IOS and JAVA 的 RSA 加密解密

在网上找了许多篇关于RSA加密解密的文章与博客，是很有帮助，但比较零散与不简洁。

　　(至于RSA的基本原理，大家可以看 阮一峰的网络日志 的 RSA算法原理（一） 和 RSA算法原理（二） )

　　这篇文章只是做一个整理，帮大家理清一下步骤的而已（ 英文版本请看 RSA Encrypt and Decrypt in IOS and JAVA ）。

　　一、首先，打开Terminal， 生成必要的公钥、私钥、证书:

openssl genrsa -out private_key.pem 1024

openssl req -new -key private_key.pem -out rsaCertReq.csr

openssl x509 -req -days 3650 -in rsaCertReq.csr -signkey private_key.pem -out rsaCert.crt

openssl x509 -outform der -in rsaCert.crt -out public_key.der　　　　　　　　　　　　　　　// Create public_key.der For IOS
 
openssl pkcs12 -export -out private_key.p12 -inkey private_key.pem -in rsaCert.crt　　// Create private_key.p12 For IOS. 这一步，请记住你输入的密码，IOS代码里会用到

openssl rsa -in private_key.pem -out rsa_public_key.pem -pubout　　　　　　　　　　　　　// Create rsa_public_key.pem For Java
　
openssl pkcs8 -topk8 -in private_key.pem -out pkcs8_private_key.pem -nocrypt　　　　　// Create pkcs8_private_key.pem For Java
           

上面七个步骤，总共生成7个文件。其中　public_key.der 和 private_key.p12 这对公钥私钥是给IOS用的， rsa_public_key.pem 和 pkcs8_private_key.pem　是给JAVA用的。

　　它们的源都来自一个私钥：private_key.pem ， 所以IOS端加密的数据，是可以被JAVA端解密的，反过来也一样。

　　二、IOS 代码:

　　先请你把 public_key.der 和 private_key.p12  拖进你的Xcode项目里去 ， 也请引入 Security.framework 以及 NSData+Base64.h/m (Download) 到项目里。

　　

　　RSAEncryptor.h:　　

#import <Foundation/Foundation.h>

@interface RSAEncryptor : NSObject



#pragma mark - Instance Methods

-(void) loadPublicKeyFromFile: (NSString*) derFilePath;
-(void) loadPublicKeyFromData: (NSData*) derData;

-(void) loadPrivateKeyFromFile: (NSString*) p12FilePath password:(NSString*)p12Password;
-(void) loadPrivateKeyFromData: (NSData*) p12Data password:(NSString*)p12Password;




-(NSString*) rsaEncryptString:(NSString*)string;
-(NSData*) rsaEncryptData:(NSData*)data ;

-(NSString*) rsaDecryptString:(NSString*)string;
-(NSData*) rsaDecryptData:(NSData*)data;





#pragma mark - Class Methods

+(void) setSharedInstance: (RSAEncryptor*)instance;
+(RSAEncryptor*) sharedInstance;

@end
           

　　RSAEncryptor.m:

#import "RSAEncryptor.h"

#import <Security/Security.h>
#import "NSData+Base64.h"


@implementation RSAEncryptor
{
    SecKeyRef publicKey;
    
    SecKeyRef privateKey;
}


-(void)dealloc
{
    CFRelease(publicKey);
    CFRelease(privateKey);
}



-(SecKeyRef) getPublicKey {
    return publicKey;
}

-(SecKeyRef) getPrivateKey {
    return privateKey;
}



-(void) loadPublicKeyFromFile: (NSString*) derFilePath
{
    NSData *derData = [[NSData alloc] initWithContentsOfFile:derFilePath];
    [self loadPublicKeyFromData: derData];
}
-(void) loadPublicKeyFromData: (NSData*) derData
{
    publicKey = [self getPublicKeyRefrenceFromeData: derData];
}

-(void) loadPrivateKeyFromFile: (NSString*) p12FilePath password:(NSString*)p12Password
{
    NSData *p12Data = [NSData dataWithContentsOfFile:p12FilePath];
    [self loadPrivateKeyFromData: p12Data password:p12Password];
}

