This commit makes major revisions to srp.js. The SRP library now works

as a class. It is instantiated by:

var srp = new SRP(username, password, server_type, base_url);

Then it is run by calling:

srp.register() 

to register a new user, and

srp.identify()

to authenticate an existing user. By default, a successful 
identification pops up an alert reading "Authentication Successful."

To change this, set srp.success to a function. For example,

srp.success = function()
{
	alert("We win!");
}

The same is true for error messages. By default, the SRP library sends 
the message to the user as an alert box, but web designers can replace
the srp.error_message function to handle the error messages differently.

The most significant part of making the SRP library into a class is that 
it cleans up the namespace. Instead of having tons of srp_Variables, we 
only add the SRP() function to the namespace, and all other variables 
are either private, public, or protected members of that class.

A few minor edits were made to views.py to support logging in with the 
modified library. I haven't made the modifications to register yet, so 
it won't work for this revision. Oops.

1 files changed, 168 insertions, 251 deletions

diff --git a/javascript/srp.js b/javascript/srp.js
index 4fcc1c9..d998ad4 100644
--- a/javascript/srp.js
+++ b/javascript/srp.js
@@ -1,264 +1,181 @@
-var srp_N = null;
-var srp_Nstr = "115b8b692e0e045692cf280b436735c77a5a9e8a9e7ed56c965f87db5b2a2ece3";
-var srp_g = null;
-var srp_k = null;
-var srp_a = null;
-var srp_A = null;
-var srp_Astr = null;
-var srp_b = null;
-var srp_B = null;
-var srp_Bstr = null;
-var srp_I = null;
-var srp_u = null;
-var srp_p = null;
-var srp_x = null;
-var srp_S = null;
-var srp_K = null;
-var srp_M = null;
-var srp_M2 = null;
-var xhr;
-var rng;
-
-var srp_url = window.location.protocol+"//"+window.location.host+"/srp/";
-function srp_register()
+function SRP(username, password, ser, base_url)
 {
-    srp_N = new BigInteger(srp_Nstr, 16); 
-    srp_g = new BigInteger("2");
-    srp_k = new BigInteger("c46d46600d87fef149bd79b81119842f3c20241fda67d06ef412d8f6d9479c58", 16);
-    srp_I = document.getElementById("srp_username").value;
-    srp_register_salt(srp_I);
-    return false;
-};
-function srp_register_salt(I)
-{
-    if( window.XMLHttpRequest)
-        xhr = new XMLHttpRequest();
-    else if (window.ActiveXObject){
-        try{
-            xhr = new ActiveXObject("Microsoft.XMLHTTP");
-        }catch (e){}
-    }
-    else
+    var Nstr = "115b8b692e0e045692cf280b436735c77a5a9e8a9e7ed56c965f87db5b2a2ece3";
+    var N = new BigInteger(Nstr, 16);
+    var g = new BigInteger("2");
+    var k = new BigInteger("c46d46600d87fef149bd79b81119842f3c20241fda67d06ef412d8f6d9479c58", 16);
+    var rng = new SecureRandom();
+    var a = new BigInteger(32, rng);
+    var A = g.modPow(a, N);
+    var Astr = A.toString(16);
+    var B = null;
+    var Bstr = null;
+    var I = username;
+    var u = null;
+    var p = password;
+    var x = null;
+    var S = null;
+    var K = null;
+    var M = null;
+    var M2 = null;
+    var xhr = null;
+    var url = base_url;
+    var server = ser;
+    var that = this;
+    
+    function paths(str)
     {
-        srp_error_message("Ajax not supported.");
-        return;
-    }
-    if(xhr){
-        var srp_handshake_url = srp_url + "register/salt/";
-        var srp_params = "I="+I;        
-        xhr.onreadystatechange = srp_register_receive_salt;
-        xhr.open("POST", srp_handshake_url, true);
-        xhr.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
-        xhr.setRequestHeader("Content-length", srp_params.length);
