EC Public key from public key bytes extracted from azure keyvault

Question

how to get public key from bytes? for example, I have public key (generated with EC algorithm, curve "secp256r1") and its encoded bytes on java, How can I create public key from these bytes in c#?

What do you mean "public key"? Is that you want to know how to get Azure Key Vault key? — Jim Xu, Feb 17 '20 at 08:13
yes, I stored one certificate inside the azure vault and i used that certificate to sign the self created jwt-token using signasync method. I want to extract the public key from the same certificate to verify the signatures of signed token — Bikramjit singh, Feb 18 '20 at 11:34
I am using the getKeyAsync method to fetch the key from vault and I am getting the ky bundle from the vault. Inside the bundle key is in byte array so i wanted to convert the byte array to get correct key — Bikramjit singh, Mar 05 '20 at 08:15

score 0 · Accepted Answer · answered Mar 05 '20 at 08:18

There are different methods to fetch the key from the vault. I used the following for the same.

var secret = keyVaultClient.GetSecretAsync(vaultAddress, "Honeywellpkiofflinetokenprime256v1cert").GetAwaiter().GetResult();
 X509Certificate2Collection exportedCertCollection = new X509Certificate2Collection();
            exportedCertCollection.Import(Convert.FromBase64String(secret.Value));


            X509Certificate2 certFromSecret = exportedCertCollection.Cast<X509Certificate2>().Single(s => s.HasPrivateKey);
            var publickeybyte = certFromSecret.GetPublicKey();
            var publicekeybyte = certFromSecret.GetPublicKeyString();
            var PublicKeyCNG= certFromSecret.GetECDsaPublicKey();


            var privateECDsa = LoadPrivateKey(FromHexString(privateKey));
            var publiccECDsa = LoadPublicKey(FromHexString(publicKey));

now you can use the same key to verify your signed information.

EC Public key from public key bytes extracted from azure keyvault

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