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I try to generate a X509Certificate2 key pair with dot-net but private key is missing

I try to create a private-public key pair with dot-net and install it in the local key store. I was confused when the private key was not installed with the public key and then I noticed that despite the certificate having the HasPrivateKey property set to true the actual PrivateKey property is null. How do I get both, private and public key to be added to the windows key store? The certificate is later needed for port binding.
My current code looks basically like this:
public static X509Certificate2 CreateSelfSigned(string issuer="", string firendly_name = "")
{
using (var key = RSA.Create(4096))
{
var req = new CertificateRequest(
$"CN={issuer}",
key,
HashAlgorithmName.SHA256,
RSASignaturePadding.Pkcs1);
req.CertificateExtensions.Add(
new X509BasicConstraintsExtension(true, false, 0, true));
req.CertificateExtensions.Add(
new X509EnhancedKeyUsageExtension(
new OidCollection
{
// Server Authentifikation
new Oid("1.3.6.1.5.5.7.3.2"),
// Client Authentifikation
new Oid("1.3.6.1.5.5.7.3.1")
},
true));
req.CertificateExtensions.Add(
new X509SubjectKeyIdentifierExtension(req.PublicKey, false));
var cert = req.CreateSelfSigned(DateTimeOffset.UtcNow.AddDays(-1),
DateTimeOffset.UtcNow.AddYears(30));
cert.FriendlyName = firendly_name;
using (var store = new X509Store(StoreName.My, StoreLocation.LocalMachine))
{
store.Open(OpenFlags.ReadWrite);
store.Add(cert);
store.Close();
}
}
}
I already searched the internet but couldn't find a solution that works for me. Really scratching my head about this one for hours. The program is a installer type of program and previously called PowerShell to create a self signed certificate which only worked half of the time and was dirty as hell. I'm limited to dot-net 4.7.2 and can't rely on external libraries very much because of project constraints.

The HasPrivateKey property set to true the actual PrivateKey property is null
You shouldn't trust or use the PrivateKey property, it's always null for ECDSA/ECDH/DH-based certificates, and can also be null (as you saw) for RSA and DSA. The GetRSAPrivateKey() method (and others, for different algorithms) is the better answer.
How do I get both, private and public key to be added to the windows key store?
The problem is that CertificateRequest binds the key as-is to the certificate. You have an ephemeral key (created by RSA.Create(4096)) so that certificate is associated with an ephemeral key. When you add it to the store the ephemeral key is then forgotten.
You could either change your key creation to create a named CNG key, or just export the cert as a PFX, re-import it with PersistKeySet, and add that to the store.
var cert = req.CreateSelfSigned(DateTimeOffset.UtcNow.AddDays(-1),
DateTimeOffset.UtcNow.AddYears(30));
cert.FriendlyName = firendly_name;
using (cert)
using (var tmpCert = new X509Certificate2(cert.Export(X509ContentType.Pfx), "", X509KeyStorageFlags.MachineKeySet | X509KeyStorageFlags.PersistKeySet))
using (var store = new X509Store(StoreName.My, StoreLocation.LocalMachine))
{
store.Open(OpenFlags.ReadWrite);
store.Add(tmpCert);
store.Close();
}

I run into a similar issue a while ago trying to add the certificate to the store from the code automatically for a docker container.
The solution I used was creating the self-certificate with the OpenSSL tool and save it on a folder inside the project. NOTE: I created a pfx certificate in order to have the private key inside the certificate.
So, I had a code like the following
using (X509Store store = new X509Store(StoreName.Root,
StoreLocation.CurrentUser, OpenFlags.ReadWrite)) {
store.Add(new
X509Certificate2("path-to-certificate/certificate-name.pfx",
"certificatePassword"));
}
NOTE2: The "StoreName.Root", and the "StoreLocation.CurrentUser" will vary depending on which store you want to save the certificate.
I hope you find this solution useful!

