secure.c

Go to the documentation of this file.

/* -*- c-basic-offset: 8 -*-
   rdesktop: A Remote Desktop Protocol client.
   Protocol services - RDP encryption and licensing
   Copyright (C) Matthew Chapman <matthewc.unsw.edu.au> 1999-2008
   Copyright 2005-2011 Peter Astrand <astrand@cendio.se> for Cendio AB
 
   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 3 of the License, or
   (at your option) any later version.
 
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
 
   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/
 
#include "precomp.h"
 
void *
rdssl_sha1_info_create(void);
void
rdssl_sha1_info_delete(void * sha1_info);
void
rdssl_sha1_clear(void * sha1_info);
void
rdssl_sha1_transform(void * sha1_info, char * data, int len);
void
rdssl_sha1_complete(void * sha1_info, char * data);
void *
rdssl_md5_info_create(void);
void
rdssl_md5_info_delete(void * md5_info);
void *
rdssl_md5_info_create(void);
void
rdssl_md5_info_delete(void * md5_info);
void
rdssl_md5_clear(void * md5_info);
void
rdssl_md5_transform(void * md5_info, char * data, int len);
void
rdssl_md5_complete(void * md5_info, char * data);
void *
rdssl_rc4_info_create(void);
void
rdssl_rc4_info_delete(void * rc4_info);
void
rdssl_rc4_set_key(void * rc4_info, char * key, int len);
void
rdssl_rc4_crypt(void * rc4_info, char * in_data, char * out_data, int len);
int
rdssl_mod_exp(char* out, int out_len, char* in, int in_len,
              char* mod, int mod_len, char* exp, int exp_len);
int
rdssl_sign_ok(char* e_data, int e_len, char* n_data, int n_len,
              char* sign_data, int sign_len, char* sign_data2, int sign_len2, char* testkey);
PCCERT_CONTEXT
rdssl_cert_read(uint8 * data, uint32 len);
void
rdssl_cert_free(PCCERT_CONTEXT context);
uint8 *
rdssl_cert_to_rkey(PCCERT_CONTEXT cert, uint32 * key_len);
RD_BOOL
rdssl_certs_ok(PCCERT_CONTEXT server_cert, PCCERT_CONTEXT cacert);
int
rdssl_rkey_get_exp_mod(uint8 * rkey, uint8 * exponent, uint32 max_exp_len, uint8 * modulus,
    uint32 max_mod_len);
void
rdssl_rkey_free(uint8 * rkey);
 
extern char g_hostname[16];
extern int g_width;
extern int g_height;
extern unsigned int g_keylayout;
extern int g_keyboard_type;
extern int g_keyboard_subtype;
extern int g_keyboard_functionkeys;
extern RD_BOOL g_encryption;
extern RD_BOOL g_licence_issued;
extern RD_BOOL g_licence_error_result;
extern RDP_VERSION g_rdp_version;
extern RD_BOOL g_console_session;
extern uint32 g_redirect_session_id;
extern int g_server_depth;
extern VCHANNEL g_channels[];
extern unsigned int g_num_channels;
extern uint8 g_client_random[SEC_RANDOM_SIZE];
 
static int g_rc4_key_len;
static void * g_rc4_decrypt_key;
static void * g_rc4_encrypt_key;
static uint32 g_server_public_key_len;
 
static uint8 g_sec_sign_key[16];
static uint8 g_sec_decrypt_key[16];
static uint8 g_sec_encrypt_key[16];
static uint8 g_sec_decrypt_update_key[16];
static uint8 g_sec_encrypt_update_key[16];
static uint8 g_sec_crypted_random[SEC_MAX_MODULUS_SIZE];
 
uint16 g_server_rdp_version = 0;
 
/* These values must be available to reset state - Session Directory */
static int g_sec_encrypt_use_count = 0;
static int g_sec_decrypt_use_count = 0;
 
