.NET

macOS / Linux / Windows

# 1) No-dependency check — identify this machine first.
uname -a 2>/dev/null || true

# 2) Dependency check — prompt before installing anything.
if ! command -v dotnet >/dev/null 2>&1; then
  echo '.NET SDK/runtime was not found.'
  printf 'Install or enable .NET SDK/runtime now? [y/N] '
  read answer
  case "$answer" in
    [Yy]*) echo 'Install .NET 9+ from your OS package manager or dotnet.microsoft.com, then rerun this snippet.' ;;
    *) echo 'Skipping .NET SDK/runtime-based check.'; exit 1 ;;
  esac
fi

# 3) .NET runtime info — offline.
dotnet --info | head -8

# .NET's SslStream cannot expose the negotiated TLS named group on any
# platform. The honest local answer is to pair .NET with the system openssl
# binary (Linux/macOS) or a winget-installed openssl (Windows):
# 1) No-dependency check — identify this machine first.
uname -a 2>/dev/null || true

# 2) Dependency check — prompt before installing anything.
if ! command -v openssl >/dev/null 2>&1; then
  echo 'OpenSSL was not found. A local PQC proof needs OpenSSL 3.5+.'
  printf 'Install OpenSSL now? [y/N] '
  read answer
  case "$answer" in
    [Yy]*)
      if command -v brew >/dev/null 2>&1; then brew install openssl@3
      elif command -v apt-get >/dev/null 2>&1; then sudo apt-get update && sudo apt-get install -y openssl
      elif command -v dnf >/dev/null 2>&1; then sudo dnf install -y openssl
      elif command -v yum >/dev/null 2>&1; then sudo yum install -y openssl
      else echo 'No supported package manager found. Install OpenSSL 3.5+ and retry.'; exit 1
      fi ;;
    *) echo 'Install OpenSSL 3.5+ and retry for a local PQC proof.'; exit 1 ;;
  esac
fi

OPENSSL=openssl
if command -v brew >/dev/null 2>&1; then
  BREW_OPENSSL="$(brew --prefix openssl@3 2>/dev/null)/bin/openssl"
  [ -x "$BREW_OPENSSL" ] && OPENSSL="$BREW_OPENSSL"
fi

$OPENSSL version
if ! $OPENSSL list -tls-groups 2>/dev/null | grep -qiE 'X25519MLKEM768|MLKEM|Kyber'; then
  echo 'This OpenSSL does not advertise ML-KEM groups. Upgrade to OpenSSL 3.5+ or load oqsprovider, then retry.'
  exit 1
fi
$OPENSSL s_client -connect example.com:443 -tls1_3 -groups X25519MLKEM768   </dev/null 2>&1 | grep -E 'Negotiated TLS1\.3 group|Server Temp Key|Cipher is|alert'

.NET SDK Version: 9.0.100
Negotiated TLS1.3 group: X25519MLKEM768
New, TLSv1.3, Cipher is TLS_AES_256_GCM_SHA384

.NET SDK Version: 8.0.404
New, TLSv1.3, Cipher is TLS_AES_256_GCM_SHA384
# (no group line — server has no overlap with offered PQ group)

Track dotnet/runtime#107568 for native PQ support in SslStream. Until then SslStream is fine for transport, but cannot answer 'was PQ used?' from inside the process.