Вы можете использовать классы X509CertificateAuthority и X509Certificate для программного создания сертификатов SSL с использованием OpenSSL.NET.Пример кода можно найти по ссылке ниже.
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// Create a configuration object using openssl.cnf file.
OpenSSL.X509.Configuration cfg = new OpenSSL.X509.Configuration("Path to your openssl configuration file i.e. openssl.cnf");
// Create a root certificate authority which will have a self signed certificate.
OpenSSL.X509.X509CertificateAuthority RootCA = OpenSSL.X509.X509CertificateAuthority.SelfSigned(cfg, new SimpleSerialNumber(),"Disinguish name for your CA", DateTime.
Now, TimeSpan.FromDays(365));
// If you want the certificate of your root CA which you just create, you can get the certificate like this.
X509Certificate RootCertificate = rootCA.certificate;
// Here you need CSR(Certificate Signing Request) which you might have already got it from your web server e.g. IIS7.0.
string strCSR = System.IO.File.ReadAllText(@"Path to your CSR file");
// You need to write the CSR string to a BIO object as shown below.
OpenSSL.Core.BIO ReqBIO = OpenSSL.Core.BIO.MemoryBuffer();
ReqBIO.Write(strCSR);
// Now you can create X509Rquest object using the ReqBIO.
OpenSSL.X509.X509Request Request = new OpenSSL.X509.X509Request(reqBIO);
// Once you have a request object, you can create a SSL Certificate which is signed by the self signed RootCA.
OpenSSL.X509.X509Certificate certificate = RootCA.ProcessRequest(Request, DateTime.Now, DateTime.Now + TimeSpan.FromDays(365));
// Now you can save this certificate to your file system.
FileStream fs = new FileStream("Path to your file where you want to create the certificate with file name", FileMode.Create, FileAccess.ReadWrite);
BinaryWriter bw = new BinaryWriter(fs);
BIO bio = BIO.MemoryBuffer();
certificate.Write(bio);
string certString = bio.ReadString();
bw.Write(certString);
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