Method validateSlopeValue

src/Encoder/AffineCipher.js:176–195

* Validates slope (a) setting value. * @param {number} a * @return {boolean|object}

(a)

   * @return {boolean|object}
   */
  validateSlopeValue (a) {
    const alphabetSetting = this.getSetting('alphabet')
    if (!alphabetSetting.isValid()) {
      // Can't validate slope without valid alphabet setting
      return false
    }

    // The value a must be chosen such that a and m are coprime
    const m = alphabetSetting.getValue().getLength()
    if (!MathUtil.isCoprime(a, m)) {
      return {
        key: 'affineCipherFunctionInvalid',
        message:
          'The value must be chosen such that it is coprime to the size ' +
          `of the alphabet (${m})`
      }
    }

    return true
  }

  /**
   * Generates a random slope setting value.