Service account cannot load the X509Certificate from windows certificate store

All, I run into an issue where the service account my ASP.NET web forms application (.Net Framework 4.6.1) runs under cannot load the X509Certificate(.pfx) from the personal store on the windows 2012 R2 server .Here is how I imported the certificate to the certificate store
I Logged into the server using the service account(domain\username) ,used mmc snap in to import the certificate to Current User Personal Certificate Store (please see screenshot at the end)
This is the code I am using to load the certificate in C#.But the certificate
is null
public X509Certificate2 Load()
{
X509Certificate2 x509Certificate = null;
var store = new X509Store(StoreName.My,StoreLocation.CurrentUser);
string thumbPrint = StripTheSpacesAndMakeItUpper(ConfigurationManager.AppSettings["pfxthumbPrint"]);
store.Open(OpenFlags.ReadOnly);
var certCollection = store.Certificates;
foreach (var x509 in certCollection)
{
if (x509.Thumbprint.Equals(thumbPrint))
{
x509Certificate = x509;
break;
}
}
store.Close();
return x509Certificate;
}
private string StripTheSpacesAndMakeItUpper(string thumbPrint)
{
if(!string.IsNullOrWhiteSpace(thumbPrint))
{
return Regex.Replace(thumbPrint, #"\s|\W", "").ToUpper();
}
return thumbPrint;
}
Any suggestions on why the method Load returns null ?
]3

I don't know how you set the value of ConfigurationManager.AppSettings["pfxthumbPrint"]. I guess you double clicked the certificate in your CurrentUser store and copied the thumbprint from the Details tab, right? If that is the case, you copied also one invisible character from the beginning of the thumbprint.
The saddest thing is that this character (I don't know what it is) is not visible in your app.config/web.config. The only way to get rid of if is to delete the first quote character with the first character of the thumbprint and type them in again manually. Or delete entire thumbprint and the quotes and type them again if you wish.

Instead of
if (x509.Thumbprint.Equals(x509CertificateFriendlyName))
Shouldn't it be
if (x509.Thumbprint.Equals(thumbPrint))
...?
Also, you appear to have x509Certificate declared as a local variable and then you discard it. Did you intend to assign the value to an instance variable perhaps? I don't even see a return statement.
Also, you're not disposing your store, although that probably isn't the cause of your issue.
Here's a different version that addresses these issues, and will also eliminate any invisible characters in the configuration entry (see pepo's answer for why).
public X509Certificate2 Load()
{
var thumbPrintFromConfig = ConfigurationManager.AppSettings["pfxthumbPrint"]
var thumbPrint = Regex.Replace(thumbPrintFromConfig.ToUpper(),"[^A-F0-9]",""); //Keep only hex digits
return Load(thumbPrint);
}
private X509Certificate2 Load(string thumbPrint)
{
using (var store = new X509Store(StoreName.My,StoreLocation.CurrentUser))
{
store.Open(OpenFlags.ReadOnly);
var cert = store
.Certificates
.OfType<X509Certificate2>()
.Where(x => x.Thumbprint == thumbPrint)
.Single();
store.Close();
return cert;
}
}

