BOOL rdp_server_establish_keys(rdpRdp* rdp, wStream* s)
{
BYTE client_random[64]; /* Should be only 32 after successful decryption, but on failure might take up to 64 bytes. */
BYTE crypt_client_random[256 + 8];
UINT32 rand_len, key_len;
UINT16 channel_id, length, sec_flags;
BYTE* mod;
BYTE* priv_exp;
if (!rdp->settings->DisableEncryption)
{
/* No RDP Security. */
return TRUE;
}
if (!rdp_read_header(rdp, s, &length, &channel_id))
{
fprintf(stderr, "rdp_server_establish_keys: invalid RDP header\n");
return FALSE;
}
if (!rdp_read_security_header(s, &sec_flags))
return FALSE;
if ((sec_flags & SEC_EXCHANGE_PKT) == 0)
{
fprintf(stderr, "rdp_server_establish_keys: missing SEC_EXCHANGE_PKT in security header\n");
return FALSE;
}
if (Stream_GetRemainingLength(s) < 4)
return FALSE;
Stream_Read_UINT32(s, rand_len);
if (Stream_GetRemainingLength(s) < rand_len + 8) /* include 8 bytes of padding */
return FALSE;
key_len = rdp->settings->RdpServerRsaKey->ModulusLength;
if (rand_len != key_len + 8)
{
fprintf(stderr, "rdp_server_establish_keys: invalid encrypted client random length\n");
return FALSE;
}
ZeroMemory(crypt_client_random, sizeof(crypt_client_random));
Stream_Read(s, crypt_client_random, rand_len);
/* 8 zero bytes of padding */
Stream_Seek(s, 8);
mod = rdp->settings->RdpServerRsaKey->Modulus;
priv_exp = rdp->settings->RdpServerRsaKey->PrivateExponent;
crypto_rsa_private_decrypt(crypt_client_random, rand_len - 8, key_len, mod, priv_exp, client_random);
/* now calculate encrypt / decrypt and update keys */
if (!security_establish_keys(client_random, rdp))
{
return FALSE;
}
rdp->do_crypt = TRUE;
if (rdp->settings->SaltedChecksum)
rdp->do_secure_checksum = TRUE;
if (rdp->settings->EncryptionMethods == ENCRYPTION_METHOD_FIPS)
{
rdp->fips_encrypt = crypto_des3_encrypt_init(rdp->fips_encrypt_key, fips_ivec);
rdp->fips_decrypt = crypto_des3_decrypt_init(rdp->fips_decrypt_key, fips_ivec);
rdp->fips_hmac = crypto_hmac_new();
return TRUE;
}
rdp->rc4_decrypt_key = crypto_rc4_init(rdp->decrypt_key, rdp->rc4_key_len);
rdp->rc4_encrypt_key = crypto_rc4_init(rdp->encrypt_key, rdp->rc4_key_len);
return TRUE;
}
BOOL rdp_server_establish_keys(rdpRdp* rdp, wStream* s)
{
BYTE* client_random = NULL;
BYTE* crypt_client_random = NULL;
UINT32 rand_len, key_len;
UINT16 channel_id, length, sec_flags;
BYTE* mod;
BYTE* priv_exp;
BOOL ret = FALSE;
if (!rdp->settings->DisableEncryption)
{
/* No RDP Security. */
return TRUE;
}
if (!rdp_read_header(rdp, s, &length, &channel_id))
{
WLog_ERR(TAG, "invalid RDP header");
return FALSE;
}
if (!rdp_read_security_header(s, &sec_flags))
{
WLog_ERR(TAG, "invalid security header");
return FALSE;
}
if ((sec_flags & SEC_EXCHANGE_PKT) == 0)
{
WLog_ERR(TAG, "missing SEC_EXCHANGE_PKT in security header");
return FALSE;
}
rdp->do_crypt_license = (sec_flags & SEC_LICENSE_ENCRYPT_SC) != 0 ? TRUE : FALSE;
if (Stream_GetRemainingLength(s) < 4)
return FALSE;
Stream_Read_UINT32(s, rand_len);
/* rand_len already includes 8 bytes of padding */
if (Stream_GetRemainingLength(s) < rand_len)
return FALSE;
key_len = rdp->settings->RdpServerRsaKey->ModulusLength;
client_random = malloc(key_len);
if (!client_random)
return FALSE;
if (rand_len != key_len + 8)
{
