Allow server public key to be anywhere from 512 bits to 2048 bits.
(Vista Beta 2 uses a 2048 bit key) git-svn-id: svn://svn.code.sf.net/p/rdesktop/code/trunk/rdesktop@1236 423420c4-83ab-492f-b58f-81f9feb106b5
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@ -62,6 +62,7 @@ enum MCS_PDU_TYPE
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/* RDP secure transport constants */
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#define SEC_RANDOM_SIZE 32
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#define SEC_MODULUS_SIZE 64
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#define SEC_MAX_MODULUS_SIZE 256
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#define SEC_PADDING_SIZE 8
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#define SEC_EXPONENT_SIZE 4
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71
secure.c
71
secure.c
@ -46,13 +46,14 @@ static int rc4_key_len;
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static RC4_KEY rc4_decrypt_key;
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static RC4_KEY rc4_encrypt_key;
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static RSA *server_public_key;
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static uint32 server_public_key_len;
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static uint8 sec_sign_key[16];
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static uint8 sec_decrypt_key[16];
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static uint8 sec_encrypt_key[16];
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static uint8 sec_decrypt_update_key[16];
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static uint8 sec_encrypt_update_key[16];
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static uint8 sec_crypted_random[SEC_MODULUS_SIZE];
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static uint8 sec_crypted_random[SEC_MAX_MODULUS_SIZE];
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uint16 g_server_rdp_version = 0;
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@ -297,14 +298,14 @@ reverse(uint8 * p, int len)
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/* Perform an RSA public key encryption operation */
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static void
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sec_rsa_encrypt(uint8 * out, uint8 * in, int len, uint8 * modulus, uint8 * exponent)
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sec_rsa_encrypt(uint8 * out, uint8 * in, int len, uint32 modulus_size, uint8 * modulus, uint8 * exponent)
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{
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BN_CTX *ctx;
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BIGNUM mod, exp, x, y;
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uint8 inr[SEC_MODULUS_SIZE];
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uint8 inr[SEC_MAX_MODULUS_SIZE];
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int outlen;
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reverse(modulus, SEC_MODULUS_SIZE);
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reverse(modulus, modulus_size);
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reverse(exponent, SEC_EXPONENT_SIZE);
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memcpy(inr, in, len);
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reverse(inr, len);
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@ -315,14 +316,14 @@ sec_rsa_encrypt(uint8 * out, uint8 * in, int len, uint8 * modulus, uint8 * expon
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BN_init(&x);
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BN_init(&y);
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BN_bin2bn(modulus, SEC_MODULUS_SIZE, &mod);
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BN_bin2bn(modulus, modulus_size, &mod);
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BN_bin2bn(exponent, SEC_EXPONENT_SIZE, &exp);
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BN_bin2bn(inr, len, &x);
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BN_mod_exp(&y, &x, &exp, &mod, ctx);
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outlen = BN_bn2bin(&y, out);
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reverse(out, outlen);
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if (outlen < SEC_MODULUS_SIZE)
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memset(out + outlen, 0, SEC_MODULUS_SIZE - outlen);
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if (outlen < modulus_size)
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memset(out + outlen, 0, modulus_size - outlen);
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BN_free(&y);
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BN_clear_free(&x);
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@ -388,14 +389,14 @@ sec_send(STREAM s, uint32 flags)
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static void
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sec_establish_key(void)
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{
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uint32 length = SEC_MODULUS_SIZE + SEC_PADDING_SIZE;
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uint32 length = server_public_key_len + SEC_PADDING_SIZE;
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uint32 flags = SEC_CLIENT_RANDOM;
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STREAM s;
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s = sec_init(flags, 76);
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s = sec_init(flags, length+4);
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out_uint32_le(s, length);
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out_uint8p(s, sec_crypted_random, SEC_MODULUS_SIZE);
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out_uint8p(s, sec_crypted_random, server_public_key_len);
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out_uint8s(s, SEC_PADDING_SIZE);
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s_mark_end(s);
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@ -507,16 +508,18 @@ sec_parse_public_key(STREAM s, uint8 ** modulus, uint8 ** exponent)
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}
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in_uint32_le(s, modulus_len);
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if (modulus_len != SEC_MODULUS_SIZE + SEC_PADDING_SIZE)
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modulus_len -= SEC_PADDING_SIZE;
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if ((modulus_len < 64) || (modulus_len > SEC_MAX_MODULUS_SIZE))
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{
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error("modulus len 0x%x\n", modulus_len);
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error("Bad server public key size (%u bits)\n", modulus_len*8);
