Dienstag, 12. April 2011

JavaSCrypt - A crypt(3) implementation in JavaScript

For my Password Generator which I plan to port to JavaScript, I need to have an implementation of crypt(3) for JavaScript.

I quickly found, a source code online, buthad some problems porting it.

Searching the web a bit more I found Michael Dipperstein's page describing a bug, or better, implementation detail which hit him. Applying his changes, I got my JavaScript version running.

So here is the - straightforward - implementation of crypt(3) in JavaScript.



<html>
<head>
<script>
/*
* This program implements the
* Proposed Federal Information Processing
* Data Encryption Standard.
* See Federal Register, March 17, 1975 (40FR12134)
*
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
*
* The source is taken from
* http://google.com/codesearch/p#ZWtxA-fyzBo/UnixArchive/PDP-11/Distributions/research/Henry_Spencer_v7/v7.tar.gz%7C118goTAkg2o/usr/src/libc/gen/crypt.c
* and bug-fixed according to
* http://michael.dipperstein.com/crypt/crypt3.c
*
* permission is granted to use this code at your own will nad risk
* I don't guarantee anything.
*
* Written 2011-04-12 by Skeeve
* mail: javascrypt.v0-1.skeeve et xoxy dot net
*/

function JavaSCrypt() {

/*
* Initial permutation,
*/
const IP = [
58,50,42,34,26,18,10, 2,
60,52,44,36,28,20,12, 4,
62,54,46,38,30,22,14, 6,
64,56,48,40,32,24,16, 8,
57,49,41,33,25,17, 9, 1,
59,51,43,35,27,19,11, 3,
61,53,45,37,29,21,13, 5,
63,55,47,39,31,23,15, 7,
];

/*
* Final permutation, FP = IP^(-1)
*/
const FP = [
40, 8,48,16,56,24,64,32,
39, 7,47,15,55,23,63,31,
38, 6,46,14,54,22,62,30,
37, 5,45,13,53,21,61,29,
36, 4,44,12,52,20,60,28,
35, 3,43,11,51,19,59,27,
34, 2,42,10,50,18,58,26,
33, 1,41, 9,49,17,57,25,
];

/*
* Permuted-choice 1 from the key bits
* to yield C and D.
* Note that bits 8,16... are left out:
* They are intended for a parity check.
*/
const PC1_C = [
57,49,41,33,25,17, 9,
1,58,50,42,34,26,18,
10, 2,59,51,43,35,27,
19,11, 3,60,52,44,36,
];

const PC1_D = [
63,55,47,39,31,23,15,
7,62,54,46,38,30,22,
14, 6,61,53,45,37,29,
21,13, 5,28,20,12, 4,
];

/*
* Sequence of shifts used for the key schedule.
*/
const shifts = [
1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1,
];

/*
* Permuted-choice 2, to pick out the bits from
* the CD array that generate the key schedule.
*/
const PC2_C = [
14,17,11,24, 1, 5,
3,28,15, 6,21,10,
23,19,12, 4,26, 8,
16, 7,27,20,13, 2,
];

const PC2_D = [
41,52,31,37,47,55,
30,40,51,45,33,48,
44,49,39,56,34,53,
46,42,50,36,29,32,
];

/*
* The C and D arrays used to calculate the key schedule.
*/

var C=new Array(28);
var D=new Array(28);
/*
* The key schedule.
* Generated from the key.
*/
var KS=new Array(
new Array(48),new Array(48),new Array(48),new Array(48),
new Array(48),new Array(48),new Array(48),new Array(48),
new Array(48),new Array(48),new Array(48),new Array(48),
new Array(48),new Array(48),new Array(48),new Array(48),
new Array(48),new Array(48),new Array(48),new Array(48)
);
/*
* Set up the key schedule from the key.
*/
function setkey(key) {
/*
* First, generate C and D by permuting
* the key. The low order bit of each
* 8-bit char is not used, so C and D are only 28
* bits apiece.
*/
for (var i=0; i<28; i++) {
C[i] = key[PC1_C[i]-1];
D[i] = key[PC1_D[i]-1];
}
/*
* To generate Ki, rotate C and D according
* to schedule and pick up a permutation
* using PC2.
*/
for (var i=0; i<16; i++) {
/*
* rotate.
*/
for (var k=0; k<shifts[i]; k++) {
var t = C[0];
for (var j=0; j<28-1; j++)
C[j] = C[j+1];
C[27] = t;
t = D[0];
for (j=0; j<28-1; j++)
D[j] = D[j+1];
D[27] = t;
}
/*
* get Ki. Note C and D are concatenated.
*/
for (var j=0; j<24; j++) {
KS[i][j] = C[PC2_C[j]-1];
KS[i][j+24] = D[PC2_D[j]-28-1];
}
}
}

