Java公钥私钥签名工具包应用实例

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package  com.locator.encryption;

import  java.io.ByteArrayOutputStream;
import  java.security.Key;
import  java.security.KeyFactory;
import  java.security.KeyPair;
import  java.security.KeyPairGenerator;
import  java.security.PrivateKey;
import  java.security.PublicKey;
import  java.security.Signature;
import  java.security.interfaces.RSAPrivateKey;
import  java.security.interfaces.RSAPublicKey;
import  java.security.spec.PKCS8EncodedKeySpec;
import  java.security.spec.X509EncodedKeySpec;
import  java.util.HashMap;
import  java.util.Map;

import  javax.crypto.Cipher;

/**

  * 

 * RSA公钥/私钥/签名工具包

  * 

 * 字符串格式的密钥在未在特殊说明情况下都为BASE64编码格式
 * 由于非对称加密速度极其缓慢，一般文件不使用它来加密而是使用对称加密，
 * 非对称加密算法可以用来对对称加密的密钥加密，这样保证密钥的安全也就保证了数据的安全
 *
 *
 */
public  class  RSAUtils{

    /**
     * 加密算法RSA
     */
    public  static  final  String KEY_ALGORITHM =  "RSA" ;

    /**
     * 签名算法
     */
    public  static  final  String SIGNATURE_ALGORITHM =  "MD5withRSA" ;

    /**
     * 获取公钥的key
     */
    private  static  final  String PUBLIC_KEY =  "LocatorPublicKey" ;

    /**
     * 获取私钥的key
     */
    private  static  final  String PRIVATE_KEY =  "LocatorPrivateKey" ;

    /**
     * RSA最大加密明文大小
     */
    private  static  final  int  MAX_ENCRYPT_BLOCK =  117 ;

    /**
     * RSA最大解密密文大小
     */
    private  static  final  int  MAX_DECRYPT_BLOCK =  128 ;

    /**

      * 

     * 生成密钥对(公钥和私钥)
     *
     *
     * @return
     * @throws Exception
     */
    public  static  Map genKeyPair()  throws  Exception {
        KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(KEY_ALGORITHM);
        keyPairGen.initialize( 1024 );
        KeyPair keyPair = keyPairGen.generateKeyPair();
        RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
        RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
        Map keyMap =  new  HashMap( 2 );
        keyMap.put(PUBLIC_KEY, publicKey);
        keyMap.put(PRIVATE_KEY, privateKey);
        return  keyMap;
    }

    /**

      * 

     * 用私钥对信息生成数字签名
     *
     *
     * @param data 已加密数据
     * @param privateKey 私钥(BASE64编码)
     *
     * @return
     * @throws Exception
     */
    public  static  String sign( byte [] data, String privateKey)  throws  Exception {
        byte [] keyBytes = Base64Utils.decode(privateKey);
        PKCS8EncodedKeySpec pkcs8KeySpec =  new  PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        PrivateKey privateK = keyFactory.generatePrivate(pkcs8KeySpec);
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initSign(privateK);
        signature.update(data);
        return  Base64Utils.encode(signature.sign());
    }

    /**

      * 

     * 校验数字签名
     *
     *
     * @param data 已加密数据
     * @param publicKey 公钥(BASE64编码)
     * @param sign 数字签名
     *
     * @return
     * @throws Exception
     *
     */
    public  static  boolean  verify( byte [] data, String publicKey, String sign)
            throws  Exception {
        byte [] keyBytes = Base64Utils.decode(publicKey);
        X509EncodedKeySpec keySpec =  new  X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        PublicKey publicK = keyFactory.generatePublic(keySpec);
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initVerify(publicK);
        signature.update(data);
        return  signature.verify(Base64Utils.decode(sign));
    }

    /**

      * 

     * 私钥解密
     *
     *
     * @param encryptedData 已加密数据
     * @param privateKey 私钥(BASE64编码)
     * @return
     * @throws Exception
     */
    public  static  byte [] decryptByPrivateKey( byte [] encryptedData, String privateKey)
            throws  Exception {
        byte [] keyBytes = Base64Utils.decode(privateKey);
        PKCS8EncodedKeySpec pkcs8KeySpec =  new  PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, privateK);
        int  inputLen = encryptedData.length;
        ByteArrayOutputStream out =  new  ByteArrayOutputStream();
        int  offSet =  0 ;
        byte [] cache;
        int  i =  0 ;
        // 对数据分段解密
        while  (inputLen - offSet >  0 ) {
            if  (inputLen - offSet > MAX_DECRYPT_BLOCK) {
                cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK);
            }  else  {
                cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet);
            }
            out.write(cache,  0 , cache.length);
            i++;
            offSet = i * MAX_DECRYPT_BLOCK;
        }
        byte [] decryptedData = out.toByteArray();
        out.close();
        return  decryptedData;
    }