#define SEC_MODULUS_SIZE 64
 
static uint8 g_testkey[176] =
{
    0x01, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00,
    0x01, 0x00, 0x00, 0x00, 0x06, 0x00, 0x5c, 0x00,
    0x52, 0x53, 0x41, 0x31, 0x48, 0x00, 0x00, 0x00,
    0x00, 0x02, 0x00, 0x00, 0x3f, 0x00, 0x00, 0x00,
    0x01, 0x00, 0x01, 0x00, 0x79, 0x6f, 0xb4, 0xdf,
    0xa6, 0x95, 0xb9, 0xa9, 0x61, 0xe3, 0xc4, 0x5e,
    0xff, 0x6b, 0xd8, 0x81, 0x8a, 0x12, 0x4a, 0x93,
    0x42, 0x97, 0x18, 0x93, 0xac, 0xd1, 0x3a, 0x38,
    0x3c, 0x68, 0x50, 0x19, 0x31, 0xb6, 0x84, 0x51,
    0x79, 0xfb, 0x1c, 0xe7, 0xe3, 0x99, 0x20, 0xc7,
    0x84, 0xdf, 0xd1, 0xaa, 0xb5, 0x15, 0xef, 0x47,
    0x7e, 0xfc, 0x88, 0xeb, 0x29, 0xc3, 0x27, 0x5a,
    0x35, 0xf8, 0xfd, 0xaa, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00,
                            0x08, 0x00, 0x48, 0x00,
    0x32, 0x3b, 0xde, 0x6f, 0x18, 0x97, 0x1e, 0xc3,
    0x6b, 0x2b, 0x2d, 0xe4, 0xfc, 0x2d, 0xa2, 0x8e,
    0x32, 0x3c, 0xf3, 0x1b, 0x24, 0x90, 0x57, 0x4d,
    0x8e, 0xe4, 0x69, 0xfc, 0x16, 0x8d, 0x41, 0x92,
    0x78, 0xc7, 0x9c, 0xb4, 0x26, 0xff, 0xe8, 0x3e,
    0xa1, 0x8a, 0xf5, 0x57, 0xc0, 0x7f, 0x3e, 0x21,
    0x17, 0x32, 0x30, 0x6f, 0x79, 0xe1, 0x36, 0xcd,
    0xb6, 0x8e, 0xbe, 0x57, 0x57, 0xd2, 0xa9, 0x36
};
 
/*
 * I believe this is based on SSLv3 with the following differences:
 *  MAC algorithm (5.2.3.1) uses only 32-bit length in place of seq_num/type/length fields
 *  MAC algorithm uses SHA1 and MD5 for the two hash functions instead of one or other
 *  key_block algorithm (6.2.2) uses 'X', 'YY', 'ZZZ' instead of 'A', 'BB', 'CCC'
 *  key_block partitioning is different (16 bytes each: MAC secret, decrypt key, encrypt key)
 *  encryption/decryption keys updated every 4096 packets
 * See http://wp.netscape.com/eng/ssl3/draft302.txt
 */
 
/*
 * 48-byte transformation used to generate master secret (6.1) and key material (6.2.2).
 * Both SHA1 and MD5 algorithms are used.
 */
void
sec_hash_48(uint8 * out, uint8 * in, uint8 * salt1, uint8 * salt2, uint8 salt)
{
    uint8 shasig[20];
    uint8 pad[4];
    void * sha;
    void * md5;
    int i;
 
    for (i = 0; i < 3; i++)
    {
        memset(pad, salt + i, i + 1);
        sha = rdssl_sha1_info_create();
        rdssl_sha1_clear(sha);
        rdssl_sha1_transform(sha, (char *)pad, i + 1);
        rdssl_sha1_transform(sha, (char *)in, 48);
        rdssl_sha1_transform(sha, (char *)salt1, 32);
        rdssl_sha1_transform(sha, (char *)salt2, 32);
        rdssl_sha1_complete(sha, (char *)shasig);
        rdssl_sha1_info_delete(sha);
        md5 = rdssl_md5_info_create();
        rdssl_md5_clear(md5);
        rdssl_md5_transform(md5, (char *)in, 48);
        rdssl_md5_transform(md5, (char *)shasig, 20);
        rdssl_md5_complete(md5, (char *)out + i * 16);
        rdssl_md5_info_delete(md5);
    }
}
 
/*
 * 16-byte transformation used to generate export keys (6.2.2).
 */
void
sec_hash_16(uint8 * out, uint8 * in, uint8 * salt1, uint8 * salt2)
{
    void * md5;
    
    md5 = rdssl_md5_info_create();
    rdssl_md5_clear(md5);
    rdssl_md5_transform(md5, (char *)in, 16);
    rdssl_md5_transform(md5, (char *)salt1, 32);
    rdssl_md5_transform(md5, (char *)salt2, 32);
    rdssl_md5_complete(md5, (char *)out);
    rdssl_md5_info_delete(md5);
}
 
/*
 * 16-byte sha1 hash
 */
void
sec_hash_sha1_16(uint8 * out, uint8 * in, uint8 * salt1)
{
    void * sha;
    sha = rdssl_sha1_info_create();
    rdssl_sha1_clear(sha);
    rdssl_sha1_transform(&sha, (char *)in, 16);
    rdssl_sha1_transform(&sha, (char *)salt1, 16);
    rdssl_sha1_complete(&sha, (char *)out);
    rdssl_sha1_info_delete(sha);
}
 
/* create string from hash */
void
sec_hash_to_string(char *out, int out_size, uint8 * in, int in_size)
{
    int k;
    memset(out, 0, out_size);
    for (k = 0; k < in_size; k++, out += 2)
    {
        sprintf(out, "%.2x", in[k]);
    }
}
 
