Ranges-based Encryptor/Decryptor

ranges-based-encryptor-decryptor.js

function encrypt(text, key) {
  //console.log('input:', text, key);
  const ranges = [ // define ranges
    'qwertyuiop', // lower 1
    'QWERTYUIOP', // upper 1
    'asdfghjkl', // lower 2
    'ASDFGHJKL', // upper 2
    'zxcvbnm,.', // lower 3
    'ZXCVBNM<>' // upper 3
  ];
  let keys = (key < 10) ? '00' + key : (key < 100) ? '0' + key : key.toString(); // convert key to string
  //console.log('keys:', key);
  let output = '';
  for (let i = 0, max = text.length; i < max; i++) {
    // check ranges
    let rangeIndex;
    findRangeIndexLoop:
    for (let r = 0, rMax = ranges.length; r < rMax; r++) {
      if (ranges[r].indexOf(text[i]) !== -1) {
        rangeIndex = r;
        break findRangeIndexLoop;
      }
    }
    //console.log('rangeIndex:', rangeIndex);
    // encrypt
    if (rangeIndex || rangeIndex === 0) {
      const currentPosition =  ranges[rangeIndex].indexOf(text[i]);
      //console.log('currentPosition:', currentPosition);
      const keyIndex = (rangeIndex >= 0 && rangeIndex <= 1) ? 0 : (rangeIndex >= 2 && rangeIndex <= 3) ? 1 : 2;
      //console.log('keyIndex:', keyIndex, ' | keys[keyIndex]:', keys[keyIndex]);
      let newPosition = currentPosition + parseInt(keys[keyIndex]);
      //console.log('newPosition:', newPosition);
      while (newPosition > ranges[rangeIndex].length - 1) {
        newPosition -= ranges[rangeIndex].length;
        //console.log('newPosition recalculated:', newPosition);
      }
      //console.log('new letter:', ranges[rangeIndex][newPosition]);
      output += ranges[rangeIndex][newPosition];
    } else {
      // if out or range use char as is
      //console.log('new letter:', text[i]);
      output += text[i];
    }
    //console.log('===');
  }
  return output;
}

function decrypt(text, key) {
  //console.log('input:', text, key);
  const ranges = [ // define ranges
    'qwertyuiop', // lower 1
    'QWERTYUIOP', // upper 1
    'asdfghjkl', // lower 2
    'ASDFGHJKL', // upper 2
    'zxcvbnm,.', // lower 3
    'ZXCVBNM<>' // upper 3
  ];
  let keys = (key < 10) ? '00' + key : (key < 100) ? '0' + key : key.toString(); // convert key to string
  //console.log('keys:', key);
  let output = '';
  
  for (let i = 0, max = text.length; i < max; i++) {
    // check ranges
    let rangeIndex;
    findRangeIndexLoop:
    for (let r = 0, rMax = ranges.length; r < rMax; r++) {
      if (ranges[r].indexOf(text[i]) !== -1) {
        rangeIndex = r;
        break findRangeIndexLoop;
      }
    }
    //console.log('rangeIndex:', rangeIndex);
    // decrypt
    if (rangeIndex || rangeIndex === 0) {
      const currentPosition =  ranges[rangeIndex].indexOf(text[i]);
      //console.log('currentPosition:', currentPosition);
      const keyIndex = (rangeIndex >= 0 && rangeIndex <= 1) ? 0 : (rangeIndex >= 2 && rangeIndex <= 3) ? 1 : 2;
      //console.log('keyIndex:', keyIndex, '| keys[keyIndex]:', keys[keyIndex]);
      let newPosition = currentPosition - parseInt(keys[keyIndex]);
      //console.log('newPosition:', newPosition);
      while (newPosition > ranges[rangeIndex].length - 1) {
        newPosition -= ranges[rangeIndex].length;
        //console.log('newPosition recalculated:', newPosition);
      }
      while (newPosition < 0) {
        newPosition += ranges[rangeIndex].length;
        //console.log('newPosition recalculated:', newPosition);
      }
      //console.log('new letter:', ranges[rangeIndex][newPosition]);
      output += ranges[rangeIndex][newPosition];
    } else {
      // if out or range use char as is
      //console.log('new letter:', text[i]);
      output += text[i];
    }
    //console.log('===');
  }
  return output;
}

encrypt("Ball", 134); // ">fdd"
encrypt("Ball", 444); // ">gff"

decrypt(">fdd", 134); // "Ball"
decrypt(">gff", 444); // "Ball"

RangesBasedEncryptorDecryptor.markdown

Ranges-based Encryptor/Decryptor

Function encrypt encrypts arbitrary string with characters.

Function decrypt decrypts previously encrypted string with function encrypt.

Both functions accept two parameters: string and integer.

The latter is a shift index for different rows.

It is always 3 digits long, i.e. value 0 means 000, 55 means 055 etc.

First digit is a shift for the first line (for both lower and upper case, i.e. ranges[0] and ranges[1]).

Second digit is a shift for the second line (for both lower and upper case, i.e. ranges[2] and ranges[3]).

Third digit is a shift for the third line (for both lower and upper case, i.e. ranges[4] and ranges[5]).

ranges is an array, all elements of odd rows are uppercase equivalents of the respective letters from the previous row:

['qwertyuiop', // lower 1 'QWERTYUIOP', // upper 1 'asdfghjkl', // lower 2 'ASDFGHJKL', // upper 2 'zxcvbnm,.', // lower 3 'ZXCVBNM<>'] // upper 3

If letter from input does not belong to any range it is passed to output as is.

A script by V.

License.