-(void) loadPrivateKeyFromData: (NSData*) p12Data password:(NSString*)p12Password
{
    privateKey = [self getPrivateKeyRefrenceFromData: p12Data password: p12Password];
}




#pragma mark - Private Methods

-(SecKeyRef) getPublicKeyRefrenceFromeData: (NSData*)derData
{
    SecCertificateRef myCertificate = SecCertificateCreateWithData(kCFAllocatorDefault, (__bridge CFDataRef)derData);
    SecPolicyRef myPolicy = SecPolicyCreateBasicX509();
    SecTrustRef myTrust;
    OSStatus status = SecTrustCreateWithCertificates(myCertificate,myPolicy,&myTrust);
    SecTrustResultType trustResult;
    if (status == noErr) {
        status = SecTrustEvaluate(myTrust, &trustResult);
    }
    SecKeyRef securityKey = SecTrustCopyPublicKey(myTrust);
    CFRelease(myCertificate);
    CFRelease(myPolicy);
    CFRelease(myTrust);
    
    return securityKey;
}


-(SecKeyRef) getPrivateKeyRefrenceFromData: (NSData*)p12Data password:(NSString*)password
{
    SecKeyRef privateKeyRef = NULL;
    NSMutableDictionary * options = [[NSMutableDictionary alloc] init];
    [options setObject: password forKey:(__bridge id)kSecImportExportPassphrase];
    CFArrayRef items = CFArrayCreate(NULL, 0, 0, NULL);
    OSStatus securityError = SecPKCS12Import((__bridge CFDataRef) p12Data, (__bridge CFDictionaryRef)options, &items);
    if (securityError == noErr && CFArrayGetCount(items) > 0) {
        CFDictionaryRef identityDict = CFArrayGetValueAtIndex(items, 0);
        SecIdentityRef identityApp = (SecIdentityRef)CFDictionaryGetValue(identityDict, kSecImportItemIdentity);
        securityError = SecIdentityCopyPrivateKey(identityApp, &privateKeyRef);
        if (securityError != noErr) {
            privateKeyRef = NULL;
        }
    }
    CFRelease(items);
    
    return privateKeyRef;
}



#pragma mark - Encrypt

-(NSString*) rsaEncryptString:(NSString*)string {
    NSData* data = [string dataUsingEncoding:NSUTF8StringEncoding];
    NSData* encryptedData = [self rsaEncryptData: data];
    NSString* base64EncryptedString = [encryptedData base64EncodedString];
    return base64EncryptedString;
}

// 加密的大小受限于SecKeyEncrypt函数，SecKeyEncrypt要求明文和密钥的长度一致，如果要加密更长的内容，需要把内容按密钥长度分成多份，然后多次调用SecKeyEncrypt来实现
-(NSData*) rsaEncryptData:(NSData*)data {
    SecKeyRef key = [self getPublicKey];
    size_t cipherBufferSize = SecKeyGetBlockSize(key);
    uint8_t *cipherBuffer = malloc(cipherBufferSize * sizeof(uint8_t));
    size_t blockSize = cipherBufferSize - 11;       // 分段加密
    size_t blockCount = (size_t)ceil([data length] / (double)blockSize);
    NSMutableData *encryptedData = [[NSMutableData alloc] init] ;
    for (int i=0; i<blockCount; i++) {
        int bufferSize = MIN(blockSize,[data length] - i * blockSize);
        NSData *buffer = [data subdataWithRange:NSMakeRange(i * blockSize, bufferSize)];
        OSStatus status = SecKeyEncrypt(key, kSecPaddingPKCS1, (const uint8_t *)[buffer bytes], [buffer length], cipherBuffer, &cipherBufferSize);
        if (status == noErr){
            NSData *encryptedBytes = [[NSData alloc] initWithBytes:(const void *)cipherBuffer length:cipherBufferSize];
            [encryptedData appendData:encryptedBytes];
        }else{
            if (cipherBuffer) {
                free(cipherBuffer);
            }
            return nil;
        }
    }
    if (cipherBuffer){
        free(cipherBuffer);
    }
    return encryptedData;
}




