Utility functions to solve the cryptopals challenges

cryptopals_utils.ts

import fs from "fs"

export enum ByteEncoding {
  Base64,
  Hex,
}

export function hexToBuff(data: string): Buffer {
  return Buffer.from(data, "hex");
}

export function B64ToBuff(data: string): Buffer {
  return Buffer.from(data, "base64");
}

export function buffTo64(data: Buffer): string {
  return data.toString("base64");
}

export function buffToHex(data: Buffer): string {
  return data.toString("hex");
}

export function fileToBuff(
  filename: string,
  encoding: ByteEncoding,
  split_lines: boolean
): Array<Buffer> {
  const data = fs.readFileSync(filename, "utf8");
  let data_lines: Array<string> = [];
  if (split_lines) {
    data_lines = data.split("\n");
  } else {
    data_lines = [data];
  }

  let output: Array<Buffer> = [];
  if (encoding === ByteEncoding.Base64) {
    output = data_lines.map((x) => B64ToBuff(x));
  } else if (encoding === ByteEncoding.Hex) {
    output = data_lines.map((x) => hexToBuff(x));
  }
  return output;
}

export function sliceBuffer(buf: Buffer, offset: number, step: number): any {
  let arr = [];
  for (let i = offset; i < buf.length; i += step) {
    arr.push(buf[i]);
  }
  return Buffer.from(arr);
}