1 files changed, 80 insertions, 0 deletions
diff --git a/src/main/java/io/github/moulberry/notenoughupdates/util/MoulSigner.java b/src/main/java/io/github/moulberry/notenoughupdates/util/MoulSigner.java
new file mode 100644
index 00000000..6510bc20
--- /dev/null
+++ b/src/main/java/io/github/moulberry/notenoughupdates/util/MoulSigner.java
@@ -0,0 +1,80 @@
+/*
+ * Copyright (C) 2022 NotEnoughUpdates contributors
+ *
+ * This file is part of NotEnoughUpdates.
+ *
+ * NotEnoughUpdates is free software: you can redistribute it
+ * and/or modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation, either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * NotEnoughUpdates is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with NotEnoughUpdates. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package io.github.moulberry.notenoughupdates.util;
+
+import io.github.moulberry.notenoughupdates.NotEnoughUpdates;
+import org.apache.commons.io.IOUtils;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
+import java.security.InvalidKeyException;
+import java.security.KeyFactory;
+import java.security.NoSuchAlgorithmException;
+import java.security.PublicKey;
+import java.security.Signature;
+import java.security.SignatureException;
+import java.security.spec.InvalidKeySpecException;
+import java.security.spec.X509EncodedKeySpec;
+
+public class MoulSigner {
+	private MoulSigner() {}
+
+	static PublicKey publicKey;
+
+	static {
+		try (InputStream is = MoulSigner.class.getResourceAsStream("/moulberry.key")) {
+			byte[] publicKeyBytes = IOUtils.toByteArray(is);
+			X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(publicKeyBytes);
+			publicKey = KeyFactory.getInstance("RSA").generatePublic(x509EncodedKeySpec);
+		} catch (IOException | NullPointerException | NoSuchAlgorithmException | InvalidKeySpecException e) {
+			NotEnoughUpdates.LOGGER.error("Cannot initialize MoulSigner", e);
+		}
+	}
+
+	public static boolean verifySignature(byte[] data, byte[] signatureBytes) {
+		if (Boolean.getBoolean("neu.noverifysignature")) return true;
+		if (publicKey == null) {
+			NotEnoughUpdates.LOGGER.warn("MoulSigner could not be initialized, will fail this request");
+			return false;
+		}
+		try {
+			Signature signature = Signature.getInstance("SHA256withRSA");
+			signature.initVerify(publicKey);
+			signature.update(data);
+			return signature.verify(signatureBytes);
+		} catch (NoSuchAlgorithmException | InvalidKeyException | SignatureException e) {
+			NotEnoughUpdates.LOGGER.error("Error while verifying signature. Considering this as invalid signature", e);
+			return false;
+		}
+	}
+
+	public static boolean verifySignature(File file) {
+		try {
+			return verifySignature(
+				IOUtils.toByteArray(file.toURI()),
+				IOUtils.toByteArray(new File(file.getParentFile(), file.getName() + ".asc").toURI())
+			);
+		} catch (IOException e) {
+			NotEnoughUpdates.LOGGER.error("Ran into an IOException while verifying a signature", e);
+			return false;
+		}
+	}
+}