Add a generated certificate to the store and update an IIS site binding

I'm running into the following and after feeling like I've exhausted various avenues of research on Google and Stack Overflow I decided to just ask my own question about it.
I'm trying to generate a personal certificate (using BouncyCastle) based on a CA certificate that I already have and own. After generating the certificate, placing it in the 'My' store, I then attempt to update my IIS website's SSL binding to use this new certificate.
What I'm noticing is that the updates to the IIS website (using ServerManager) are not throwing exception, yet when I go to the IIS Manager console I notice the website's binding has no SSL certificate selected. When I attempt to select the certificate that I created (shows up fine as a viable option) I get the following error message:
A specified logon session does not exist. It may already have been terminated. (Exception from HRESULT: 0x80070520)
As a test I exported my generated certificate (with the private key) and reinstalled it via the wizard and then once again tried setting up the binding (via IIS Manager) which worked.
Because of this behavior I assumed it was an issue with how I was generating or adding the certificate to the store. I was hoping someone may have some idea of what the issue I'm having may be. The following are the relevant functions (I believe) used in creating the certificate, adding it to the store, and updating the website's binding programmatically:
Main function the generates that get the CA certificate private key, generates the personal self-signed certificate, and updates the sites binding:
public static bool GenerateServerCertificate(
X509Certificate2 CACert,
bool addToStore,
DateTime validUntil)
{
try
{
if (CACert.PrivateKey == null)
{
throw new CryptoException("Authority certificate has no private key");
}
var key = DotNetUtilities.GetKeyPair(CACert.PrivateKey).Private;
byte[] certHash = GenerateCertificateBasedOnCAPrivateKey(
addToStore,
key,
validUntil);
using (ServerManager manager = new ServerManager())
{
Site site = manager.Sites.Where(q => q.Name == "My Site").FirstOrDefault();
if (site == null)
{
return false;
}
foreach (Binding binding in site.Bindings)
{
if (binding.Protocol == "https")
{
binding.CertificateHash = certHash;
binding.CertificateStoreName = "MY";
}
}
manager.CommitChanges();
}
}
catch(Exception ex)
{
LOG.Error("Error generating certitifcate", ex);
return false;
}
return true;
}
Generating the certificate based on the CA private key:
public static byte[] GenerateCertificateBasedOnCAPrivateKey(
bool addToStore,
AsymmetricKeyParameter issuerPrivKey,
DateTime validUntil,
int keyStrength = 2048)
{
string subjectName = $"CN={CertSubjectName}";
// Generating Random Numbers
CryptoApiRandomGenerator randomGenerator = new CryptoApiRandomGenerator();
SecureRandom random = new SecureRandom(randomGenerator);
ISignatureFactory signatureFactory = new Asn1SignatureFactory("SHA512WITHRSA", issuerPrivKey, random);
// The Certificate Generator
X509V3CertificateGenerator certificateGenerator = new X509V3CertificateGenerator();
certificateGenerator.AddExtension(
X509Extensions.ExtendedKeyUsage,
true,
new ExtendedKeyUsage((new List<DerObjectIdentifier> { new DerObjectIdentifier("1.3.6.1.5.5.7.3.1") })));
// Serial Number
BigInteger serialNumber = BigIntegers.CreateRandomInRange(BigInteger.One, BigInteger.ValueOf(Int64.MaxValue), random);
certificateGenerator.SetSerialNumber(serialNumber);
// Issuer and Subject Name
X509Name subjectDN = new X509Name(subjectName);
X509Name issuerDN = new X509Name(CACertificateName);
certificateGenerator.SetIssuerDN(issuerDN);
certificateGenerator.SetSubjectDN(subjectDN);
// Valid For
DateTime notBefore = DateTime.UtcNow.Date;
DateTime notAfter = validUntil > notBefore ? validUntil : notBefore.AddYears(1);
certificateGenerator.SetNotBefore(notBefore);
certificateGenerator.SetNotAfter(notAfter);
// Subject Public Key
AsymmetricCipherKeyPair subjectKeyPair;
var keyGenerationParameters = new KeyGenerationParameters(random, keyStrength);
var keyPairGenerator = new RsaKeyPairGenerator();
keyPairGenerator.Init(keyGenerationParameters);
subjectKeyPair = keyPairGenerator.GenerateKeyPair();
certificateGenerator.SetPublicKey(subjectKeyPair.Public);
// Generating the Certificate
Org.BouncyCastle.X509.X509Certificate certificate = certificateGenerator.Generate(signatureFactory);
// correcponding private key
PrivateKeyInfo info = PrivateKeyInfoFactory.CreatePrivateKeyInfo(subjectKeyPair.Private);
// merge into X509Certificate2
X509Certificate2 x509 = new X509Certificate2(certificate.GetEncoded());
Asn1Sequence seq = (Asn1Sequence)Asn1Object.FromByteArray(info.ParsePrivateKey().GetDerEncoded());
if (seq.Count != 9)
{
throw new PemException("Malformed sequence in RSA private key");
}
RsaPrivateKeyStructure rsa = RsaPrivateKeyStructure.GetInstance(seq);
RsaPrivateCrtKeyParameters rsaparams = new RsaPrivateCrtKeyParameters(
rsa.Modulus,
rsa.PublicExponent,
rsa.PrivateExponent,
rsa.Prime1,
rsa.Prime2,
rsa.Exponent1,
rsa.Exponent2,
rsa.Coefficient);
x509.PrivateKey = DotNetUtilities.ToRSA(rsaparams);
if (addToStore)
{
// Add certificate to the Personal store
AddCertToStore(x509, StoreName.My, StoreLocation.LocalMachine, "Certificate Friendly Name");
}
return x509.GetCertHash();
}
Adding the certificate to the store:
private static void AddCertToStore(X509Certificate2 cert, StoreName storeName, StoreLocation storeLocation, string friendlyName)
{
X509Store store = new X509Store(storeName, storeLocation);
try
{
store.Open(OpenFlags.ReadWrite);
store.Add(cert);
if (!string.IsNullOrWhiteSpace(friendlyName)) {
var certs = store.Certificates.Find(X509FindType.FindBySubjectDistinguishedName, cert.Subject, true);
if (certs.Count > 0)
{
certs[0].FriendlyName = friendlyName;
}
}
}
finally
{
store.Close();
}
}
Just a final note, I have tried a few things from what I've seen on various sites in regards to that error (doesn't seem very clear what the issue is):
This works on a different box (my personal development machine) but I hit these snags on a server machine (running Windows Server 2012 R2)
The IIS Help dialog informs me the machine is running IIS 8.5
Verified the validity generated certificate and the CA certificate with CertUtil.exe
Verified the generated certificate and the CA certificate had a private key that could be found
Verified administrators (and eventually even my logged in account) had access to where the private key file for both the CA certificate and the generated certificate.
Any ideas what my issue could be?
Update:
I was able to get some results by doing the following:
Export my certificate to a file programmatically by doing File.WriteAllBytes(filePath, cert.Export(X509ContentType.Pkcs12, password));
Then I import this certificate file to the store by doing:
var cert = new X509Certificate2(certFilePath, certPassword, X509KeyStorageFlags.Exportable | X509KeyStorageFlags.MachineKeySet | X509KeyStorageFlags.PersistKeySet);
// My original AddCertToStore function
AddCertToStore(cert, StoreName.My, StoreLocation.LocalMachine, "Friendly Name");
Finally, I set the binding as I was doing earlier:
using (ServerManager manager = new ServerManager())
{
Site site = manager.Sites.Where(q => q.Name == "My Site").FirstOrDefault();
if (site == null)
{
return false;
}
foreach (Binding binding in site.Bindings)
{
if (binding.Protocol == "https")
{
binding.CertificateHash = certHash;
binding.CertificateStoreName = "MY";
}
}
manager.CommitChanges();
}
Doing it this way works, but I don't see why I would have export the certificate to a file, THEN load it into a X509Certificate2 object, add to the store, and finally set up the binding.

