Exporting a Certificate as BASE-64 encoded .cer

Question

I am trying to export a cert without the private key as as BASE-64 encoded file, same as exporting it from windows. When exported from windows I am able to open the .cer fil

Answer 1

For those implementing something similar in .NET Core, here's the code, based on what tyranid did. Base64FormattingOptions.InsertLineBreaks doesn't exist in .NET Core, so I had to implement my own way to do line breaking.

    // Certificates content has 64 characters per lines
    private const int MaxCharactersPerLine = 64;

    /// 

    /// Export a certificate to a PEM format string
    /// 
    /// The certificate to export
    /// A PEM encoded string
    public static string ExportToPem(this X509Certificate2 cert)
    {
        var builder = new StringBuilder();
        var certContentBase64 = Convert.ToBase64String(cert.Export(X509ContentType.Cert));
        // Calculates the max number of lines this certificate will take.
        var certMaxNbrLines = Math.Ceiling((double)certContentBase64.Length / MaxCharactersPerLine);

        builder.AppendLine("-----BEGIN CERTIFICATE-----");
        for (var index = 0; index < certMaxNbrLines; index++)
        {
            var maxSubstringLength = index * MaxCharactersPerLine + MaxCharactersPerLine > certContentBase64.Length
                ? certContentBase64.Length - index * MaxCharactersPerLine
                : MaxCharactersPerLine;
            builder.AppendLine(certContentBase64.Substring(index * MaxCharactersPerLine, maxSubstringLength));
        }
        builder.AppendLine("-----END CERTIFICATE-----");

        return builder.ToString();
    }