/* Reduce key entropy from 64 to 40 bits */
static void
sec_make_40bit(uint8 * key)
{
    key[0] = 0xd1;
    key[1] = 0x26;
    key[2] = 0x9e;
}
 
/* Generate encryption keys given client and server randoms */
static void
sec_generate_keys(uint8 * client_random, uint8 * server_random, int rc4_key_size)
{
    uint8 pre_master_secret[48];
    uint8 master_secret[48];
    uint8 key_block[48];
 
    /* Construct pre-master secret */
    memcpy(pre_master_secret, client_random, 24);
    memcpy(pre_master_secret + 24, server_random, 24);
 
    /* Generate master secret and then key material */
    sec_hash_48(master_secret, pre_master_secret, client_random, server_random, 'A');
    sec_hash_48(key_block, master_secret, client_random, server_random, 'X');
 
    /* First 16 bytes of key material is MAC secret */
    memcpy(g_sec_sign_key, key_block, 16);
 
    /* Generate export keys from next two blocks of 16 bytes */
    sec_hash_16(g_sec_decrypt_key, &key_block[16], client_random, server_random);
    sec_hash_16(g_sec_encrypt_key, &key_block[32], client_random, server_random);
 
    if (rc4_key_size == 1)
    {
        DEBUG(("40-bit encryption enabled\n"));
        sec_make_40bit(g_sec_sign_key);
        sec_make_40bit(g_sec_decrypt_key);
        sec_make_40bit(g_sec_encrypt_key);
        g_rc4_key_len = 8;
    }
    else
    {
        DEBUG(("rc_4_key_size == %d, 128-bit encryption enabled\n", rc4_key_size));
        g_rc4_key_len = 16;
    }
 
    /* Save initial RC4 keys as update keys */
    memcpy(g_sec_decrypt_update_key, g_sec_decrypt_key, 16);
    memcpy(g_sec_encrypt_update_key, g_sec_encrypt_key, 16);
 
    /* Initialise RC4 state arrays */
 
    rdssl_rc4_info_delete(g_rc4_decrypt_key);
    g_rc4_decrypt_key = rdssl_rc4_info_create(); 
    rdssl_rc4_set_key(g_rc4_decrypt_key, (char *)g_sec_decrypt_key, g_rc4_key_len); 
 
    rdssl_rc4_info_delete(g_rc4_encrypt_key);
    g_rc4_encrypt_key = rdssl_rc4_info_create(); 
    rdssl_rc4_set_key(g_rc4_encrypt_key, (char *)g_sec_encrypt_key, g_rc4_key_len); 
}
 
static uint8 pad_54[40] = {
    54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54,
    54, 54, 54,
    54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54,
    54, 54, 54
};
 
static uint8 pad_92[48] = {
    92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92,
    92, 92, 92, 92, 92, 92, 92,
    92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92,
    92, 92, 92, 92, 92, 92, 92
};
 
/* Output a uint32 into a buffer (little-endian) */
void
buf_out_uint32(uint8 * buffer, uint32 value)
{
    buffer[0] = (value) & 0xff;
    buffer[1] = (value >> 8) & 0xff;
    buffer[2] = (value >> 16) & 0xff;
    buffer[3] = (value >> 24) & 0xff;
}
 
/* Generate a MAC hash (5.2.3.1), using a combination of SHA1 and MD5 */
void
sec_sign(uint8 * signature, int siglen, uint8 * session_key, int keylen, uint8 * data, int datalen)
{
    uint8 shasig[20];
    uint8 md5sig[16];
    uint8 lenhdr[4];
    void * sha;
    void * md5;
 
    buf_out_uint32(lenhdr, datalen);
 
    sha = rdssl_sha1_info_create();
    rdssl_sha1_clear(sha);
    rdssl_sha1_transform(sha, (char *)session_key, keylen);
    rdssl_sha1_transform(sha, (char *)pad_54, 40);
    rdssl_sha1_transform(sha, (char *)lenhdr, 4);
    rdssl_sha1_transform(sha, (char *)data, datalen);
    rdssl_sha1_complete(sha, (char *)shasig);
    rdssl_sha1_info_delete(sha);
 
    md5 = rdssl_md5_info_create();
    rdssl_md5_clear(md5);
    rdssl_md5_transform(md5, (char *)session_key, keylen);
    rdssl_md5_transform(md5, (char *)pad_92, 48);
    rdssl_md5_transform(md5, (char *)shasig, 20);
    rdssl_md5_complete(md5, (char *)md5sig);
    rdssl_md5_info_delete(md5); 
 
    memcpy(signature, md5sig, siglen);
}
 
/* Update an encryption key */
static void
sec_update(uint8 * key, uint8 * update_key)
{
    uint8 shasig[20];
    void * sha;
    void * md5;
    void * update;
 
