JAVA RSA公钥私钥学习笔记

来源：互联网发布：bi 数据分析编辑：程序博客网时间：2024/06/05 21:17

工作中遇到一个银行对接项目，对接双方采用交换公钥方式，使用对方公钥加密/验签，已方私钥解密/签名。

这里就用到了java的非对称加密“RSA”

1 生成RSA密钥对

package utils;import java.security.InvalidKeyException;import java.security.Key;import java.security.KeyFactory;import java.security.KeyPair;import java.security.KeyPairGenerator;import java.security.MessageDigest;import java.security.NoSuchAlgorithmException;import java.security.PrivateKey;import java.security.PublicKey;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.HashMap;import java.util.Map;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 MyRSAutils{public static final String KEY_ALGORITHM = "RSA";    public static final String CIPHER_ALGORITHM = "RSA/ECB/PKCS1Padding";public static final String PUBLIC_KEY = "publicKey";public static final String PRIVATE_KEY = "privateKey"; public static void main(String[] args) throws Exception {     String txt="aaaaaaaaaaaaaaaaaaaaaaaaaaaa";//原文                //获得密钥对Map        Map<String, byte[]> keyMap=generateKeyBytes();        //获得公钥        String publicKeyStr=encryptBASE64(keyMap.get(PUBLIC_KEY));        //获得密钥        String privateKeyStr=encryptBASE64(keyMap.get(PRIVATE_KEY));        //将私钥规范        PrivateKey privateKey = restorePrivateKey(decryptBASE64(privateKeyStr));        //将原文更具私钥加密        byte[] encodedText = RSAEncode(privateKey, txt.getBytes("UTF-8"));        //私钥签名后的数据         String privateResult = byteArrayToHexString(encodedText);//报文头前面256位的私钥签名后的结果privateResult        System.out.println("签名后的256位数据 " + privateResult);        PublicKey publicKey = restorePublicKey(decryptBASE64(publicKeyStr));        // 公钥解密        System.out.println("公钥解密: "+ RSADecode(publicKey, hexStringToByte(privateResult)));       } /**  * 生成密钥对。注意这里是生成密钥对KeyMap，再由密钥对获取公私钥  方法每运行一次获得一对不同的公钥私钥。  *  * @return */public static Map<String , byte [] > getKeyMap(){       //返回生成指定算法的 public/private 密钥对的 KeyPairGenerator 对象。 参数RSA算法       KeyPairGenerator keyPairGenerator=KeyPairGenerator.getInstance(KEY_ALGORITHM);       //初始化RSA长度，RSA密钥长度必须是64的倍数，在512~65536之间。默认是1024       keyPairGenerator.initialize(KEY_SIZE);            //生成一个密钥对            KeyPair keyPair = keyPairGenerator.generateKeyPair();            //获得公钥            RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();            //获得私钥            RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();            Map<String, byte[]> keyMap = new HashMap<String, byte[]>(2);            //可以通过getEncoded()方法获取返回类型为byte[]的数组            keyMap.put(PUBLIC_KEY, publicKey.getEncoded());            keyMap.put(PRIVATE_KEY, privateKey.getEncoded());        } catch (NoSuchAlgorithmException e) {            // TODO Auto-generated catch block            e.printStackTrace();           return null;        }         return keyMap;  }    /**     * 公钥，X509EncodedKeySpec 用于构建公钥的规范     *      * @param keyBytes     * @return     */    public static PublicKey restorePublicKey(byte[] keyBytes) {        X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(keyBytes);        try {            KeyFactory factory = KeyFactory.getInstance(KEY_ALGORITHM);            PublicKey publicKey = factory.generatePublic(x509EncodedKeySpec);            return publicKey;        } catch (NoSuchAlgorithmException e) {            // TODO Auto-generated catch block            e.printStackTrace();        } catch (InvalidKeySpecException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }        return null;    }    /**     * 私钥，PKCS8EncodedKeySpec 用于构建私钥的规范     *      * @param keyBytes     * @return     */    public static PrivateKey restorePrivateKey(byte[] keyBytes) {        PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(                keyBytes);            KeyFactory factory;            try {                factory = KeyFactory.getInstance(KEY_ALGORITHM);                  PrivateKey privateKey = factory                  .generatePrivate(pkcs8EncodedKeySpec);                  return privateKey;            } catch (NoSuchAlgorithmException e) {                // TODO Auto-generated catch block                e.printStackTrace();            } catch (InvalidKeySpecException e) {                // TODO Auto-generated catch block                e.printStackTrace();            }        return null;    }   /**     * 加密     *      * @param key     * @param plainText     * @return     */    public static byte[] RSAEncode(PrivateKey key, byte[] plainText) {        try {            Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM);            cipher.init(Cipher.ENCRYPT_MODE, key);            return cipher.doFinal(plainText);        } catch (NoSuchAlgorithmException e) {            // TODO Auto-generated catch block            e.printStackTrace();        } catch (NoSuchPaddingException e) {            // TODO Auto-generated catch block            e.printStackTrace();        } catch (InvalidKeyException e) {            // TODO Auto-generated catch block            e.printStackTrace();        } catch (IllegalBlockSizeException e) {            // TODO Auto-generated catch block            e.printStackTrace();        } catch (BadPaddingException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }        return null;    }    /**     *解密     *      * @param key     * @param encodedText     * @return     */    public static String RSADecode(PublicKey key, byte[] encodedText) {        try {            Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM);            cipher.init(Cipher.DECRYPT_MODE, key);            return new String(cipher.doFinal(encodedText));        } catch (NoSuchAlgorithmException e) {            // TODO Auto-generated catch block            e.printStackTrace();        } catch (NoSuchPaddingException e) {            // TODO Auto-generated catch block            e.printStackTrace();        } catch (InvalidKeyException e) {            // TODO Auto-generated catch block            e.printStackTrace();        } catch (IllegalBlockSizeException e) {            // TODO Auto-generated catch block            e.printStackTrace();        } catch (BadPaddingException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }        return null;    }/**将String转换为字节数组**/public static byte[] decryptBASE64(String key) throws Exception{        return (new BASE64Decoder()).decodeBuffer(key);    }/**将字节数组转换为String**/    public static String encryptBASE64(byte[] key) throws Exception{        return (new BASE64Encoder()).encodeBuffer(key);    } // 将字节转换为十六进制字符串    private static String byteToHexString(byte ib) {        char[] Digit = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A',                'B', 'C', 'D', 'E', 'F' };        char[] ob = new char[2];        ob[0] = Digit[(ib >>> 4) & 0X0F];        ob[1] = Digit[ib & 0X0F];        String s = new String(ob);        return s;    }    // 将字节数组转换为十六进制字符串    private static String byteArrayToHexString(byte[] bytearray) {        String strDigest = "";        for (int i = 0; i < bytearray.length; i++)        {            strDigest += byteToHexString(bytearray[i]);        }        return strDigest;    }//16进制字符串转为字节数组    public static byte[] hexStringToByte(String hex){        int len = (hex.length()/2);        byte[] result = new byte[len];        char[] achar=hex.toCharArray();        for(int i=0;i<len;i++){            int pos=i*2;            result[i]=(byte)(toByte(achar[pos])<<4|toByte(achar[pos+1]));        }        return result;    }    public static int toByte(char c){        byte b=(byte)"0123456789ABCDEF".indexOf(c);        return b;    }

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