https://www.humanistische-vereinigung.de/typo3/sysext/rsaauth/resources/jsbn/rsa.js

1// Depends on jsbn.js and rng.js
2
3// Version 1.1: support utf-8 encoding in pkcs1pad2
4
5// convert a (hex) string to a bignum object
6function parseBigInt(str,r) {
7  return new BigInteger(str,r);
8}
9
10function linebrk(s,n) {
11  var ret = "";
12  var i = 0;
13  while(i + n < s.length) {
14    ret += s.substring(i,i+n) + "\n";
15    i += n;
16  }
17  return ret + s.substring(i,s.length);
18}
19
20function byte2Hex(b) {
21  if(b < 0x10)
22    return "0" + b.toString(16);
23  else
24    return b.toString(16);
25}
26
27// PKCS#1 (type 2, random) pad input string s to n bytes, and return a bigint
28function pkcs1pad2(s,n) {
29  if(n < s.length + 11) { // TODO: fix for utf-8
30    alert("Message too long for RSA");
31    return null;
32  }
33  var ba = new Array();
34  var i = s.length - 1;
35  while(i >= 0 && n > 0) {
36    var c = s.charCodeAt(i--);
37    if(c < 128) { // encode using utf-8
38      ba[--n] = c;
39    }
40    else if((c > 127) && (c < 2048)) {
41      ba[--n] = (c & 63) | 128;
42      ba[--n] = (c >> 6) | 192;
43    }
44    else {
45      ba[--n] = (c & 63) | 128;
46      ba[--n] = ((c >> 6) & 63) | 128;
47      ba[--n] = (c >> 12) | 224;
48    }
49  }
50  ba[--n] = 0;
51  var rng = new SecureRandom();
52  var x = new Array();
53  while(n > 2) { // random non-zero pad
54    x[0] = 0;
55    while(x[0] == 0) rng.nextBytes(x);
56    ba[--n] = x[0];
57  }
58  ba[--n] = 2;
59  ba[--n] = 0;
60  return new BigInteger(ba);
61}
62
63// "empty" RSA key constructor
64function RSAKey() {
65  this.n = null;
66  this.e = 0;
67  this.d = null;
68  this.p = null;
69  this.q = null;
70  this.dmp1 = null;
71  this.dmq1 = null;
72  this.coeff = null;
73}
74
75// Set the public key fields N and e from hex strings
76function RSASetPublic(N,E) {
77  if(N != null && E != null && N.length > 0 && E.length > 0) {
78    this.n = parseBigInt(N,16);
79    this.e = parseInt(E,16);
80  }
81  else
82    alert("Invalid RSA public key");
83}
84
85// Perform raw public operation on "x": return x^e (mod n)
86function RSADoPublic(x) {
87  return x.modPowInt(this.e, this.n);
88}
89
90// Return the PKCS#1 RSA encryption of "text" as an even-length hex string
91function RSAEncrypt(text) {
92  var m = pkcs1pad2(text,(this.n.bitLength()+7)>>3);
93  if(m == null) return null;
94  var c = this.doPublic(m);
95  if(c == null) return null;
96  var h = c.toString(16);
97  if((h.length & 1) == 0) return h; else return "0" + h;
98}
99
100// Return the PKCS#1 RSA encryption of "text" as a Base64-encoded string
101//function RSAEncryptB64(text) {
102//  var h = this.encrypt(text);
103//  if(h) return hex2b64(h); else return null;
104//}
105
106// protected
107RSAKey.prototype.doPublic = RSADoPublic;
108
109// public
110RSAKey.prototype.setPublic = RSASetPublic;
111RSAKey.prototype.encrypt = RSAEncrypt;
112//RSAKey.prototype.encrypt_b64 = RSAEncryptB64;