    sha = rdssl_sha1_info_create();
    rdssl_sha1_clear(sha);
    rdssl_sha1_transform(sha, (char *)update_key, g_rc4_key_len);
    rdssl_sha1_transform(sha, (char *)pad_54, 40);
    rdssl_sha1_transform(sha, (char *)key, g_rc4_key_len);
    rdssl_sha1_complete(sha, (char *)shasig);
    rdssl_sha1_info_delete(sha);
 
    md5 = rdssl_md5_info_create();
    rdssl_md5_clear(md5);
    rdssl_md5_transform(md5, (char *)update_key, g_rc4_key_len);
    rdssl_md5_transform(md5, (char *)pad_92, 48);
    rdssl_md5_transform(md5, (char *)shasig, 20);
    rdssl_md5_complete(md5, (char *)key);
    rdssl_md5_info_delete(md5);
 
 
    update = rdssl_rc4_info_create();
    rdssl_rc4_set_key(update, (char *)key, g_rc4_key_len);
    rdssl_rc4_crypt(update, (char *)key, (char *)key, g_rc4_key_len);
    rdssl_rc4_info_delete(update);
 
    if (g_rc4_key_len == 8)
        sec_make_40bit(key);
}
 
/* Encrypt data using RC4 */
static void
sec_encrypt(uint8 * data, int length)
{
    if (g_sec_encrypt_use_count == 4096)
    {
        sec_update(g_sec_encrypt_key, g_sec_encrypt_update_key);
        rdssl_rc4_set_key(g_rc4_encrypt_key, (char *)g_sec_encrypt_key, g_rc4_key_len);
        g_sec_encrypt_use_count = 0;
    }
 
    rdssl_rc4_crypt(g_rc4_encrypt_key, (char *)data, (char *)data, length);
    g_sec_encrypt_use_count++;
}
 
/* Decrypt data using RC4 */
void
sec_decrypt(uint8 * data, int length)
{
    if (g_sec_decrypt_use_count == 4096)
    {
        sec_update(g_sec_decrypt_key, g_sec_decrypt_update_key);
        rdssl_rc4_set_key(g_rc4_decrypt_key, (char *)g_sec_decrypt_key, g_rc4_key_len);
        g_sec_decrypt_use_count = 0;
    }
 
    rdssl_rc4_crypt(g_rc4_decrypt_key,(char *)data, (char *)data, length);
    g_sec_decrypt_use_count++;
}
 
/* Perform an RSA public key encryption operation */
static void
sec_rsa_encrypt(uint8 * out, uint8 * in, int len, uint32 modulus_size, uint8 * modulus,
        uint8 * exponent)
{
    rdssl_mod_exp((char *)out, 64, (char *)in, 32, (char *)modulus, 64, (char *)exponent, 4);
}
 
/* Initialise secure transport packet */
STREAM
sec_init(uint32 flags, int maxlen)
{
    int hdrlen;
    STREAM s;
 
    if (!g_licence_issued && !g_licence_error_result)
        hdrlen = (flags & SEC_ENCRYPT) ? 12 : 4;
    else
        hdrlen = (flags & SEC_ENCRYPT) ? 12 : 0;
    s = mcs_init(maxlen + hdrlen);
    s_push_layer(s, sec_hdr, hdrlen);
 
    return s;
}
 
/* Transmit secure transport packet over specified channel */
void
sec_send_to_channel(STREAM s, uint32 flags, uint16 channel)
{
    int datalen;
 
#ifdef WITH_SCARD
    scard_lock(SCARD_LOCK_SEC);
#endif
 
    s_pop_layer(s, sec_hdr);
    if ((!g_licence_issued && !g_licence_error_result) || (flags & SEC_ENCRYPT))
        out_uint32_le(s, flags);
 
    if (flags & SEC_ENCRYPT)
    {
        flags &= ~SEC_ENCRYPT;
        datalen = s->end - s->p - 8;
 
#ifdef WITH_DEBUG
        DEBUG(("Sending encrypted packet:\n"));
        hexdump(s->p + 8, datalen);
#endif
 
        sec_sign(s->p, 8, g_sec_sign_key, g_rc4_key_len, s->p + 8, datalen);
        sec_encrypt(s->p + 8, datalen);
    }
 
    mcs_send_to_channel(s, channel);
 
#ifdef WITH_SCARD
    scard_unlock(SCARD_LOCK_SEC);
#endif
}
 
/* Transmit secure transport packet */
 
void
sec_send(STREAM s, uint32 flags)
{
    sec_send_to_channel(s, flags, MCS_GLOBAL_CHANNEL);
}
 
