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Diffstat (limited to 'lib/srp.js')
| -rw-r--r-- | lib/srp.js | 386 |
1 files changed, 386 insertions, 0 deletions
diff --git a/lib/srp.js b/lib/srp.js new file mode 100644 index 0000000..6af54ea --- /dev/null +++ b/lib/srp.js @@ -0,0 +1,386 @@ +function SRP() +{ + // Variables that will be used in the SRP protocol + 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); + while(A.mod(N) == 0) + { + a = new BigInteger(32, rng); + A = g.modPow(a, N); + } + var Astr = A.toString(16); + var S = null; + var K = null; + var M = null; + var M2 = null; + var url = document.getElementById("srp_url").value; + var server = document.getElementById("srp_server").value; + var that = this; + var authenticated = false; + var I = document.getElementById("srp_username").value; + var p = document.getElementById("srp_password").value; + var xhr = null; + + // *** Accessor methods *** + + // allows setting the random number A for testing + + this.calculateAndSetA = function(_a) + { + a = new BigInteger(_a, 16); + A = g.modPow(a, N); + Astr = A.toString(16); + return Astr; + }; + + // Returns the user's identity + this.getI = function() + { + return I; + }; + + // Returns the XMLHttpRequest object + this.getxhr = function() + { + return xhr; + }; + + // Returns the base URL + this.geturl = function() + { + return url; + }; + // Returns the BigInteger, g + this.getg = function() + { + return g; + }; + + // Returns the BigInteger, N + this.getN = function() + { + return N; + }; + + // Calculates the X value and return it as a BigInteger + this.calcX = function(s) + { + return new BigInteger(SHA256(s + SHA256(I + ":" + p)), 16); + }; + + // Translates the django path to PHP and ASP.NET paths + this.paths = function(str) + { + // For now, str will be the django path + // This function will translate for other backends. + if(server == "django") + { + return str; + } + }; + + // Check whether or not a variable is defined + function isdefined ( variable) + { + return (typeof(window[variable]) != "undefined"); + }; + + // *** Actions *** + + // Perform ajax requests at the specified url, with the specified parameters + // Calling back the specified function. + this.ajaxRequest = function(full_url, params, callback) + { + 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 = function() { + if(xhr.readyState == 4 && xhr.status == 200) { + callback(parseResponse()); + } + }; + xhr.open("POST", full_url, true); + xhr.setRequestHeader("Content-type", "application/x-www-form-urlencoded"); + xhr.setRequestHeader("Content-length", params.length); + xhr.send(params); + } + else + { + that.error_message("Ajax failed."); + } + }; + + function parseResponse() { + if (responseIsXML()) { + return parseXML(xhr.responseXML); + } else if (responseIsJSON()) { + return JSON.parse(xhr.responseText); + } + }; + + function responseIsXML() { + return (xhr.responseType == 'document') || + (xhr.getResponseHeader("Content-Type").indexOf('application/xml') >= 0) + } + + function responseIsJSON() { + return (xhr.responseType == 'json') || + (xhr.getResponseHeader("Content-Type").indexOf('application/json') >= 0) + } + + function parseXML(xml) { + if (xml.getElementsByTagName("r").length > 0) { + return parseAttributesOfElement(xml.getElementsByTagName("r")[0]); + } else { + return parseNodes(xml.childNodes); + } + }; + + function parseAttributesOfElement(elem) { + var response = {}; + for (var i = 0; i < elem.attributes.length; i++) { + var attrib = elem.attributes[i]; + if (attrib.specified) { + response[attrib.name] = attrib.value; + } + } + return response; + }; + + function parseNodes(nodes) { + var response = {}; + for (var i = 0; i < nodes.length; i++) { + var node = nodes[i]; + response[node.tagName] = node.textContent || true; + } + return response; + }; + + // Start the login process by identifying the user + this.identify = function() + { + var handshake_url = url + that.paths("handshake/"); + var params = "I="+I+"&A="+Astr; + that.ajaxRequest(handshake_url, params, receive_salts); + }; + + // Receive login salts from the server, start calculations + function receive_salts(response) + { + if(response.error) { + that.error_message(response.error); + } + // B = 0 will make the algorithm always succeed - refuse such a server + // answer + else if(response.B == 0) { + that.error_message("Server send random number 0 - this is not allowed"); + } + // If there is no algorithm specified, calculate M given s, B, and P + else if(!response.a) + { + calculations(response.s, response.B, p); + that.ajaxRequest(url+that.paths("authenticate/"), "M="+M, confirm_authentication); + } + // If there is an algorithm specified, start the login process + else { + upgrade(response.s, response.B, response.a, response.d); + } + }; + // Calculate S, M, and M2 + // This is the client side of the SRP specification + function calculations(s, ephemeral, pass) + { + //S -> C: s | B + var B = new BigInteger(ephemeral, 16); + var Bstr = ephemeral; + // u = H(A,B) + var u = new BigInteger(SHA256(Astr + Bstr), 