#pragma mark - Decrypt

-(NSString*) rsaDecryptString:(NSString*)string {
    NSData* data = [NSData dataFromBase64String: string];
    NSData* decryptData = [self rsaDecryptData: data];
    NSString* result = [[NSString alloc] initWithData: decryptData encoding:NSUTF8StringEncoding];
    return result;
}

-(NSData*) rsaDecryptData:(NSData*)data {
    SecKeyRef key = [self getPrivateKey];
    size_t cipherLen = [data length];
    void *cipher = malloc(cipherLen);
    [data getBytes:cipher length:cipherLen];
    size_t plainLen = SecKeyGetBlockSize(key) - 12;
    void *plain = malloc(plainLen);
    OSStatus status = SecKeyDecrypt(key, kSecPaddingPKCS1, cipher, cipherLen, plain, &plainLen);
    
    if (status != noErr) {
        return nil;
    }
    
    NSData *decryptedData = [[NSData alloc] initWithBytes:(const void *)plain length:plainLen];
    
    return decryptedData;
}








#pragma mark - Class Methods

static RSAEncryptor* sharedInstance = nil;

+(void) setSharedInstance: (RSAEncryptor*)instance
{
    sharedInstance = instance;
}

+(RSAEncryptor*) sharedInstance
{
    return sharedInstance;
}
           

好了，那么，我们就可以在main.m里做个测试了:

　　main.m:

#import "AppDelegate.h"
#import "RSAEncryptor.h"

int main(int argc, char *argv[])
{
    @autoreleasepool {
        
        RSAEncryptor* rsaEncryptor = [[RSAEncryptor alloc] init];
        NSString* publicKeyPath = [[NSBundle mainBundle] pathForResource:@"public_key" ofType:@"der"];
        NSString* privateKeyPath = [[NSBundle mainBundle] pathForResource:@"private_key" ofType:@"p12"];
        [rsaEncryptor loadPublicKeyFromFile: publicKeyPath];
        [rsaEncryptor loadPrivateKeyFromFile: privateKeyPath password:@"ISAACS"];    // 这里，请换成你生成p12时的密码
        
        NSString* restrinBASE64STRING = [rsaEncryptor rsaEncryptString:@"I.O.S"];
        NSLog(@"Encrypted: %@", restrinBASE64STRING);       // 请把这段字符串Copy到JAVA这边main()里做测试
        NSString* decryptString = [rsaEncryptor rsaDecryptString: restrinBASE64STRING];
        NSLog(@"Decrypted: %@", decryptString);
        
        
        // System.out.println the encrypt string from Java , and paste it here
        // 这里请换成你的JAVA这边产生的加密的Base64 Encode的字符串
//        NSString* rsaEncrypyBase64 = [NSString stringWithFormat:@"%@\r%@\r%@",
//                                      @"ZNKCVpFYd4Oi2pecLhDXHh+8kWltUMLdBIBDeTvU5kWpTQ8cA1Y+7wKO3d/M8bhULYf1FhWt80Cg",
//                                      @"7e73SV5r+wSlgGWBvTIxqgTWFS4ELGzsEJpVVSlK1oXF0N2mugOURUILjeQrwn1QTcVdXXTMQ0wj",
//                                      @"50GNwnHbAwyLvsY5EUY="];
//        
//        NSString* resultString = [rsaEncryptor rsaDecryptString: rsaEncrypyBase64];
//        NSLog(@"Decrypt Java RSA String: %@", resultString);
        
        
        return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));
    }
}
           

三、 JAVA 代码：

　　

