C# RSA 无长度限制加密解密示例-蒲公英云

C# RSA 无长度限制加密解密示例

电玩女神 2022-07-15 07:58 275阅读 0赞

RSA 是一种非对称加密算法。由于算法特性，加密和解密过程用不同密钥，即公钥和私钥，而被广泛应用于数字证书的安全管理。在具体应用中，公钥用加密而私钥用于解密，或私钥用于数字签名而公钥用于签名验证。由于非对称加密算法比价复杂，耗时较长，所以一般在网络环境中RAS 被应用于签名认证，或小数据传输，如 AES 对称密钥传输。

在.Net 框架中，默认提供的辅助类只能对密钥长度大小相同的数据进行加密解密。此文提供C# RSA 算法示例一座优化，可以不限数据大小。此实例仅供交流学习。

RSA 加密

public string RsaEncrypt(string rawInput, string publicKey)
        {
            if (string.IsNullOrEmpty(rawInput))
            {
                return string.Empty;
            }
            if(string.IsNullOrWhiteSpace(publicKey))
            {
                throw new ArgumentException("Invalid Public Key");
            }
            using (var rsaProvider = new RSACryptoServiceProvider())
            {
                var inputBytes = Encoding.UTF8.GetBytes(rawInput);//有含义的字符串转化为字节流
                rsaProvider.FromXmlString(publicKey);//载入公钥
                int bufferSize = (rsaProvider.KeySize / 8) - 11;//单块最大长度
                var buffer = new byte[bufferSize];
                using (MemoryStream inputStream = new MemoryStream(inputBytes),
                     outputStream = new MemoryStream())
                {
                    while (true)
                    { //分段加密
                        int readSize = inputStream.Read(buffer, 0, bufferSize);
                        if (readSize <= 0)
                        {
                            break;
                        }
                        var temp = new byte[readSize];
                        Array.Copy(buffer, 0, temp, 0, readSize);
                        var encryptedBytes = rsaProvider.Encrypt(temp, false);
                        outputStream.Write(encryptedBytes, 0, encryptedBytes.Length);
                    }
                    return Convert.ToBase64String(outputStream.ToArray());//转化为字节流方便传输
                }
            }
        }

RSA 解密

public string RsaDecrypt(string encryptedInput, string privateKey)
        {
            if (string.IsNullOrEmpty(encryptedInput))
            {
                return string.Empty;
            }
            if (string.IsNullOrWhiteSpace(privateKey))
            {
                throw new ArgumentException("Invalid Private Key");
            }
            using (var rsaProvider = new RSACryptoServiceProvider())
            {
                var inputBytes = Convert.FromBase64String(encryptedInput);
                rsaProvider.FromXmlString(privateKey);
                int bufferSize = rsaProvider.KeySize / 8;
                var buffer = new byte[bufferSize];
                using (MemoryStream inputStream = new MemoryStream(inputBytes),
                     outputStream = new MemoryStream())
                {
                    while (true)
                    {
                        int readSize = inputStream.Read(buffer, 0, bufferSize);
                        if (readSize <= 0)
                        {
                            break;
                        }
                        var temp = new byte[readSize];
                        Array.Copy(buffer, 0, temp, 0, readSize);
                        var rawBytes = rsaProvider.Decrypt(temp, false);
                        outputStream.Write(rawBytes, 0, rawBytes.Length);
                    }
                    return Encoding.UTF8.GetString(outputStream.ToArray());
                }
            }
        }