 
/* Transfer the client random to the server */
static void
sec_establish_key(void)
{
    uint32 length = g_server_public_key_len + SEC_PADDING_SIZE;
    uint32 flags = SEC_EXCHANGE_PKT;
    STREAM s;
 
    s = sec_init(flags, length + 4);
 
    out_uint32_le(s, length);
    out_uint8p(s, g_sec_crypted_random, g_server_public_key_len);
    out_uint8s(s, SEC_PADDING_SIZE);
 
    s_mark_end(s);
    sec_send(s, flags);
}
 
/* Output connect initial data blob */
static void
sec_out_mcs_data(STREAM s, uint32 selected_protocol)
{
    int hostlen = 2 * strlen(g_hostname);
    int length = 162 + 76 + 12 + 4;
    unsigned int i;
    uint32 cluster_flags = 0;
 
    if (g_num_channels > 0)
        length += g_num_channels * 12 + 8;
 
    if (hostlen > 30)
        hostlen = 30;
 
    /* Generic Conference Control (T.124) ConferenceCreateRequest */
    out_uint16_be(s, 5);
    out_uint16_be(s, 0x14);
    out_uint8(s, 0x7c);
    out_uint16_be(s, 1);
 
    out_uint16_be(s, (length | 0x8000));    /* remaining length */
 
    out_uint16_be(s, 8);    /* length? */
    out_uint16_be(s, 16);
    out_uint8(s, 0);
    out_uint16_le(s, 0xc001);
    out_uint8(s, 0);
 
    out_uint32_le(s, 0x61637544);   /* OEM ID: "Duca", as in Ducati. */
    out_uint16_be(s, ((length - 14) | 0x8000)); /* remaining length */
 
    /* Client information */
    out_uint16_le(s, SEC_TAG_CLI_INFO);
    out_uint16_le(s, 216);  /* length */
    out_uint16_le(s, (g_rdp_version >= RDP_V5) ? 4 : 1);    /* RDP version. 1 == RDP4, 4 >= RDP5 to RDP8 */
    out_uint16_le(s, 8);
    out_uint16_le(s, g_width);
    out_uint16_le(s, g_height);
    out_uint16_le(s, 0xca01);
    out_uint16_le(s, 0xaa03);
    out_uint32_le(s, g_keylayout);
    out_uint32_le(s, 2600); /* Client build. We are now 2600 compatible :-) */
 
    /* Unicode name of client, padded to 32 bytes */
    rdp_out_unistr(s, g_hostname, hostlen);
    out_uint8s(s, 30 - hostlen);
 
    /* See
       http://msdn.microsoft.com/library/default.asp?url=/library/en-us/wceddk40/html/cxtsksupportingremotedesktopprotocol.asp */
    out_uint32_le(s, g_keyboard_type);
    out_uint32_le(s, g_keyboard_subtype);
    out_uint32_le(s, g_keyboard_functionkeys);
    out_uint8s(s, 64);  /* reserved? 4 + 12 doublewords */
    out_uint16_le(s, 0xca01);   /* colour depth? */
    out_uint16_le(s, 1);
 
    out_uint32(s, 0);
    out_uint8(s, g_server_depth);
    out_uint16_le(s, 0x0700);
    out_uint8(s, 0);
    out_uint32_le(s, 1);
    out_uint8s(s, 64);
    out_uint32_le(s, selected_protocol);    /* End of client info */
 
    /* Write a Client Cluster Data (TS_UD_CS_CLUSTER) */
    out_uint16_le(s, SEC_TAG_CLI_CLUSTER);  /* header.type */
    out_uint16_le(s, 12);   /* length */
 
    cluster_flags |= SEC_CC_REDIRECTION_SUPPORTED;
    cluster_flags |= (SEC_CC_REDIRECT_VERSION_3 << 2);
 
    if (g_console_session || g_redirect_session_id != 0)
        cluster_flags |= SEC_CC_REDIRECT_SESSIONID_FIELD_VALID;
 
    out_uint32_le(s, cluster_flags);
    out_uint32(s, g_redirect_session_id);
 
    /* Client encryption settings */
    out_uint16_le(s, SEC_TAG_CLI_CRYPT);
    out_uint16_le(s, 12);   /* length */
    out_uint32_le(s, g_encryption ? 0x3 : 0);   /* encryption supported, 128-bit supported */
    out_uint32(s, 0);   /* Unknown */
 