-        xhr.setRequestHeader("Connection", "close");
-        
-        xhr.send(srp_params);
+        // For now, str will be the django path
+        // This function will translate for other backends.
+        if(server == "django")
+        {
+            return str;
+        }
     }
-    else
+    function ajaxRequest(full_url, params, callback)
     {
-        srp_error_message("Ajax failed.");
-    }
-};
-function srp_register_receive_salt()
-{
-    if(xhr.readyState == 4 && xhr.status == 200) {
-		if(xhr.responseXML.getElementsByTagName("salt").length > 0)
-		{
-		    s = innerxml(xhr.responseXML.getElementsByTagName("salt")[0]);
-		    srp_x = srp_calculate_x(s);
-		    v = srp_g.modPow(srp_x, srp_N);
-		    srp_register_send_verifier(v.toString(16));
-		}
-		else if(xhr.responseXML.getElementsByTagName("error").length > 0)
-		{
-		    srp_error_message(innerxml(xhr.responseXML.getElementsByTagName("error")[0]));
-		}
-	}
-};
-function srp_register_send_verifier(v)
-{
-    if( window.XMLHttpRequest)
-        xhr = new XMLHttpRequest();
-    else if (window.ActiveXObject){
-        try{
-            xhr = new ActiveXObject("Microsoft.XMLHTTP");
-        }catch (e){}
+        if(!xhr)
+        {
+            if( window.XMLHttpRequest)
+                xhr = new XMLHttpRequest();
+            else if (window.ActiveXObject){
+                try{
+                    xhr = new ActiveXObject("Microsoft.XMLHTTP");
+                }catch (e){}
+            }
+            else
+            {
+                that.error_message("Ajax not supported.");
+                return;
+            }
+        }
+        if(xhr){
+            xhr.onreadystatechange = callback;
+            xhr.open("POST", full_url, true);
+            xhr.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
+            xhr.setRequestHeader("Content-length", params.length);
+            xhr.setRequestHeader("Connection", "close");
+            
+            xhr.send(params);
+        }
+        else
+        {
+            that.error_message("Ajax failed.");
+        }        
     }
-    else
+    
+    this.register = function()
     {
-        srp_error_message("Ajax not supported.");
-        return;
-    }
-    if(xhr){
-        var srp_params = "v="+v;
-        var srp_auth_url = srp_url+ "register/user/";
-
-        xhr.onreadystatechange = srp_register_user;
-        xhr.open("POST", srp_auth_url, true);
-        xhr.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
-        xhr.setRequestHeader("Content-length", srp_params.length);
-        xhr.setRequestHeader("Connection", "close");
-        
-        xhr.send(srp_params);
-    }
-    else
+        var handshake_url = url + paths("register/salt/");
+        var params = "I="+I;
+        ajaxRequest(handshake_url, params, register_receive_salt);
+    };
+    function register_receive_salt()
     {
-        srp_error_message("Ajax failed.");
-    }
-};
-function srp_register_user()
-{
-    if(xhr.readyState == 4 && xhr.status == 200) {
-		if(xhr.responseXML.getElementsByTagName("ok").length > 0)
-		{
-		    srp_identify();
+        if(xhr.readyState == 4 && xhr.status == 200) {
+	        if(xhr.responseXML.getElementsByTagName("salt").length > 0)
+	        {
+	            var s = innerxml(xhr.responseXML.getElementsByTagName("salt")[0]);
+	            x = new BigInteger(SHA256(s + SHA256(I + ":" + p)), 16);
+	            var v = g.modPow(x, N);
+	            register_send_verifier(v.toString(16));
+	        }
+	        else if(xhr.responseXML.getElementsByTagName("error").length > 0)
+	        {
+	            that.error_message(innerxml(xhr.responseXML.getElementsByTagName("error")[0]));