16); + // x = H(s, H(I:p)) + var x = new BigInteger(SHA256(s + SHA256(I + ":" + pass)), 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); + M2 = SHA256(A.toString(16) + M + S.toString(16)); + //M2 = H(A, M, K) + }; + + // Receive M2 from the server and verify it + function confirm_authentication(response) + { + if(response.M) + { + if(response.M == M2) + { + authenticated = true; + that.success(); + } + else + that.error_message("Server key does not match"); + } + else if (response.error) + that.error_message(response.error); + }; + + // *** Upgrades *** + + // Start the process to upgrade the user's account + function upgrade(s,ephemeral,algo,dsalt) + { + // First we need to import the hash functions + import_hashes(); + + // Once the hash functions are imported, do the calculations using the hashpass as the password + function do_upgrade() + { + // If sha1 and md5 are still undefined, sleep again + if(!isdefined("SHA1") || !isdefined("MD5")) + { + window.setTimeout(do_upgrade, 10); + return; + } + if(algo == "sha1") + hashfun = SHA1; + else if(algo == "md5") + hashfun = MD5; + //alert(hashfun(dsalt+p)); + calculations(s, ephemeral, hashfun(dsalt+p)); + that.ajaxRequest(url+that.paths("upgrade/authenticate/"), "M="+M, confirm_upgrade); + }; + window.setTimeout(do_upgrade,10); + }; + + // Encrypt plaintext using slowAES + function encrypt(plaintext) + { + var key = cryptoHelpers.toNumbers(that.key()); + var byteMessage = cryptoHelpers.convertStringToByteArray(plaintext); + var iv = new Array(16); + rng.nextBytes(iv); + var paddedByteMessage = slowAES.getPaddedBlock(byteMessage, 0, byteMessage.length, slowAES.modeOfOperation.CFB); + var ciphertext = slowAES.encrypt(paddedByteMessage, slowAES.modeOfOperation.CFB, key, key.length, iv).cipher; + var retstring = cryptoHelpers.base64.encode(iv.concat(ciphertext)); + while(retstring.indexOf("+",0) > -1) + retstring = retstring.replace("+", "_"); + return retstring; + }; + + // Receive the server's M, confirming that the server has HASH(p) + // Next, send P in plaintext (this is the **only** time it should ever be sent plain text) + function confirm_upgrade(response) + { + if(response.M) + { + if(response.M == M2) + { + K = SHA256(S.toString(16)); + var auth_url = url + that.paths("upgrade/verifier/"); + that.ajaxRequest(auth_url, "p="+encrypt(p)+"&l="+p.length, confirm_verifier); + } + else + that.error_message("Server key does not match"); + } + else if (response.error) + { + that.error_message(response.error); + } + }; + + // After sending the password, check that the response is OK, then reidentify + function confirm_verifier(response) + { + K = null; + if(response.ok) + that.identify(); + else + that.error_message("Verifier could not be confirmed"); + }; + + // This loads javascript libraries. Fname is the path to the library to be imported + function import_file(fname) + { + var scriptElt = document.createElement('script'); + scriptElt.type = 'text/javascript'; + scriptElt.src = fname; + document.getElementsByTagName('head')[0].appendChild(scriptElt); + }; + // If we need SHA1 or MD5, we need to load the javascript files + function import_hashes() + { + // First check that the functions aren't already loaded + if(isdefined("SHA1") && isdefined("MD5")) return; + // Get the directory that this javascript file was loaded from + var arr=that.srpPath.split("/"); + var path = arr.slice(0, arr.length-1).join("/"); + // If this file is called srp.min.js, we will load the packed hash file + if(arr[arr.length-1] == "srp.min.js") + import_file(path+"/crypto.min.js"); + // Otherwise, this file is presumably srp.js, and we will load individual hash files + else + { + import_file(path+"/MD5.js"); + import_file(path+"/SHA1.js"); + import_file(path+"/cryptoHelpers.js"); + import_file(path+"/aes.js"); + } + } + + // This function is called when authentication is successful. + // Developers can set this to other functions in specific implementations + // and change the functionality. + this.success = function() + { + var forward_url = document.getElementById("srp_forward").value; + if(forward_url.charAt(0) != "#") + window.location = forward_url; + else + { + window.location = forward_url; + alert("Login successful."); + } + }; + // If someone wants to use the session key for encrypting traffic, they can + // access the key with this function. + this.key = function() + { + if(K == null) + if(authenticated) + { + K = SHA256(S.toString(16)); + return K; + } + else + that.error_message("User has not been authenticated."); + else + return K; + }; + + // If an error occurs, raise it as an alert. + // Developers can set this to an alternative function to handle erros differently. + this.error_message = function(t) + { + alert(t); + }; + }; + // This line is run while the document is loading + // It gets a list of all <script> tags and finds the last instance. + // The path to this script is the "src" attribute of that tag. + SRP.prototype.srpPath = document.getElementsByTagName('script')[document.getElementsByTagName('script').length-1].getAttribute("src"); |