security_HG2021.js

// use (16 chars of) 'password' to encrypt 'plaintext'

function encrypt(plaintext, password) {
    var v = new Array(2), k = new Array(4), s = "", i;
  
    plaintext = escape(plaintext);  // use escape() so only have single-byte chars to encode
  
    // build key directly from 1st 16 chars of password
    for (var i=0; i<4; i++) 
        k[i] = Str4ToLong(password.slice(i*4,(i+1)*4));
  
    for (i=0; i<plaintext.length; i+=8) {  // encode plaintext into s in 64-bit (8 char) blocks
      v[0] = Str4ToLong(plaintext.slice(i,i+4));  // ... note this is 'electronic codebook' mode
      v[1] = Str4ToLong(plaintext.slice(i+4,i+8));
      console.log(v)
      code(v, k);
      console.log(v)
      console.log(LongToBase16(v[0]) , LongToBase16(v[1]))
    //   console.log(plaintext.slice(i,i+4),plaintext.slice(i+4,i+8))
    //   console.log(LongToBase16(v[0]),LongToBase16(v[1]))
      s += LongToBase16(v[0]) + LongToBase16(v[1]);
      //s += LongToStr4(v[0]) + LongToStr4(v[1]);

    }
  
    return escCtrlCh(s);
  }


function LongToBase16(long) {
    let base16 = '';
    for (let i = 0x3;i >= 0x0 ;i--) {
        let v = (long >> 0x8 *i & 0xff).toString(0x10);
        if (parseInt('0x' + v) <= 0xf) v = '0' + v;
        base16 += v;
    }
    return base16;
}
  

function Base16ToLong(base16) {
    let long = 0x0;
    for (let i = 0; i < 8; i += 2) {
        let v = parseInt('0x' + (base16).slice(i, i + 2));
        long = (long << 0x8) + v;
    }
    return long;
}


  // use (16 chars of) 'password' to decrypt 'ciphertext' with xTEA
  
function decrypt(ciphertext, password) {
  var v = new Array(2), k = new Array(4), s = "", i;

  for (var i=0; i<4; i++) k[i] = Str4ToLong(password.slice(i*4,(i+1)*4));

  ciphertext = unescCtrlCh(ciphertext);
  for (i=0; i<ciphertext.length; i+=16) {  // decode ciphertext into s in 64-bit (8 char) blocks
    v[0] = Base16ToLong(ciphertext.slice(i,i+8)) ;
    v[1] = Base16ToLong(ciphertext.slice(i+8,i+16)) ;
    console.log(v)
    decode(v, k);
    console.log(v)
    s += LongToStr4(v[0]) + LongToStr4(v[1]);
  }
//LongToBase16(Base16ToLong('d7a18d1f')  - 17179869184)
//LongToBase16(Base16ToLong('d7a18d1f') +4294967296)

  // strip trailing null chars resulting from filling 4-char blocks:
  s = s.replace(/\0+$/, '');

  return unescape(s);
}

  
  
  function code(v, k) {
    // Extended TEA: this is the 1997 revised version of Needham & Wheeler's algorithm
    // params: v[2] 64-bit value block; k[4] 128-bit key
    var y = v[0], z = v[1];
    var delta = 0x9E3779B9, limit = delta*32, sum = 0;
  
    while (sum != limit) {
      y += (z<<4 ^ z>>>5)+z ^ sum+k[sum & 3];
      sum += delta;
      z += (y<<4 ^ y>>>5)+y ^ sum+k[sum>>>11 & 3];
      // note: unsigned right-shift '>>>' is used in place of original '>>', due to lack
      // of 'unsigned' type declaration in JavaScript (thanks to Karsten Kraus for this)
    }
    v[0] = y; v[1] = z;
  }
  
  function decode(v, k) {
    var y = v[0], z = v[1];
    var delta = 0x9E3779B9, sum = delta*32;
  
    while (sum != 0) {
      z -= (y<<4 ^ y>>>5)+y ^ sum+k[sum>>>11 & 3];
      sum -= delta;
      y -= (z<<4 ^ z>>>5)+z ^ sum+k[sum & 3];
    }
    v[0] = y; v[1] = z;
  }
  
  
  // supporting functions
  
  function Str4ToLong(s) {  // convert 4 chars of s to a numeric long
    var v = 0;
    for (var i=0; i<4; i++) v |= s.charCodeAt(i) << i*8;
    return isNaN(v) ? 0 : v;
  }
  
  function LongToStr4(v) {  // convert a numeric long to 4 char string
    var s = String.fromCharCode(v & 0xFF, v>>8 & 0xFF, v>>16 & 0xFF, v>>24 & 0xFF);
    return s;
  }
  
  function escCtrlCh(str) {  // escape control chars which might cause problems with encrypted texts
    return str.replace(/[\0\t\n\v\f\r\xa0'"!]/g, function(c) { return '!' + c.charCodeAt(0) + '!'; });
  }
  
  function unescCtrlCh(str) {  // unescape potentially problematic nulls and control characters
    return str.replace(/!\d\d?\d?!/g, function(c) { return String.fromCharCode(c.slice(1,-1)); });
  }


// let enc = encrypt('123aaaa','123aaaa')
// console.log(enc)
// console.log(decrypt(enc,'123aaaa'))

cipher ='6fbde674819a59bfa12092565b4ca2a7a11dc670c678681daf4afb6704b82f0c'
pwd  ='1356853149054377'
plaintext = decrypt(cipher,pwd)
console.log(plaintext)