在计算机软件开发世界中，编程语言种类极多，数据在各种语言的表现形式可能有所差异，但数据本身的处理可能，或者说本质上是完全一样的；比如数据在某个算法中的运算过程是一样的。在这里，我以加密与解密来作为例子说明。
在C++下，我使用OPENSSL库生成了RSA的公私钥对与DES加密之用的会话密钥，并将这三者及加密结果写入文件以备在Java环境下使用。
在C++程序中，我使用使用公钥来加密了DES的会话密钥，然后在Java下使用私钥来解密会话密钥；在运算结果中，我未做其它方面的码制转换，即按密钥的初始格式DER编码，数学运算结果也是按DER编码来实现。
在Java程序中，我从之前所存储的几个文件中取得密钥与加密结果来做解密。我使用了BC的JCE，即bcprov-jdk14-119.jar，在使用之前，需要先安装此JCE：
假设JDK：jdk1.4jre
把BC包放到JRE下的ext：jdk1.4jrelibext
修改文件jdk1.4jrelibsecurityjava.security：
#
# List of providers and their preference orders (see above):
#
security.provider.1=sun.security.provider.Sun
security.provider.2=com.sun.net.ssl.internal.ssl.Provider
security.provider.3=com.sun.rsajca.Provider
security.provider.4=com.sun.crypto.provider.SunJCE
security.provider.5=sun.security.jgss.SunProvider
security.provider.6=org.bouncycastle.jce.provider.BouncyCastleProvider
======================================================================
C++程序源码：
#include
#include
#include
//#define _RSA_KEY_PAIR_GENERATE_//密钥是否要生成 只需要在第一次运行时打开此宏
#define _RSA_KEY_PAIR_TOFILE_//密钥对是否要写入文件
#define MAX_RSA_KEY_LENGTH 512 //密钥的最大长度是512字节
#define PUBKEY_ENCRYPT
#define PRIKEY_DECRYPT
#pragma comment(lib, "../lib/libeay32.lib")
static const char * PUBLIC_KEY_FILE = "pubkey.key";
static const char * PRIVATE_KEY_FILE = "prikey.key";
int RsaKeyPairGen(void)
{
RSA *rsa = NULL;
#ifdef _RSA_KEY_PAIR_GENERATE_
//生成RSA密钥对：
rsa = RSA_new();
rsa = RSA_generate_key(1024, 0x10001, NULL, NULL);
#endif
//把密钥对写入文件，以后从文件里读取
#ifdef _RSA_KEY_PAIR_TOFILE_
unsigned char ucPubKey[MAX_RSA_KEY_LENGTH] = {0}, ucPriKey[MAX_RSA_KEY_LENGTH] = {0};
int len = i2d_RSAPublicKey(rsa,NULL);
unsigned char* pt = ucPubKey;
len = i2d_RSAPublicKey(rsa, &pt);
FILE *fpubkey = NULL;
fpubkey = fopen(PUBLIC_KEY_FILE, "wb");
if(fpubkey == NULL)
{
cout << "fopen pubkey.key failed!" << endl;
return 0x01;
}
fwrite(ucPubKey, 1, len, fpubkey);
fclose(fpubkey);
len = i2d_RSAPrivateKey(rsa,NULL);
unsigned char* pt2 = ucPriKey;
len = i2d_RSAPrivateKey(rsa,&pt2);
FILE *fprikey = NULL;
fprikey = fopen(PRIVATE_KEY_FILE, "wb");
if(fprikey == NULL)
{
cout << "fopen prikey.key failed!" << endl;
return 0x02;
}
fwrite(ucPriKey, 1, len, fprikey);
fclose(fprikey);
#endif
if(rsa != NULL)
{
RSA_free(rsa);
rsa = NULL;
}
return 0;
}
//从文件里读取私钥的数据，取得RSA格式的私钥：
int GetPriKey(unsigned char *pucPriKeyData, unsigned long KeyDataLen, RSA* *priRsa)
{
unsigned char *Pt = pucPriKeyData;
*priRsa = d2i_RSAPrivateKey(NULL, &Pt, KeyDataLen);
if(priRsa == NULL)
{
cout << "priRsa == NULL!" << endl;
return 0x22;
}
return 0;
}
//取得RSA格式的公钥：
int GetPubKey(unsigned char *pucPubKeyData,unsigned long KeyDataLen, RSA* *pubRsa)
{
unsigned char *Pt = pucPubKeyData;
