swc/bundler/tests/.cache/deno/aab811f3d3ff29b5d650759606c1f0209392bd63.ts

// Loaded from https://deno.land/x/god_crypto@v1.4.3/src/rsa/eme_oaep.ts


import { createHash } from "./../hash.ts";
import { mgf1 } from "./primitives.ts";
import { concat, xor, random_bytes } from "./../helper.ts";

/**
 * https://tools.ietf.org/html/rfc3447#page-10
 * 
 * @param label 
 * @param m 
 * @param k 
 * @param algorithm 
 */
export function eme_oaep_encode(
  label: Uint8Array,
  m: Uint8Array,
  k: number,
  algorithm: "sha1" | "sha256",
): Uint8Array {
  const labelHash = new Uint8Array(
    createHash(algorithm).update(label).digest(),
  );

  const ps = new Uint8Array(k - labelHash.length * 2 - 2 - m.length);
  const db = concat(labelHash, ps, [0x01], m);
  const seed = random_bytes(labelHash.length);
  const dbMask = mgf1(seed, k - labelHash.length - 1, algorithm);
  const maskedDb = xor(db, dbMask);
  const seedMask = mgf1(maskedDb, labelHash.length, algorithm);
  const maskedSeed = xor(seed, seedMask);

  return concat([0x00], maskedSeed, maskedDb);
}

export function eme_oaep_decode(
  label: Uint8Array,
  c: Uint8Array,
  k: number,
  algorithm: "sha1" | "sha256",
): Uint8Array {
  const labelHash = new Uint8Array(
    createHash(algorithm).update(label).digest(),
  );
  const maskedSeed = c.slice(1, 1 + labelHash.length);
  const maskedDb = c.slice(1 + labelHash.length);
  const seedMask = mgf1(maskedDb, labelHash.length, algorithm);
  const seed = xor(maskedSeed, seedMask);
  const dbMask = mgf1(seed, k - labelHash.length - 1, algorithm);
  const db = xor(maskedDb, dbMask);

  let ptr = labelHash.length;
  while (ptr < db.length && db[ptr] === 0) ptr++;

  return db.slice(ptr + 1);
}