lightsword/lib/pkcs7.ts

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/*
 * pkcs7.pad
 * https://github.com/brightcove/pkcs7
 *
 * Copyright (c) 2014 Brightcove
 * Licensed under the apache2 license.
 */

'use strict'

// Pre-define the padding values

const PADDING = [
  [16, 16, 16, 16,
   16, 16, 16, 16,
   16, 16, 16, 16,
   16, 16, 16, 16],

  [15, 15, 15, 15,
   15, 15, 15, 15,
   15, 15, 15, 15,
   15, 15, 15],

  [14, 14, 14, 14,
   14, 14, 14, 14,
   14, 14, 14, 14,
   14, 14],

  [13, 13, 13, 13,
   13, 13, 13, 13,
   13, 13, 13, 13,
   13],

  [12, 12, 12, 12,
   12, 12, 12, 12,
   12, 12, 12, 12],

  [11, 11, 11, 11,
   11, 11, 11, 11,
   11, 11, 11],

  [10, 10, 10, 10,
   10, 10, 10, 10,
   10, 10],

  [9, 9, 9, 9,
   9, 9, 9, 9,
   9],

  [8, 8, 8, 8,
   8, 8, 8, 8],

  [7, 7, 7, 7,
   7, 7, 7],

  [6, 6, 6, 6,
   6, 6],

  [5, 5, 5, 5,
   5],

  [4, 4, 4, 4],

  [3, 3, 3],

  [2, 2],

  [1]
];

export function pad(plaintext: Buffer | Uint8Array | Array<number>): Uint8Array {
  var padding = PADDING[(plaintext.length % 16) || 0],
      result = new Uint8Array(plaintext.length + padding.length);
  result.set(<ArrayLike<number>>plaintext);
  result.set(padding, plaintext.length);
  return result;
};

export function unpad(padded: Buffer | Uint8Array): Uint8Array {
  return padded.subarray(0, padded.length - padded[padded.length - 1]);
};

export const PKCS7Size = 16;