force cipher suite for PowerShell session without changing system settings

Adam Aronow 6 Reputation points

Is there a .NET/PowerShell equivalent to the -cipher switch in OpenSSL? That is, to attempt an HTTPS connection using a particular cipher suite without changing the cipher order in all of Windows?

For instance, the following command will succeed against a system with Diffie-Hellman key exchange enabled, but will fail otherwise:
openssl s_client -connect -cipher "DHE"

The PowerShell script below will connect at the strongest negotiated cipher, so when run against a host that supports both DiffieHellman and ECDH_Ephem key exchange, it will always show the latter, unless I first remove all cipher suites except TLS_DHE ones using Disable-TlsCipherSuite. However I don't want to do that, since that impacts TCP connections for the entire OS. Is there a way to do it on a per-session basis?

   $remotehost = ''  
   $port = '443'  
   $protocol = 'TLS12'  
   $clientcert = $null  
   $checkrevocation = $true  
   $keyexchanges = @{  
   	0     = 'None'  
   	9216  = 'RsaSign'  
   	41984 = 'RsaKeyX'  
   	43522 = 'DiffieHellman'	  
   	44550 = 'ECDH_Ephem'  
   $tcpclient = new-object "System.Net.Sockets.TcpClient"  
   try {  
   	$tcpclient.Connect([System.String]$remotehost, [System.Int32]$port)  
   catch {"Error making TCP connection to $remotehost" + ":" + $port}  
   [System.Net.Security.SslStream]$sslstream = $null  
   try {  
   	$sslstream = new-object System.Net.Security.SslStream(  
   catch {'Error establishing SSL stream.'}  
   try {  
   		$remotehost, $clientcert, $protocol, $checkrevocation)  
   	$keyex = [int]$sslstream.KeyExchangeAlgorithm  
   	'Connection successful with key exchange algorithm: ' + $keyexchanges.$keyex  
   catch {"Connection with $protocol failed."}  
   try {  
   catch {}  
.NET Runtime
.NET Runtime
.NET: Microsoft Technologies based on the .NET software framework.Runtime: An environment required to run apps that aren't compiled to machine language.
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Windows Server PowerShell
Windows Server PowerShell
Windows Server: A family of Microsoft server operating systems that support enterprise-level management, data storage, applications, and communications.PowerShell: A family of Microsoft task automation and configuration management frameworks consisting of a command-line shell and associated scripting language.
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