RSA Android 实现

Android 开发时使用RSA加密时使用的类，方便使用时拷贝

package com.cnepay.mobile.bts.utils;import java.io.BufferedReader;import java.io.IOException;import java.io.InputStream;import java.io.InputStreamReader;import java.math.BigInteger;import java.security.KeyFactory;import java.security.KeyPair;import java.security.KeyPairGenerator;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.RSAPublicKeySpec;import java.security.spec.X509EncodedKeySpec;import javax.crypto.Cipher;/** * @author xugang * @date 2014年8月22日 下午1:44:23 */public final class RSAUtils{    private static String RSA = "RSA";    private static String TRANSFORMATION = "RSA/ECB/PKCS1Padding";    /**     * 随机生成RSA密钥对(默认密钥长度为1024)     *      * @return     */    public static KeyPair generateRSAKeyPair()    {        return generateRSAKeyPair(1024);    }    /**     * 随机生成RSA密钥对     *      * @param keyLength     *            密钥长度，范围：512～2048<br>     *            一般1024     * @return     */    public static KeyPair generateRSAKeyPair(int keyLength)    {        try        {            KeyPairGenerator kpg = KeyPairGenerator.getInstance(RSA);            kpg.initialize(keyLength);            return kpg.genKeyPair();        } catch (NoSuchAlgorithmException e)        {            e.printStackTrace();            return null;        }    }    /**     * 用公钥加密 <br>     * 每次加密的字节数，不能超过密钥的长度值减去11     *      * @param data     *            需加密数据的byte数据     * @param publicKey     *            公钥     * @return 加密后的byte型数据     */    public static byte[] encryptData(byte[] data, PublicKey publicKey)    {        try        {            Cipher cipher = Cipher.getInstance(TRANSFORMATION);            // 编码前设定编码方式及密钥            cipher.init(Cipher.ENCRYPT_MODE, publicKey);            // 传入编码数据并返回编码结果            return cipher.doFinal(data);        } catch (Exception e)        {            e.printStackTrace();            return null;        }    }    /**     * 用私钥解密     *      * @param encryptedData     *            经过encryptedData()加密返回的byte数据     * @param privateKey     *            私钥     * @return     */    public static byte[] decryptData(byte[] encryptedData, PrivateKey privateKey)    {        try        {            Cipher cipher = Cipher.getInstance(TRANSFORMATION);            cipher.init(Cipher.DECRYPT_MODE, privateKey);            return cipher.doFinal(encryptedData);        } catch (Exception e)        {            return null;        }    }    /**     * 通过公钥byte[](publicKey.getEncoded())将公钥还原，适用于RSA算法     *      * @param keyBytes     * @return     * @throws NoSuchAlgorithmException     * @throws InvalidKeySpecException     */    public static PublicKey getPublicKey(byte[] keyBytes) throws NoSuchAlgorithmException,            InvalidKeySpecException    {        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);        KeyFactory keyFactory = KeyFactory.getInstance(RSA);        PublicKey publicKey = keyFactory.generatePublic(keySpec);        return publicKey;    }    /**     * 通过私钥byte[]将公钥还原，适用于RSA算法     *      * @param keyBytes     * @return     * @throws NoSuchAlgorithmException     * @throws InvalidKeySpecException     */    public static PrivateKey getPrivateKey(byte[] keyBytes) throws NoSuchAlgorithmException,            InvalidKeySpecException    {        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);        KeyFactory keyFactory = KeyFactory.getInstance(RSA);        PrivateKey privateKey = keyFactory.generatePrivate(keySpec);        return privateKey;    }    /**     * 使用N、e值还原公钥     *      * @param modulus     * @param publicExponent     * @return     * @throws NoSuchAlgorithmException     * @throws InvalidKeySpecException     */    public static PublicKey getPublicKey(String modulus, String publicExponent)            throws NoSuchAlgorithmException, InvalidKeySpecException    {        BigInteger bigIntModulus = new BigInteger(modulus);        BigInteger bigIntPrivateExponent = new BigInteger(publicExponent);        RSAPublicKeySpec keySpec = new RSAPublicKeySpec(bigIntModulus, bigIntPrivateExponent);        KeyFactory keyFactory = KeyFactory.getInstance(RSA);        PublicKey publicKey = keyFactory.generatePublic(keySpec);        return publicKey;    }    /**     * 使用N、d值还原私钥     *      * @param modulus     * @param privateExponent     * @return     * @throws NoSuchAlgorithmException     * @throws InvalidKeySpecException     */    public static PrivateKey getPrivateKey(String modulus, String privateExponent)            throws NoSuchAlgorithmException, InvalidKeySpecException    {        BigInteger bigIntModulus = new BigInteger(modulus);        BigInteger bigIntPrivateExponent = new BigInteger(privateExponent);        RSAPublicKeySpec keySpec = new RSAPublicKeySpec(bigIntModulus, bigIntPrivateExponent);        KeyFactory keyFactory = KeyFactory.getInstance(RSA);        PrivateKey privateKey = keyFactory.generatePrivate(keySpec);        return privateKey;    }    /**     * 从字符串中加载公钥     *      * @param publicKeyStr     *            公钥数据字符串     * @throws Exception     *             加载公钥时产生的异常     */    public static PublicKey loadPublicKey(String publicKeyStr) throws Exception    {        try        {            byte[] buffer = Base64Utils.decode(publicKeyStr);            KeyFactory keyFactory = KeyFactory.getInstance(RSA);            X509EncodedKeySpec keySpec = new X509EncodedKeySpec(buffer);            return keyFactory.generatePublic(keySpec);        } catch (NoSuchAlgorithmException e)        {            throw new Exception("无此算法");        } catch (InvalidKeySpecException e)        {            throw new Exception("公钥非法");        } catch (NullPointerException e)        {            throw new Exception("公钥数据为空");        }    }    /**     * 从字符串中加载私钥<br>     * 加载时使用的是PKCS8EncodedKeySpec（PKCS#8编码的Key指令）。     *      * @param privateKeyStr     * @return     * @throws Exception     */    public static PrivateKey loadPrivateKey(String privateKeyStr) throws Exception    {        try        {            byte[] buffer = Base64Utils.decode(privateKeyStr);            // X509EncodedKeySpec keySpec = new X509EncodedKeySpec(buffer);            PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(buffer);            KeyFactory keyFactory = KeyFactory.getInstance(RSA);            return (RSAPrivateKey) keyFactory.generatePrivate(keySpec);        } catch (NoSuchAlgorithmException e)        {            throw new Exception("无此算法");        } catch (InvalidKeySpecException e)        {            throw new Exception("私钥非法");        } catch (NullPointerException e)        {            throw new Exception("私钥数据为空");        }    }    /**     * 从文件中输入流中加载公钥     *      * @param in     *            公钥输入流     * @throws Exception     *             加载公钥时产生的异常     */    public static PublicKey loadPublicKey(InputStream in) throws Exception    {        try        {            return loadPublicKey(readKey(in));        } catch (IOException e)        {            throw new Exception("公钥数据流读取错误");        } catch (NullPointerException e)        {            throw new Exception("公钥输入流为空");        }    }    /**     * 从文件中加载私钥     *      *            私钥文件名     * @return 是否成功     * @throws Exception     */    public static PrivateKey loadPrivateKey(InputStream in) throws Exception    {        try        {            return loadPrivateKey(readKey(in));        } catch (IOException e)        {            throw new Exception("私钥数据读取错误");        } catch (NullPointerException e)        {            throw new Exception("私钥输入流为空");        }    }    /**     * 读取密钥信息     *      * @param in     * @return     * @throws IOException     */    private static String readKey(InputStream in) throws IOException    {        BufferedReader br = new BufferedReader(new InputStreamReader(in));        String readLine = null;        StringBuilder sb = new StringBuilder();        while ((readLine = br.readLine()) != null)        {            if (readLine.charAt(0) == '-')            {                continue;            } else            {                sb.append(readLine);                sb.append('\r');            }        }        return sb.toString();    }    /**     * 打印公钥信息     *      * @param publicKey     */    public static void printPublicKeyInfo(PublicKey publicKey)    {        RSAPublicKey rsaPublicKey = (RSAPublicKey) publicKey;        System.out.println("----------RSAPublicKey----------");        System.out.println("Modulus.length=" + rsaPublicKey.getModulus().bitLength());        System.out.println("Modulus=" + rsaPublicKey.getModulus().toString());        System.out.println("PublicExponent.length=" + rsaPublicKey.getPublicExponent().bitLength());        System.out.println("PublicExponent=" + rsaPublicKey.getPublicExponent().toString());    }    public static void printPrivateKeyInfo(PrivateKey privateKey)    {        RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) privateKey;        System.out.println("----------RSAPrivateKey ----------");        System.out.println("Modulus.length=" + rsaPrivateKey.getModulus().bitLength());        System.out.println("Modulus=" + rsaPrivateKey.getModulus().toString());        System.out.println("PrivateExponent.length=" + rsaPrivateKey.getPrivateExponent().bitLength());        System.out.println("PrivatecExponent=" + rsaPrivateKey.getPrivateExponent().toString());    }}