { goto error; } /* ensure p is prime */ if ((err = is_prime(&p, &primality)) != CRYPT_OK) { goto done; } if (primality == 0) { err = CRYPT_FAIL_TESTVECTOR; goto done; } if ((err = mp_sub_d(&p, 1, &tmp)) != MP_OKAY) { goto error; } if ((err = mp_div_2(&tmp, &tmp)) != MP_OKAY) { goto error; } /* ensure (p-1)/2 is prime */ if ((err = is_prime(&tmp, &primality)) != CRYPT_OK) { goto done; } if (primality == 0) { err = CRYPT_FAIL_TESTVECTOR; goto done; } /* now see if g^((p-1)/2) mod p is in fact 1 */ if ((err = mp_exptmod(&g, &tmp, &p, &tmp)) != MP_OKAY) { goto error; } if (mp_cmp_d(&tmp, 1)) { err = CRYPT_FAIL_TESTVECTOR; goto done; } } err = CRYPT_OK; goto done; error: err = mpi_to_ltc_error(err); done: mp_clear_multi(&tmp, &g, &p, NULL); return err; } /** Get the min and max DH key sizes (octets) @param low [out] The smallest key size supported @param high [out] The largest key size supported */ void dh_sizes(int *low, int *high) { int x; LTC_ARGCHK(low != NULL); LTC_ARGCHK(high != NULL); *low = INT_MAX; *high = 0; for (x = 0; sets[x].size != 0; x++) { if (*low > sets[x].size) *low = sets[x].size; if (*high < sets[x].size) *high = sets[x].size; } } /** Returns the key size of a given DH key (octets) @param key The DH key to get the size of @return The size if valid or INT_MAX if not */ int dh_get_size(dh_key *key) { LTC_ARGCHK(key != NULL); if (is_valid_idx(key->idx) == 1) { return sets[key->idx].size; } else { return INT_MAX; /* large value that would cause dh_make_key() to fail */ } } /** Make a DH key [private key pair] @param prng An active PRNG state @param wprng The index for the PRNG you desire to use @param keysize The key size (octets) desired @param key [out] Where the newly created DH key will be stored @return CRYPT_OK if successful, note: on error all allocated memory will be freed automatically. */ int dh_make_key(prng_state *prng, int wprng, int keysize, dh_key *key) { unsigned char *buf; unsigned long x; mp_int p, g; int err; LTC_ARGCHK(key != NULL); /* good prng? */ if ((err = prng_is_valid(wprng)) != CRYPT_OK) { return err; } /* find key size */ for (x = 0; (keysize > sets[x].size) && (sets[x].size != 0); x++); #ifdef FAST_PK keysize = MIN(sets[x].size, 32); #else keysize = sets[x].size; #endif if (sets[x].size == 0) { return CRYPT_INVALID_KEYSIZE; } key->idx = x; /* allocate buffer */ buf = XMALLOC(keysize); if (buf == NULL) { return CRYPT_MEM; } /* make up random string */ if (prng_descriptor[wprng].read(buf, keysize, prng) != (unsigned long)keysize) { err = CRYPT_ERROR_READPRNG; goto error2; } /* init parameters */ if ((err = mp_init_multi(&g, &p, &key->x, &key->y, NULL)) != MP_OKAY) { goto error; } if ((err = mp_read_radix(&g, sets[key->idx].base, 64)) != MP_OKAY) { goto error; } if ((err = mp_read_radix(&p, sets[key->idx].prime, 64)) != MP_OKAY) { goto error; } /* load the x value */ if ((err = mp_read_unsigned_bin(&key->x, buf, keysize)) != MP_OKAY) { goto error; } if ((err = mp_exptmod(&g, &key->x, &p, &key->y)) != MP_OKAY) { goto error; } key->type = PK_PRIVATE; if ((err = mp_shrink(&key->x)) != MP_OKAY) { goto error; } if ((err = mp_shrink(&key->y)) != MP_OKAY) { goto error; } /* free up ram */ err = CRYPT_OK; goto done; error: err = mpi_to_ltc_error(err); error2: mp_clear_multi(&key->x, &key->y, NULL); done: #ifdef LTC_CLEAN_STACK zeromem(buf, keysize); #endif mp_clear_multi(&p, &g, NULL); XFREE(buf); return err; } /** Free the allocated ram for a DH key @param key The key which you wish to free */ void dh_free(dh_key *key) { LTC_ARGCHK(key != NULL); mp_clear_multi(&key->x, &key->y, NULL); } /** Export a DH key to a binary packet @param out [out] The destination for the key @param outlen [in/out] The max size and resulting size of the DH key @param type Which type of key (PK_PRIVATE or PK_PUBLIC) @param key The key you wish to export @return CRYPT_OK if successful */ int