Initial QSfera import

Server/vendor/github.com/nats-io/nats-server/v2/server/ciphersuites.go

@@ -0,0 +1,73 @@
+// Copyright 2016-2025 The NATS Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package server
+
+import (
+	"crypto/fips140"
+	"crypto/tls"
+)
+
+func init() {
+	for _, cs := range tls.CipherSuites() {
+		cipherMap[cs.Name] = cs
+		cipherMapByID[cs.ID] = cs
+	}
+	for _, cs := range tls.InsecureCipherSuites() {
+		cipherMap[cs.Name] = cs
+		cipherMapByID[cs.ID] = cs
+	}
+}
+
+var cipherMap = map[string]*tls.CipherSuite{}
+var cipherMapByID = map[uint16]*tls.CipherSuite{}
+
+func defaultCipherSuites() []uint16 {
+	ciphers := tls.CipherSuites()
+	defaults := make([]uint16, 0, len(ciphers))
+	for _, cs := range ciphers {
+		defaults = append(defaults, cs.ID)
+	}
+	return defaults
+}
+
+// Where we maintain available curve preferences
+var curvePreferenceMap = map[string]tls.CurveID{
+	"X25519MLKEM768": tls.X25519MLKEM768,
+	"X25519":         tls.X25519,
+	"CurveP256":      tls.CurveP256,
+	"CurveP384":      tls.CurveP384,
+	"CurveP521":      tls.CurveP521,
+}
+
+// reorder to default to the highest level of security.  See:
+// https://blog.bracebin.com/achieving-perfect-ssl-labs-score-with-go
+func defaultCurvePreferences() []tls.CurveID {
+	if fips140.Enabled() {
+		// X25519 is not FIPS-approved by itself, but it is when
+		// combined with MLKEM768.
+		return []tls.CurveID{
+			tls.X25519MLKEM768, // post-quantum
+			tls.CurveP256,
+			tls.CurveP384,
+			tls.CurveP521,
+		}
+	}
+	return []tls.CurveID{
+		tls.X25519MLKEM768, // post-quantum
+		tls.X25519,         // faster than P256, arguably more secure
+		tls.CurveP256,
+		tls.CurveP384,
+		tls.CurveP521,
+	}
+}