RSAUtils加密解密

import org.apache.commons.codec.binary.Base64;

import org.apache.commons.io.IOUtils;

import javax.crypto.Cipher;

import java.io.ByteArrayOutputStream;

import java.security.*;

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;

public class RSAUtils {

    public static final String CHARSET = "UTF-8";

    public static final String RSA_ALGORITHM = "RSA";

    public static Map<String, String> createKeys(int keySize){

        //为RSA算法创建一个KeyPairGenerator对象

        KeyPairGenerator kpg;

        try{

            kpg = KeyPairGenerator.getInstance(RSA_ALGORITHM);

        }catch(NoSuchAlgorithmException e){

            throw new IllegalArgumentException("No such algorithm-->[" + RSA_ALGORITHM + "]");

        }

        //初始化KeyPairGenerator对象,密钥长度

        kpg.initialize(keySize);

        //生成密匙对

        KeyPair keyPair = kpg.generateKeyPair();

        //得到公钥

        Key publicKey = keyPair.getPublic();

        String publicKeyStr = Base64.encodeBase64URLSafeString(publicKey.getEncoded());

        //得到私钥

        Key privateKey = keyPair.getPrivate();

        // 私钥的base64

        String privateKeyStr = Base64.encodeBase64URLSafeString(privateKey.getEncoded());

        Map<String, String> keyPairMap = new HashMap<String, String>();

        keyPairMap.put("publicKey", publicKeyStr);

        keyPairMap.put("privateKey", privateKeyStr);

        return keyPairMap;

    }

    /**

     * 得到私钥

     * @param privateKey 密钥字符串（经过base64编码）

     * @throws Exception

     */

    public static RSAPrivateKey getPrivateKey(String privateKey) throws NoSuchAlgorithmException, InvalidKeySpecException {

        //通过PKCS#8编码的Key指令获得私钥对象

        KeyFactory keyFactory = KeyFactory.getInstance(RSA_ALGORITHM);

        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(Base64.decodeBase64(privateKey));

        RSAPrivateKey key = (RSAPrivateKey) keyFactory.generatePrivate(pkcs8KeySpec);

        return key;

    }

    /**

     * 得到公钥

     * @param publicKey 密钥字符串（经过base64编码）

     * @throws Exception

     */

    public static RSAPublicKey getPublicKey(String publicKey) throws NoSuchAlgorithmException, InvalidKeySpecException {

        //通过X509编码的Key指令获得公钥对象

        KeyFactory keyFactory = KeyFactory.getInstance(RSA_ALGORITHM);

        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(Base64.decodeBase64(publicKey));

        RSAPublicKey key = (RSAPublicKey) keyFactory.generatePublic(x509KeySpec);

        return key;

    }

    /**

     * 公钥加密

     * @param data

     * @param publicKey

     * @return

     */

    public static String publicEncrypt(String data, RSAPublicKey publicKey){

        try{

            Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);

            cipher.init(Cipher.ENCRYPT_MODE, publicKey);

            return Base64.encodeBase64URLSafeString(rsaSplitCodec(cipher, Cipher.ENCRYPT_MODE, data.getBytes(CHARSET), publicKey.getModulus().bitLength()));

        }catch(Exception e){

            throw new RuntimeException("加密字符串[" + data + "]时遇到异常", e);

        }

    }

    /**

     * 私钥解密

     * @param data

     * @param privateKey

     * @return

     */

    public static String privateDecrypt(String data, RSAPrivateKey privateKey){

        try{

            Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);

            cipher.init(Cipher.DECRYPT_MODE, privateKey);

            return new String(rsaSplitCodec(cipher, Cipher.DECRYPT_MODE, Base64.decodeBase64(data), privateKey.getModulus().bitLength()), CHARSET);

        }catch(Exception e){

            throw new RuntimeException("解密字符串[" + data + "]时遇到异常", e);

        }

    }

    private static byte[] rsaSplitCodec(Cipher cipher, int opmode, byte[] datas, int keySize){

        int maxBlock = 0;

        if(opmode == Cipher.DECRYPT_MODE){

            maxBlock = keySize / 8;

        }else{

            maxBlock = keySize / 8 - 11;

        }

        ByteArrayOutputStream out = new ByteArrayOutputStream();

        int offSet = 0;

        byte[] buff;

        int i = 0;

        try{

            while(datas.length > offSet){

                if(datas.length-offSet > maxBlock){

                    buff = cipher.doFinal(datas, offSet, maxBlock);

                }else{

                    buff = cipher.doFinal(datas, offSet, datas.length-offSet);

                }

                out.write(buff, 0, buff.length);

                i++;

                offSet = i * maxBlock;

            }

        }catch(Exception e){

            throw new RuntimeException("加解密阀值为["+maxBlock+"]的数据时发生异常", e);

        }

        byte[] resultDatas = out.toByteArray();

        IOUtils.closeQuietly(out);

        return resultDatas;

    }

}

RSAUtils

<dependency>
    <groupId>commons-codec</groupId>
    <artifactId>commons-codec</artifactId>
    <version>1.11</version>
</dependency>
<dependency>
    <groupId>commons-io</groupId>
    <artifactId>commons-io</artifactId>
    <version>2.5</version>
</dependency>