dh_export(unsigned char *out, unsigned long *outlen, int type, dh_key *key) { unsigned long y, z; int err; LTC_ARGCHK(out != NULL); LTC_ARGCHK(outlen != NULL); LTC_ARGCHK(key != NULL); /* can we store the static header? */ if (*outlen < (PACKET_SIZE + 2)) { return CRYPT_BUFFER_OVERFLOW; } if (type == PK_PRIVATE && key->type != PK_PRIVATE) { return CRYPT_PK_NOT_PRIVATE; } /* header */ y = PACKET_SIZE; /* header */ out[y++] = type; out[y++] = (unsigned char)(sets[key->idx].size / 8); /* export y */ OUTPUT_BIGNUM(&key->y, out, y, z); if (type == PK_PRIVATE) { /* export x */ OUTPUT_BIGNUM(&key->x, out, y, z); } /* store header */ packet_store_header(out, PACKET_SECT_DH, PACKET_SUB_KEY); /* store len */ *outlen = y; return CRYPT_OK; } /** Import a DH key from a binary packet @param in The packet to read @param inlen The length of the input packet @param key [out] Where to import the key to @return CRYPT_OK if successful, on error all allocated memory is freed automatically */ int dh_import(const unsigned char *in, unsigned long inlen, dh_key *key) { unsigned long x, y, s; int err; LTC_ARGCHK(in != NULL); LTC_ARGCHK(key != NULL); /* make sure valid length */ if ((2+PACKET_SIZE) > inlen) { return CRYPT_INVALID_PACKET; } /* check type byte */ if ((err = packet_valid_header((unsigned char *)in, PACKET_SECT_DH, PACKET_SUB_KEY)) != CRYPT_OK) { return err; } /* init */ if ((err = mp_init_multi(&key->x, &key->y, NULL)) != MP_OKAY) { return mpi_to_ltc_error(err); } /* advance past packet header */ y = PACKET_SIZE; /* key type, e.g. private, public */ key->type = (int)in[y++]; /* key size in bytes */ s = (unsigned long)in[y++] * 8; for (x = 0; (s > (unsigned long)sets[x].size) && (sets[x].size != 0); x++); if (sets[x].size == 0) { err = CRYPT_INVALID_KEYSIZE; goto error; } key->idx = (int)x; /* type check both values */ if ((key->type != PK_PUBLIC) && (key->type != PK_PRIVATE)) { err = CRYPT_PK_TYPE_MISMATCH; goto error; } /* is the key idx valid? */ if (is_valid_idx(key->idx) != 1) { err = CRYPT_PK_TYPE_MISMATCH; goto error; } /* load public value g^x mod p*/ INPUT_BIGNUM(&key->y, in, x, y, inlen); if (key->type == PK_PRIVATE) { INPUT_BIGNUM(&key->x, in, x, y, inlen); } /* eliminate private key if public */ if (key->type == PK_PUBLIC) { mp_clear(&key->x); } return CRYPT_OK; error: mp_clear_multi(&key->y, &key->x, NULL); return err; } /** Create a DH shared secret. @param private_key The private DH key in the pair @param public_key The public DH key in the pair @param out [out] The destination of the shared data @param outlen [in/out] The max size and resulting size of the shared data. @return CRYPT_OK if successful */ int dh_shared_secret(dh_key *private_key, dh_key *public_key, unsigned char *out, unsigned long *outlen) { mp_int tmp, p; unsigned long x; int err; LTC_ARGCHK(private_key != NULL); LTC_ARGCHK(public_key != NULL); LTC_ARGCHK(out != NULL); LTC_ARGCHK(outlen != NULL); /* types valid? */ if (private_key->type != PK_PRIVATE) { return CRYPT_PK_NOT_PRIVATE; } /* same idx? */ if (private_key->idx != public_key->idx) { return CRYPT_PK_TYPE_MISMATCH; } /* compute y^x mod p */ if ((err = mp_init_multi(&tmp, &p, NULL)) != MP_OKAY) { return mpi_to_ltc_error(err); } if ((err = mp_read_radix(&p, (char *)sets[private_key->idx].prime, 64)) != MP_OKAY) { goto error; } if ((err = mp_exptmod(&public_key->y, &private_key->x, &p, &tmp)) != MP_OKAY) { goto error; } /* enough space for output? */ x = (unsigned long)mp_unsigned_bin_size(&tmp); if (*outlen < x) { err = CRYPT_BUFFER_OVERFLOW; goto done; } if ((err = mp_to_unsigned_bin(&tmp, out)) != MP_OKAY) { goto error; } *outlen = x; err = CRYPT_OK; goto done; error: err = mpi_to_ltc_error(err); done: mp_clear_multi(&p, &tmp, NULL); return err; } #include "dh_sys.c" #endif /* $Source: /cvs/libtom/libtomcrypt/src/pk/dh/dh.c,v $ */ /* $Revision: 1.3 $ */ /* $Date: 2005/05/05 14:35:59 $ */