    DEBUG_RDP5(("g_num_channels is %d\n", g_num_channels));
    if (g_num_channels > 0)
    {
        out_uint16_le(s, SEC_TAG_CLI_CHANNELS);
        out_uint16_le(s, g_num_channels * 12 + 8);  /* length */
        out_uint32_le(s, g_num_channels);   /* number of virtual channels */
        for (i = 0; i < g_num_channels; i++)
        {
            DEBUG_RDP5(("Requesting channel %s\n", g_channels[i].name));
            out_uint8a(s, g_channels[i].name, 8);
            out_uint32_be(s, g_channels[i].flags);
        }
    }
 
    s_mark_end(s);
}
 
/* Parse a public key structure */
static RD_BOOL
sec_parse_public_key(STREAM s, uint8 * modulus, uint8 * exponent)
{
    uint32 magic, modulus_len;
 
    in_uint32_le(s, magic);
    if (magic != SEC_RSA_MAGIC)
    {
        error("RSA magic 0x%x\n", magic);
        return False;
    }
 
    in_uint32_le(s, modulus_len);
    modulus_len -= SEC_PADDING_SIZE;
    if ((modulus_len < SEC_MODULUS_SIZE) || (modulus_len > SEC_MAX_MODULUS_SIZE))
    {
        error("Bad server public key size (%u bits)\n", modulus_len * 8);
        return False;
    }
 
    in_uint8s(s, 8);    /* modulus_bits, unknown */
    in_uint8a(s, exponent, SEC_EXPONENT_SIZE);
    in_uint8a(s, modulus, modulus_len);
    in_uint8s(s, SEC_PADDING_SIZE);
    g_server_public_key_len = modulus_len;
 
    return s_check(s);
}
 
/* Parse a public signature structure */
static RD_BOOL
sec_parse_public_sig(STREAM s, uint32 len, uint8 * modulus, uint8 * exponent)
{
    uint8 signature[SEC_MAX_MODULUS_SIZE];
    uint8 signature_[SEC_MAX_MODULUS_SIZE];
    uint32 sig_len;
 
    if (len != 72)
    {
        return True;
    }
    memset(signature, 0, sizeof(signature));
    sig_len = len - 8;
    in_uint8a(s, signature, sig_len);
    if(rdssl_sign_ok((char *)exponent, SEC_EXPONENT_SIZE, (char *)modulus, g_server_public_key_len,
                     (char *)signature_, SEC_MODULUS_SIZE, (char *)signature, sig_len, (char *)g_testkey))
    {
        DEBUG_RDP5(("key signature doesn't match test key\n"));
    }
    return s_check(s);
}
 
/* Parse a crypto information structure */
static RD_BOOL
sec_parse_crypt_info(STREAM s, uint32 * rc4_key_size,
             uint8 ** server_random, uint8 * modulus, uint8 * exponent)
{
    uint32 crypt_level, random_len, rsa_info_len;
    uint32 cacert_len, cert_len, flags;
    PCCERT_CONTEXT cacert, server_cert;
    BYTE *server_public_key;
    uint16 tag, length;
    uint8 *next_tag, *end;
 
    in_uint32_le(s, *rc4_key_size); /* 1 = 40-bit, 2 = 128-bit */
    in_uint32_le(s, crypt_level);   /* 1 = low, 2 = medium, 3 = high */
    if (crypt_level == 0)
    {
        /* no encryption */
        return False;
    }
 
    in_uint32_le(s, random_len);
    in_uint32_le(s, rsa_info_len);
 
    if (random_len != SEC_RANDOM_SIZE)
    {
        error("random len %d, expected %d\n", random_len, SEC_RANDOM_SIZE);
        return False;
    }
 
    in_uint8p(s, *server_random, random_len);
 
    /* RSA info */
    end = s->p + rsa_info_len;
    if (end > s->end)
        return False;
 
    in_uint32_le(s, flags); /* 1 = RDP4-style, 0x80000002 = X.509 */
    if (flags & 1)
    {
        DEBUG_RDP5(("We're going for the RDP4-style encryption\n"));
        in_uint8s(s, 8);    /* unknown */
 
        while (s->p < end)
        {
            in_uint16_le(s, tag);
            in_uint16_le(s, length);
 
            next_tag = s->p + length;
 
            switch (tag)
            {
                case SEC_TAG_PUBKEY:
                    if (!sec_parse_public_key(s, modulus, exponent))
                        return False;
                    DEBUG_RDP5(("Got Public key, RDP4-style\n"));
 
                    break;
 
                case SEC_TAG_KEYSIG:
                    if (!sec_parse_public_sig(s, length, modulus, exponent))
                        return False;
                    break;
 
                default:
                    unimpl("crypt tag 0x%x\n", tag);
            }
 
            s->p = next_tag;
        }
    }
    else
    {
        uint32 certcount;
 
        DEBUG_RDP5(("We're going for the RDP5-style encryption\n"));
        in_uint32_le(s, certcount); /* Number of certificates */
        if (certcount < 2)
        {
            error("Server didn't send enough X509 certificates\n");
            return False;
        }
        for (; certcount > 2; certcount--)
        {       /* ignore all the certificates between the root and the signing CA */
            uint32 ignorelen;
            PCCERT_CONTEXT ignorecert;
 
            DEBUG_RDP5(("Ignored certs left: %d\n", certcount));
            in_uint32_le(s, ignorelen);
            DEBUG_RDP5(("Ignored Certificate length is %d\n", ignorelen));
            ignorecert = rdssl_cert_read(s->p, ignorelen);
            in_uint8s(s, ignorelen);
            if (ignorecert == NULL)
            {   /* XXX: error out? */
                DEBUG_RDP5(("got a bad cert: this will probably screw up the rest of the communication\n"));
            }
 
#ifdef WITH_DEBUG_RDP5
            DEBUG_RDP5(("cert #%d (ignored):\n", certcount));
            rdssl_cert_print_fp(stdout, ignorecert);
#endif
        }
        /* Do da funky X.509 stuffy
 
           "How did I find out about this?  I looked up and saw a
           bright light and when I came to I had a scar on my forehead
           and knew about X.500"
           - Peter Gutman in a early version of 
           http://www.cs.auckland.ac.nz/~pgut001/pubs/x509guide.txt
         */
        in_uint32_le(s, cacert_len);
        DEBUG_RDP5(("CA Certificate length is %d\n", cacert_len));
        cacert = rdssl_cert_read(s->p, cacert_len);
        in_uint8s(s, cacert_len);
        if (NULL == cacert)
        {
            error("Couldn't load CA Certificate from server\n");
            return False;
        }
        in_uint32_le(s, cert_len);
        DEBUG_RDP5(("Certificate length is %d\n", cert_len));
        server_cert = rdssl_cert_read(s->p, cert_len);
        in_uint8s(s, cert_len);
        if (NULL == server_cert)
        {
            rdssl_cert_free(cacert);
            error("Couldn't load Certificate from server\n");
            return False;
        }
        if (!rdssl_certs_ok(server_cert, cacert))
        {
            rdssl_cert_free(server_cert);
            rdssl_cert_free(cacert);
            error("Security error CA Certificate invalid\n");
            return False;
        }
        rdssl_cert_free(cacert);
        in_uint8s(s, 16);   /* Padding */
        server_public_key = rdssl_cert_to_rkey(server_cert, &g_server_public_key_len);
        if (NULL == server_public_key)
        {
            DEBUG_RDP5(("Didn't parse X509 correctly\n"));
            rdssl_cert_free(server_cert);
            return False;
        }
        rdssl_cert_free(server_cert);
        if ((g_server_public_key_len < SEC_MODULUS_SIZE) ||
            (g_server_public_key_len > SEC_MAX_MODULUS_SIZE))
        {
            error("Bad server public key size (%u bits)\n",
                  g_server_public_key_len * 8);
            rdssl_rkey_free(server_public_key);
            return False;
        }
        if (rdssl_rkey_get_exp_mod(server_public_key, exponent, SEC_EXPONENT_SIZE,
                       modulus, SEC_MAX_MODULUS_SIZE) != 0)
        {
            error("Problem extracting RSA exponent, modulus");
            rdssl_rkey_free(server_public_key);
            return False;
        }
        rdssl_rkey_free(server_public_key);
        return True;    /* There's some garbage here we don't care about */
    }
    return s_check_end(s);
}
 
/* Process crypto information blob */
static void
sec_process_crypt_info(STREAM s)
{
    uint8 *server_random = NULL;
    uint8 modulus[SEC_MAX_MODULUS_SIZE];
    uint8 exponent[SEC_EXPONENT_SIZE];
    uint32 rc4_key_size;
 
    memset(modulus, 0, sizeof(modulus));
    memset(exponent, 0, sizeof(exponent));
    if (!sec_parse_crypt_info(s, &rc4_key_size, &server_random, modulus, exponent))
    {
        DEBUG(("Failed to parse crypt info\n"));
        return;
    }
    DEBUG(("Generating client random\n"));
    generate_random(g_client_random);
    sec_rsa_encrypt(g_sec_crypted_random, g_client_random, SEC_RANDOM_SIZE,
            g_server_public_key_len, modulus, exponent);
    sec_generate_keys(g_client_random, server_random, rc4_key_size);
}
 
 
/* Process SRV_INFO, find RDP version supported by server */
static void
sec_process_srv_info(STREAM s)
{
    in_uint16_le(s, g_server_rdp_version);
    DEBUG_RDP5(("Server RDP version is %d\n", g_server_rdp_version));
    if (1 == g_server_rdp_version)
    {
        g_rdp_version = RDP_V4;
        g_server_depth = 8;
    }
}
 
