Revamp signatures and break header caching on FF

Signatures, instead of consisting of the secure salt followed by the unique
value generated from the URL, are now the unique value generated from the
policy value (which will follow them) succeeded by the URL.

CSP headers are now _always_ cleared on FF, regardless of whether the page
is whitelisted or not. This means whitelisting takes effect on page reload,
rather than only when caching occurs. However, it obviously presents security
issues; refinment will occur in a future commit.

1 files changed, 13 insertions, 13 deletions

diff --git a/common/misc.js b/common/misc.js
index 825a117..036eb45 100644
--- a/common/misc.js
+++ b/common/misc.js
@@ -35,9 +35,9 @@ function gen_unique(url)
 function get_secure_salt()
 {
     if (is_chrome)
-	return browser.runtime.getManifest().key.substring(0, 36);
+	return browser.runtime.getManifest().key.substring(0, 50);
     else
-	return browser.runtime.getURL("dummy").substr(16, 36);
+	return browser.runtime.getURL("dummy");
 }
 
 /*
@@ -107,19 +107,19 @@ function is_privileged_url(url)
 /* Extract any policy present in the URL */
 function url_extract_policy(url)
 {
+    var policy_string;
     const targets = url_extract_target(url);
-    const key = '#' + get_secure_salt();
-    targets.sig = key + gen_unique(targets.base_url);
     
-    if (targets.target && targets.target.startsWith(key)) {
-	targets.signed = true;
-	if (targets.target.startsWith(targets.sig))
-	    try {
-		const policy_string = targets.target.substring(101);
-		targets.policy = JSON.parse(decodeURIComponent(policy_string));
-	    } catch (e) {
-		/* TODO what should happen here? */
-	    }
+    try {
+	policy_string = targets.target.substring(65);
+	targets.policy = JSON.parse(decodeURIComponent(policy_string));
+    } catch (e) {
+	/* TODO what should happen here? */
+    }
+    
+    if (targets.policy) {
+	const sig = gen_unique(policy_string + targets.base_url);
+	targets.valid_sig = targets.target.substring(1, 65) === sig;
     }
 
     return targets;