1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
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;
};
}
|