/*
* The E bit-selection table.
*/
var E= new Array(48);
var e= [
32, 1, 2, 3, 4, 5,
4, 5, 6, 7, 8, 9,
8, 9,10,11,12,13,
12,13,14,15,16,17,
16,17,18,19,20,21,
20,21,22,23,24,25,
24,25,26,27,28,29,
28,29,30,31,32, 1,
];

/*
* The 8 selection functions.
* For some reason, they give a 0-origin
* index, unlike everything else.
*/
const S= [
[
14, 4,13, 1, 2,15,11, 8, 3,10, 6,12, 5, 9, 0, 7,
0,15, 7, 4,14, 2,13, 1,10, 6,12,11, 9, 5, 3, 8,
4, 1,14, 8,13, 6, 2,11,15,12, 9, 7, 3,10, 5, 0,
15,12, 8, 2, 4, 9, 1, 7, 5,11, 3,14,10, 0, 6,13,
],
[
15, 1, 8,14, 6,11, 3, 4, 9, 7, 2,13,12, 0, 5,10,
3,13, 4, 7,15, 2, 8,14,12, 0, 1,10, 6, 9,11, 5,
0,14, 7,11,10, 4,13, 1, 5, 8,12, 6, 9, 3, 2,15,
13, 8,10, 1, 3,15, 4, 2,11, 6, 7,12, 0, 5,14, 9,
],
[
10, 0, 9,14, 6, 3,15, 5, 1,13,12, 7,11, 4, 2, 8,
13, 7, 0, 9, 3, 4, 6,10, 2, 8, 5,14,12,11,15, 1,
13, 6, 4, 9, 8,15, 3, 0,11, 1, 2,12, 5,10,14, 7,
1,10,13, 0, 6, 9, 8, 7, 4,15,14, 3,11, 5, 2,12,
],
[
7,13,14, 3, 0, 6, 9,10, 1, 2, 8, 5,11,12, 4,15,
13, 8,11, 5, 6,15, 0, 3, 4, 7, 2,12, 1,10,14, 9,
10, 6, 9, 0,12,11, 7,13,15, 1, 3,14, 5, 2, 8, 4,
3,15, 0, 6,10, 1,13, 8, 9, 4, 5,11,12, 7, 2,14,
],
[
2,12, 4, 1, 7,10,11, 6, 8, 5, 3,15,13, 0,14, 9,
14,11, 2,12, 4, 7,13, 1, 5, 0,15,10, 3, 9, 8, 6,
4, 2, 1,11,10,13, 7, 8,15, 9,12, 5, 6, 3, 0,14,
11, 8,12, 7, 1,14, 2,13, 6,15, 0, 9,10, 4, 5, 3,
],
[
12, 1,10,15, 9, 2, 6, 8, 0,13, 3, 4,14, 7, 5,11,
10,15, 4, 2, 7,12, 9, 5, 6, 1,13,14, 0,11, 3, 8,
9,14,15, 5, 2, 8,12, 3, 7, 0, 4,10, 1,13,11, 6,
4, 3, 2,12, 9, 5,15,10,11,14, 1, 7, 6, 0, 8,13,
],
[
4,11, 2,14,15, 0, 8,13, 3,12, 9, 7, 5,10, 6, 1,
13, 0,11, 7, 4, 9, 1,10,14, 3, 5,12, 2,15, 8, 6,
1, 4,11,13,12, 3, 7,14,10,15, 6, 8, 0, 5, 9, 2,
6,11,13, 8, 1, 4,10, 7, 9, 5, 0,15,14, 2, 3,12,
],
[
13, 2, 8, 4, 6,15,11, 1,10, 9, 3,14, 5, 0,12, 7,
1,15,13, 8,10, 3, 7, 4,12, 5, 6,11, 0,14, 9, 2,
7,11, 4, 1, 9,12,14, 2, 0, 6,10,13,15, 3, 5, 8,
2, 1,14, 7, 4,10, 8,13,15,12, 9, 0, 3, 5, 6,11,
],
];

/*
* P is a permutation on the selected combination
* of the current L and key.
*/
const P= [
16, 7,20,21,
29,12,28,17,
1,15,23,26,
5,18,31,10,
2, 8,24,14,
32,27, 3, 9,
19,13,30, 6,
22,11, 4,25,
];

/*
* The combination of the key and the input, before selection.
*/
var preS= new Array(48);