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return False;
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}
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in_uint8s(s, 8); /* modulus_bits, unknown */
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in_uint8p(s, *exponent, SEC_EXPONENT_SIZE);
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in_uint8p(s, *modulus, SEC_MODULUS_SIZE);
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in_uint8p(s, *modulus, modulus_len);
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in_uint8s(s, SEC_PADDING_SIZE);
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server_public_key_len = modulus_len;
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return s_check(s);
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}
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@ -544,9 +547,15 @@ sec_parse_x509_key(X509 * cert)
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}
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server_public_key = RSAPublicKey_dup((RSA *) epk->pkey.ptr);
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EVP_PKEY_free(epk);
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server_public_key_len = RSA_size(server_public_key);
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if ((server_public_key_len < 64) || (server_public_key_len > SEC_MAX_MODULUS_SIZE))
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{
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error("Bad server public key size (%u bits)\n", server_public_key_len*8);
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return False;
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}
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return True;
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}
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@ -719,7 +728,6 @@ sec_process_crypt_info(STREAM s)
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uint8 *server_random, *modulus, *exponent;
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uint8 client_random[SEC_RANDOM_SIZE];
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uint32 rc4_key_size;
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uint8 inr[SEC_MODULUS_SIZE];
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if (!sec_parse_crypt_info(s, &rc4_key_size, &server_random, &modulus, &exponent))
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{
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@ -728,29 +736,30 @@ sec_process_crypt_info(STREAM s)
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}
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DEBUG(("Generating client random\n"));
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/* Generate a client random, and hence determine encryption keys */
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/* This is what the MS client do: */
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memset(inr, 0, SEC_RANDOM_SIZE);
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/* *ARIGL!* Plaintext attack, anyone?
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I tried doing:
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generate_random(inr);
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..but that generates connection errors now and then (yes,
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"now and then". Something like 0 to 3 attempts needed before a
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successful connection. Nice. Not!
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*/
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generate_random(client_random);
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if (NULL != server_public_key)
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{ /* Which means we should use
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RDP5-style encryption */
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uint8 inr[SEC_MAX_MODULUS_SIZE];
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uint32 padding_len = server_public_key_len - SEC_RANDOM_SIZE;
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memcpy(inr + SEC_RANDOM_SIZE, client_random, SEC_RANDOM_SIZE);
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reverse(inr + SEC_RANDOM_SIZE, SEC_RANDOM_SIZE);
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/* This is what the MS client do: */
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memset(inr, 0, padding_len);
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/* *ARIGL!* Plaintext attack, anyone?
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I tried doing:
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generate_random(inr);
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..but that generates connection errors now and then (yes,
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"now and then". Something like 0 to 3 attempts needed before a
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successful connection. Nice. Not!
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*/
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memcpy(inr + padding_len, client_random, SEC_RANDOM_SIZE);
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reverse(inr + padding_len, SEC_RANDOM_SIZE);
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RSA_public_encrypt(SEC_MODULUS_SIZE,
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RSA_public_encrypt(server_public_key_len,
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inr, sec_crypted_random, server_public_key, RSA_NO_PADDING);
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reverse(sec_crypted_random, SEC_MODULUS_SIZE);
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reverse(sec_crypted_random, server_public_key_len);
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RSA_free(server_public_key);
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server_public_key = NULL;
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@ -758,7 +767,7 @@ sec_process_crypt_info(STREAM s)
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else
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{ /* RDP4-style encryption */
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sec_rsa_encrypt(sec_crypted_random,
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client_random, SEC_RANDOM_SIZE, modulus, exponent);
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client_random, SEC_RANDOM_SIZE, server_public_key_len, modulus, exponent);
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}
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sec_generate_keys(client_random, server_random, rc4_key_size);
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}
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