1 files changed, 160 insertions, 0 deletions
diff --git a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/affirmation/LinkedIdentity.java b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/affirmation/LinkedIdentity.java
new file mode 100644
index 000000000..dcbaa1c1c
--- /dev/null
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/affirmation/LinkedIdentity.java
@@ -0,0 +1,160 @@
+package org.sufficientlysecure.keychain.pgp.affirmation;
+
+import org.spongycastle.bcpg.UserAttributeSubpacket;
+import org.spongycastle.util.Strings;
+import org.spongycastle.util.encoders.Hex;
+import org.sufficientlysecure.keychain.Constants;
+import org.sufficientlysecure.keychain.util.Log;
+
+import java.net.URI;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.Map.Entry;
+import java.util.Set;
+
+public class LinkedIdentity {
+
+    protected byte[] mData;
+    public final String mNonce;
+    public final URI mSubUri;
+    final Set<String> mFlags;
+    final HashMap<String,String> mParams;
+
+    protected LinkedIdentity(byte[] data, String nonce, Set<String> flags,
+                             HashMap<String, String> params, URI subUri) {
+        if ( ! nonce.matches("[0-9a-zA-Z]+")) {
+            throw new AssertionError("bug: nonce must be hexstring!");
+        }
+
+        mData = data;
+        mNonce = nonce;
+        mFlags = flags;
+        mParams = params;
+        mSubUri = subUri;
+    }
+
+    LinkedIdentity(String nonce, Set<String> flags,
+                   HashMap<String, String> params, URI subUri) {
+        this(null, nonce, flags, params, subUri);
+    }
+
+    public byte[] encode() {
+        if (mData != null) {
+            return mData;
+        }
+
+        StringBuilder b = new StringBuilder();
+        b.append("pgpid:");
+
+        // add flags
+        if (mFlags != null) {
+            boolean first = true;
+            for (String flag : mFlags) {
+                if (!first) {
+                    b.append(";");
+                }
+                first = false;
+                b.append(flag);
+            }
+        }
+
+        // add parameters
+        if (mParams != null) {
+            boolean first = true;
+            Iterator<Entry<String, String>> it = mParams.entrySet().iterator();
+            while (it.hasNext()) {
+                if (!first) {
+                    b.append(";");
+                }
+                first = false;
+                Entry<String, String> entry = it.next();
+                b.append(entry.getKey()).append("=").append(entry.getValue());
+            }
+        }
+
+        b.append("@");
+        b.append(mSubUri);
+
+        byte[] nonceBytes = Hex.decode(mNonce);
+        byte[] data = Strings.toUTF8ByteArray(b.toString());
+
+        byte[] result = new byte[data.length+12];
+        System.arraycopy(nonceBytes, 0, result, 0, 12);
+        System.arraycopy(data, 0, result, 12, result.length);
+
+        return result;
+    }
+
+    /** This method parses an affirmation from a UserAttributeSubpacket, or returns null if the
+     * subpacket can not be parsed as a valid affirmation.
+     */
+    public static LinkedIdentity parseAffirmation(UserAttributeSubpacket subpacket) {
+        if (subpacket.getType() != 100) {
+            return null;
+        }
+
+        byte[] data = subpacket.getData();
+        String nonce = Hex.toHexString(data, 0, 12);
+
+        try {
+            return parseUri(nonce, Strings.fromUTF8ByteArray(Arrays.copyOfRange(data, 12, data.length)));
+
+        } catch (IllegalArgumentException e) {
+            Log.e(Constants.TAG, "error parsing uri in (suspected) affirmation packet");
+            return null;
+        }
+    }
+
+    protected static LinkedIdentity parseUri (String nonce, String uriString) {
+        URI uri = URI.create(uriString);
+
+        if ("pgpid".equals(uri.getScheme())) {
+            Log.e(Constants.TAG, "unknown uri scheme in (suspected) affirmation packet");
+            return null;
+        }
+
+        if (!uri.isOpaque()) {
+            Log.e(Constants.TAG, "non-opaque uri in (suspected) affirmation packet");
+            return null;
+        }
+
+        String specific = uri.getSchemeSpecificPart();
+        if (!specific.contains("@")) {
+            Log.e(Constants.TAG, "unknown uri scheme in affirmation packet");
+            return null;
+        }
+
+        String[] pieces = specific.split("@", 2);
+        URI subUri = URI.create(pieces[1]);
+
+        Set<String> flags = new HashSet<String>();
+        HashMap<String,String> params = new HashMap<String,String>();
+        {
+            String[] rawParams = pieces[0].split(";");
+            for (String param : rawParams) {
+                String[] p = param.split("=", 2);
+                if (p.length == 1) {
+                    flags.add(param);
+                } else {
+                    params.put(p[0], p[1]);
+                }
+            }
+        }
+
+        return new LinkedIdentity(nonce, flags, params, subUri);
+
+    }
+
+    public static String generateNonce() {
+        // TODO make this actually random
+        // byte[] data = new byte[96];
+        // new SecureRandom().nextBytes(data);
+        // return Hex.toHexString(data);
+
+        // debug for now
+        return "0123456789ABCDEF01234567";
+    }
+
+}