使用公鑰加密字符串作為 C# 中的文本

Question

我收到了一個 txt 格式的公鑰。 （BEGIN CERTIFICATE---END CERTIFICATE）我想使用 C# 中的此密鑰加密我的消息並將其發送出去。

同樣，我有我的文本格式的私鑰。 我已經與第三方共享了我的公鑰，他們用它來加密消息。 我想使用我的私鑰以 TEXT 格式解密消息。 我如何在 C# 中做到這一點？

請幫忙。

Answer 1

public class MyCrypto
{
    public X509Certificate2 GetDecryptionCertificate(string certificateName)
    {
        var my = new X509Store(StoreName.My, StoreLocation.LocalMachine);
        my.Open(OpenFlags.ReadOnly);
        var collection = my.Certificates.Find(X509FindType.FindBySubjectName, certificateName, false);
        if (collection.Count == 1)
        {
            return collection[0];
        }
        else if (collection.Count > 1)
        {
            throw new Exception(string.Format("More than one certificate with name '{0}' found in store LocalMachine/My.", certificateName));
        }
        else
        {
            throw new Exception(string.Format("Certificate '{0}' not found in store LocalMachine/My.", certificateName));
        }
    }

    public X509Certificate2 GetEncryptionCertificate(string filePath)
    {
        var collection = new X509Certificate2Collection();
        collection.Import(filePath);
        return collection[0];

    }

    public string EncryptRsa(string input, X509Certificate2 x509Certificate2)
    {
        var output = string.Empty;

        using (RSA csp = (RSA)x509Certificate2.PublicKey.Key)
        {
            byte[] bytesData = Encoding.UTF8.GetBytes(input);
            byte[] bytesEncrypted = csp.Encrypt(bytesData, RSAEncryptionPadding.OaepSHA1);
            output = Convert.ToBase64String(bytesEncrypted);
        }
        return output;
    }

    public string DecryptRsa(string encrypted, X509Certificate2 x509Certificate2)
    {
        var text = string.Empty;

        using (RSA csp = (RSA)x509Certificate2.PrivateKey)
        {
            byte[] bytesEncrypted = Convert.FromBase64String(encrypted);
            byte[] bytesDecrypted = csp.Decrypt(bytesEncrypted, RSAEncryptionPadding.OaepSHA1);
            text = Encoding.UTF8.GetString(bytesDecrypted);
        }
        return text;
    }

 
}