1 files changed, 98 insertions, 0 deletions
diff --git a/pg/src/main/java/org/spongycastle/bcpg/sig/Features.java b/pg/src/main/java/org/spongycastle/bcpg/sig/Features.java
new file mode 100644
index 00000000..02ee5790
--- /dev/null
+++ b/pg/src/main/java/org/spongycastle/bcpg/sig/Features.java
@@ -0,0 +1,98 @@
+package org.spongycastle.bcpg.sig;
+
+import org.spongycastle.bcpg.SignatureSubpacket;
+import org.spongycastle.bcpg.SignatureSubpacketTags;
+
+public class Features
+    extends SignatureSubpacket
+{
+
+    /** Identifier for the modification detection feature */
+    public static final byte FEATURE_MODIFICATION_DETECTION = 1;
+
+    private static final byte[] featureToByteArray(byte feature)
+    {
+        byte[] data = new byte[1];
+        data[0] = feature;
+        return data;
+    }
+
+    public Features(boolean critical, byte[] data)
+    {
+        super(SignatureSubpacketTags.FEATURES, critical, data);
+    }
+
+    public Features(boolean critical, byte feature)
+    {
+        super(SignatureSubpacketTags.FEATURES, critical, featureToByteArray(feature));
+    }
+
+    /**
+     * Returns if modification detection is supported.
+     */
+    public boolean supportsModificationDetection()
+    {
+        return supportsFeature(FEATURE_MODIFICATION_DETECTION);
+    }
+
+
+//    /**  Class should be immutable.
+//     * Set modification detection support.
+//     */
+//    public void setSupportsModificationDetection(boolean support)
+//    {
+//        setSupportsFeature(FEATURE_MODIFICATION_DETECTION, support);
+//    }
+
+
+    /**
+     * Returns if a particular feature is supported.
+     */
+    public boolean supportsFeature(byte feature)
+    {
+        for (int i = 0; i < data.length; i++)
+        {
+            if (data[i] == feature)
+            {
+                return true;
+            }
+        }
+        return false;
+    }
+
+
+    /**
+     * Sets support for a particular feature.
+     */
+    private void setSupportsFeature(byte feature, boolean support)
+    {
+        if (feature == 0)
+        {
+            throw new IllegalArgumentException("feature == 0");
+        }
+        if (supportsFeature(feature) != support)
+        {
+            if (support == true)
+            {
+                byte[] temp = new byte[data.length + 1];
+                System.arraycopy(data, 0, temp, 0, data.length);
+                temp[data.length] = feature;
+                data = temp;
+            }
+            else
+            {
+                for (int i = 0; i < data.length; i++)
+                {
+                    if (data[i] == feature)
+                    {
+                        byte[] temp = new byte[data.length - 1];
+                        System.arraycopy(data, 0, temp, 0, i);
+                        System.arraycopy(data, i + 1, temp, i, temp.length - i);
+                        data = temp;
+                        break;
+                    }
+                }
+            }
+        }
+    }
+}