From 0461d76899379cb1e2ecd15456d2e6eb4fb8fa60 Mon Sep 17 00:00:00 2001
From: Azul <azul@riseup.net>
Date: Tue, 21 Aug 2012 17:59:11 +0200
Subject: moved srp-js files from lib to src

---
 src/srp_session.js | 138 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 138 insertions(+)
 create mode 100644 src/srp_session.js

(limited to 'src/srp_session.js')

diff --git a/src/srp_session.js b/src/srp_session.js
new file mode 100644
index 0000000..93bfbe5
--- /dev/null
+++ b/src/srp_session.js
@@ -0,0 +1,138 @@
+SRP.prototype.Session = function() {
+  
+  // Variables session 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 authenticated = false;
+  var I = document.getElementById("srp_username").value;
+  var pass = document.getElementById("srp_password").value;
+  var V;
+  var salt;
+
+  // *** 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;
+  };
+
+  this.getAstr = function() {
+    return Astr;
+  }
+
+  // Returns the user's identity
+  this.getI = function()
+  {
+    return I;
+  };
+
+  // some 16 byte random number
+  this.getSalt = function() {
+    salt = salt || new BigInteger(64, rng).toString(16);
+    return salt
+  }
+
+  // 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 + ":" + pass)), 16);
+  };
+
+  this.getV = function(salt)
+  {
+    V = V || this.getg().modPow(this.calcX(salt), this.getN());
+    return V;
+  }
+
+  // Calculate S, M, and M2
+  // This is the client side of the SRP specification
+  this.calculations = function(salt, ephemeral)
+  {    
+    //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(salt + 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)
+  };
+
+  this.getM = function() {
+    return M;
+  }
+
+  this.validate = function(serverM2) {
+    authenticated = (serverM2 && serverM2 == M2)
+    return authenticated;
+  }
+
+  // If someone wants to use the session key for encrypting traffic, they can
+  // access the key with this function.
+  this.key = function()
+  {
+    if(K) return K;
+    if(authenticated) {
+      K = SHA256(S.toString(16));
+      return K;
+    }
+    else
+      this.onError("User has not been authenticated.");
+  };
+
+  // Encrypt plaintext using slowAES
+  this.encrypt = function(plaintext)
+  {
+    var key = cryptoHelpers.toNumbers(session.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;
+  };
+}
-- 
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