The ToRSA method most likely creates an ephemeral RSA key, so when the references are all gone the key gets deleted. Exporting the ephemeral structure into a PFX then re-importing it with PersistKeySet is one way to turn it into a persisted key. Others exist, but that one is one of the less convoluted ones.
You don't actually have to write it to a file, though.
byte[] pkcs12Blob = cert.Export(X509ContentType.Pkcs12, password);
ver certWithPersistedKey = new X509Certificate2(pkcs12Blob, password, allTheFlagsYouAlreadySet);
There are also other subtleties going on, like setting the PrivateKey property has different behaviors for a cert instance that was loaded from a store and one which was loaded from bytes... the PFX/PKCS#12 export/import works around all of those.

For us, it was related to an invalid certificate. We went to IIS >> Server Certificates and exported the certificate from there.
The certificate was correctly bound to IIS site after that.

CMS signing in .NET with certificate chain not in local trusted certificate store

I have X509 certificates that are stored on the network. I can read the chain from remote windows certificate store. I need to sign some data and include chain to the signature to make it possible to validate it later.
The problem is that I can't find a way to put certificate chain to the CsmSigner. I have read that it takes certificate from constructor parameter and tries to build a chain with X509Chain.Build. It ignores Certificates list values and fails (obviously) because no certificate can be found in the local Windows cert store.
Please find below my test code (that works only if certificates were saved locally to the windows cert store)
protected byte[] SignWithSystem(byte[] data, X509Certificate2 cert, X509Certificate[] chain)
{
ContentInfo contentInfo = new ContentInfo(data);
SignedCms signedCms = new SignedCms(contentInfo, true);
CmsSigner cmsSigner = new CmsSigner(cert);
cmsSigner.DigestAlgorithm = new Oid("2.16.840.1.101.3.4.2.1"); //sha256
cmsSigner.IncludeOption = X509IncludeOption.WholeChain;
if (chain != null)
{
//adding cert chain to signer
cmsSigner.Certificates.AddRange(chain);
signedCms.Certificates.AddRange(chain);
}
signedCms.ComputeSignature(cmsSigner); //fails here with System.Security.Cryptography.CryptographicException : A certificate chain could not be built to a trusted root authority.
byte[] signedPkcs = signedCms.Encode();
return signedPkcs;
}
Is there any way to make it work without uploading certificates to the local store? Should I use any alternative signer?
I can try to upload certificates to the store but the problems are that
I have to add and remove certificates (permissions have to be granted)
There are several processes that applies signature so cross-process synchronization have to be added.
This is not that I'd like to do.

