The Get-Authentication method is failing with the new AzureAD module.

[punit-bhatt]

The Get-Authentication method is failing with the new AzureAD modules. This is because there is no AcquireToken() method available anymore.
You need to replace it with the following method, keeping everything else the same.

### <summary>
### Gets the authentication result to key vaults.
### </summary>
function Get-Authentication
{
    # Vault resources endpoint
    $ArmResource = "https://vault.azure.net"
    # Well known client ID for AzurePowerShell used to authenticate scripts to Azure AD.
    $ClientId = "1950a258-227b-4e31-a9cf-717495945fc2"
    $RedirectUri = "urn:ietf:wg:oauth:2.0:oob"
    $AuthorityUri = "https://login.windows.net/$TenantId"
    $AuthContext = New-Object "Microsoft.IdentityModel.Clients.ActiveDirectory.AuthenticationContext" `
        -ArgumentList $AuthorityUri
    $PlatformParameters = New-Object "Microsoft.IdentityModel.Clients.ActiveDirectory.PlatformParameters" `
        -ArgumentList "Auto", $null
    $AuthResult = $AuthContext.AcquireTokenAsync($ArmResource, $ClientId, $RedirectUri, $PlatformParameters)

    return $AuthResult.Result
}

This uses the method AcquireTokenAsync() which requires an additional parameter - PlatformParameters object.
This has been tested with AzureAD modules - 2.0.1.16 and 2.0.2.16

Originally posted by @punit1396 in #1 (comment)

[punit-bhatt]

This issue has been resolved and the updated Authentication mechanism can be found in the CopyKeys-Az script.