Decrypt and verify the profile payment address

[signal-cli] / lib / src / main / java / org / asamk / signal / manager / util / PaymentUtils.java

diff --git a/lib/src/main/java/org/asamk/signal/manager/util/PaymentUtils.java b/lib/src/main/java/org/asamk/signal/manager/util/PaymentUtils.java
new file mode 100644 (file)
index 0000000..6c34d9c
--- /dev/null
+++ b/lib/src/main/java/org/asamk/signal/manager/util/PaymentUtils.java
@@ -0,0 +1,52 @@
+package org.asamk.signal.manager.util;
+
+import com.google.protobuf.ByteString;
+
+import org.signal.libsignal.protocol.IdentityKey;
+import org.signal.libsignal.protocol.IdentityKeyPair;
+import org.signal.libsignal.protocol.ecc.ECPrivateKey;
+import org.signal.libsignal.protocol.ecc.ECPublicKey;
+import org.whispersystems.signalservice.internal.push.SignalServiceProtos;
+
+public class PaymentUtils {
+
+    private PaymentUtils() {
+    }
+
+    /**
+     * Signs the supplied address bytes with the {@link IdentityKeyPair}'s private key and returns a proto that includes it, and it's signature.
+     */
+    public static SignalServiceProtos.PaymentAddress signPaymentsAddress(
+            byte[] publicAddressBytes, ECPrivateKey privateKey
+    ) {
+        byte[] signature = privateKey.calculateSignature(publicAddressBytes);
+
+        return SignalServiceProtos.PaymentAddress.newBuilder()
+                .setMobileCoinAddress(SignalServiceProtos.PaymentAddress.MobileCoinAddress.newBuilder()
+                        .setAddress(ByteString.copyFrom(publicAddressBytes))
+                        .setSignature(ByteString.copyFrom(signature)))
+                .build();
+    }
+
+    /**
+     * Verifies that the payments address is signed with the supplied {@link IdentityKey}.
+     * <p>
+     * Returns the validated bytes if so, otherwise returns null.
+     */
+    public static byte[] verifyPaymentsAddress(
+            SignalServiceProtos.PaymentAddress paymentAddress, ECPublicKey publicKey
+    ) {
+        if (!paymentAddress.hasMobileCoinAddress()) {
+            return null;
+        }
+
+        byte[] bytes = paymentAddress.getMobileCoinAddress().getAddress().toByteArray();
+        byte[] signature = paymentAddress.getMobileCoinAddress().getSignature().toByteArray();
+
+        if (signature.length != 64 || !publicKey.verifySignature(bytes, signature)) {
+            return null;
+        }
+
+        return bytes;
+    }
+}