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/**
* FreeRDP: A Remote Desktop Protocol Implementation
* Cryptographic Abstraction Layer
*
* Copyright 2011-2012 Marc-Andre Moreau <marcandre.moreau@gmail.com>
* Copyright 2023 Armin Novak <anovak@thincast.com>
* Copyright 2023 Thincast Technologies GmbH
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <errno.h>
#include <openssl/objects.h>
#include <openssl/bn.h>
#include <freerdp/config.h>
#include <winpr/crt.h>
#include <winpr/assert.h>
#include <freerdp/log.h>
#include <freerdp/crypto/crypto.h>
#include "crypto.h"
#include "privatekey.h"
#define TAG FREERDP_TAG("crypto")
static SSIZE_T crypto_rsa_common(const BYTE* input, size_t length, UINT32 key_length,
const BYTE* modulus, const BYTE* exponent, size_t exponent_size,
BYTE* output, size_t out_length)
{
BN_CTX* ctx = NULL;
int output_length = -1;
BYTE* input_reverse = NULL;
BYTE* modulus_reverse = NULL;
BYTE* exponent_reverse = NULL;
BIGNUM* mod = NULL;
BIGNUM* exp = NULL;
BIGNUM* x = NULL;
BIGNUM* y = NULL;
size_t bufferSize = 0;
if (!input || !modulus || !exponent || !output)
return -1;
if ((size_t)exponent_size > INT_MAX / 2)
return -1;
if (key_length >= INT_MAX / 2 - exponent_size)
return -1;
bufferSize = 2ULL * key_length + exponent_size;
if ((size_t)length > bufferSize)
bufferSize = (size_t)length;
input_reverse = (BYTE*)calloc(bufferSize, 1);
if (!input_reverse)
return -1;
modulus_reverse = input_reverse + key_length;
exponent_reverse = modulus_reverse + key_length;
memcpy(modulus_reverse, modulus, key_length);
crypto_reverse(modulus_reverse, key_length);
memcpy(exponent_reverse, exponent, exponent_size);
crypto_reverse(exponent_reverse, exponent_size);
memcpy(input_reverse, input, length);
crypto_reverse(input_reverse, length);
if (!(ctx = BN_CTX_new()))
goto fail;
if (!(mod = BN_new()))
goto fail;
if (!(exp = BN_new()))
goto fail;
if (!(x = BN_new()))
goto fail;
if (!(y = BN_new()))
goto fail;
if (!BN_bin2bn(modulus_reverse, key_length, mod))
goto fail;
if (!BN_bin2bn(exponent_reverse, exponent_size, exp))
goto fail;
if (!BN_bin2bn(input_reverse, length, x))
goto fail;
if (BN_mod_exp(y, x, exp, mod, ctx) != 1)
goto fail;
output_length = BN_bn2bin(y, output);
if (output_length < 0)
goto fail;
if ((size_t)output_length > out_length)
goto fail;
crypto_reverse(output, output_length);
if ((size_t)output_length < key_length)
{
size_t diff = key_length - output_length;
if ((size_t)output_length + diff > out_length)
diff = out_length - (size_t)output_length;
memset(output + output_length, 0, diff);
}
fail:
BN_free(y);
BN_clear_free(x);
BN_free(exp);
BN_free(mod);
BN_CTX_free(ctx);
free(input_reverse);
return output_length;
}
static SSIZE_T crypto_rsa_public(const BYTE* input, size_t length, const rdpCertInfo* cert,
BYTE* output, size_t output_length)
{
WINPR_ASSERT(cert);
return crypto_rsa_common(input, length, cert->ModulusLength, cert->Modulus, cert->exponent,
sizeof(cert->exponent), output, output_length);
}
static SSIZE_T crypto_rsa_private(const BYTE* input, size_t length, const rdpPrivateKey* key,
BYTE* output, size_t output_length)
{
WINPR_ASSERT(key);
const rdpCertInfo* info = freerdp_key_get_info(key);
WINPR_ASSERT(info);
size_t PrivateExponentLength = 0;
const BYTE* PrivateExponent = freerdp_key_get_exponent(key, &PrivateExponentLength);
return crypto_rsa_common(input, length, info->ModulusLength, info->Modulus, PrivateExponent,
PrivateExponentLength, output, output_length);
}
SSIZE_T crypto_rsa_public_encrypt(const BYTE* input, size_t length, const rdpCertInfo* cert,
BYTE* output, size_t output_length)
{
return crypto_rsa_public(input, length, cert, output, output_length);
}
SSIZE_T crypto_rsa_public_decrypt(const BYTE* input, size_t length, const rdpCertInfo* cert,
BYTE* output, size_t output_length)
{
return crypto_rsa_public(input, length, cert, output, output_length);
}
SSIZE_T crypto_rsa_private_encrypt(const BYTE* input, size_t length, const rdpPrivateKey* key,
BYTE* output, size_t output_length)
{
return crypto_rsa_private(input, length, key, output, output_length);
}
SSIZE_T crypto_rsa_private_decrypt(const BYTE* input, size_t length, const rdpPrivateKey* key,
BYTE* output, size_t output_length)
{
return crypto_rsa_private(input, length, key, output, output_length);
}
void crypto_reverse(BYTE* data, size_t length)
{
if (length < 1)
return;
for (size_t i = 0, j = length - 1; i < j; i++, j--)
{
const BYTE temp = data[i];
data[i] = data[j];
data[j] = temp;
}
}
char* crypto_read_pem(const char* filename, size_t* plength)
{
char* pem = NULL;
FILE* fp = NULL;
WINPR_ASSERT(filename);
if (plength)
*plength = 0;
fp = winpr_fopen(filename, "r");
if (!fp)
goto fail;
const int rs = _fseeki64(fp, 0, SEEK_END);
if (rs < 0)
goto fail;
const SSIZE_T size = _ftelli64(fp);
if (size < 0)
goto fail;
const int rc = _fseeki64(fp, 0, SEEK_SET);
if (rc < 0)
goto fail;
pem = calloc(size + 1, sizeof(char));
if (!pem)
goto fail;
const size_t fr = fread(pem, (size_t)size, 1, fp);
if (fr != 1)
goto fail;
if (plength)
*plength = (size_t)strnlen(pem, size);
fclose(fp);
return pem;
fail:
{
char buffer[8192] = { 0 };
WLog_WARN(TAG, "Failed to read PEM from file '%s' [%s]", filename,
winpr_strerror(errno, buffer, sizeof(buffer)));
}
if (fp)
fclose(fp);
free(pem);
return NULL;
}
BOOL crypto_write_pem(const char* filename, const char* pem, size_t length)
{
WINPR_ASSERT(filename);
WINPR_ASSERT(pem || (length == 0));
WINPR_ASSERT(filename);
WINPR_ASSERT(pem);
const size_t size = strnlen(pem, length) + 1;
size_t rc = 0;
FILE* fp = winpr_fopen(filename, "w");
if (!fp)
goto fail;
rc = fwrite(pem, 1, size, fp);
fclose(fp);
fail:
if (rc == 0)
{
char buffer[8192] = { 0 };
WLog_WARN(TAG, "Failed to write PEM [%" PRIuz "] to file '%s' [%s]", length, filename,
winpr_strerror(errno, buffer, sizeof(buffer)));
}
return rc == size;
}
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