amper5and · jerith666 · Oct 30, 2013
diff --git a/.gitignore b/.gitignore
@@ -3,4 +3,8 @@
 node_modules
 test
 .c9revisions
-index.html
+index.html
+*~
+secret-gen.js
+shares.txt
+*-share.html
diff --git a/README.md b/README.md
@@ -94,7 +94,10 @@ To use it in node.js:
 To use it in the browser, include *secrets.js* or *secrets.min.js* (minified using Google Closure Compiler)
 
 	<script src="secrets.min.js"></script>
+
+To create stand-alone HTML files that each contain one share of a secret, plus a form with an in-line copy of secrets.js to recover the secret:
 
+	make-secret-shares.sh
 
 ## API
 
@@ -232,4 +235,4 @@ secrets.js is released under the MIT License. See `LICENSE`.
 * Operate on [node.js streams](http://nodejs.org/api/stream.html)
 * [Cheater-detection](http://h.web.umkc.edu/harnl/papers/J68.pdf)
 * [Dynamic threshold](http://www1.spms.ntu.edu.sg/~ctartary/Dynamic_Threshold_INSCRYPT2006.pdf)
-* Investigate speed enhancements in polynomial evaluation and polynomial interpolation
+* Investigate speed enhancements in polynomial evaluation and polynomial interpolation
diff --git a/make-secret-shares.sh b/make-secret-shares.sh
@@ -0,0 +1,103 @@
+#!/usr/bin/env bash
+
+echo "name your secret: ";
+read name;
+
+echo "enter secret: ";
+read secret;
+
+echo "enter names of shares, separated by spaces: ";
+read shares;
+
+sharect=$(echo $shares | tr ' ' '\n' | wc -l);
+
+echo "how many of the $sharect shares ($shares) are required to recover the $name secret?";
+read threshold;
+
+#construct a js file that will generate and print the shares
+
+#stub out just enough of the browser environment
+#expected by secrets.js to get things working
+cat > secret-gen.js <<EOF
+module = { "exports" : { "init" : function(){} } };
+GLOBAL = { "console" : { "warn" : function(s){ /*print(s);*/ } } };
+secrets = {"_processShare":"foo"};
+EOF
+
+cat secrets.js >> secret-gen.js;
+echo >> secret-gen.js;
+
+cat >> secret-gen.js <<EOF
+ps = secrets._processShare
+secrets = module['exports']
+secrets._processShare = ps
+
+var pw = '$secret';
+
+// convert the secret text into a hex string
+var pwHex = secrets.str2hex(pw);
+
+// split into n shares, with given threshold
+var shares = secrets.share(pwHex, $sharect, $threshold, 512);
+
+for(var i=0;i<$sharect;i++){
+    print(shares[i]);
+}
+
+EOF
+
+js secret-gen.js > shares.txt
+
+rm -f ${name}-*-share.html
+
+for i in $(seq 1 $sharect); do
+    share=$(head -n $i shares.txt | tail -n 1);
+    sharename=$(echo $shares | tr ' ' '\n' | head -n $i | tail -n 1);
+    sharefile="${name}-${sharename}-share.html";
+
+    cat > ${sharefile} <<EOF
+<html><head><title>Share ${sharename} of ${name}</title>
+<script>
+EOF
+    cat secrets.js >> ${sharefile};
+    cat >> ${sharefile} <<EOF
+
+recoverSecret = function (){
+    shares = new Array("$share");
+    for(var i=0;i<${threshold}-1;i++){
+	shares[i+1] = document.getElementById("share-" + (i+2)).value;
+    }
+    alert(secrets.hex2str(secrets.combine(shares)));
+}
+
+</script>
+</head>
+<body>
+<h1><center>Shared Secret &quot;${name}&quot;</center></h1>
+<h2>This secret was split into ${sharect} &quot;shares&quot;.  Any ${threshold} of those can be combined to recover the secret.</h2>
+<h3>Your share (labeled &quot;${sharename}&quot;) is: <em>${share}</em></h3>
+<h3>You can send your share to someone else to help them recover the secret.</h3>
+<h3>Or, you can get shares from others and enter them below (in any order) to recover the secret yourself.</h3>
+<form action="javascript:recoverSecret()">
+EOF
+
+    for i in $(seq 2 ${threshold}); do
+	echo "<p><input id=\"share-$i\" type=\"text\" size=\"50\" name=\"share-$i\"/></p>" >> ${sharefile}
+    done;
+
+    cat >> ${sharefile} <<EOF
+<input type="submit" value="Recover Secret"/>
+</form>
+</body>
+</html>
+EOF
+
+done
+
+rm secret-gen.js shares.txt;
+
+echo;
+echo "shares generated in the following files:";
+ls ${name}-*-share.html;
+echo;
+echo "so long as $threshold of these files remain together, your secret is exposed!";