RSA非对称加密，分段加解密的技术实现

1 年前

悟空来也

红客联盟，专注于网络安全和个人隐私保护，专业反果诈和隐私敲诈

 * 公钥加密
     * @param encryptingStr
     * @param publicKeyStr
     * @return
    public static String encryptByPublicKey(String encryptingStr, String publicKeyStr) {
        try {
            // 将公钥由字符串转为UTF-8格式的字节数组
            byte[] publicKeyBytes = decryptBase64(publicKeyStr);
            // 获得公钥
            X509EncodedKeySpec keySpec = new X509EncodedKeySpec(publicKeyBytes);
            // 取得待加密数据
            byte[] data = encryptingStr.getBytes("UTF-8");
            KeyFactory factory;
            factory = KeyFactory.getInstance("RSA");
            PublicKey publicKey = factory.generatePublic(keySpec);
            // 对数据加密
            Cipher cipher = Cipher.getInstance(factory.getAlgorithm());
            cipher.init(Cipher.ENCRYPT_MODE, publicKey);
            // 返回加密后由Base64编码的加密信息
            int inputLen = data.length;
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            int offSet = 0;
            byte[] cache;
            int i = 0;
            // 对数据分段解密
            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);
                offSet = i * MAX_ENCRYPT_BLOCK;
            byte[] decryptedData = out.toByteArray();
            out.close();
            return encryptBase64(decryptedData);
        } catch (Exception e) {
            e.printStackTrace();
        return null;
    }

上面是公钥加密

下面是私钥解密

  /**
     * 私钥解密
     * @param encryptedStr
     * @param privateKeyStr
     * @return
    public static String decryptByPrivateKey(String encryptedStr, String privateKeyStr) {
        try {
            // 对私钥解密
            byte[] privateKeyBytes = decryptBase64(privateKeyStr);
            // 获得私钥
            PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(privateKeyBytes);
            // 获得待解密数据
            byte[] data = decryptBase64(encryptedStr);
            KeyFactory factory = KeyFactory.getInstance("RSA");
            PrivateKey privateKey = factory.generatePrivate(keySpec);
            // 对数据解密
            Cipher cipher = Cipher.getInstance(factory.getAlgorithm());
            cipher.init(Cipher.DECRYPT_MODE, privateKey);
            // 返回UTF-8编码的解密信息
            int inputLen = data.length;
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            int offSet = 0;
            byte[] cache;
            int i = 0;
            // 对数据分段解密
            while (inputLen - offSet > 0) {
                if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
                    cache = cipher.doFinal(data, offSet, MAX_DECRYPT_BLOCK);
                } else {
                    cache = cipher.doFinal(data, offSet, inputLen - offSet);
                out.write(cache, 0, cache.length);
                offSet = i * MAX_DECRYPT_BLOCK;
            byte[] decryptedData = out.toByteArray();
            out.close();
            return new String(decryptedData, "UTF-8");