java与IOS之间的RSA加解密
很简单的一个需求，ipad端给密码RSA加密，传到java后台，解密。RSA加密算法是基于一个密钥对的，分为公钥和私钥，一般情况公钥加密，私钥解密，但也可私钥加密，公钥解密。还可以验签，就是先用私钥对数据进行加密，然后对加密后的数据进行签名，得到一个签名值。然后再用公钥先验签，证明是对应私钥加密过的数据才解密。主要是为了防止来源不确定的数据。根据上面的介绍，大家也都知道，RSA算法的关键就是密钥对，我和IOS的同事各自找了RSA的算法实现代码，都能正常根据密钥对加解密。问题是我们各自使用对方的密钥对就不能加解密成功。IOS同事也是一个新手。连RSA算法是个什么概念都没搞清楚，我也懂点IOS。所以就陪着他一起看代码，找资料。看到底什么原因引起的密钥对不能共用。后来找到下面这篇文章：
Java中使用OpenSSL生成的RSA公私钥进行数据加解密
原来在用mac 系统中自带的openssl生成的密钥对文件是X509编码格式的。而我们JAVA所需的私钥文件是PKCS#8编码格式的。。所以要将在mac 系统中生成的私钥文件转下码就行了。转码方式参考上面链接。附下java代码：
import java.io.BufferedReader;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 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 RSAEncrypt {private static final String DEFAULT_PUBLIC_KEY= "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQChDzcjw/rWgFwnxunbKp7/4e8w" + "\r" + "/UmXx2jk6qEEn69t6N2R1i/LmcyDT1xr/T2AHGOiXNQ5V8W4iCaaeNawi7aJaRht" + "\r" + "Vx1uOH/2U378fscEESEG8XDqll0GCfB1/TjKI2aitVSzXOtRs8kYgGU78f7VmDNg" + "\r" + "XIlk3gdhnzh+uoEQywIDAQAB" + "\r"; private static final String DEFAULT_PRIVATE_KEY= "MIICdQIBADANBgkqhkiG9w0BAQEFAASCAl8wggJbAgEAAoGBAKEPNyPD+taAXCfG" + "\r" + "6dsqnv/h7zD9SZfHaOTqoQSfr23o3ZHWL8uZzINPXGv9PYAcY6Jc1DlXxbiIJpp4" + "\r" + "1rCLtolpGG1XHW44f/ZTfvx+xwQRIQbxcOqWXQYJ8HX9OMojZqK1VLNc61GzyRiA" + "\r" + "ZTvx/tWYM2BciWTeB2GfOH66gRDLAgMBAAECgYBp4qTvoJKynuT3SbDJY/XwaEtm" + "\r" + "u768SF9P0GlXrtwYuDWjAVue0VhBI9WxMWZTaVafkcP8hxX4QZqPh84td0zjcq3j" + "\r" + "DLOegAFJkIorGzq5FyK7ydBoU1TLjFV459c8dTZMTu+LgsOTD11/V/Jr4NJxIudo" + "\r" + "MBQ3c4cHmOoYv4uzkQJBANR+7Fc3e6oZgqTOesqPSPqljbsdF9E4x4eDFuOecCkJ" + "\r" + "DvVLOOoAzvtHfAiUp+H3fk4hXRpALiNBEHiIdhIuX2UCQQDCCHiPHFd4gC58yyCM" + "\r" + "6Leqkmoa+6YpfRb3oxykLBXcWx7DtbX+ayKy5OQmnkEG+MW8XB8wAdiUl0/tb6cQ" + "\r" + "FaRvAkBhvP94Hk0DMDinFVHlWYJ3xy4pongSA8vCyMj+aSGtvjzjFnZXK4gIjBjA" + "\r" + "2Z9ekDfIOBBawqp2DLdGuX2VXz8BAkByMuIh+KBSv76cnEDwLhfLQJlKgEnvqTvX" + "\r" + "TB0TUw8avlaBAXW34/5sI+NUB1hmbgyTK/T/IFcEPXpBWLGO+e3pAkAGWLpnH0Zh" + "\r" + "Fae7oAqkMAd3xCNY6ec180tAe57hZ6kS+SYLKwb4gGzYaCxc22vMtYksXHtUeamo" + "\r" + "1NMLzI2ZfUoX" + "\r"; /** * 私钥 */ private RSAPrivateKey privateKey; /** * 公钥 */ private RSAPublicKey publicKey; /** * 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'}; /** * 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 & 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 & 0x0f)]); if (i<data.length-1){ stringBuilder.append(' '); } } return stringBuilder.toString(); } public static void main(String[] args){ RSAEncrypt rsaEncrypt= new RSAEncrypt(); //rsaEncrypt.genKeyPair(); //加载公钥 try { rsaEncrypt.loadPublicKey(RSAEncrypt.DEFAULT_PUBLIC_KEY); System.out.println("加载公钥成功"); } catch (Exception e) { System.err.println(e.getMessage()); System.err.println("加载公钥失败"); } //加载私钥 try { rsaEncrypt.loadPrivateKey(RSAEncrypt.DEFAULT_PRIVATE_KEY); System.out.println("加载私钥成功"); } catch (Exception e) { System.err.println(e.getMessage()); System.err.println("加载私钥失败"); } //测试字符串 String encryptStr= "abc"; System.out.println("私钥长度："+rsaEncrypt.getPrivateKey().toString().length()); System.out.println("公钥长度："+rsaEncrypt.getPublicKey().toString().length()); try { //加密 byte[] cipher = rsaEncrypt.encrypt(rsaEncrypt.getPublicKey(), encryptStr.getBytes()); //解密 byte[] plainText = rsaEncrypt.decrypt(rsaEncrypt.getPrivateKey(), cipher); System.out.println("密文长度:"+ cipher.length); System.out.println(RSAEncrypt.byteArrayToString(cipher)); System.out.println("明文长度:"+ plainText.length); System.out.println(RSAEncrypt.byteArrayToString(plainText)); System.out.println(new String(plainText)); } catch (Exception e) { System.err.println(e.getMessage()); } }}
提供两种方式加载密钥对，可通过字符串或者文件流，文件是指生成的.pem文件才可以哦。
另外附一份IOS中加密方法，不过这里要求的文件是der。
http://blog.yorkgu.me/2011/10/27/rsa-in-ios-using-publick-key-generated-by-openssl/ IOS中加密后返回的NSdata对象，可以对NSdata对象进行base64编码转换成字符串，然后java用BASE64Decoder解码之后，就转换成了byte[]，可直接用上面方法解密。。。
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