Example CMS Signing with BouncyCastle for .NET
You could use the BouncyCastle crypto library for .NET, which contains its own X509 certificate and CMS signing machinery. A lot of the examples and documentation on the web are for Java, as BouncyCastle was a Java library first. I've used the answer to this Stackoverflow question as a starting point for the certificate and key loading, and added the CMS signing. You may have to tweak parameters to produce the results you want for your use case.
I've made the signing function look approximately like yours, but note the private key is a separate parameter now.
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using Org.BouncyCastle.Cms;
using Org.BouncyCastle.Pkcs;
using Org.BouncyCastle.X509;
using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.X509.Store;
class Program
{
protected static byte[] SignWithSystem(byte[] data, AsymmetricKeyParameter key, X509Certificate cert, X509Certificate[] chain)
{
var generator = new CmsSignedDataGenerator();
// Add signing key
generator.AddSigner(
key,
cert,
"2.16.840.1.101.3.4.2.1"); // SHA256 digest ID
var storeCerts = new List<X509Certificate>();
storeCerts.Add(cert); // NOTE: Adding end certificate too
storeCerts.AddRange(chain); // I'm assuming the chain collection doesn't contain the end certificate already
// Construct a store from the collection of certificates and add to generator
var storeParams = new X509CollectionStoreParameters(storeCerts);
var certStore = X509StoreFactory.Create("CERTIFICATE/COLLECTION", storeParams);
generator.AddCertificates(certStore);
// Generate the signature
var signedData = generator.Generate(
new CmsProcessableByteArray(data),
false); // encapsulate = false for detached signature
return signedData.GetEncoded();
}
static void Main(string[] args)
{
try
{
// Load end certificate and signing key
AsymmetricKeyParameter key;
var signerCert = ReadCertFromFile(#"C:\Temp\David.p12", "pin", out key);
// Read CA cert
var caCert = ReadCertFromFile(#"C:\Temp\CA.cer");
var certChain = new X509Certificate[] { caCert };
var result = SignWithSystem(
Guid.NewGuid().ToByteArray(), // Any old data for sake of example
key,
signerCert,
certChain);
File.WriteAllBytes(#"C:\Temp\Signature.data", result);
}
catch (Exception ex)
{
Console.WriteLine("Failed : " + ex.ToString());
Console.ReadKey();
}
}
public static X509Certificate ReadCertFromFile(string strCertificatePath)
{
// Create file stream object to read certificate
using (var keyStream = new FileStream(strCertificatePath, FileMode.Open, FileAccess.Read))
{
var parser = new X509CertificateParser();
return parser.ReadCertificate(keyStream);
}
}
// This reads a certificate from a file.
// Thanks to: http://blog.softwarecodehelp.com/2009/06/23/CodeForRetrievePublicKeyFromCertificateAndEncryptUsingCertificatePublicKeyForBothJavaC.aspx
public static X509Certificate ReadCertFromFile(string strCertificatePath, string strCertificatePassword, out AsymmetricKeyParameter key)
{
key = null;
// Create file stream object to read certificate
using (var keyStream = new FileStream(strCertificatePath, FileMode.Open, FileAccess.Read))
{
// Read certificate using BouncyCastle component
var inputKeyStore = new Pkcs12Store();
inputKeyStore.Load(keyStream, strCertificatePassword.ToCharArray());
var keyAlias = inputKeyStore.Aliases.Cast<string>().FirstOrDefault(n => inputKeyStore.IsKeyEntry(n));
// Read Key from Aliases
if (keyAlias == null)
throw new NotImplementedException("Alias");
key = inputKeyStore.GetKey(keyAlias).Key;
//Read certificate into 509 format
return (X509Certificate)inputKeyStore.GetCertificate(keyAlias).Certificate;
}
}
}
.NET CMS (Quick-fix with rest of chain omitted from signature)
I can reproduce your problem with a certificate whose root is not in the trusted certificate store, and confirm that adding the certificate chain to the cmsSigner/signedCms Certificates collection does not avoid the A certificate chain could not be built to a trusted root authority error.
You can sign successfully by setting cmsSigner.IncludeOption = X509IncludeOption.EndCertOnly;
However, if you do this, you will not get the rest of the chain in the signature. This probably isn't what you want.
As an aside, in your example you are using X509Certificate for the array of certificates in the chain, but passing them to an X509Certificate2Collection (note the "2" in there). X509Certificate2 derives from X509Certificate, but if its not actually an X509Certificate2 that you put in one of those collections, you'll get a cast error if something iterates over the collection (you don't get an error when adding a certificate of the wrong type unfortunately, because X509Certificate2Collection also derives from X509CertificateCollection and inherits its add methods).