+	        }
         }
-    }
-};
-function srp_identify()
-{
-    srp_N = new BigInteger(srp_Nstr, 16);
-    srp_g = new BigInteger("2");
-    srp_k = new BigInteger("c46d46600d87fef149bd79b81119842f3c20241fda67d06ef412d8f6d9479c58", 16); 
-    rng = new SecureRandom();
-    srp_a = new BigInteger(32, rng);
-    // A = g**a % N
-    srp_A = srp_g.modPow(srp_a, srp_N); 
-    srp_I = document.getElementById("srp_username").value;
-
-    srp_Astr = srp_A.toString(16);
-    // C -> S: A | I
-    srp_send_identity(srp_Astr, srp_I);
-    return false;
-};
-function srp_send_identity(Astr, I)
-{
-    if( window.XMLHttpRequest)
-        xhr = new XMLHttpRequest();
-    else if (window.ActiveXObject){
-        try{
-            xhr = new ActiveXObject("Microsoft.XMLHTTP");
-        }catch (e){}
-    }
-    else
+    };
+    function register_send_verifier(v)
     {
-        srp_error_message("Ajax not supported.");
-        return;
-    }
-    if(xhr){
-        var srp_handshake_url = srp_url + "handshake/";
-        var srp_params = "I="+I+"&A="+Astr;        
-        xhr.onreadystatechange = srp_receive_salts;
-        xhr.open("POST", srp_handshake_url, true);
-        xhr.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
-        xhr.setRequestHeader("Content-length", srp_params.length);
-        xhr.setRequestHeader("Connection", "close");
-        
-        xhr.send(srp_params);
-    }
-    else
+        var params = "v="+v;
+        var auth_url = url + paths("register/user/");
+        ajaxRequest(auth_url, params, register_user);
+    };
+    function register_user()
     {
-        srp_error_message("Ajax failed.");
-    }
-};
-function srp_receive_salts()
-{
-    if(xhr.readyState == 4 && xhr.status == 200) {
-		if(xhr.responseXML.getElementsByTagName("r").length > 0)
-		{
-		    response = xhr.responseXML.getElementsByTagName("r")[0];
-		    srp_calculations(response.getAttribute("s"), response.getAttribute("B"));
-		}
-		else if(xhr.responseXML.getElementsByTagName("error").length > 0)
-		{
-		    // This probably means A % N == 0, which means we need to generate
-	        // a new A and reidentify.
-            srp_identify();
-		}
-	}
-};
-
-function srp_calculate_x(s)
-{
-    var p = document.getElementById("srp_password").value;
-    return new BigInteger(SHA256(s + SHA256(srp_I + ":" + p)), 16);
-};
-
-function srp_calculations(s, B)
-{    
-    //S -> C: s | B
-    srp_B = new BigInteger(B, 16); 
-    srp_Bstr = B;
-    // u = H(A,B)
-    srp_u = new BigInteger(SHA256(srp_Astr + srp_Bstr), 16); 
-    // x = H(s, H(I:p))
-    srp_x = srp_calculate_x(s);
-    //S = (B - kg^x) ^ (a + ux)
-    var kgx = srp_k.multiply(srp_g.modPow(srp_x, srp_N));  
-    var aux = srp_a.add(srp_u.multiply(srp_x)); 
-    srp_S = srp_B.subtract(kgx).modPow(aux, srp_N); 
-    // M = H(H(N) xor H(g), H(I), s, A, B, K)
-    var Mstr = srp_A.toString(16) + srp_B.toString(16) + srp_S.toString(16); 
-    srp_M = SHA256(Mstr);
-    srp_send_hash(srp_M);
-    //M2 = H(A, M, K)
-    srp_M2 = SHA256(srp_A.toString(16) + srp_M + srp_S.toString(16)); 
-};
-
-
-function srp_send_hash(M)
-{
-    if( window.XMLHttpRequest)
-        xhr = new XMLHttpRequest();
-    else if (window.ActiveXObject){
-        try{
-            xhr = new ActiveXObject("Microsoft.XMLHTTP");
-        }catch (e){}
-    }
-    else
+        if(xhr.readyState == 4 && xhr.status == 200) {
+		    if(xhr.responseXML.getElementsByTagName("ok").length > 0)
+		    {
+		        this.identify();
+            }
+        }
+    };
+    
+    function innerxml (node)
     {
-        srp_error_message("Ajax not supported.");
-        return;
-    }
-    if(xhr){