/*
* The payoff: encrypt a block.
*/

function encrypt(block, edflag) {
/*
* The current block, divided into 2 halves.
*/
var L= new Array(32);
var R= new Array(32);
var tempL= new Array(32);
var f= new Array(32);

/*
* First, permute the bits in the input
*/
for (var j=0; j<32; j++) {
L[j] = block[IP[j]-1];
R[j] = block[IP[j+32]-1];
}
/*
* Perform an encryption operation 16 times.
*/
for (var ii=0; ii<16; ii++) {
/*
* Set direction
*/
var i= (edflag>0) ? 15-ii : ii;
/*
* Save the R array,
* which will be the new L.
*/
for (var j=0; j<32; j++)
tempL[j] = R[j];
/*
* Expand R to 48 bits using the E selector;
* exclusive-or with the current key bits.
*/
for (var j=0; j<48; j++)
preS[j] = R[E[j]-1] ^ KS[i][j];
/*
* The pre-select bits are now considered
* in 8 groups of 6 bits each.
* The 8 selection functions map these
* 6-bit quantities into 4-bit quantities
* and the results permuted
* to make an f(R, K).
* The indexing into the selection functions
* is peculiar; it could be simplified by
* rewriting the tables.
*/
for (var j=0; j<8; j++) {
var t = 6*j;
var k = S[j][(preS[t+0]<<5)+
(preS[t+1]<<3)+
(preS[t+2]<<2)+
(preS[t+3]<<1)+
(preS[t+4]<<0)+
(preS[t+5]<<4)];
t = 4*j;
f[t+0] = (k>>3)&01;
f[t+1] = (k>>2)&01;
f[t+2] = (k>>1)&01;
f[t+3] = (k>>0)&01;
}
/*
* The new R is L ^ f(R, K).
* The f here has to be permuted first, though.
*/
for (var j=0; j<32; j++)
R[j] = L[j] ^ f[P[j]-1];
/*
* Finally, the new L (the original R)
* is copied back.
*/
for (var j=0; j<32; j++)
L[j] = tempL[j];
}
/*
* The output L and R are reversed.
*/
for (var j=0; j<32; j++) {
var t = L[j];
L[j] = R[j];
R[j] = t;
}
/*
* The final output
* gets the inverse permutation of the very original.
*/
for(var j = 0; j < 64; j++) {
var i = FP[j]-1;
if (i < 32)
block[j] = L[i];
else
block[j] = R[i - 32];
}
return block;
}

this.crypt= function (pw,salt) {
const charZ= "Z".charCodeAt(0);
const char9= "9".charCodeAt(0);
const charDot= ".".charCodeAt(0);
var i;
var j;
var c;
var temp;
var block= new Array(66);
var iobuf= new Array(16);
for(var i=0; i<66; i++)
block[i] = 0;
var ii;
for(i=0, ii=0; ii<pw.length && (c= pw.charCodeAt(ii)) && i<64; i++, ii++){
for(j=0; j<7; j++, i++)
block[i] = (c>>(6-j)) & 01;
}
setkey(block);

for(i=0; i<66; i++)
block[i] = 0;

for(i=0;i<48;i++)
E[i] = e[i];

for(i=0;i<2;i++){
c = salt.charCodeAt(i);
iobuf[i] = c;
if(c > charZ) c -= 6;
if(c > char9) c -= 7;
c -= charDot;
for(j=0;j<6;j++){
if(((c>>j) & 01) > 0){
temp = E[6*i+j];
E[6*i+j] = E[6*i+j+24];
E[6*i+j+24] = temp;
}
}
}

for(i=0; i<25; i++)
block= encrypt(block,0);

for(i=0; i<11; i++){
c = 0;
for(j=0; j<6; j++){
c <<= 1;
c |= block[6*i+j];
}
c += charDot;
if(c > char9) c += 7;
if(c > charZ) c += 6;
iobuf[i+2] = c;
}
iobuf[i+2] = 0;
if(iobuf[1]==0)
iobuf[1] = iobuf[0];
var result="";
for (i=0; iobuf[i]>0; ++i) {
result+= String.fromCharCode(iobuf[i]);
}
return(result);
}

}
var javascrypt= new JavaSCrypt;
</script>
</head>
<body>
<form action="javascript:false;">
Pass: <input type="text" name="pwd">
<br>
Salt: <input type="text" name="salt" maxlength="2">
<br/>
<button onclick="this.form.result.value=javascrypt.crypt(this.form.pwd.value, this.form.salt.value)">encrypt</button>
<br>
<input type="text" name="result" disabled="disabled">
</body>
</html>


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