Adding sample code that creates detached PKCS7 signature using BouncyCastle (thanks to softwariness) without Certificate store.
It uses .net X509Certificate2 instances as input parameter. First certificate in collection have to be linked with private key to sign data.
Also I'd like to note that it is not possible to read private key associated with certificate from remote Windows cert store using .net X509Certificate2.PrivateKey property. By default private key is not loaded with certificate using X509Store(#"\\remotemachine\MY", StoreLocation.LocalMachine) and when X509Certificate2.PrivateKey property is accessed on local machine it fails with error "Keyset does not exist".
public void SignWithBouncyCastle(Collection<X509Certificate2> netCertificates)
{
// first cert have to be linked with private key
var signCert = netCertificates[0];
var Cert = Org.BouncyCastle.Security.DotNetUtilities.FromX509Certificate(signCert);
var data = Encoding.ASCII.GetBytes(Cert.SubjectDN.ToString());
var bcCertificates = netCertificates.Select(_ => Org.BouncyCastle.Security.DotNetUtilities.FromX509Certificate(_)).ToList();
var x509Certs = X509StoreFactory.Create("Certificate/Collection", new X509CollectionStoreParameters(bcCertificates));
var msg = new CmsProcessableByteArray(data);
var gen = new CmsSignedDataGenerator();
var privateKey = Org.BouncyCastle.Security.DotNetUtilities.GetKeyPair(signCert.PrivateKey).Private;
gen.AddSigner(privateKey, Cert, CmsSignedDataGenerator.DigestSha256);
gen.AddCertificates(x509Certs);
var signature = gen.Generate(msg, false).GetEncoded();
Trace.TraceInformation("signed");
CheckSignature(data, signature);
Trace.TraceInformation("checked");
try
{
CheckSignature(new byte[100], signature);
}
catch (CryptographicException cex)
{
Trace.TraceInformation("signature was checked for modified data '{0}'", cex.Message);
}
}
void CheckSignature(byte[] data, byte[] signature)
{
var ci = new ContentInfo(data);
SignedCms signedCms = new SignedCms(ci, true);
signedCms.Decode(signature);
foreach (X509Certificate cert in signedCms.Certificates)
Trace.TraceInformation("certificate found {0}", cert.Subject);
signedCms.CheckSignature(true);
}

To be clear, I am no security or cryptography expert.. but per my knowledge, for receiver to be able to validate the signature, the root certificate in the certificate chain you used for signing, must already be a trusted root for the receiver.
If the receiver does not have the root certificate already in their store, and marked as a trusted root... then doesn't matter how you sign the data.. it will fail validation on receiver end. And this is by design.
See more at Chain of trust
Hence the only real solution to your problem I see is to ensure that the root certificate is provisioned as trusted root on both ends... Typically done by a Certificate Authority.
Enterprise application scenario - Typically in an enterprise some group in IT department (who have access to all machines in the domain - like domain admins) would enable this scenario by ensuring that every computer in the domain has root certificate owned by this group, present on every machine as trusted root, and an application developer in the enterprise typically requests a new certificate for use with their application, which has the chain of trust going back to the root certificate already distributed to all machines in the domain.
Found out contact person for this group in your company, and have them issue a certificate you can use for signature.
Internet application scenario - There are established Certificate Authorities, who own their root certificates, and work with OS vendors to ensure that their root certificates are in trusted store, as the OS vendor ships the OS to it's customers. (One reason why using pirated OS can be harmful. It's not just about viruses / malware..). And that is why when you use a certificate issued by VeriSign to sign the data, the signature can be validated by most other machines in the world.

CertificateStore's Certificates.Find() doesn't actually find the certificate

Here's my simple method:
private static X509Certificate2 GetCertificateFromStore(StoreLocation storeLocation, string certName) {
var store = new X509Store(StoreLocation.LocalMachine);
try {
store.Open(OpenFlags.ReadOnly);
var certs = store.Certificates.Find(X509FindType.FindBySubjectName, certName, true);
return certs.Count == 0 ? null : certs[0];
}
finally {
store.Close();
}
}
Debug locals show that store.Certificates has been loaded and contains two certificates — the default "localhost" one and one I've imported, so the correct store has been successfully opened.
However, the Find() method always returns an empty result, regardless of which certificate I search for and whether I use FindBySubjectName or FindByThumbprint.
Any ideas what could be wrong? It is a simple console app created for the sole purpose of learning & testing certificate loading, i.e., virtually nothing in project configuration or anywhere else is other than default.

Try false as your third parameter to the store.Certificates.Find() method - its possible your your certificates are not valid and are being excluded.