 
/* Process connect response data blob */
void
sec_process_mcs_data(STREAM s)
{
    uint16 tag, length;
    uint8 *next_tag;
    uint8 len;
 
    in_uint8s(s, 21);   /* header (T.124 ConferenceCreateResponse) */
    in_uint8(s, len);
    if (len & 0x80)
        in_uint8(s, len);
 
    while (s->p < s->end)
    {
        in_uint16_le(s, tag);
        in_uint16_le(s, length);
 
        if (length <= 4)
            return;
 
        next_tag = s->p + length - 4;
 
        switch (tag)
        {
            case SEC_TAG_SRV_INFO:
                sec_process_srv_info(s);
                break;
 
            case SEC_TAG_SRV_CRYPT:
                sec_process_crypt_info(s);
                break;
 
            case SEC_TAG_SRV_CHANNELS:
                /* FIXME: We should parse this information and
                   use it to map RDP5 channels to MCS 
                   channels */
                break;
 
            default:
                unimpl("response tag 0x%x\n", tag);
        }
 
        s->p = next_tag;
    }
}
 
/* Receive secure transport packet */
STREAM
sec_recv(uint8 * rdpver)
{
    uint16 sec_flags;
    /* uint16 sec_flags_hi; */
    uint16 channel;
    STREAM s;
 
    while ((s = mcs_recv(&channel, rdpver)) != NULL)
    {
        if (rdpver != NULL)
        {
            if (*rdpver != 3)
            {
                if (*rdpver & 0x80)
                {
                    in_uint8s(s, 8);    /* signature */
                    sec_decrypt(s->p, s->end - s->p);
                }
                return s;
            }
        }
        if (g_encryption || (!g_licence_issued && !g_licence_error_result))
        {
            /* TS_SECURITY_HEADER */
            in_uint16_le(s, sec_flags);
            in_uint8s(s, 2); /* sec_flags_hi */
 
            if (g_encryption)
            {
                if (sec_flags & SEC_ENCRYPT)
                {
                    in_uint8s(s, 8);    /* signature */
                    sec_decrypt(s->p, s->end - s->p);
                }
 
                if (sec_flags & SEC_LICENSE_PKT)
                {
                    licence_process(s);
                    continue;
                }
 
                if (sec_flags & SEC_REDIRECTION_PKT)    /* SEC_REDIRECT_ENCRYPT */
                {
                    uint8 swapbyte;
 
                    in_uint8s(s, 8);    /* signature */
                    sec_decrypt(s->p, s->end - s->p);
 
                    /* Check for a redirect packet, starts with 00 04 */
                    if (s->p[0] == 0 && s->p[1] == 4)
                    {
                        /* for some reason the PDU and the length seem to be swapped.
                           This isn't good, but we're going to do a byte for byte
                           swap.  So the first four values appear as: 00 04 XX YY,
                           where XX YY is the little endian length. We're going to
                           use 04 00 as the PDU type, so after our swap this will look
                           like: XX YY 04 00 */
                        swapbyte = s->p[0];
                        s->p[0] = s->p[2];
                        s->p[2] = swapbyte;
 
                        swapbyte = s->p[1];
                        s->p[1] = s->p[3];
                        s->p[3] = swapbyte;
 
                        swapbyte = s->p[2];
                        s->p[2] = s->p[3];
                        s->p[3] = swapbyte;
                    }
#ifdef WITH_DEBUG
                    /* warning!  this debug statement will show passwords in the clear! */
                    hexdump(s->p, s->end - s->p);
#endif
                }
            }
            else
            {
                if (sec_flags & SEC_LICENSE_PKT)
                {
                    licence_process(s);
                    continue;
                }
                s->p -= 4;
            }
        }
 
        if (channel != MCS_GLOBAL_CHANNEL)
        {
            channel_process(s, channel);
            if (rdpver != NULL)
                *rdpver = 0xff;
            return s;
        }
 
        return s;
    }
 
    return NULL;
}
 
/* Establish a secure connection */
RD_BOOL
sec_connect(char *server, char *username, char *domain, char *password, RD_BOOL reconnect)
{
    uint32 selected_proto;
    struct stream mcs_data;
 
    /* Start a MCS connect sequence */
    if (!mcs_connect_start(server, username, domain, password, reconnect, &selected_proto))
        return False;
 
    /* We exchange some RDP data during the MCS-Connect */
    mcs_data.size = 512;
    mcs_data.p = mcs_data.data = (uint8 *) xmalloc(mcs_data.size);
    sec_out_mcs_data(&mcs_data, selected_proto);
 
    /* finalize the MCS connect sequence */
    if (!mcs_connect_finalize(&mcs_data))
        return False;
 
    /* sec_process_mcs_data(&mcs_data); */
    if (g_encryption)
        sec_establish_key();
    xfree(mcs_data.data);
    return True;
}
 
/* Disconnect a connection */
void
sec_disconnect(void)
{
    mcs_disconnect();
}
 
/* reset the state of the sec layer */
void
sec_reset_state(void)
{
    g_server_rdp_version = 0;
    g_sec_encrypt_use_count = 0;
    g_sec_decrypt_use_count = 0;
    g_licence_issued = 0;
    g_licence_error_result = 0;
    mcs_reset_state();
}