IOS & JAVA RSA Encryption & Decryption

　　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 36500 -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 端:

　　2017.0306更新，文章过时了啦，大家请参考一个大神的Github: Objective-C-RSA

　　三、 JAVA 端：

　　RSAEncryptor.java：

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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/Love/Desktop/RSA_KEYS/rsa_public_key.pem";        // replace your public key path here
        String publicKeyPath =  "/Users/Love/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();  
    }  
 
 
｝