I do not know about a PowerShell equivalent, but the following could help nevertheless, either to do the same thing manually or for someone to build the appropriate PowerShell script.
From the name and what I read,
nscurl is a wrapper around
curl that just makes sure that the server conforms to Apple requirements which are TLS 1.2 and PFS in summary
curl --verbose already gives you things like
SSL connection using TLSv1.2 / ECDHE-RSA-AES128-GCM-SHA256 so you need to display that properly and then test values against Apple full specification.
Apple full requirements (https://www.apple.com/business/docs/iOS_Security_Guide.pdf) are in fact:
- cipher selection to include only suites
that provide forward secrecy, specifically ECDHE_ECDSA_AES and
ECDHE_RSA_AES in GCM or CBC mode and RSA_AES could be added if forward secrecy is disabled on some domain
- Servers must support TLS v1.2 and forward secrecy
- certificates must be valid and signed using SHA-256 or better with a minimum 2048-bit RSA key or 256-bit elliptic curve key
So all of this is basically given by
curl --verbose or even
In fact, reading https://forums.developer.apple.com/thread/14816 you discover there is another tool provided called
TLSTool that can help, and based on its API it is clearly a wrapper around