RSA-如何检查公钥信息？

Question

I encrypt and decrypt data using the RSACryptoServiceProvider in C#, and when I generate a new keypair, I return the private key to the caller of the method and then save the public key to a homemade PKI (just a dictionary with the keyBlob and a unique identifier).

My problem is this: since I need to store the public key, I don't want to accidentally store a private key in the PKI. However, since I also need to actually write the private key to a file, I am working with byte arrays exported with the ExportCspBlob method.

My question:
How do I ensure, by checking the byte[] that I parse into my StoreKey method, that it is in fact a public key and it does not contain private key information?

For clarification, here is the relevant code:

public static bool StoreKey(byte[] publicKeyParameters, string uniqueIdentifier)
{
    bool success = false;
    if (!keyCollection.ContainsKey(uniqueIdentifier))
    {
        if (!keyCollection.ContainsValue(publicKeyParameters))
        {
            keyCollection.Add(uniqueIdentifier, publicKeyParameters);
            success = true;
        }
    }
    return success;
}

And the GenerateKeys method:

public static byte[] GenerateKeys(string uniqueIdentifier)
{
    byte[] privateKeyBlob;

    using (var rsa = new RSACryptoServiceProvider(4096))
    {
        try
        {
            byte[] publicKey = rsa.ExportCspBlob(false);

            privateKeyBlob = rsa.ExportCspBlob(true);

            PublicKeyInfrastructure.StoreKey(publicKey, uniqueIdentifier);
        }
        finally
        {
            //// Clear the RSA key container, deleting generated keys.
            rsa.PersistKeyInCsp = false;
        }
    }
    return privateKeyBlob;
}

Since I am working on two different classes, I would like to abstain from initializing a RSACryptoServiceProvider in my PKI, just to import the key and check for it. Is this possible?

Answer 1

According to MSDN, the output of ExportCspBlob is compatible with CAPI, and according to the documentation for the CAPI BLOBHEADER , the first byte represents the key type. Specifically, if the first byte is 0x07, it's a private key, whereas 0x06 is a public key.