*pubRsa = d2i_RSAPublicKey(NULL, &Pt, KeyDataLen);
if(pubRsa == NULL)
{
cout << "pubRsa == NULL!" << endl;
return 0x31;
}
return 0;
}
//公钥加密会话密钥：
int encSessionKeybyRsaPubKey(RSA *rsa, unsigned char *ucKey, unsigned long ulKeyLen,
unsigned char *outData, unsigned long *pulOutLen)
{
return (*pulOutLen = RSA_public_encrypt(ulKeyLen, ucKey, outData, rsa, 1));
}
//私钥解密会话密钥：
int decSessionKeybyRsaPriKey(RSA *rsa, unsigned char *InData, unsigned long ulDataLen,
unsigned char *ucKey, unsigned long *pulKeyLen)
{
return (*pulKeyLen = RSA_private_decrypt(ulDataLen, InData, ucKey, rsa, 1));
}
int main(int argc, char* argv[])
{
unsigned char ucKey[8] = {0x01, 0x03, 0x99, 0x4,
0x80, 0x65, 0x34, 0x08};
unsigned char ucEncryptedKey[512] = {0}, ucDecryptedKey[512] = {0};
unsigned long encrypted_len = 0, decrypted_len = 0;
#ifdef _RSA_KEY_PAIR_GENERATE_
RsaKeyPairGen();
#endif
//取得公钥：
unsigned char ucPubKey[MAX_RSA_KEY_LENGTH] = {0};
FILE *fpubkey = NULL;
fpubkey = fopen(PUBLIC_KEY_FILE, "rb");
if(fpubkey == NULL)
{
cout << "fopen pubkey.key failed!" << endl;
return 0x03;
}
fseek(fpubkey, 0, SEEK_END);
int len_PK = ftell(fpubkey);
fseek(fpubkey, 0, SEEK_SET);
fread(ucPubKey, 1, len_PK, fpubkey);
fclose(fpubkey);
#ifdef PUBKEY_ENCRYPT
RSA *pRsaPubKey = NULL;
pRsaPubKey = RSA_new();
GetPubKey(ucPubKey, len_PK, &pRsaPubKey);
//公钥加密：
encSessionKeybyRsaPubKey(pRsaPubKey, ucKey, sizeof(ucKey), ucEncryptedKey, &encrypted_len);
//write to file:
FILE *fp = NULL;
fp = fopen("ucKey.data", "wb");
fwrite(ucEncryptedKey, 1, encrypted_len, fp);
fclose(fp);
if(pRsaPubKey != NULL)
{
RSA_free(pRsaPubKey); pRsaPubKey = NULL;
}
#endif
//取得私钥：
unsigned char ucPriKey[MAX_RSA_KEY_LENGTH] = {0};
FILE *fprikey = NULL;
fprikey = fopen(PRIVATE_KEY_FILE, "rb");
if(fprikey == NULL)
{
cout << "fopen prikey.key failed!" << endl;
return 0x02;
}
fseek(fprikey, 0, SEEK_END);
int len_SK = ftell(fprikey);
fseek(fprikey, 0, SEEK_SET);
fread(ucPriKey, 1, len_SK, fprikey);
fclose(fprikey);
#ifdef PRIKEY_DECRYPT
RSA *pRsaPriKey = NULL;
pRsaPriKey = RSA_new();
GetPriKey(ucPriKey, len_SK, &pRsaPriKey);
//私钥解密：
FILE *fp1 = NULL;
fp1 = fopen("ucKey.data", "rb");
int len = ftell(fp1);
fseek(fp1, 0, SEEK_SET);
fread(ucPriKey, 1, len_SK, fp1);
fclose(fp1);
decSessionKeybyRsaPriKey(pRsaPriKey, ucEncryptedKey, encrypted_len, ucDecryptedKey, &decrypted_len);
if(pRsaPriKey != NULL)
{
RSA_free(pRsaPriKey); pRsaPriKey = NULL;
}
//数据对比：
if(0 == memcmp(ucKey, ucDecryptedKey, decrypted_len))
{
cout << "OK!" << endl;
}
else
{
cout << "FAILED!" << endl;
}
#endif
return 0;
}
======================================================================
Java程序源码：
