public unsafe X509Certificate2 GenerateCertificate(X509Certificate2 issuingCertificate, PrivateKey privateKey, X500DistinguishedName dn, string[] dnsNames, IPAddress[] ipAddresses = null, HashAlgorithm?signatureAlgorithm = null, DateTime?notBefore = null, DateTime?notAfter = null)
{
if (!issuingCertificate.HasPrivateKey)
{
throw new ArgumentException("Issuing certificate must have a private key.", nameof(issuingCertificate));
}
IntPtr basicEncodedDataPtr = IntPtr.Zero, certExtensionPtr = IntPtr.Zero;
var serialNumber = new byte[16];
var rng = RandomNumberGenerator.Create();
rng.GetNonZeroBytes(serialNumber);
serialNumber[15] &= 0x7F;
fixed(byte *dnPtr = dn.RawData, issuerDnPtr = issuingCertificate.SubjectName.RawData, serialNumberPtr = serialNumber)
{
try
{
var blob = new NATIVE_CRYPTOAPI_BLOB
{
cbData = (uint)dn.RawData.Length,
pbData = dnPtr
};
var signingSignatureAlgorithmIdentifier = new CRYPT_ALGORITHM_IDENTIFIER
{
pszObjId = issuingCertificate.SignatureAlgorithm.Value
};
using (var signingKey = ExtractKey(issuingCertificate))
{
var signingAlgorithmIdentifier = new CRYPT_ALGORITHM_IDENTIFIER
{
pszObjId = signatureAlgorithm != null?HashAlgorithmToSignatureAlgorithm(signingKey, signatureAlgorithm.Value) : issuingCertificate.SignatureAlgorithm.Value
};
using (PublicKeyInfo publicKey = privateKey.ToPublicKey(), signingPublicKey = signingKey.ToPublicKey())
{
using (var extensions = new MarshalX509ExtensionCollection())
{
using (extensions.Freeze())
{
var usage = X509KeyUsageFlags.DigitalSignature;
if (privateKey.AlgorithmGroup == AlgorithmGroup.RSA)
{
//Key encipherment is not valid for DSA/ECDSA
usage |= X509KeyUsageFlags.KeyEncipherment;
}
extensions.Add(new X509BasicConstraintsExtension(false, false, 0, true));
extensions.Add(new X509KeyUsageExtension(usage, true));
extensions.Add(new X509EnhancedKeyUsageExtension(new OidCollection {
new Oid(OIDs.EKU_SERVER)
}, false));
extensions.Add(new X509SubjectAlternativeNameExtension(DnsAltNamesFromArray(dnsNames, ipAddresses ?? new IPAddress[0]), false));
using (var sha1 = new SHA1CryptoServiceProvider())
{
var issuingKeyId = sha1.ComputeHash(signingPublicKey.Key);
extensions.Add(new X509SubjectKeyIdentifierExtension(sha1.ComputeHash(publicKey.Key), false));
extensions.Add(new X509AuthorityKeyIdentifierExtension(issuingKeyId, null));
}
}
var certInfo = new CERT_INFO();
certInfo.Subject = blob;
certInfo.SerialNumber = new NATIVE_CRYPTOAPI_BLOB {
cbData = (uint)serialNumber.Length, pbData = serialNumberPtr
};
certInfo.SubjectPublicKeyInfo = publicKey.PublicKey;
certInfo.dwVersion = CertificateVersion.CERT_V3;
certInfo.Issuer = new NATIVE_CRYPTOAPI_BLOB {
cbData = (uint)issuingCertificate.SubjectName.RawData.Length, pbData = issuerDnPtr
};
certInfo.SignatureAlgorithm = signingAlgorithmIdentifier;
certInfo.NotAfter = FileTimeHelper.ToFileTimeStructureUtc(notAfter ?? DateTime.Now.AddHours(-1).AddYears(5));
certInfo.NotBefore = FileTimeHelper.ToFileTimeStructureUtc(notBefore ?? DateTime.Now.AddHours(-1));
certInfo.cExtension = extensions.Extensions.cExtension;
certInfo.rgExtension = extensions.Extensions.rgExtension;
var size = 0u;
var CERT_INFO_TYPE = (IntPtr)2;
if (!Crypt32.CryptSignAndEncodeCertificate(signingKey.Handle, signingKey.KeySpec, EncodingType.X509_ASN_ENCODING, CERT_INFO_TYPE, ref certInfo, ref signingSignatureAlgorithmIdentifier, IntPtr.Zero, IntPtr.Zero, ref size))
{
throw new Win32Exception(Marshal.GetLastWin32Error());
}
var buffer = Marshal.AllocHGlobal((int)size);
if (!Crypt32.CryptSignAndEncodeCertificate(signingKey.Handle, signingKey.KeySpec, EncodingType.X509_ASN_ENCODING, CERT_INFO_TYPE, ref certInfo, ref signingSignatureAlgorithmIdentifier, IntPtr.Zero, buffer, ref size))
{
throw new Win32Exception(Marshal.GetLastWin32Error());
}
const int CERT_KEY_PROV_INFO_PROP_ID = 2;
var certificate = new X509Certificate2(SerializeCertificate(buffer, size));
var keyProvInfo = new CRYPT_KEY_PROV_INFO
{
cProvParam = 0,
dwKeySpec = privateKey.KeySpec,
dwProvType = privateKey.Handle.IsNCryptKey ? ProviderType.CNG : ProviderType.PROV_RSA_AES,
pwszProvName = privateKey.ProviderName,
dwFlags = 0,
pwszContainerName = privateKey.Name
};
if (!Crypt32.CertSetCertificateContextProperty(certificate.Handle, CERT_KEY_PROV_INFO_PROP_ID, 0u, ref keyProvInfo))
{
throw new Win32Exception(Marshal.GetLastWin32Error());
}
return(new X509Certificate2(certificate));
}
}
}
}
finally
{
Marshal.FreeHGlobal(basicEncodedDataPtr);
Marshal.FreeHGlobal(certExtensionPtr);
}
}
}
