如下代码:
ublic class RSAUtils { private static String RSA = "RSA"; /** * 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(RSA); // 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(RSA); 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 Exception { 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 (RSAPublicKey) 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 * * @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()); } /** * TODO rsa解密 * @param mContext * @param encryptContent 需要解密的字符 * @return 解密完成的字符 */ public static String decodeInfo(Context mContext,String encryptContent){ String decodeStr; try { // 从字符串中得到私钥 // PrivateKey privateKey = RSAUtils.loadPrivateKey(PRIVATE_KEY); // 从文件中得到私钥 InputStream inPrivate = mContext.getResources().getAssets().open("pkcs8_rsa_private_key.pem"); PrivateKey privateKey = RSAUtils.loadPrivateKey(inPrivate); // 因为RSA加密后的内容经Base64再加密转换了一下，所以先Base64解密回来再给RSA解密 byte[] decryptByte = RSAUtils.decryptData(Base64Utils.decode(encryptContent), privateKey); decodeStr = new String(decryptByte); } catch (Exception e) { decodeStr=""; } return decodeStr; } public static String encodeInfo(Context mContext,String source){ String encodeStr; try { // 从字符串中得到公钥 // PublicKey publicKey = RSAUtils.loadPublicKey(PUCLIC_KEY); // 从文件中得到公钥 InputStream inPublic = mContext.getResources().getAssets().open("rsa_public_key.pem"); PublicKey publicKey = RSAUtils.loadPublicKey(inPublic); // 加密 byte[] encryptByte = RSAUtils.encryptData(source.getBytes(), publicKey); // 为了方便观察吧加密后的数据用base64加密转一下，要不然看起来是乱码,所以解密是也是要用Base64先转换 encodeStr = Base64Utils.encode(encryptByte); } catch (Exception e) { encodeStr=""; } return encodeStr; } }