-        var srp_params = "M="+M;
-        var srp_auth_url = srp_url+ "authenticate/";
-
-        xhr.onreadystatechange = srp_confirm_authentication;
-        xhr.open("POST", srp_auth_url, true);
-        xhr.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
-        xhr.setRequestHeader("Content-length", srp_params.length);
-        xhr.setRequestHeader("Connection", "close");
-        
-        xhr.send(srp_params);
-    }
-    else
+        return node.firstChild.nodeValue;
+    };
+    this.identify = function()
     {
-        srp_error_message("Ajax failed.");
-    }
-};
-
-function srp_confirm_authentication()
-{
-    if(xhr.readyState == 4 && xhr.status == 200) {
-        if(xhr.responseXML.getElementsByTagName("M").length > 0)
-		{
-		    if(innerxml(xhr.responseXML.getElementsByTagName("M")[0]) == srp_M2)
-		        srp_success();
-		    else
-		        srp_error_message("Server key does not match");
-		}
-		else if (xhr.responseXML.getElementsByTagName("error").length > 0)
-		{
-		    srp_error_message(innerxml(xhr.responseXML.getElementsByTagName("error")[0]));
-		}
-    }
-};
-function innerxml (node)
-{
-    return node.firstChild.nodeValue;
-};
-function srp_error_message(t)
-{
-    alert(t);
+        var handshake_url = url + paths("handshake/");
+        var params = "I="+I+"&A="+Astr;
+        ajaxRequest(handshake_url, params, receive_salts);
+    };
+    function receive_salts()
+    {
+        if(xhr.readyState == 4 && xhr.status == 200) {
+		    if(xhr.responseXML.getElementsByTagName("r").length > 0)
+		    {
+		        var response = xhr.responseXML.getElementsByTagName("r")[0];
+		        calculations(response.getAttribute("s"), response.getAttribute("B"));
+		    }
+		    else if(xhr.responseXML.getElementsByTagName("error").length > 0)
+		    {
+		        // This probably means A % N == 0, which means we need to generate
+	            // a new A and reidentify.
+                this.identify();
+		    }
+	    }
+    };
+    function calculations(s, ephemeral)
+    {    
+        //S -> C: s | B
+        B = new BigInteger(ephemeral, 16); 
+        Bstr = ephemeral;
+        // u = H(A,B)
+        u = new BigInteger(SHA256(Astr + Bstr), 16); 
+        // x = H(s, H(I:p))
+        x = new BigInteger(SHA256(s + SHA256(I + ":" + p)), 16);
+        //S = (B - kg^x) ^ (a + ux)
+        var kgx = k.multiply(g.modPow(x, N));  
+        var aux = a.add(u.multiply(x)); 
+        S = B.subtract(kgx).modPow(aux, N); 
+        // M = H(H(N) xor H(g), H(I), s, A, B, K)
+        var Mstr = A.toString(16) + B.toString(16) + S.toString(16); 
+        M = SHA256(Mstr);
+        send_hash(M);
+        //M2 = H(A, M, K)
+        M2 = SHA256(A.toString(16) + M + S.toString(16)); 
+    };
+    function send_hash(M)
+    {
+        var params = "M="+M;
+        var auth_url = url+paths("authenticate/");
+        ajaxRequest(auth_url, params, confirm_authentication);
+    };
+    function confirm_authentication()
+    {
+        if(xhr.readyState == 4 && xhr.status == 200) {
+            if(xhr.responseXML.getElementsByTagName("M").length > 0)
+		    {
+		        if(innerxml(xhr.responseXML.getElementsByTagName("M")[0]) == M2)
+		            that.success();
+		        else
+		            that.error_message("Server key does not match");
+		    }
+		    else if (xhr.responseXML.getElementsByTagName("error").length > 0)
+		    {
+		        that.error_message(innerxml(xhr.responseXML.getElementsByTagName("error")[0]));
+		    }
+        }
+    };
+    this.success = function()
+    {
+        alert("Authentication successful.");
+    };
+    this.error_message = function(t)
+    {
+        alert(t);
+    };
 };