　　RSAEncryptor.java：

package com.modules.Encryptor;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.security.InvalidKeyException;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.ArrayList;
import java.util.List;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;

import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

public class RSAEncryptor {

    
    public static void main(String[] args){  
        
        String privateKeyPath = "/Users/Isaacs/Desktop/RSA_KEYS/rsa_public_key.pem";        // replace your public key path here
        String publicKeyPath =  "/Users/Isaacs/Desktop/RSA_KEYS/pkcs8_private_key.pem";     // replace your private path here
        RSAEncryptor rsaEncryptor = new RSAEncryptor(privateKeyPath, publicKeyPath);

        try {
            
            String test = "JAVA";
            String testRSAEnWith64 = rsaEncryptor.encryptWithBase64(test);
            String testRSADeWith64 = rsaEncryptor.decryptWithBase64(testRSAEnWith64);
            System.out.println("\nEncrypt: \n" + testRSAEnWith64);
            System.out.println("\nDecrypt: \n" + testRSADeWith64);
            
            // NSLog the encrypt string from Xcode , and paste it here.
            // 请粘贴来自IOS端加密后的字符串
//            String rsaBase46StringFromIOS =
//                    "nIIV7fVsHe8QquUbciMYbbumoMtbBuLsCr2yMB/WAhm+S/kGRPlf+k2GH8imZIYQ" + "\r" +
//                    "QBDssVLQmS392QlxS87hnwMRJIzWw6vdRv/k79TgTfu6tI/9QTqIOvNlQIqtIcVm" + "\r" +
//                    "R/suvydoymKgdlB+ce5/tHSxfqEOLLrL1Zl2PqJSP4A=";
//            
//            String decryptStringFromIOS = rsaEncryptor.decryptWithBase64(rsaBase46StringFromIOS);
//            System.out.println("Decrypt result from ios client: \n" + decryptStringFromIOS);
            
        } catch (Exception e) {
            e.printStackTrace();
        }

    }





    /**
     * @param publicKeyFilePath     
     * @param privateKeyFilePath    
     */
    public RSAEncryptor(String publicKeyFilePath, String privateKeyFilePath) throws Exception {
        String public_key = getKeyFromFile(publicKeyFilePath);
        String private_key = getKeyFromFile(privateKeyFilePath);
        loadPublicKey(public_key);  
        loadPrivateKey(private_key);  
    }
    public RSAEncryptor() {
        // load the PublicKey and PrivateKey manually
    }
    
    
    public String getKeyFromFile(String filePath) throws Exception {
        BufferedReader bufferedReader = new BufferedReader(new FileReader(filePath));
        
        String line = null;
        List<String> list = new ArrayList<String>();
        while ((line = bufferedReader.readLine()) != null){
            list.add(line);
        }
        
        // remove the firt line and last line
        StringBuilder stringBuilder = new StringBuilder();
        for (int i = 1; i < list.size() - 1; i++) {
            stringBuilder.append(list.get(i)).append("\r");
        }
        
        String key = stringBuilder.toString();
        return key;
    }
    
    public String decryptWithBase64(String base64String) throws Exception {
        //  http://commons.apache.org/proper/commons-codec/ : org.apache.commons.codec.binary.Base64
        // sun.misc.BASE64Decoder
        byte[] binaryData = decrypt(getPrivateKey(), new BASE64Decoder().decodeBuffer(base64String) /*org.apache.commons.codec.binary.Base64.decodeBase64(base46String.getBytes())*/);
        String string = new String(binaryData);
        return string;
    }
    
    public String encryptWithBase64(String string) throws Exception {
        //  http://commons.apache.org/proper/commons-codec/ : org.apache.commons.codec.binary.Base64
        // sun.misc.BASE64Encoder
        byte[] binaryData = encrypt(getPublicKey(), string.getBytes());
        String base64String = new BASE64Encoder().encodeBuffer(binaryData) /* org.apache.commons.codec.binary.Base64.encodeBase64(binaryData) */;
        return base64String;
    }
  
    
    
    // convenient properties
    public static RSAEncryptor sharedInstance = null;
    public static void setSharedInstance (RSAEncryptor rsaEncryptor) {
        sharedInstance = rsaEncryptor;
    }
    
    
    
    
    // From: http://blog.csdn.net/chaijunkun/article/details/7275632

    /** 
     * 私钥 
     */  
    private RSAPrivateKey privateKey;  
  
    /** 
     * 公钥 
     */  
    private RSAPublicKey publicKey;  
      
