【签名加解密】c# rsa 解密超过128报错解决

分段解密

public string DecryptJava(string privateKeyJava, string data, string encoding = "UTF-8")
        {
            RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
            rsa.FromPrivateKeyJavaString(privateKeyJava);
            byte[] encryptData = Convert.FromBase64String(data);
            byte[] dencryContent = null;
            #region 分段解密
            if (encryptData == null || encryptData.Length <= 0)
            {
                throw new NotSupportedException();
            }

            int keySize = rsa.KeySize / 8;
            byte[] buffer = new byte[keySize];

            using (MemoryStream input = new MemoryStream(encryptData))
            using (MemoryStream output = new MemoryStream())
            {
                while (true)
                {
                    int readLine = input.Read(buffer, 0, keySize);
                    if (readLine <= 0)
                    {
                        break;
                    }
                    byte[] temp = new byte[readLine];
                    Array.Copy(buffer, 0, temp, 0, readLine);
                    byte[] decrypt = rsa.Decrypt(temp, false);
                    output.Write(decrypt, 0, decrypt.Length);
                }
                dencryContent = output.ToArray();
            }
            #endregion
            return Encoding.UTF8.GetString(dencryContent);
        }
补充：
/// <summary>
/// RSA加载JAVA PrivateKey
/// </summary>
/// <param name="privateJavaKey">java提供的第三方私钥</param>
/// <returns></returns>
public static void FromPrivateKeyJavaString(this RSA rsa, string privateJavaKey)
{
string xmlPrivateKey = rsa.ConvertToXmlPrivateKey(privateJavaKey);
rsa.FromXmlString(xmlPrivateKey);
}

 

/// <summary>
/// 把java的私钥转换成.net的xml格式
/// </summary>
/// <param name="rsa"></param>
/// <param name="privateJavaKey"></param>
/// <returns></returns>
public static string ConvertToXmlPrivateKey(this RSA rsa, string privateJavaKey)
{
RsaPrivateCrtKeyParameters privateKeyParam = (RsaPrivateCrtKeyParameters)PrivateKeyFactory.CreateKey(Convert.FromBase64String(privateJavaKey));
string xmlPrivateKey = string.Format("<RSAKeyValue><Modulus>{0}</Modulus><Exponent>{1}</Exponent><P>{2}</P><Q>{3}</Q><DP>{4}</DP><DQ>{5}</DQ><InverseQ>{6}</InverseQ><D>{7}</D></RSAKeyValue>",
Convert.ToBase64String(privateKeyParam.Modulus.ToByteArrayUnsigned()),
Convert.ToBase64String(privateKeyParam.PublicExponent.ToByteArrayUnsigned()),
Convert.ToBase64String(privateKeyParam.P.ToByteArrayUnsigned()),
Convert.ToBase64String(privateKeyParam.Q.ToByteArrayUnsigned()),
Convert.ToBase64String(privateKeyParam.DP.ToByteArrayUnsigned()),
Convert.ToBase64String(privateKeyParam.DQ.ToByteArrayUnsigned()),
Convert.ToBase64String(privateKeyParam.QInv.ToByteArrayUnsigned()),
Convert.ToBase64String(privateKeyParam.Exponent.ToByteArrayUnsigned()));
return xmlPrivateKey;
}