android RSA(日志)

import android.util.Base64;

import xxxxx.BuildConfig;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.security.Key;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.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;

import javax.crypto.Cipher;

public class RSAUtil implements  ISecurity{

    public static final String CHARSET = "UTF-8";
    //因为后台java 默认的填充模式为RSA/ECB/PKCS1Padding"， 而android端的不是，所以得设置和后一样的
    public static final String RSA_ALGORITHM = "RSA/ECB/PKCS1Padding";

    static {
        Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
    }

    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");
        } 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.encodeToString(publicKey.getEncoded(), Base64.DEFAULT);
        //得到私钥
        Key privateKey = keyPair.getPrivate();
        String privateKeyStr = Base64.encodeToString(privateKey.getEncoded(), Base64.DEFAULT);
        Map<String, String> keyPairMap = new HashMap<String, String>();
        keyPairMap.put("publicKey", publicKeyStr);
        keyPairMap.put("privateKey", privateKeyStr);

        return keyPairMap;
    }

    /**
     * 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");
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(Base64.decode(publicKey, Base64.DEFAULT));
        RSAPublicKey key = (RSAPublicKey) keyFactory.generatePublic(x509KeySpec);
        return key;
    }

    /**
     * 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");
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(Base64.decode(privateKey, Base64.DEFAULT));
        RSAPrivateKey key = (RSAPrivateKey) keyFactory.generatePrivate(pkcs8KeySpec);
        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.encodeToString(rsaSplitCodec(cipher, Cipher.ENCRYPT_MODE, data.getBytes(CHARSET), publicKey.getModulus().bitLength()), Base64.DEFAULT);
        } 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.decode(data, Base64.DEFAULT), privateKey.getModulus().bitLength()), CHARSET);
        } catch (Exception e) {
            throw new RuntimeException("解密字符串[" + data + "]时遇到异常", e);
        }
    }

    /**
     * 私钥加密
     *
     * @param data
     * @param privateKey
     * @return
     */

    public static String privateEncrypt(String data, RSAPrivateKey privateKey) {
        try {
            Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
            cipher.init(Cipher.ENCRYPT_MODE, privateKey);
            return Base64.encodeToString(rsaSplitCodec(cipher, Cipher.ENCRYPT_MODE, data.getBytes(CHARSET), privateKey.getModulus().bitLength()), Base64.DEFAULT);
        } catch (Exception e) {
            throw new RuntimeException("加密字符串[" + data + "]时遇到异常", e);
        }
    }

    /**
     * 公钥解密
     *
     * @param data
     * @param publicKey
     * @return
     */

    public static String publicDecrypt(String data, RSAPublicKey publicKey) {
        try {
            Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
            cipher.init(Cipher.DECRYPT_MODE, publicKey);
            return new String(rsaSplitCodec(cipher, Cipher.DECRYPT_MODE, Base64.decode(data, Base64.DEFAULT), publicKey.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();
        try {
            if(out!=null){
                out.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        return resultDatas;
    }

    public static void main(String[] args) throws Exception {
        Map<String, String> keyMap = RSAUtil.createKeys(1024);
        String publicKey = keyMap.get("publicKey");
        String privateKey = keyMap.get("privateKey");
        System.out.println("公钥: \n\r" + publicKey);
        System.out.println("私钥： \n\r" + privateKey);
        System.out.println("公钥加密——私钥解密");
        String str = "RSA是一种非对称加密算法，加密和解密使用不同的密钥。通信双方各握有一对密钥（称为公钥和私钥）中的一把，己方密钥加密的数据，只有对方密钥能够解密。RSA基于一个数论事实：将两个大素数相乘十分容易，但想要对其乘积进行因式分解却极其困 难，因此可以将乘积公开作为加密密钥，即公钥，而两个大素数组合成私钥。公钥是可提供给任何人使用，私钥则为自己所有，供解密之用。假使甲方握有公钥，乙方握有私钥，则通信过程如下：甲方发送数据给乙方。";
        System.out.println("\r明文：\r\n" + str);
        System.out.println("\r明文大小：\r\n" + str.getBytes().length);
        String encodedData = RSAUtil.publicEncrypt(str, RSAUtil.getPublicKey(publicKey));
        System.out.println("密文：\r\n" + encodedData);
        String decodedData = RSAUtil.privateDecrypt(encodedData, RSAUtil.getPrivateKey(privateKey));
        System.out.println("解密后文字: \r\n" + decodedData);


    }

    @Override
    public String decrypte(String cipherText) throws Exception {
        return RSAUtil.privateDecrypt(cipherText, RSAUtil.getPrivateKey(BuildConfig.RSA_PRIVATE_KEY));
    }

    @Override
    public String encrypte(String plainText) throws Exception {
        return RSAUtil.publicEncrypt(plainText, RSAUtil.getPublicKey(BuildConfig.RSA_PUBLIC_KEY));
    }
}

ISecurity 这个接口只有2个方法  

String decrypte(String cipherText) 

String encrypte(String plainText)