    /** 
     * 获取私钥 
     * @return 当前的私钥对象 
     */  
    public RSAPrivateKey getPrivateKey() {  
        return privateKey;  
    }  
  
    /** 
     * 获取公钥 
     * @return 当前的公钥对象 
     */  
    public RSAPublicKey getPublicKey() {  
        return publicKey;  
    }  
  
    /** 
     * 随机生成密钥对 
     */  
    public void genKeyPair(){  
        KeyPairGenerator keyPairGen= null;  
        try {  
            keyPairGen= KeyPairGenerator.getInstance("RSA");  
        } catch (NoSuchAlgorithmException e) {  
            e.printStackTrace();  
        }  
        keyPairGen.initialize(1024, new SecureRandom());  
        KeyPair keyPair= keyPairGen.generateKeyPair();  
        this.privateKey= (RSAPrivateKey) keyPair.getPrivate();  
        this.publicKey= (RSAPublicKey) keyPair.getPublic();  
    }  
  
    /** 
     * 从文件中输入流中加载公钥 
     * @param in 公钥输入流 
     * @throws Exception 加载公钥时产生的异常 
     */  
    public void loadPublicKey(InputStream in) throws Exception{  
        try {  
            BufferedReader br= new BufferedReader(new InputStreamReader(in));  
            String readLine= null;  
            StringBuilder sb= new StringBuilder();  
            while((readLine= br.readLine())!=null){  
                if(readLine.charAt(0)=='-'){  
                    continue;  
                }else{  
                    sb.append(readLine);  
                    sb.append('\r');  
                }  
            }  
            loadPublicKey(sb.toString());  
        } catch (IOException e) {  
            throw new Exception("公钥数据流读取错误");  
        } catch (NullPointerException e) {  
            throw new Exception("公钥输入流为空");  
        }  
    }  
  
    /** 
     * 从字符串中加载公钥 
     * @param publicKeyStr 公钥数据字符串 
     * @throws Exception 加载公钥时产生的异常 
     */  
    public void loadPublicKey(String publicKeyStr) throws Exception{  
        try {  
            BASE64Decoder base64Decoder= new BASE64Decoder();  
            byte[] buffer= base64Decoder.decodeBuffer(publicKeyStr);
            KeyFactory keyFactory= KeyFactory.getInstance("RSA");  
            X509EncodedKeySpec keySpec= new X509EncodedKeySpec(buffer);  
            this.publicKey= (RSAPublicKey) keyFactory.generatePublic(keySpec);  
        } catch (NoSuchAlgorithmException e) {  
            throw new Exception("无此算法");  
        } catch (InvalidKeySpecException e) {  
            throw new Exception("公钥非法");  
        } catch (IOException e) {  
            throw new Exception("公钥数据内容读取错误");  
        } catch (NullPointerException e) {  
            throw new Exception("公钥数据为空");  
        }  
    }  
  
    /** 
     * 从文件中加载私钥 
     * @param keyFileName 私钥文件名 
     * @return 是否成功 
     * @throws Exception  
     */  
    public void loadPrivateKey(InputStream in) throws Exception{  
        try {  
            BufferedReader br= new BufferedReader(new InputStreamReader(in));  
            String readLine= null;  
            StringBuilder sb= new StringBuilder();  
            while((readLine= br.readLine())!=null){  
                if(readLine.charAt(0)=='-'){  
                    continue;  
                }else{  
                    sb.append(readLine);  
                    sb.append('\r');  
                }  
            }  
            loadPrivateKey(sb.toString());  
        } catch (IOException e) {  
            throw new Exception("私钥数据读取错误");  
        } catch (NullPointerException e) {  
            throw new Exception("私钥输入流为空");  
        }  
    }  
  
    public void loadPrivateKey(String privateKeyStr) throws Exception{  
        try {  
            BASE64Decoder base64Decoder= new BASE64Decoder();  
            byte[] buffer= base64Decoder.decodeBuffer(privateKeyStr);  
            PKCS8EncodedKeySpec keySpec= new PKCS8EncodedKeySpec(buffer);  
            KeyFactory keyFactory= KeyFactory.getInstance("RSA");  
            this.privateKey= (RSAPrivateKey) keyFactory.generatePrivate(keySpec);  
        } catch (NoSuchAlgorithmException e) {  
            throw new Exception("无此算法");  
        } catch (InvalidKeySpecException e) {  
            e.printStackTrace();
            throw new Exception("私钥非法");  
        } catch (IOException e) {  
            throw new Exception("私钥数据内容读取错误");  
        } catch (NullPointerException e) {  
            throw new Exception("私钥数据为空");  
        }  
    }  
  
