android、ios与服务器端php使用rsa加密解密通讯

http://alunblog.duapp.com/?p=50

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最近做手机项目，服务器端使用的是php，客户端分别有android版及ios版，在部分通讯环节需要对内容进行加密，RSA加密演算法是一种非对称加密演算法，能够较好达到要求，不过如果服务器架设https服务，较为麻烦，系统效率也不高，我们只需要在部分重要接口上使用RSA加密解密就行。

首先，准备工作

下载RSA密钥生成工具openssl，点击下载，解压缩至独立的文件夹，进入其中的bin目录，执行以下命令：

openssl genrsa -out rsa_private_key.pem 1024

openssl pkcs8 -topk8 -inform PEM -in rsa_private_key.pem -outform PEM -nocrypt -out private_key.pem

openssl rsa -in rsa_private_key.pem -pubout -out rsa_public_key.pem

第一条命令生成原始 RSA私钥文件 rsa_private_key.pem，第二条命令将原始 RSA私钥转换为 pkcs8格式，第三条生成RSA公钥 rsa_public_key.pem

从上面看出通过私钥能生成对应的公钥，因此我们将私钥private_key.pem用在服务器端，公钥发放给android跟ios等前端

第二步，php服务器端，使用openssl方法来进行加密解密类，代码如下：

<?php
/**
* @author alun (http://alunblog.duapp.com)
* @version 1.0
* @created 2013-5-17
*/

class Rsa
{
private static $PRIVATE_KEY = '-----BEGIN PRIVATE KEY-----
MIICdgIBADANBgkqhkiG9w0BAQEFAASCAmAwggJcAgEAAoGBAM9nUm7rPNhSgvsd
jMuCd5E7IMJB/80A1YY7jYV9fBCKdhVKmqea26QYuw6FW7B00fppEUTSazduSmn9
Yvhx9UOCcI75b0nq9FWm5O4P+Kp8l31M1pwsJ3cm+DceGOrFsl47vh9idiqj+abI
lJ4sTmJmDghmbks9YFlZSndQsIBlAgMBAAECgYAasa6vbgF3yi7niScc7l7bR2Pw
/LOivA+/ZhzR6JO2QUvvc5myJsFMPo6c0Nc7P93iv/EkDX0VNlHHkIBTf79URHXM
gXwMad4pHAeOiqxk5A9w/szDCBoETngtoqQGJq+QINxwPVvDEO4i224Uj3MKg2fo
4SDy3P1GCAAj1ahNoQJBAP4FV9vLWdLOOwOLnBpXt6vru4HT5VIf9fCeBIemuQ4C
/yRtgU38zXWgZ8AAmS6EjBEUDnN/tWid6UBKfgPDwAkCQQDRBP+Y9wIYIaSxeL7B
nHhPT25yAJCGK+l6r2qeaHVQr81O9YjusEi8E2M5OxCRolKxC3L7hrLJX8z1oyOV
dNx9AkBqYGhzpgv+qNiz2mJL8dH8ECMc8lTFeJbw5eu1tw8mHAEnCyisNSMBkGQC
Vv3PKjjR6hlHKwMYRZDpmIh/IRmpAkEAr1soLGaeZSxkhVetgbUJ4k/bct0yYr4Y
ZQshwcAVHBpBforT1JwkiVUim3MIFYY/JbVbQ9XfzL4Ir9OsGMkv6QJAPaQnyNY5
/D0PhXqODOM6jtAHHRfaSi4gve6AZ0iRz6YlB8beJ1ywZaJZWD9Cuw3zy4dDpCOn
A4tBsIdpMMoT+w==
-----END PRIVATE KEY-----';
/**
*返回对应的私钥
*/
private static function getPrivateKey(){

$privKey = self::$PRIVATE_KEY;

return openssl_pkey_get_private($privKey);
}

/**
* 私钥加密
*/
public static function privEncrypt($data)
{
if(!is_string($data)){
return null;
}
return openssl_private_encrypt($data,$encrypted,self::getPrivateKey())? base64_encode($encrypted) : null;
}

/**
* 私钥解密
*/
public static function privDecrypt($encrypted)
{
if(!is_string($encrypted)){
return null;
}
return (openssl_private_decrypt(base64_decode($encrypted), $decrypted, self::getPrivateKey()))? $decrypted : null;
}
}

