Sample2_BackupAndRestoreAsync.cs

// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT License. See License.txt in the project root for
// license information.

using Azure.Identity;
using NUnit.Framework;
using System;
using System.IO;
using System.Threading;
using System.Threading.Tasks;

namespace Azure.Security.KeyVault.Keys.Samples
{
    /// <summary>
    /// Sample demonstrates how to backup and restore keys in the Key Vault
    /// using the asynchronous methods of the KeyClient.
    /// </summary>
    [Category("Live")]
    public partial class BackupAndRestore
    {
        [Test]
        [Ignore("https://github.com/Azure/azure-sdk-for-net/issues/6514")]
        public async Task BackupAndRestoreAsync()
        {
            // Environment variable with the Key Vault endpoint.
            string keyVaultUrl = Environment.GetEnvironmentVariable("AZURE_KEYVAULT_URL");
            
            // Instantiate a key client that will be used to call the service. Notice that the client is using default Azure
            // credentials. To make default credentials work, ensure that environment variables 'AZURE_CLIENT_ID',
            // 'AZURE_CLIENT_KEY' and 'AZURE_TENANT_ID' are set with the service principal credentials.
            var client = new KeyClient(new Uri(keyVaultUrl), new DefaultAzureCredential());

            // Let's create a RSA key valid for 1 year. If the key
            // already exists in the Key Vault, then a new version of the key is created.
            string rsaKeyName = $"CloudRsaKey-{Guid.NewGuid()}";
            var rsaKey = new RsaKeyCreateOptions(rsaKeyName, hsm: false, keySize: 2048)
            {
                Expires = DateTimeOffset.Now.AddYears(1)
            };

            Key storedKey = await client.CreateRsaKeyAsync(rsaKey);

            // Backups are good to have if in case keys get accidentally deleted by you.
            // For long term storage, it is ideal to write the backup to a file, disk, database, etc.
            // For the purposes of this sample, we are storing the bakup in a temporary memory area.
            byte[] byteKey = await client.BackupKeyAsync(rsaKeyName);

            using (var memoryStream = new MemoryStream())
            {
                memoryStream.Write(byteKey, 0, byteKey.Length);

                // The storage account key is no longer in use, so you delete it.
                await client.DeleteKeyAsync(rsaKeyName);

                // To ensure the key is deleted on server side.
                Assert.IsTrue(await WaitForDeletedKeyAsync(client, rsaKeyName));

                // If the keyvault is soft-delete enabled, then for permanent deletion, deleted key needs to be purged.
                await client.PurgeDeletedKeyAsync(rsaKeyName);

                // After sometime, the key is required again. We can use the backup value to restore it in the Key Vault.
                KeyBase restoredKey = await client.RestoreKeyAsync(memoryStream.ToArray());

                AssertKeysEqual((KeyBase)storedKey, restoredKey);
            }
        }

        private async Task<bool> WaitForDeletedKeyAsync(KeyClient client, string keyName)
        {
            int maxIterations = 20;
            for (int i = 0; i < maxIterations; i++)
            {
                try
                {
                    await client.GetDeletedKeyAsync(keyName);
                    return true;
                }
                catch
                {
                    await Task.Delay(5000);
                }
            }
            return false;
        }
    }
}