======================================================================
package jrsaencrypt;
import java.io.*;
import java.security.*;
import java.security.spec.*;
import java.security.PublicKey;
import java.security.PrivateKey;
import java.security.KeyFactory;
import javax.crypto.Cipher.*;
/**
*
Title:
*
Description:
*
Copyright: Copyright (c) 2005
*
Company:
* @author not attributable
* @version 1.0
*/
public class RsaKeyGen {
public RsaKeyGen() {
}
/**
* 生成RSA密钥对
* @return
*/
int generateRsaKeyPair() {
//generate an RSA key pair
try {
KeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA");
keyGen.initialize(1024);
KeyPair pair = keyGen.generateKeyPair();
System.out.println(pair.getPublic().getFormat());
System.out.println(pair.getPublic().getAlgorithm());
System.out.println("
RSA public Key:");
byte[] bPubKey = pair.getPublic().getEncoded();
System.out.println(bPubKey.length);
for (int i = 0; i < bPubKey.length; i++) {
System.out.print(bPubKey[i] + " ");
}
System.out.println("
RSA private Key:");
byte[] bPriKey = pair.getPrivate().getEncoded();
System.out.println(bPriKey.length);
for (int i = 0; i < bPriKey.length; i++) {
System.out.print(bPriKey[i] + " ");
}
}
catch (Exception e) {
e.printStackTrace();
}
return 0;
}
/**
* 从公钥数据取得公钥
* @param bPubKeyInput
* @return
*/
PublicKey getRsaPubKey(byte[] bPubKeyInput) {
byte[] bX509PubKeyHeader = {
48, -127, -97, 48, 13, 6, 9, 42, -122, 72, -122, -9, 13, 1, 1, 1, 5, 0,
3, -127, -115, 0};
try {
byte[] bPubKey = new byte[bPubKeyInput.length + bX509PubKeyHeader.length];
System.arraycopy(bX509PubKeyHeader, 0, bPubKey, 0,
bX509PubKeyHeader.length);
System.arraycopy(bPubKeyInput, 0, bPubKey, bX509PubKeyHeader.length,
bPubKeyInput.length);
X509EncodedKeySpec rsaKeySpec = new X509EncodedKeySpec(bPubKey);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
rsaPubKey = keyFactory.generatePublic(rsaKeySpec);
}
catch (Exception e) {
e.printStackTrace();
}
return rsaPubKey;
}
/**
* 从私钥数据取得私钥
* @param bPriKeyInput
* @return
*/
PrivateKey getRsaPriKey(byte[] bPriKeyInput) {
byte[] bX509PriKeyHeader = {
48, -126, 2, 117, 2, 1, 0, 48, 13, 6, 9, 42,
-122, 72, -122, -9, 13, 1, 1, 1, 5, 0, 4, -126, 2, 95};
try {
byte[] bPriKey = new byte[bX509PriKeyHeader.length + bPriKeyInput.length];
System.arraycopy(bX509PriKeyHeader, 0, bPriKey, 0,
bX509PriKeyHeader.length);
System.arraycopy(bPriKeyInput, 0, bPriKey, bX509PriKeyHeader.length,
bPriKeyInput.length);
PKCS8EncodedKeySpec rsaKeySpec = new PKCS8EncodedKeySpec(bPriKey);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
rsaPriKey = keyFactory.generatePrivate(rsaKeySpec);
}
catch (Exception e) {
e.printStackTrace();
}
return rsaPriKey;
}
/**
* 从文件里取得数据
