From 19e8087642f3bb621d5c41db7f5f144345ab3c53 Mon Sep 17 00:00:00 2001
From: Samuel Holland <samuel@sholland.org>
Date: Tue, 1 Aug 2017 01:08:56 -0500
Subject: Keypair: Create class for generating/storing keys

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 .../main/java/com/wireguard/crypto/Keypair.java    | 65 ++++++++++++++++++++++
 1 file changed, 65 insertions(+)
 create mode 100644 app/src/main/java/com/wireguard/crypto/Keypair.java

(limited to 'app/src/main/java/com/wireguard/crypto')

diff --git a/app/src/main/java/com/wireguard/crypto/Keypair.java b/app/src/main/java/com/wireguard/crypto/Keypair.java
new file mode 100644
index 00000000..ef2a4b31
--- /dev/null
+++ b/app/src/main/java/com/wireguard/crypto/Keypair.java
@@ -0,0 +1,65 @@
+package com.wireguard.crypto;
+
+import android.util.Base64;
+
+import java.security.SecureRandom;
+
+/**
+ * Represents a Curve25519 keypair as used by WireGuard.
+ */
+
+public class Keypair {
+    private static final int KEY_LENGTH = 32;
+    public static final int KEY_STRING_LENGTH = 44;
+
+    private static byte[] generatePrivateKey() {
+        final SecureRandom secureRandom = new SecureRandom();
+        final byte privateKey[] = new byte[KEY_LENGTH];
+        secureRandom.nextBytes(privateKey);
+        privateKey[0] &= 248;
+        privateKey[31] &= 127;
+        privateKey[31] |= 64;
+        return privateKey;
+    }
+
+    private static byte[] generatePublicKey(byte privateKey[]) {
+        final byte publicKey[] = new byte[KEY_LENGTH];
+        Curve25519.eval(publicKey, 0, privateKey, null);
+        return publicKey;
+    }
+
+    private static byte[] parseKey(String key) {
+        final byte keyBytes[] = Base64.decode(key, Base64.NO_WRAP);
+        if (keyBytes.length != KEY_LENGTH)
+            throw new IndexOutOfBoundsException("Key is not the correct length");
+        return keyBytes;
+    }
+
+    private static String unParseKey(byte keyBytes[]) {
+        return Base64.encodeToString(keyBytes, Base64.NO_WRAP);
+    }
+
+    private final byte privateKey[];
+    private final byte publicKey[];
+
+    public Keypair() {
+        this(generatePrivateKey());
+    }
+
+    private Keypair(byte privateKey[]) {
+        this.privateKey = privateKey;
+        publicKey = generatePublicKey(privateKey);
+    }
+
+    public Keypair(String privateKey) {
+        this(parseKey(privateKey));
+    }
+
+    public String getPrivateKey() {
+        return unParseKey(privateKey);
+    }
+
+    public String getPublicKey() {
+        return unParseKey(publicKey);
+    }
+}
-- 
cgit v1.2.3