Use correct sig algorithm for each digest version.

Fixes #91.

src/main/java/com/threerings/getdown/data/Application.java

@@ -1472,7 +1472,7 @@ public class Application
     protected void downloadConfigFile ()
         throws IOException
     {
-        downloadControlFile(CONFIG_FILE, false);
+        downloadControlFile(CONFIG_FILE, 0);
     }
 
     /**
@@ -1533,7 +1533,7 @@ public class Application
         throws IOException
     {
         for (int version = 1; version <= Digest.VERSION; version++) {
-            downloadControlFile(Digest.digestFile(version), true);
+            downloadControlFile(Digest.digestFile(version), version);
         }
     }
 
@@ -1548,13 +1548,17 @@ public class Application
      * validation implementation, at-will (ie, via an Applet).
      *
      * <p> TODO: Switch to PKCS #7 or CMS.
+     *
+     * @param sigVersion if {@code 0} no validation will be performed, if {@code > 0} then this
+     * should indicate the version of the digest file being validated which indicates which
+     * algorithm to use to verify the signature. See {@link Digest#VESRION}.
      */
-    protected void downloadControlFile (String path, boolean validateSignature)
+    protected void downloadControlFile (String path, int sigVersion)
         throws IOException
     {
         File target = downloadFile(path);
 
-        if (validateSignature) {
+        if (sigVersion > 0) {
             if (_signers.isEmpty()) {
                 log.info("No signers, not verifying file", "path", path);
 
@@ -1576,7 +1580,7 @@ public class Application
                     FileInputStream dataInput = null;
                     try {
                         dataInput = new FileInputStream(target);
-                        Signature sig = Signature.getInstance(Digest.SIG_ALGO);
+                        Signature sig = Signature.getInstance(Digest.sigAlgorithm(sigVersion));
                         sig.initVerify(cert);
                         while ((length = dataInput.read(buffer)) != -1) {
                             sig.update(buffer, 0, length);

src/main/java/com/threerings/getdown/data/Digest.java

@@ -29,9 +29,6 @@ public class Digest
     /** The current version of the digest protocol. */
     public static final int VERSION = 2;
 
-    /** The current algorithm used to sign digest files. */
-    public static final String SIG_ALGO = "SHA256withRSA";
-
     /**
      * Returns the name of the digest file for the specified protocol version.
      */
@@ -40,6 +37,17 @@ public class Digest
         return FILE_NAME + infix + FILE_SUFFIX;
     }
 
+    /**
+     * Returns the crypto algorithm used to sign digest files of the specified version.
+     */
+    public static String sigAlgorithm (int version) {
+        switch (version) {
+        case 1: return "SHA1withRSA";
+        case 2: return "SHA256withRSA";
+        default: throw new IllegalArgumentException("Invalid digest version " + version);
+        }
+    }
+
     /**
      * Creates a digest file at the specified location using the supplied list of resources.
      * @param version the version of the digest protocol to use.

src/main/java/com/threerings/getdown/tools/AppletParamSigner.java

@@ -43,7 +43,7 @@ public class AppletParamSigner
             store.load(new BufferedInputStream(new FileInputStream(keystore)),
                        storepass.toCharArray());
             PrivateKey key = (PrivateKey)store.getKey(alias, keypass.toCharArray());
-            Signature sig = Signature.getInstance(Digest.SIG_ALGO);
+            Signature sig = Signature.getInstance(Digest.sigAlgorithm(Digest.VERSION));
             sig.initSign(key);
             sig.update(params.getBytes());
             String signed = new String(Base64.encodeBase64(sig.sign()));

src/main/java/com/threerings/getdown/tools/Digester.java

@@ -110,7 +110,7 @@ public class Digester
             PrivateKey key = (PrivateKey)store.getKey(storeAlias, storePass.toCharArray());
 
             // sign the digest file
-            String algo = version > 1 ? Digest.SIG_ALGO : "SHA1withRSA";
+            String algo = Digest.sigAlgorithm(version);
             Signature sig = Signature.getInstance(algo);
             dataInput = new FileInputStream(inputFile);
             byte[] buffer = new byte[8192];