Skip to content

Instantly share code, notes, and snippets.

@yutopio
Created February 20, 2017 12:14
Show Gist options
  • Save yutopio/a217a4af63cf6bcf0a530c14c074cf8f to your computer and use it in GitHub Desktop.
Save yutopio/a217a4af63cf6bcf0a530c14c074cf8f to your computer and use it in GitHub Desktop.
Certificate generation with BouncyCastle C#
using Org.BouncyCastle.Asn1.Pkcs;
using Org.BouncyCastle.Asn1.Sec;
using Org.BouncyCastle.Asn1.X509;
using Org.BouncyCastle.Asn1.X9;
using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Crypto.Generators;
using Org.BouncyCastle.Crypto.Operators;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Math;
using Org.BouncyCastle.Security;
using Org.BouncyCastle.X509;
using System;
using System.IO;
class Program
{
static SecureRandom secureRandom = new SecureRandom();
static AsymmetricCipherKeyPair GenerateRsaKeyPair(int length)
{
var keygenParam = new KeyGenerationParameters(secureRandom, length);
var keyGenerator = new RsaKeyPairGenerator();
keyGenerator.Init(keygenParam);
return keyGenerator.GenerateKeyPair();
}
static AsymmetricCipherKeyPair GenerateEcKeyPair(string curveName)
{
var ecParam = SecNamedCurves.GetByName(curveName);
var ecDomain = new ECDomainParameters(ecParam.Curve, ecParam.G, ecParam.N);
var keygenParam = new ECKeyGenerationParameters(ecDomain, secureRandom);
var keyGenerator = new ECKeyPairGenerator();
keyGenerator.Init(keygenParam);
return keyGenerator.GenerateKeyPair();
}
static X509Certificate GenerateCertificate(
X509Name issuer, X509Name subject,
AsymmetricKeyParameter issuerPrivate,
AsymmetricKeyParameter subjectPublic)
{
ISignatureFactory signatureFactory;
if (issuerPrivate is ECPrivateKeyParameters)
{
signatureFactory = new Asn1SignatureFactory(
X9ObjectIdentifiers.ECDsaWithSha256.ToString(),
issuerPrivate);
}
else
{
signatureFactory = new Asn1SignatureFactory(
PkcsObjectIdentifiers.Sha256WithRsaEncryption.ToString(),
issuerPrivate);
}
var certGenerator = new X509V3CertificateGenerator();
certGenerator.SetIssuerDN(issuer);
certGenerator.SetSubjectDN(subject);
certGenerator.SetSerialNumber(BigInteger.ValueOf(1));
certGenerator.SetNotAfter(DateTime.UtcNow.AddHours(1));
certGenerator.SetNotBefore(DateTime.UtcNow);
certGenerator.SetPublicKey(subjectPublic);
return certGenerator.Generate(signatureFactory);
}
static bool ValidateSelfSignedCert(X509Certificate cert, ICipherParameters pubKey)
{
cert.CheckValidity(DateTime.UtcNow);
var tbsCert = cert.GetTbsCertificate();
var sig = cert.GetSignature();
var signer = SignerUtilities.GetSigner(cert.SigAlgName);
signer.Init(false, pubKey);
signer.BlockUpdate(tbsCert, 0, tbsCert.Length);
return signer.VerifySignature(sig);
}
static void Main(string[] args)
{
var caName = new X509Name("CN=TestCA");
var eeName = new X509Name("CN=TestEE");
var caKey = GenerateEcKeyPair("secp256r1");
var eeKey = GenerateRsaKeyPair(2048);
var caCert = GenerateCertificate(caName, caName, caKey.Private, caKey.Public);
var eeCert = GenerateCertificate(caName, eeName, caKey.Private, eeKey.Public);
var caOk = ValidateSelfSignedCert(caCert, caKey.Public);
var eeOk = ValidateSelfSignedCert(eeCert, caKey.Public);
using (var f = File.OpenWrite("ca.cer"))
{
var buf = caCert.GetEncoded();
f.Write(buf, 0, buf.Length);
}
using (var f = File.OpenWrite("ee.cer"))
{
var buf = eeCert.GetEncoded();
f.Write(buf, 0, buf.Length);
}
}
}
@vlad-G
Copy link

vlad-G commented Jan 12, 2021

This works well generating .cer and .pfx I'm probably missing something but what is the password for the certificate file?

@yutopio
Copy link
Author

yutopio commented Jan 18, 2021

Sorry this code does not write the private key output to files. It will be stored in caKey and eeKey. If you want to write pfx to file, you'll need to use Pkcs12Store and give the password to Save method.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment