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subtle/x25519.go

@@ -0,0 +1,25 @@
+package subtle
+
+import (
+	"crypto/rand"
+
+	"golang.org/x/crypto/curve25519"
+)
+
+// GeneratePrivateKeyX25519 generates a new 32-byte private key.
+func GeneratePrivateKeyX25519() ([]byte, error) {
+	privKey := make([]byte, curve25519.ScalarSize)
+	_, err := rand.Read(privKey)
+	return privKey, err
+}
+
+// ComputeSharedSecretX25519 returns the 32-byte shared key, i.e.
+// privKey * pubValue on the curve.
+func ComputeSharedSecretX25519(privKey, pubValue []byte) ([]byte, error) {
+	return curve25519.X25519(privKey, pubValue)
+}
+
+// PublicFromPrivateX25519 computes privKey's corresponding public key.
+func PublicFromPrivateX25519(privKey []byte) ([]byte, error) {
+	return ComputeSharedSecretX25519(privKey, curve25519.Basepoint)
+}