* @param strFileName
* @param bFBytes
* @return
*/
int getBytesbyFileName(String strFileName, byte[] bFBytes) {
int fSize = 0;
try {
FileInputStream fIn = new FileInputStream(strFileName);
fSize = fIn.available();
System.out.print("file's size: ");
System.out.println(fSize);
fSize = fIn.read(bFBytes);
fIn.close();
}
catch (Exception e) {
e.printStackTrace();
}
return fSize;
}
/**
* 公钥加密
* @param bKey
* @return
*/
byte[] rsaPubKeyEncrypt(byte[] bKey) {
try {
// Provider prvd = Security.getProvider("BouncyCastle");
javax.crypto.Cipher rsaPKenc = javax.crypto.Cipher.getInstance(
"RSA/ECB/PKCS1Padding");
rsaPKenc.init(javax.crypto.Cipher.ENCRYPT_MODE, rsaPubKey);
bEncryptedData = rsaPKenc.doFinal(bKey);
}
catch (Exception e) {
e.printStackTrace();
}
return bEncryptedData;
}
/**
* 私钥解密
* @param bEncryptedKey
* @return
*/
byte[] rsaPriKeyDecrypt(byte[] bEncryptedKey) {
try {
javax.crypto.Cipher rsaSKDec = javax.crypto.Cipher.getInstance(
"RSA/ECB/PKCS1Padding");
rsaSKDec.init(javax.crypto.Cipher.DECRYPT_MODE, rsaPriKey);
byte[] bDecrypt = rsaSKDec.doFinal(bEncryptedKey);
// System.out.println("rsa decrypted result[before clean]:");
// for (int i = 0; i < bDecrypt.length; i++) {
// System.out.print(bDecrypt[i] + " ");
// }
// System.out.println();
int i = 0;
// for (i = bDecrypt.length; i > 1; i--) {
// if (bDecrypt[i-1] == 0) {
// System.out.println("i=" + i);
// break;
// }
// } //for
bDecryptedData = new byte[bDecrypt.length - i];
System.arraycopy(bDecrypt, i, bDecryptedData, 0, bDecrypt.length - i);
}
catch (Exception e) {
e.printStackTrace();
}
return bDecryptedData;
}
public static void main(String[] args) {
RsaKeyGen rsaKeyGen1 = new RsaKeyGen();
// rsaKeyGen1.generateRsaKeyPair();
// byte[] bPubKey = new byte[140];
// int len = rsaKeyGen1.getBytesbyFileName("pubkey.key", bPubKey);
// rsaKeyGen1.getRsaPubKey(bPubKey);
byte[] bPriKey = new byte[607];
int len2 = rsaKeyGen1.getBytesbyFileName("prikey.key", bPriKey);
rsaKeyGen1.getRsaPriKey(bPriKey);
// byte[] bKey = {
// 1, 2, 3, 4, 5, 6, 7, 8};
// //encrypt:
// byte[] bEncKey = rsaKeyGen1.rsaPubKeyEncrypt(bKey);
// System.out.println("rsa encrypted result:");
// for (int i = 0; i < bEncKey.length; i++) {
// System.out.print(bEncKey[i] + " ");
// }
// System.out.println();
byte[] bEncKey = new byte[128];
int len0 = rsaKeyGen1.getBytesbyFileName("ucKey.data", bEncKey);
byte[] bDecKey = rsaKeyGen1.rsaPriKeyDecrypt(bEncKey);
System.out.println("rsa decrypted result:");
for (int i = 0; i < bDecKey.length; i++) {
System.out.print(bDecKey[i] + " ");
}
System.out.println();
}
PublicKey rsaPubKey;
PrivateKey rsaPriKey;
byte[] bEncryptedData;
byte[] bDecryptedData;
}