Azure key vault private.pem read using bouncy castle [on hold]

I am using a nuget package: Org.BouncyCastle, in order to sign requests with SHA256withRSA. I have the "private.pem" file uploaded in azure key vault in secrets. I have created an Azure Key Vault and uploaded the private.pem file to the secrets.
I also have an azure active directory. Here, I created a new application registration. The application type chosen is "Web app/API". I gave it a name and the url. I can not find any clientSecret. From their documentation, I understood that the applicationId of the key in key vault is the clientId. Where can I find ClientSecret and how can I read (using Org.BouncyCastle) the "private.pem" file from the secrets in key vault?
Here is the program.cs config snippet.

SHA256withRSA

var host = WebHost.CreateDefaultBuilder(args).ConfigureAppConfiguration((ctx, config) => {
var buildConfig = config.Build();
var keyVaultConfigBuilder = new ConfigurationBuilder();

keyVaultConfigBuilder.AddAzureKeyVault(
"https://[mykey].vault.azure.net/",
buildConfig["ClientId"],
buildConfig["ClientSecret"]);

var keyVaultConfig = keyVaultConfigBuilder.Build();

config.AddConfiguration(keyVaultConfig);
})
.UseStartup<Startup>()
.UseConfiguration(Configuration);


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This is about a particular site API...
– arnt
2 days ago

1 Answer
1

Use this code To convert a pfx file to pem file. This is assuming you already have a pfx file that you're trying to convert.

As far the client secret is concerned, when you create the service principal you can find the client secret

public static X509Certificate2 ConvertFromPfxToPem(string filename)
{
using (System.IO.FileStream fs = System.IO.File.OpenRead(filename))
{
byte data = new byte[fs.Length];
byte res = null;
fs.Read(data, 0, data.Length);
if (data[0] != 0x30)
{
res = GetPem("CERTIFICATE", data);
}
X509Certificate2 x509 = new X509Certificate2(res); //Exception hit here
return x509;
}
}

private static byte GetPem(string type, byte data)
{
string pem = Encoding.UTF8.GetString(data);
string header = String.Format("-----BEGIN {0}-----", type);
string footer = String.Format("-----END {0}-----", type);
int start = pem.IndexOf(header) + header.Length;
int end = pem.IndexOf(footer, start);
string base64 = pem.Substring(start, (end - start));
base64 = base64.Replace(System.Environment.NewLine, "");
base64 = base64.Replace('-', '+');
base64 = base64.Replace('_', '/');
return Convert.FromBase64String(base64);
}

public static RSACryptoServiceProvider PemFileReader(){
RsaPrivateCrtKeyParameters keyParams;
using (var reader = File.OpenText("cert.pem")) // file containing RSA PKCS1 private key
{
keyParams = ((RsaPrivateCrtKeyParameters)new PemReader(reader).ReadObject());
}

RSAParameters rsaParameters = new RSAParameters();
rsaParameters.Modulus = keyParams.Modulus.ToByteArrayUnsigned();
rsaParameters.P = keyParams.P.ToByteArrayUnsigned();
rsaParameters.Q = keyParams.Q.ToByteArrayUnsigned();
rsaParameters.DP = keyParams.DP.ToByteArrayUnsigned();
rsaParameters.DQ = keyParams.DQ.ToByteArrayUnsigned();
rsaParameters.InverseQ = keyParams.QInv.ToByteArrayUnsigned();
rsaParameters.D = keyParams.Exponent.ToByteArrayUnsigned();
rsaParameters.Exponent = keyParams.PublicExponent.ToByteArrayUnsigned();
RSACryptoServiceProvider rsaKey = new RSACryptoServiceProvider(2048);
rsaKey.ImportParameters(rsaParameters);
return rsaKey;
}