?>

打开private_key.pem，将上面的$PRIVATE_KEY，替换成private_key.pem的内容即可，服务器端我们只需要使用私钥来加密解密。

第三步，android前端，使用java的Cipher类来实现加密解密类，代码如下：

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.InputStream;
import java.security.KeyFactory;
import java.security.NoSuchAlgorithmException;
import java.security.PublicKey;
import java.security.spec.X509EncodedKeySpec;
import javax.crypto.Cipher;

import android.util.Base64;

/**
* @author alun (http://alunblog.duapp.com)
* @version 1.0
* @created 2013-5-17
*/
public class Rsa {
private static final String RSA_PUBLICE =
"MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDPZ1Ju6zzYUoL7HYzLgneROyDC" + "\r" +
"Qf/NANWGO42FfXwQinYVSpqnmtukGLsOhVuwdNH6aRFE0ms3bkpp/WL4cfVDgnCO" + "\r" +
"+W9J6vRVpuTuD/iqfJd9TNacLCd3Jvg3HhjqxbJeO74fYnYqo/mmyJSeLE5iZg4I" + "\r" +
"Zm5LPWBZWUp3ULCAZQIDAQAB";
private static final String ALGORITHM = "RSA";

/**
* 得到公钥
* @param algorithm
* @param bysKey
* @return
*/
private static PublicKey getPublicKeyFromX509(String algorithm,
String bysKey) throws NoSuchAlgorithmException, Exception {
byte[] decodedKey = Base64.decode(bysKey,Base64.DEFAULT);
X509EncodedKeySpec x509 = new X509EncodedKeySpec(decodedKey);

KeyFactory keyFactory = KeyFactory.getInstance(algorithm);
return keyFactory.generatePublic(x509);
}

/**
* 使用公钥加密
* @param content
* @param key
* @return
*/
public static String encryptByPublic(String content) {
try {
PublicKey pubkey = getPublicKeyFromX509(ALGORITHM, RSA_PUBLICE);

Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
cipher.init(Cipher.ENCRYPT_MODE, pubkey);

byte plaintext[] = content.getBytes("UTF-8");
byte[] output = cipher.doFinal(plaintext);

String s = new String(Base64.encode(output,Base64.DEFAULT));

return s;

} catch (Exception e) {
return null;
}
}

/**
* 使用公钥解密
* @param content 密文
* @param key 商户私钥
* @return 解密后的字符串
*/
public static String decryptByPublic(String content) {
try {
PublicKey pubkey = getPublicKeyFromX509(ALGORITHM, RSA_PUBLICE);
Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
cipher.init(Cipher.DECRYPT_MODE, pubkey);
InputStream ins = new ByteArrayInputStream(Base64.decode(content,Base64.DEFAULT));
ByteArrayOutputStream writer = new ByteArrayOutputStream();
byte[] buf = new byte[128];
int bufl;
while ((bufl = ins.read(buf)) != -1) {
byte[] block = null;
if (buf.length == bufl) {
block = buf;
} else {
block = new byte[bufl];
for (int i = 0; i < bufl; i++) {
block[i] = buf[i];
}
}
writer.write(cipher.doFinal(block));
}
return new String(writer.toByteArray(), "utf-8");
} catch (Exception e) {
return null;
}
}

}

需要注意的是，在初始化Cipher对象时，一定要指明使用"RSA/ECB/PKCS1Padding"格式如Cipher.getInstance("RSA/ECB/PKCS1Padding");

打开rsa_public_key.pem文件，将上面代码的RSA_PUBLICE替换成其中内容即可。

第四步，ios前端，iOS上没有直接处理RSA加密的API，网上说的大多数也是处理X.509的证书的方法来实现，不过X.509证书是带签名的，在php端openssl_pkey_get_private方法获取密钥时，第二个参数需要传签名，而android端实现X.509证书加密解密较为不易，在这里我们利用ios兼容c程序的特点，利用openssl的api实现rsa的加密解密，代码如下：

CRSA.h代码：

#import <Foundation/Foundation.h>
#include <openssl/rsa.h>
#include <openssl/pem.h>
#include <openssl/err.h>

typedef enum {
KeyTypePublic,
KeyTypePrivate
}KeyType;

typedef enum {
RSA_PADDING_TYPE_NONE       = RSA_NO_PADDING,
RSA_PADDING_TYPE_PKCS1      = RSA_PKCS1_PADDING,
RSA_PADDING_TYPE_SSLV23     = RSA_SSLV23_PADDING
}RSA_PADDING_TYPE;