WLog_ERR(TAG, "invalid encrypted client random length");
goto end2;
}
crypt_client_random = calloc(1, rand_len);
if (!crypt_client_random)
goto end2;
Stream_Read(s, crypt_client_random, rand_len);
mod = rdp->settings->RdpServerRsaKey->Modulus;
priv_exp = rdp->settings->RdpServerRsaKey->PrivateExponent;
crypto_rsa_private_decrypt(crypt_client_random, rand_len - 8, key_len, mod, priv_exp, client_random);
/* now calculate encrypt / decrypt and update keys */
if (!security_establish_keys(client_random, rdp))
{
goto end;
}
rdp->do_crypt = TRUE;
if (rdp->settings->EncryptionMethods == ENCRYPTION_METHOD_FIPS)
{
rdp->fips_encrypt = crypto_des3_encrypt_init(rdp->fips_encrypt_key, fips_ivec);
if (!rdp->fips_encrypt)
{
WLog_ERR(TAG, "unable to allocate des3 encrypt key");
goto end;
}
rdp->fips_decrypt = crypto_des3_decrypt_init(rdp->fips_decrypt_key, fips_ivec);
if (!rdp->fips_decrypt)
{
WLog_ERR(TAG, "unable to allocate des3 decrypt key");
goto end;
}
rdp->fips_hmac = crypto_hmac_new();
if (!rdp->fips_hmac)
{
WLog_ERR(TAG, "unable to allocate fips hmac");
goto end;
}
ret = TRUE;
goto end;
}
rdp->rc4_decrypt_key = crypto_rc4_init(rdp->decrypt_key, rdp->rc4_key_len);
if (!rdp->rc4_decrypt_key)
{
WLog_ERR(TAG, "unable to allocate rc4 decrypt key");
goto end;
}
rdp->rc4_encrypt_key = crypto_rc4_init(rdp->encrypt_key, rdp->rc4_key_len);
if (!rdp->rc4_encrypt_key)
{
WLog_ERR(TAG, "unable to allocate rc4 encrypt key");
goto end;
}
ret = TRUE;
end:
if (crypt_client_random)
free(crypt_client_random);
end2:
if (client_random)
free(client_random);
return ret;
}
static boolean rdp_server_establish_keys(rdpRdp* rdp, STREAM* s)
{
uint8 client_random[64]; /* Should be only 32 after successfull decryption, but on failure might take up to 64 bytes. */
uint8 crypt_client_random[256 + 8];
uint32 rand_len, key_len;
uint16 channel_id, length, sec_flags;
uint8* mod;
uint8* priv_exp;
if (rdp->settings->encryption == false)
{
/* No RDP Security. */
return true;
}
if (!rdp_read_header(rdp, s, &length, &channel_id))
{
printf("rdp_server_establish_keys: invalid RDP header\n");
return false;
}
rdp_read_security_header(s, &sec_flags);
if ((sec_flags & SEC_EXCHANGE_PKT) == 0)
{
printf("rdp_server_establish_keys: missing SEC_EXCHANGE_PKT in security header\n");
return false;
}
stream_read_uint32(s, rand_len);
key_len = rdp->settings->server_key->modulus.length;
if (rand_len != key_len + 8)
{
printf("rdp_server_establish_keys: invalid encrypted client random length\n");
return false;
}
memset(crypt_client_random, 0, sizeof(crypt_client_random));
stream_read(s, crypt_client_random, rand_len);
/* 8 zero bytes of padding */
stream_seek(s, 8);
mod = rdp->settings->server_key->modulus.data;
priv_exp = rdp->settings->server_key->private_exponent.data;
crypto_rsa_private_decrypt(crypt_client_random, rand_len - 8, key_len, mod, priv_exp, client_random);
/* now calculate encrypt / decrypt and update keys */
if (!security_establish_keys(client_random, rdp))
{
return false;
}
rdp->do_crypt = true;
if (rdp->settings->salted_checksum)
rdp->do_secure_checksum = true;
if (rdp->settings->encryption_method == ENCRYPTION_METHOD_FIPS)
{
uint8 fips_ivec[8] = { 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF };
rdp->fips_encrypt = crypto_des3_encrypt_init(rdp->fips_encrypt_key, fips_ivec);
rdp->fips_decrypt = crypto_des3_decrypt_init(rdp->fips_decrypt_key, fips_ivec);
rdp->fips_hmac = crypto_hmac_new();
return true;
}
rdp->rc4_decrypt_key = crypto_rc4_init(rdp->decrypt_key, rdp->rc4_key_len);
rdp->rc4_encrypt_key = crypto_rc4_init(rdp->encrypt_key, rdp->rc4_key_len);
return true;
}
BOOL rdp_server_establish_keys(rdpRdp* rdp, wStream* s)
{
BYTE* client_random = NULL;
BYTE* crypt_client_random = NULL;
UINT32 rand_len, key_len;
UINT16 channel_id, length, sec_flags;
BYTE* mod;
BYTE* priv_exp;
BOOL ret = FALSE;
if (!rdp->settings->UseRdpSecurityLayer)
{
/* No RDP Security. */
return TRUE;
}
if (!rdp_read_header(rdp, s, &length, &channel_id))
{
WLog_ERR(TAG, "invalid RDP header");
return FALSE;
}
if (!rdp_read_security_header(s, &sec_flags, NULL))
{
WLog_ERR(TAG, "invalid security header");
return FALSE;
}
if ((sec_flags & SEC_EXCHANGE_PKT) == 0)
{
WLog_ERR(TAG, "missing SEC_EXCHANGE_PKT in security header");
return FALSE;
}
rdp->do_crypt_license = (sec_flags & SEC_LICENSE_ENCRYPT_SC) != 0 ? TRUE : FALSE;
if (Stream_GetRemainingLength(s) < 4)
return FALSE;
Stream_Read_UINT32(s, rand_len);
/* rand_len already includes 8 bytes of padding */
if (Stream_GetRemainingLength(s) < rand_len)
return FALSE;
key_len = rdp->settings->RdpServerRsaKey->ModulusLength;
client_random = malloc(key_len);
if (!client_random)
return FALSE;
if (rand_len != key_len + 8)
{
WLog_ERR(TAG, "invalid encrypted client random length");
free(client_random);
goto end;
}
crypt_client_random = calloc(1, rand_len);
if (!crypt_client_random)
{
free(client_random);
goto end;
}
Stream_Read(s, crypt_client_random, rand_len);
mod = rdp->settings->RdpServerRsaKey->Modulus;
priv_exp = rdp->settings->RdpServerRsaKey->PrivateExponent;
if (crypto_rsa_private_decrypt(crypt_client_random, rand_len - 8, key_len, mod, priv_exp, client_random) <= 0)
{
free(client_random);
goto end;
}
rdp->settings->ClientRandom = client_random;
rdp->settings->ClientRandomLength = 32;
/* now calculate encrypt / decrypt and update keys */
if (!security_establish_keys(client_random, rdp))
goto end;
rdp->do_crypt = TRUE;
if (rdp->settings->EncryptionMethods == ENCRYPTION_METHOD_FIPS)
{
rdp->fips_encrypt = winpr_Cipher_New(WINPR_CIPHER_DES_EDE3_CBC,
WINPR_ENCRYPT,
rdp->fips_encrypt_key,
fips_ivec);
if (!rdp->fips_encrypt)
{
WLog_ERR(TAG, "unable to allocate des3 encrypt key");
goto end;
}
rdp->fips_decrypt = winpr_Cipher_New(WINPR_CIPHER_DES_EDE3_CBC,
WINPR_DECRYPT,
rdp->fips_decrypt_key,
fips_ivec);
if (!rdp->fips_decrypt)
{
WLog_ERR(TAG, "unable to allocate des3 decrypt key");
goto end;
}
ret = TRUE;
goto end;
}
rdp->rc4_decrypt_key = winpr_RC4_New(rdp->decrypt_key, rdp->rc4_key_len);
rdp->rc4_encrypt_key = winpr_RC4_New(rdp->encrypt_key, rdp->rc4_key_len);
if (!rdp->rc4_decrypt_key || !rdp->rc4_encrypt_key)
goto end;
ret = TRUE;
end:
free(crypt_client_random);
if (!ret)
{
winpr_Cipher_Free(rdp->fips_encrypt);
winpr_Cipher_Free(rdp->fips_decrypt);
winpr_RC4_Free(rdp->rc4_encrypt_key);
winpr_RC4_Free(rdp->rc4_decrypt_key);
rdp->fips_encrypt = NULL;
rdp->fips_decrypt = NULL;
rdp->rc4_encrypt_key = NULL;
rdp->rc4_decrypt_key = NULL;
}
return ret;
}
