C#数字签名 SHA256withRSA

#region 公钥验签
/// <summary>
/// 公钥验签
/// </summary>
/// <param name="sign">签名</param>
/// <param name="content">明文</param>
/// <param name="publicKey">公钥</param>
/// <returns></returns>
 static bool PublicKeyVerifySign(string sign, string content, string publicKey)
{
    try
    {
        //.net core2.2及其以下版本使用，重写FromXmlString(string)方法
        RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
        rsa.FromXmlString(publicKey);
        byte[] signature = Convert.FromBase64String(sign);
        SHA256Managed sha256 = new SHA256Managed();
        RSAPKCS1SignatureDeformatter df = new RSAPKCS1SignatureDeformatter(rsa);
        df.SetHashAlgorithm("SHA256");
        byte[] compareByte = sha256.ComputeHash(Encoding.UTF8.GetBytes(content));
        return df.VerifySignature(compareByte, signature);
    }
    catch (Exception)
    {
        return false;
    }
}
#endregion

/// <summary>
/// RSA公钥格式转换，java->.net
/// </summary>
/// <param name="publicKey">java生成的公钥</param>
/// <returns></returns>
static string RSAPublicKeyJavaToDotNet(string publicKey)
{
    RsaKeyParameters publicKeyParam = (RsaKeyParameters)PublicKeyFactory.CreateKey(Convert.FromBase64String(publicKey));
    return string.Format("<RSAKeyValue><Modulus>{0}</Modulus><Exponent>{1}</Exponent></RSAKeyValue>",
        Convert.ToBase64String(publicKeyParam.Modulus.ToByteArrayUnsigned()),
        Convert.ToBase64String(publicKeyParam.Exponent.ToByteArrayUnsigned()));
}

/// <summary>
/// RSA私钥格式转换，java->.net
/// </summary>
/// <param name="privateKey">java生成的RSA私钥</param>
/// <returns></returns>
static string RSAPrivateKeyJavaToDotNet(string privateKey)
{
    RsaPrivateCrtKeyParameters privateKeyParam = (RsaPrivateCrtKeyParameters)PrivateKeyFactory.CreateKey(Convert.FromBase64String(privateKey));

    return 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()));
}
#region 私钥签名

/// <summary>
/// 私钥签名
/// </summary>
/// <param name="content"></param>
/// <returns></returns>
static string PrivateKeySign(string content, string privateKey)
{
    var rsa = new RSACryptoServiceProvider();
    rsa.FromXmlString(privateKey);
    var rsaClear = new RSACryptoServiceProvider();
    var paras = rsa.ExportParameters(true);
    rsaClear.ImportParameters(paras);
    using (var sha256 = new SHA256CryptoServiceProvider())
    {
        var signData = rsa.SignData(Encoding.UTF8.GetBytes(content), sha256);
        return Convert.ToBase64String(signData);
    }
}
#endregion