java rsa 公钥加密

 注意JAVA 的STRING .getBytes() 默认取的是操作系统的编码，最好统一UTF-8.

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package javaapplication1;

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;

/**
 *
 * @author jk
 */
public class RSAUtils {

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

     //  public static final String ECB_PKCS1_PADDING = "RSA";//加密填充方式

      public static final String ECB_PKCS1_PADDING = "RSA/ECB/PKCS1Padding";//加密填充方式

       private static final int _rsa_keysize = 1024;
       
    /**
     * RSA最大加密明文大小,keysize=1024, (1024/8)-11=117
     */
    private static final int MAX_ENCRYPT_BLOCK = (_rsa_keysize/8)-11;

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

    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
        String getAgorithm = keyFactory.getAlgorithm();
        getAgorithm = ECB_PKCS1_PADDING;
        Cipher cipher = Cipher.getInstance(getAgorithm);
        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;
    }

    /**
     * java端公钥加密
     */
    public static String encryptedDataOnJava(String data, String PUBLICKEY) {
        try {
            data = Base64Utils.encode(encryptByPublicKey(data.getBytes(_charset), PUBLICKEY));
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return data;
    }

}

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package javaapplication1;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import org.apache.commons.codec.binary.Base64;

/**
 *  */
/**
 * <p>
 * BASE64编码解码工具包
 * </p>
 * <p>
 * 依赖javabase64-1.3.1.jar
 * </p>
 *
 * @author IceWee
 * @date 2012-5-19
 * @version 1.0
 */
public class Base64Utils {

    /**
     *      */
    /**
     * 文件读取缓冲区大小
     */
    private static final int CACHE_SIZE = 1024;

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

    /**
     *      */
    /**
     * <p>
     * BASE64字符串解码为二进制数据
     * </p>
     *
     * @param base64
     * @return
     * @throws Exception
     */
    public static byte[] decode(String str) throws Exception {
        Base64 _base64 = new Base64();
        return _base64.decodeBase64(str.getBytes(_charset));
    }

    /**
     *      */
    /**
     * <p>
     * 二进制数据编码为BASE64字符串
     * </p>
     *
     * @param bytes
     * @return
     * @throws Exception
     */
    public static String encode(byte[] bytes) throws Exception {
        Base64 _base64 = new Base64();
        return new String(_base64.encodeBase64Chunked(bytes));
    }

    /**
     *      */
    /**
     * <p>
     * 将文件编码为BASE64字符串
     * </p>
     * <p>
     * 大文件慎用，可能会导致内存溢出
     * </p>
     *
     * @param filePath 文件绝对路径
     * @return
     * @throws Exception
     */
    public static String encodeFile(String filePath) throws Exception {
        byte[] bytes = fileToByte(filePath);
        return encode(bytes);
    }

    /**
     *      */
    /**
     * <p>
     * BASE64字符串转回文件
     * </p>
     *
     * @param filePath 文件绝对路径
     * @param base64 编码字符串
     * @throws Exception
     */
    public static void decodeToFile(String filePath, String base64) throws Exception {
        byte[] bytes = decode(base64);
        byteArrayToFile(bytes, filePath);
    }

    /**
     *      */
    /**
     * <p>
     * 文件转换为二进制数组
     * </p>
     *
     * @param filePath 文件路径
     * @return
     * @throws Exception
     */
    public static byte[] fileToByte(String filePath) throws Exception {
        byte[] data = new byte[0];
        File file = new File(filePath);
        if (file.exists()) {
            FileInputStream in = new FileInputStream(file);
            ByteArrayOutputStream out = new ByteArrayOutputStream(2048);
            byte[] cache = new byte[CACHE_SIZE];
            int nRead = 0;
            while ((nRead = in.read(cache)) != -1) {
                out.write(cache, 0, nRead);
                out.flush();
            }
            out.close();
            in.close();
            data = out.toByteArray();
        }
        return data;
    }

    /**
     *      */
    /**
     * <p>
     * 二进制数据写文件
     * </p>
     *
     * @param bytes 二进制数据
     * @param filePath 文件生成目录
     */
    public static void byteArrayToFile(byte[] bytes, String filePath) throws Exception {
        InputStream in = new ByteArrayInputStream(bytes);
        File destFile = new File(filePath);
        if (!destFile.getParentFile().exists()) {
            destFile.getParentFile().mkdirs();
        }
        destFile.createNewFile();
        OutputStream out = new FileOutputStream(destFile);
        byte[] cache = new byte[CACHE_SIZE];
        int nRead = 0;
        while ((nRead = in.read(cache)) != -1) {
            out.write(cache, 0, nRead);
            out.flush();
        }
        out.close();
        in.close();
    }

}

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