使用CreateSignature

Question

我有一些代码可以创建数字签名。消息和签名从一个系统传递到另一个系统。收到后，验证签名。此代码已通过Fortify运行，该服务可分析安全漏洞的代码。 Fortify报告＆＃34; RSACryptography.cs中的方法CreateDigitalSignature（）执行公钥RSA加密而没有OAEP填充＆＃34;。

我在RSACryptoServiceProvider.Encrypt（）方法上看到一个参数，如果为true，表示使用OAEP填充。但我没有使用Encrypt（）。我使用RSAPKCS1SignatureFormatter生成RSAPKCS1SignatureDeformatter来验证签名。所以我的问题是如何添加填充？我应该在发送之前加密签名吗？看我的代码，我已经标记了＆＃34;我需要做什么＆＃34;我添加了加密和解密调用的地方。这是我需要做什么或其他什么？

// create a digital signature
// returns true if successful. Also, the public key (as an xml string) that can be sent to the other party to verify messages sent
public bool CreateDigitalSignature(string msgToSend, out string publicKey, out string signature)
{
    bool rc = false;
    publicKey = null;
    signature = null;

    try
    {
        // get the hash of the message to send
        byte[] hashValue = GetHashedBytes(msgToSend);

        // Load or generate a public/private key pair.  
        // If it already exists in the key container it will be loaded, otherwise, a new key pair is created
        CspParameters cp = new CspParameters();
        cp.KeyContainerName = KeyStoreContainerName;

        RSACryptoServiceProvider RSA = new RSACryptoServiceProvider(cp);

        // get some info about the key:
        CspKeyContainerInfo info = new CspKeyContainerInfo(cp);

        //Create an RSAPKCS1SignatureFormatter object and pass it the RSACryptoServiceProvider to transfer the private key.  
        RSAPKCS1SignatureFormatter RSAFormatter = new RSAPKCS1SignatureFormatter(RSA);

        // Set the hash algorithm
        RSAFormatter.SetHashAlgorithm(hashAlgorithm);  // "SHA256", "SHA1", etc.

        //Create a signature for the hashed value of the data
        byte[] signedHashValue = RSAFormatter.CreateSignature(hashValue);

        // fortify says I need to use OAEP padding
        // IS THIS WHAT I NEED TO DO? Encrypt the signature before I convert it to a string?
        signedHashValue = RSA.Encrypt(signedHashValue, true);

        // convert the signature to a string
        signature = Convert.ToBase64String(signedHashValue);

        // get the public key to return so it can be pased to the receiver and used to verify the signature
        // There are two ways - either export the parameters or create an xml string
        // Using export: This gets public key inforation only (specify true to get both public and private keys)
        // RSAParameters RSAKeyInfo = RSA.ExportParameters(false);

        // get a string value of the public key
        publicKey = RSA.ToXmlString(false);

        // demonstration only. how to get the private key
        //string privateKey = RSA.ToXmlString(true);

        rc = true;
    }
    catch (Exception ex)
    {
        throw ex;
    }
    return rc;
}

然后验证签名：

public bool VerifySignature(string origintalData, string publicKeyXml, string signature)
{
    bool verified = false;
    try
    {
        // get the hashed value of the original data. used the specified algoritm stored in the this class
        byte[] hashValue = GetHashedBytes(origintalData);

        // get a byte array of the signature
        byte[] signaturebytes = Convert.FromBase64String(signature);

        // create a crypto provider
        RSACryptoServiceProvider RSA = new RSACryptoServiceProvider();

        // set the public key of the crypto service provider
        RSA.FromXmlString(publicKeyXml);

        // create a deformatter
        RSAPKCS1SignatureDeformatter RSADeformatter = new RSAPKCS1SignatureDeformatter(RSA);

        // set the hash algorithm. The sender must use the same algorithm
        RSADeformatter.SetHashAlgorithm(hashAlgorithm);

        // As per Fortify, need to use OAEP padding
        // IS THIS WHAT i NEED TO DO - decrypt the signature before veryfying it?
        signaturebytes = RSA.Decrypt(signaturebytes, true);

        // verify the signature
        verified = RSADeformatter.VerifySignature(hashValue, signaturebytes);
    }
    catch (Exception ex)
    {
        throw ex;
    }
    return verified;
}

更新： 从.Net 4.5.1升级到4.6.1后。我可以用

byte[] signedHashValue = RSA.SignData(bytes, HashAlgorithmName.SHA256, RSASignaturePadding.Pkcs1)

和相应的方法

RSA.VerifyData(System.Text.Encoding.UTF8.GetBytes(originalData), signaturebytes, HashAlgorithmName.SHA256, RSASignaturePadding.Pkcs1)

但我无法指定RSASignaturePadding.Pss。如果我这样做，我会得到一个异常＆＃34;指定的填充模式对此算法无效。＆＃34;

我也得到了和以前一样的签名，所以我觉得我还没有真正完成任何事情。无法使用AOEP填充？