    /**

      * 

     * 公钥解密
     *
     *
     * @param encryptedData 已加密数据
     * @param publicKey 公钥(BASE64编码)
     * @return
     * @throws Exception
     */
    public  static  byte [] decryptByPublicKey( byte [] encryptedData, String publicKey)
            throws  Exception {
        byte [] keyBytes = Base64Utils.decode(publicKey);
        X509EncodedKeySpec x509KeySpec =  new  X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key publicK = keyFactory.generatePublic(x509KeySpec);
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, publicK);
        int  inputLen = encryptedData.length;
        ByteArrayOutputStream out =  new  ByteArrayOutputStream();
        int  offSet =  0 ;
        byte [] cache;
        int  i =  0 ;
        // 对数据分段解密
        while  (inputLen - offSet >  0 ) {
            if  (inputLen - offSet > MAX_DECRYPT_BLOCK) {
                cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK);
            }  else  {
                cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet);
            }
            out.write(cache,  0 , cache.length);
            i++;
            offSet = i * MAX_DECRYPT_BLOCK;
        }
        byte [] decryptedData = out.toByteArray();
        out.close();
        return  decryptedData;
    }

    /**

      * 

     * 公钥加密
     *
     *
     * @param data 源数据
     * @param publicKey 公钥(BASE64编码)
     * @return
     * @throws Exception
     */
    public  static  byte [] encryptByPublicKey( byte [] data, String publicKey)
            throws  Exception {
        byte [] keyBytes = Base64Utils.decode(publicKey);
        X509EncodedKeySpec x509KeySpec =  new  X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key publicK = keyFactory.generatePublic(x509KeySpec);
        // 对数据加密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, publicK);
        int  inputLen = data.length;
        ByteArrayOutputStream out =  new  ByteArrayOutputStream();
        int  offSet =  0 ;
        byte [] cache;
        int  i =  0 ;
        // 对数据分段加密
        while  (inputLen - offSet >  0 ) {
            if  (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
                cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);
            }  else  {
                cache = cipher.doFinal(data, offSet, inputLen - offSet);
            }
            out.write(cache,  0 , cache.length);
            i++;
            offSet = i * MAX_ENCRYPT_BLOCK;
        }
        byte [] encryptedData = out.toByteArray();
        out.close();
        return  encryptedData;
    }

    /**

      * 

     * 私钥加密
     *
     *
     * @param data 源数据
     * @param privateKey 私钥(BASE64编码)
     * @return
     * @throws Exception
     */
    public  static  byte [] encryptByPrivateKey( byte [] data, String privateKey)
            throws  Exception {
        byte [] keyBytes = Base64Utils.decode(privateKey);
        PKCS8EncodedKeySpec pkcs8KeySpec =  new  PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, privateK);
        int  inputLen = data.length;
        ByteArrayOutputStream out =  new  ByteArrayOutputStream();
        int  offSet =  0 ;
        byte [] cache;
        int  i =  0 ;
        // 对数据分段加密
        while  (inputLen - offSet >  0 ) {
            if  (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
                cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);
            }  else  {
                cache = cipher.doFinal(data, offSet, inputLen - offSet);
            }
            out.write(cache,  0 , cache.length);
            i++;
            offSet = i * MAX_ENCRYPT_BLOCK;
        }
        byte [] encryptedData = out.toByteArray();
        out.close();
        return  encryptedData;
    }

    /**

      * 

     * 获取私钥
     *
     *
     * @param keyMap 密钥对
     * @return
     * @throws Exception
     */
    public  static  String getPrivateKey(Map keyMap)
            throws  Exception {
        Key key = (Key) keyMap.get(PRIVATE_KEY);
        return  Base64Utils.encode(key.getEncoded());
    }

    /**

      * 

     * 获取公钥
     *
     *
     * @param keyMap 密钥对
     * @return
     * @throws Exception
     */
    public  static  String getPublicKey(Map keyMap)
            throws  Exception {
        Key key = (Key) keyMap.get(PUBLIC_KEY);
        return  Base64Utils.encode(key.getEncoded());
    }

}