diff options
Diffstat (limited to 'libtomcrypt/src/pk/dh/dh_sys.c')
| -rw-r--r-- | libtomcrypt/src/pk/dh/dh_sys.c | 499 |
1 files changed, 0 insertions, 499 deletions
diff --git a/libtomcrypt/src/pk/dh/dh_sys.c b/libtomcrypt/src/pk/dh/dh_sys.c deleted file mode 100644 index 4f10556..0000000 --- a/libtomcrypt/src/pk/dh/dh_sys.c +++ /dev/null @@ -1,499 +0,0 @@ -/* 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, tomstdenis@gmail.com, http://libtomcrypt.org - */ - -/** - @file dh_sys.c - DH Crypto, Tom St Denis -*/ - -/** - Encrypt a short symmetric key with a public DH key - @param in The symmetric key to encrypt - @param inlen The length of the key (octets) - @param out [out] The ciphertext - @param outlen [in/out] The max size and resulting size of the ciphertext - @param prng An active PRNG state - @param wprng The index of the PRNG desired - @param hash The index of the hash desired (must produce a digest of size >= the size of the plaintext) - @param key The public key you wish to encrypt with. - @return CRYPT_OK if successful -*/ -int dh_encrypt_key(const unsigned char *in, unsigned long inlen, - unsigned char *out, unsigned long *outlen, - prng_state *prng, int wprng, int hash, - dh_key *key) -{ - unsigned char *pub_expt, *dh_shared, *skey; - dh_key pubkey; - unsigned long x, y, z, hashsize, pubkeysize; - int err; - - LTC_ARGCHK(in != NULL); - LTC_ARGCHK(out != NULL); - LTC_ARGCHK(outlen != NULL); - LTC_ARGCHK(key != NULL); - - /* check that wprng/hash are not invalid */ - if ((err = prng_is_valid(wprng)) != CRYPT_OK) { - return err; - } - - if ((err = hash_is_valid(hash)) != CRYPT_OK) { - return err; - } - - if (inlen > hash_descriptor[hash].hashsize) { - return CRYPT_INVALID_HASH; - } - - /* allocate memory */ - pub_expt = XMALLOC(DH_BUF_SIZE); - dh_shared = XMALLOC(DH_BUF_SIZE); - skey = XMALLOC(MAXBLOCKSIZE); - if (pub_expt == NULL || dh_shared == NULL || skey == NULL) { - if (pub_expt != NULL) { - XFREE(pub_expt); - } - if (dh_shared != NULL) { - XFREE(dh_shared); - } - if (skey != NULL) { - XFREE(skey); - } - return CRYPT_MEM; - } - - /* make a random key and export the public copy */ - if ((err = dh_make_key(prng, wprng, dh_get_size(key), &pubkey)) != CRYPT_OK) { - goto LBL_ERR; - } - - pubkeysize = DH_BUF_SIZE; - if ((err = dh_export(pub_expt, &pubkeysize, PK_PUBLIC, &pubkey)) != CRYPT_OK) { - dh_free(&pubkey); - goto LBL_ERR; - } - - /* now check if the out buffer is big enough */ - if (*outlen < (1 + 4 + 4 + PACKET_SIZE + pubkeysize + inlen)) { - dh_free(&pubkey); - err = CRYPT_BUFFER_OVERFLOW; - goto LBL_ERR; - } - - /* make random key */ - hashsize = hash_descriptor[hash].hashsize; - - x = DH_BUF_SIZE; - if ((err = dh_shared_secret(&pubkey, key, dh_shared, &x)) != CRYPT_OK) { - dh_free(&pubkey); - goto LBL_ERR; - } - dh_free(&pubkey); - - z = MAXBLOCKSIZE; - if ((err = hash_memory(hash, dh_shared, x, skey, &z)) != CRYPT_OK) { - goto LBL_ERR; - } - - /* store header */ - packet_store_header(out, PACKET_SECT_DH, PACKET_SUB_ENC_KEY); - - /* output header */ - y = PACKET_SIZE; - - /* size of hash name and the name itself */ - out[y++] = hash_descriptor[hash].ID; - - /* length of DH pubkey and the key itself */ - STORE32L(pubkeysize, out+y); - y += 4; - for (x = 0; x < pubkeysize; x++, y++) { - out[y] = pub_expt[x]; - } - - /* Store the encrypted key */ - STORE32L(inlen, out+y); - y += 4; - - for (x = 0; x < inlen; x++, y++) { - out[y] = skey[x] ^ in[x]; - } - *outlen = y; - - err = CRYPT_OK; -LBL_ERR: -#ifdef LTC_CLEAN_STACK - /* clean up */ - zeromem(pub_expt, DH_BUF_SIZE); - zeromem(dh_shared, DH_BUF_SIZE); - zeromem(skey, MAXBLOCKSIZE); -#endif - XFREE(skey); - XFREE(dh_shared); - XFREE(pub_expt); - - return err; -} - -/** - Decrypt a DH encrypted symmetric key - @param in The DH encrypted packet - @param inlen The length of the DH encrypted packet - @param out The plaintext - @param outlen [in/out] The max size and resulting size of the plaintext - @param key The private DH key corresponding to the public key that encrypted the plaintext - @return CRYPT_OK if successful -*/ -int dh_decrypt_key(const unsigned char *in, unsigned long inlen, - unsigned char *out, unsigned long *outlen, - dh_key *key) -{ - unsigned char *shared_secret, *skey; - unsigned long x, y, z, hashsize, keysize; - int hash, err; - dh_key pubkey; - - LTC_ARGCHK(in != NULL); - LTC_ARGCHK(out != NULL); - LTC_ARGCHK(outlen != NULL); - LTC_ARGCHK(key != NULL); - - /* right key type? */ - if (key->type != PK_PRIVATE) { - return CRYPT_PK_NOT_PRIVATE; - } - - /* allocate ram */ - shared_secret = XMALLOC(DH_BUF_SIZE); - skey = XMALLOC(MAXBLOCKSIZE); - if (shared_secret == NULL || skey == NULL) { - if (shared_secret != NULL) { - XFREE(shared_secret); - } - if (skey != NULL) { - XFREE(skey); - } - return CRYPT_MEM; - } - - /* check if initial header should fit */ - if (inlen < PACKET_SIZE+1+4+4) { - err = CRYPT_INVALID_PACKET; - goto LBL_ERR; - } else { - inlen -= PACKET_SIZE+1+4+4; - } - - /* is header correct? */ - if ((err = packet_valid_header((unsigned char *)in, PACKET_SECT_DH, PACKET_SUB_ENC_KEY)) != CRYPT_OK) { - goto LBL_ERR; - } - - /* now lets get the hash name */ - y = PACKET_SIZE; - hash = find_hash_id(in[y++]); - if (hash == -1) { - err = CRYPT_INVALID_HASH; - goto LBL_ERR; - } - - /* common values */ - hashsize = hash_descriptor[hash].hashsize; - - /* get public key */ - LOAD32L(x, in+y); - - /* now check if the imported key will fit */ - if (inlen < x) { - err = CRYPT_INVALID_PACKET; - goto LBL_ERR; - } else { - inlen -= x; - } - - y += 4; - if ((err = dh_import(in+y, x, &pubkey)) != CRYPT_OK) { - goto LBL_ERR; - } - y += x; - - /* make shared key */ - x = DH_BUF_SIZE; - if ((err = dh_shared_secret(key, &pubkey, shared_secret, &x)) != CRYPT_OK) { - dh_free(&pubkey); - goto LBL_ERR; - } - dh_free(&pubkey); - - z = MAXBLOCKSIZE; - if ((err = hash_memory(hash, shared_secret, x, skey, &z)) != CRYPT_OK) { - goto LBL_ERR; - } - - /* load in the encrypted key */ - LOAD32L(keysize, in+y); - - /* will the out fit as part of the input */ - if (inlen < keysize) { - err = CRYPT_INVALID_PACKET; - goto LBL_ERR; - } else { - inlen -= keysize; - } - - if (keysize > *outlen) { - err = CRYPT_BUFFER_OVERFLOW; - goto LBL_ERR; - } - y += 4; - - *outlen = keysize; - - for (x = 0; x < keysize; x++, y++) { - out[x] = skey[x] ^ in[y]; - } - - err = CRYPT_OK; -LBL_ERR: -#ifdef LTC_CLEAN_STACK - zeromem(shared_secret, DH_BUF_SIZE); - zeromem(skey, MAXBLOCKSIZE); -#endif - - XFREE(skey); - XFREE(shared_secret); - - return err; -} - -/* perform an ElGamal Signature of a hash - * - * The math works as follows. x is the private key, M is the message to sign - - 1. pick a random k - 2. compute a = g^k mod p - 3. compute b = (M - xa)/k mod p - 4. Send (a,b) - - Now to verify with y=g^x mod p, a and b - - 1. compute y^a * a^b = g^(xa) * g^(k*(M-xa)/k) - = g^(xa + (M - xa)) - = g^M [all mod p] - - 2. Compare against g^M mod p [based on input hash]. - 3. If result of #2 == result of #1 then signature valid -*/ - -/** - Sign a message digest using a DH private key - @param in The data to sign - @param inlen The length of the input (octets) - @param out [out] The destination of the signature - @param outlen [in/out] The max size and resulting size of the output - @param prng An active PRNG state - @param wprng The index of the PRNG desired - @param key A private DH key - @return CRYPT_OK if successful -*/ -int dh_sign_hash(const unsigned char *in, unsigned long inlen, - unsigned char *out, unsigned long *outlen, - prng_state *prng, int wprng, dh_key *key) -{ - mp_int a, b, k, m, g, p, p1, tmp; - unsigned char *buf; - unsigned long x, y; - int err; - - LTC_ARGCHK(in != NULL); - LTC_ARGCHK(out != NULL); - LTC_ARGCHK(outlen != NULL); - LTC_ARGCHK(key != NULL); - - /* check parameters */ - if (key->type != PK_PRIVATE) { - return CRYPT_PK_NOT_PRIVATE; - } - - if ((err = prng_is_valid(wprng)) != CRYPT_OK) { - return err; - } - - /* is the IDX valid ? */ - if (is_valid_idx(key->idx) != 1) { - return CRYPT_PK_INVALID_TYPE; - } - - /* allocate ram for buf */ - buf = XMALLOC(520); - - /* make up a random value k, - * since the order of the group is prime - * we need not check if gcd(k, r) is 1 - */ - if (prng_descriptor[wprng].read(buf, sets[key->idx].size, prng) != - (unsigned long)(sets[key->idx].size)) { - err = CRYPT_ERROR_READPRNG; - goto LBL_ERR; - } - - /* init bignums */ - if ((err = mp_init_multi(&a, &b, &k, &m, &p, &g, &p1, &tmp, NULL)) != MP_OKAY) { - err = mpi_to_ltc_error(err); - goto LBL_ERR; - } - - /* load k and m */ - if ((err = mp_read_unsigned_bin(&m, (unsigned char *)in, inlen)) != MP_OKAY) { goto error; } - if ((err = mp_read_unsigned_bin(&k, buf, sets[key->idx].size)) != MP_OKAY) { goto error; } - - /* load g, p and p1 */ - 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; } - if ((err = mp_sub_d(&p, 1, &p1)) != MP_OKAY) { goto error; } - if ((err = mp_div_2(&p1, &p1)) != MP_OKAY) { goto error; } /* p1 = (p-1)/2 */ - - /* now get a = g^k mod p */ - if ((err = mp_exptmod(&g, &k, &p, &a)) != MP_OKAY) { goto error; } - - /* now find M = xa + kb mod p1 or just b = (M - xa)/k mod p1 */ - if ((err = mp_invmod(&k, &p1, &k)) != MP_OKAY) { goto error; } /* k = 1/k mod p1 */ - if ((err = mp_mulmod(&a, &key->x, &p1, &tmp)) != MP_OKAY) { goto error; } /* tmp = xa */ - if ((err = mp_submod(&m, &tmp, &p1, &tmp)) != MP_OKAY) { goto error; } /* tmp = M - xa */ - if ((err = mp_mulmod(&k, &tmp, &p1, &b)) != MP_OKAY) { goto error; } /* b = (M - xa)/k */ - - /* check for overflow */ - if ((unsigned long)(PACKET_SIZE + 4 + 4 + mp_unsigned_bin_size(&a) + mp_unsigned_bin_size(&b)) > *outlen) { - err = CRYPT_BUFFER_OVERFLOW; - goto