@interface CRSA : NSObject{
RSA *_rsa;
}
+ (id)shareInstance;
- (BOOL)importRSAKeyWithType:(KeyType)type;
- (int)getBlockSizeWithRSA_PADDING_TYPE:(RSA_PADDING_TYPE)padding_type;
- (NSString *) encryptByRsa:(NSString*)content withKeyType:(KeyType)keyType;
- (NSString *) decryptByRsa:(NSString*)content withKeyType:(KeyType)keyType;
@end

CRSA.m代码

#import "CRSA.h"

#define BUFFSIZE  1024
#import "Base64.h"

#define PADDING RSA_PADDING_TYPE_PKCS1
@implementation CRSA

+ (id)shareInstance
{
static CRSA *_crsa = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
_crsa = [[self alloc] init];
});
return _crsa;
}
- (BOOL)importRSAKeyWithType:(KeyType)type
{
FILE *file;
NSString *keyName = type == KeyTypePublic ? @"public_key" : @"private_key";
NSString *keyPath = [[NSBundle mainBundle] pathForResource:keyName ofType:@"pem"];

file = fopen([keyPath UTF8String], "rb");

if (NULL != file)
{
if (type == KeyTypePublic)
{
_rsa = PEM_read_RSA_PUBKEY(file, NULL, NULL, NULL);
assert(_rsa != NULL);
}
else
{
_rsa = PEM_read_RSAPrivateKey(file, NULL, NULL, NULL);
assert(_rsa != NULL);
}

fclose(file);

return (_rsa != NULL) ? YES : NO;
}

return NO;
}

- (NSString *) encryptByRsa:(NSString*)content withKeyType:(KeyType)keyType
{
if (![self importRSAKeyWithType:keyType])
return nil;

int status;
int length  = [content length];
unsigned char input[length + 1];
bzero(input, length + 1);
int i = 0;
for (; i < length; i++)
{
input[i] = [content characterAtIndex:i];
}

NSInteger  flen = [self getBlockSizeWithRSA_PADDING_TYPE:PADDING];

char *encData = (char*)malloc(flen);
bzero(encData, flen);

switch (keyType) {
case KeyTypePublic:
status = RSA_public_encrypt(length, (unsigned char*)input, (unsigned char*)encData, _rsa, PADDING);
break;

default:
status = RSA_private_encrypt(length, (unsigned char*)input, (unsigned char*)encData, _rsa, PADDING);
break;
}

if (status)
{
NSData *returnData = [NSData dataWithBytes:encData length:status];
free(encData);
encData = NULL;

NSString *ret = [returnData base64EncodedString];
return ret;
}

free(encData);
encData = NULL;

return nil;
}

- (NSString *) decryptByRsa:(NSString*)content withKeyType:(KeyType)keyType
{
if (![self importRSAKeyWithType:keyType])
return nil;

int status;

NSData *data = [content base64DecodedData];
int length = [data length];

NSInteger flen = [self getBlockSizeWithRSA_PADDING_TYPE:PADDING];
char *decData = (char*)malloc(flen);
bzero(decData, flen);

switch (keyType) {
case KeyTypePublic:
status = RSA_public_decrypt(length, (unsigned char*)[data bytes], (unsigned char*)decData, _rsa, PADDING);
break;

default:
status = RSA_private_decrypt(length, (unsigned char*)[data bytes], (unsigned char*)decData, _rsa, PADDING);
break;
}

if (status)
{
NSMutableString *decryptString = [[NSMutableString alloc] initWithBytes:decData length:strlen(decData) encoding:NSASCIIStringEncoding];
free(decData);
decData = NULL;

return decryptString;
}

free(decData);
decData = NULL;

return nil;
}

- (int)getBlockSizeWithRSA_PADDING_TYPE:(RSA_PADDING_TYPE)padding_type
{
int len = RSA_size(_rsa);

if (padding_type == RSA_PADDING_TYPE_PKCS1 || padding_type == RSA_PADDING_TYPE_SSLV23) {
len -= 11;
}

return len;
}
@end

其中openssl api包，我们可以在第一步RSA密钥生成工具openssl的include文件夹中得到，完整代码包请点击这里下载