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HybridEncryption.cpp
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HybridEncryption.cpp
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/*-
* Copyright (c) 2009, Moxie Marlinspike
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 4. Neither the name of this program nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include "HybridEncryption.h"
#include <openssl/dh.h>
#include <openssl/bn.h>
#include <openssl/x509.h>
#include <openssl/evp.h>
#include <openssl/rand.h>
#include <openssl/aes.h>
#include <openssl/rsa.h>
#include <iostream>
#include <cstdlib>
#include <cstring>
#include <cstdio>
#define PADDING_OVERHEAD 42
#define AES_KEY_SIZE 128/8
void HybridEncryption::AES_encrypt(unsigned char *keyMaterial, int keyLength,
unsigned char *out, unsigned char *in, int len)
{
AES_KEY key;
unsigned char ivec[AES_BLOCK_SIZE];
unsigned char ecount_buf[AES_BLOCK_SIZE];
unsigned int num = 0;
memset(ivec, 0, sizeof(ivec));
memset(ecount_buf, 0, sizeof(ecount_buf));
AES_set_encrypt_key(keyMaterial, keyLength*8, &key);
AES_ctr128_encrypt(in, out, len, &key, ivec, ecount_buf, &num);
}
void HybridEncryption::encryptInHybridChunk(unsigned char* plaintext, int plaintextLength,
unsigned char** encrypted, int *encryptedLength,
RSA *rsa)
{
int pkSize = RSA_size(rsa);
int firstChunkLength = pkSize - PADDING_OVERHEAD - AES_KEY_SIZE;
int secondChunkLength = plaintextLength - firstChunkLength;
*encryptedLength = pkSize + secondChunkLength;
*encrypted = (unsigned char*)malloc(*encryptedLength);
unsigned char symmetricKey[AES_KEY_SIZE];
RAND_bytes(symmetricKey, sizeof(symmetricKey));
unsigned char *rsaEnvelope = (unsigned char*)malloc(pkSize - PADDING_OVERHEAD);
memcpy(rsaEnvelope, symmetricKey, sizeof(symmetricKey));
memcpy(rsaEnvelope+sizeof(symmetricKey), plaintext, firstChunkLength);
RSA_public_encrypt(pkSize - PADDING_OVERHEAD, rsaEnvelope,
*encrypted, rsa, RSA_PKCS1_OAEP_PADDING);
AES_encrypt(symmetricKey, sizeof(symmetricKey), (*encrypted) + pkSize,
plaintext + firstChunkLength, secondChunkLength);
free(rsaEnvelope);
}
void HybridEncryption::encryptInSingleChunk(unsigned char* plaintext, int plaintextLength,
unsigned char** encrypted, int *encryptedLength,
RSA *rsa)
{
*encryptedLength = RSA_size(rsa);
*encrypted = (unsigned char*)malloc(*encryptedLength);
RSA_public_encrypt(plaintextLength, plaintext, *encrypted, rsa, RSA_PKCS1_OAEP_PADDING);
}
void HybridEncryption::encrypt(unsigned char *plaintext, int plaintextLength,
unsigned char **encrypted, int *encryptedLength,
RSA *rsa)
{
if (plaintextLength < (RSA_size(rsa) - PADDING_OVERHEAD)) {
encryptInSingleChunk(plaintext, plaintextLength, encrypted, encryptedLength, rsa);
} else {
encryptInHybridChunk(plaintext, plaintextLength, encrypted, encryptedLength, rsa);
}
}