Method performEncode

src/Encoder/RailFenceCipher.js:55–82

* Performs encode on given content. * @protected * @param {Chain} content * @return {number[]|string|Uint8Array|Chain} Encoded content

(content)

   * @return {number[]|string|Uint8Array|Chain} Encoded content
   */
  performEncode (content) {
    const { key: rows, offset } = this.getSettingValues()
    const length = content.getLength()

    // Cycle after which fence matrix repeats
    const cycle = rows * 2 - 2

    // Prepare an empty string for each row
    const fenceRows = new Array(rows).fill('')

    // X -->
    //   W     I     R     E     E
    // Y  E   D S   E E   E A   C
    // |   A E   C V   D L   T N
    // V    R     O     F     O
    let x, y

    // Go through plaintext characters
    for (x = 0; x < length; x++) {
      // Calculate at what y position the fence is for the current x position
      y = rows - 1 - Math.abs(cycle / 2 - (x + offset) % cycle)
      // Append the the current plaintext character to the respective fence row
      fenceRows[y] += content.getCharAt(x)
    }

    // Glue fence rows together
    return fenceRows.join('')
  }

  /**
   * Performs decode on given content.