    /** 
     * 加密过程 
     * @param publicKey 公钥 
     * @param plainTextData 明文数据 
     * @return 
     * @throws Exception 加密过程中的异常信息 
     */  
    public byte[] encrypt(RSAPublicKey publicKey, byte[] plainTextData) throws Exception{  
        if(publicKey== null){  
            throw new Exception("加密公钥为空, 请设置");  
        }  
        Cipher cipher= null;  
        try {  
            cipher= Cipher.getInstance("RSA");//, new BouncyCastleProvider());  
            cipher.init(Cipher.ENCRYPT_MODE, publicKey);  
            byte[] output= cipher.doFinal(plainTextData);  
            return output;  
        } catch (NoSuchAlgorithmException e) {  
            throw new Exception("无此加密算法");  
        } catch (NoSuchPaddingException e) {  
            e.printStackTrace();  
            return null;  
        }catch (InvalidKeyException e) {  
            throw new Exception("加密公钥非法,请检查");  
        } catch (IllegalBlockSizeException e) {  
            throw new Exception("明文长度非法");  
        } catch (BadPaddingException e) {  
            throw new Exception("明文数据已损坏");  
        }  
    }  
  
    /** 
     * 解密过程 
     * @param privateKey 私钥 
     * @param cipherData 密文数据 
     * @return 明文 
     * @throws Exception 解密过程中的异常信息 
     */  
    public byte[] decrypt(RSAPrivateKey privateKey, byte[] cipherData) throws Exception{  
        if (privateKey== null){  
            throw new Exception("解密私钥为空, 请设置");  
        }  
        Cipher cipher= null;  
        try {  
            cipher= Cipher.getInstance("RSA");//, new BouncyCastleProvider());  
            cipher.init(Cipher.DECRYPT_MODE, privateKey);  
            byte[] output= cipher.doFinal(cipherData);  
            return output;  
        } catch (NoSuchAlgorithmException e) {  
            throw new Exception("无此解密算法");  
        } catch (NoSuchPaddingException e) {  
            e.printStackTrace();  
            return null;  
        }catch (InvalidKeyException e) {  
            throw new Exception("解密私钥非法,请检查");  
        } catch (IllegalBlockSizeException e) {  
            throw new Exception("密文长度非法");  
        } catch (BadPaddingException e) {  
            throw new Exception("密文数据已损坏");  
        }         
    }  
  
    
    
    /** 
     * 字节数据转字符串专用集合 
     */  
    private static final char[] HEX_CHAR= {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'}; 
    
    /** 
     * 字节数据转十六进制字符串 
     * @param data 输入数据 
     * @return 十六进制内容 
     */  
    public static String byteArrayToString(byte[] data){  
        StringBuilder stringBuilder= new StringBuilder();  
        for (int i=0; i<data.length; i++){  
            //取出字节的高四位 作为索引得到相应的十六进制标识符 注意无符号右移  
            stringBuilder.append(HEX_CHAR[(data[i] & 0xf0)>>> 4]);  
            //取出字节的低四位 作为索引得到相应的十六进制标识符  
            stringBuilder.append(HEX_CHAR[(data[i] & 0x0f)]);  
            if (i<data.length-1){  
                stringBuilder.append(' ');  
            }  
        }  
        return stringBuilder.toString();  
    }  


｝
           

同样的，main()函数里有几行注释了的代码，打开注释， 请复制上面IOS端的加密字符串来替换掉，这样，来测试一下来自IOS端的加密数据能不能被JAVA端解密。(答案也是能的)