LBL_ERR; - } - - /* store header */ - y = PACKET_SIZE; - - /* now store them both (a,b) */ - x = (unsigned long)mp_unsigned_bin_size(&a); - STORE32L(x, out+y); y += 4; - if ((err = mp_to_unsigned_bin(&a, out+y)) != MP_OKAY) { goto error; } - y += x; - - x = (unsigned long)mp_unsigned_bin_size(&b); - STORE32L(x, out+y); y += 4; - if ((err = mp_to_unsigned_bin(&b, out+y)) != MP_OKAY) { goto error; } - y += x; - - /* check if size too big */ - if (*outlen < y) { - err = CRYPT_BUFFER_OVERFLOW; - goto LBL_ERR; - } - - /* store header */ - packet_store_header(out, PACKET_SECT_DH, PACKET_SUB_SIGNED); - *outlen = y; - - err = CRYPT_OK; - goto LBL_ERR; -error: - err = mpi_to_ltc_error(err); -LBL_ERR: - mp_clear_multi(&tmp, &p1, &g, &p, &m, &k, &b, &a, NULL); - - XFREE(buf); - - return err; -} - - -/** - Verify the signature given - @param sig The signature - @param siglen The length of the signature (octets) - @param hash The hash that was signed - @param hashlen The length of the hash (octets) - @param stat [out] Result of signature comparison, 1==valid, 0==invalid - @param key The public DH key that signed the hash - @return CRYPT_OK if succsessful (even if signature is invalid) -*/ -int dh_verify_hash(const unsigned char *sig, unsigned long siglen, - const unsigned char *hash, unsigned long hashlen, - int *stat, dh_key *key) -{ - mp_int a, b, p, g, m, tmp; - unsigned long x, y; - int err; - - LTC_ARGCHK(sig != NULL); - LTC_ARGCHK(hash != NULL); - LTC_ARGCHK(stat != NULL); - LTC_ARGCHK(key != NULL); - - /* default to invalid */ - *stat = 0; - - /* check initial input length */ - if (siglen < PACKET_SIZE+4+4) { - return CRYPT_INVALID_PACKET; - } - - /* header ok? */ - if ((err = packet_valid_header((unsigned char *)sig, PACKET_SECT_DH, PACKET_SUB_SIGNED)) != CRYPT_OK) { - return err; - } - - /* get hash out of packet */ - y = PACKET_SIZE; - - /* init all bignums */ - if ((err = mp_init_multi(&a, &p, &b, &g, &m, &tmp, NULL)) != MP_OKAY) { - return mpi_to_ltc_error(err); - } - - /* load a and b */ - INPUT_BIGNUM(&a, sig, x, y, siglen); - INPUT_BIGNUM(&b, sig, x, y, siglen); - - /* load p and g */ - if ((err = mp_read_radix(&p, sets[key->idx].prime, 64)) != MP_OKAY) { goto error1; } - if ((err = mp_read_radix(&g, sets[key->idx].base, 64)) != MP_OKAY) { goto error1; } - - /* load m */ - if ((err = mp_read_unsigned_bin(&m, (unsigned char *)hash, hashlen)) != MP_OKAY) { goto error1; } - - /* find g^m mod p */ - if ((err = mp_exptmod(&g, &m, &p, &m)) != MP_OKAY) { goto error1; } /* m = g^m mod p */ - - /* find y^a * a^b */ - if ((err = mp_exptmod(&key->y, &a, &p, &tmp)) != MP_OKAY) { goto error1; } /* tmp = y^a mod p */ - if ((err = mp_exptmod(&a, &b, &p, &a)) != MP_OKAY) { goto error1; } /* a = a^b mod p */ - if ((err = mp_mulmod(&a, &tmp, &p, &a)) != MP_OKAY) { goto error1; } /* a = y^a * a^b mod p */ - - /* y^a * a^b == g^m ??? */ - if (mp_cmp(&a, &m) == 0) { - *stat = 1; - } - - /* clean up */ - err = CRYPT_OK; - goto done; -error1: - err = mpi_to_ltc_error(err); -error: -done: - mp_clear_multi(&tmp, &m, &g, &p, &b, &a, NULL); - return err; -} - - -/* $Source: /cvs/libtom/libtomcrypt/src/pk/dh/dh_sys.c,v $ */ -/* $Revision: 1.3 $ */ -/* $Date: 2005/05/05 14:35:59 $ */ |