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BrunORC

•Created by BrunORC on 10/27/2022 in #help

❔ X509 Certificate from base64 string

I am trying to transform a base64 string I receive from a previous webrequest into a x509 certificate btu all I get is a

CryptographicException: Unable to decode certificate.

CryptographicException: Unable to decode certificate.

. The public key I got in base64 is this one:

MFwwDQYJKoZIhvcNAQEBBQADSwAwSAJBALOexE7WXZM/aq8S0umcDGptu7BHSF5KNq/O5PA1jP54HzNQuSDjyd/3Fp3SOWUr6RC8nQKfYqPRXkOVce73h50CAwEAAQ==

MFwwDQYJKoZIhvcNAQEBBQADSwAwSAJBALOexE7WXZM/aq8S0umcDGptu7BHSF5KNq/O5PA1jP54HzNQuSDjyd/3Fp3SOWUr6RC8nQKfYqPRXkOVce73h50CAwEAAQ==

and I intend to later use it in an RSACryptoServiceProvider to encrypt some data. I have the same code in Java working properly and can't understand what might be wrong in the C# version. Java code from public key string into X509 cert.

final X509EncodedKeySpec keySpec = new X509EncodedKeySpec(Base64.getDecoder().decode(publicKeyString.getBytes()));

final X509EncodedKeySpec keySpec = new X509EncodedKeySpec(Base64.getDecoder().decode(publicKeyString.getBytes()));

C# version 1 from public key string into X509 cert with error:

byte[] publicKeyBytes = Convert.FromBase64String(base64publicKey);
X509Certificate2 cert = new X509Certificate2(publicKeyBytes);
return cert;

byte[] publicKeyBytes = Convert.FromBase64String(base64publicKey);
X509Certificate2 cert = new X509Certificate2(publicKeyBytes);
return cert;

C# version 2 from public key string into X509 cert with error:

byte[] publicKeyBytes = Convert.FromBase64String(base64publicKey);
X509Certificate2 cert = null;
string certFile = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString());
try {
    File.WriteAllBytes(certFile, publicKeyBytes);
    string certText = File.ReadAllText(certFile);
    cert = new X509Certificate2(certFile);
} finally {
    File.Delete(certFile);
}
return cert;

byte[] publicKeyBytes = Convert.FromBase64String(base64publicKey);
X509Certificate2 cert = null;
string certFile = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString());
try {
    File.WriteAllBytes(certFile, publicKeyBytes);
    string certText = File.ReadAllText(certFile);
    cert = new X509Certificate2(certFile);
} finally {
    File.Delete(certFile);
}
return cert;

I have tried other options, all of which failed so far.

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