@hackbg/miscreant-esm/src/internals/block.dist.mjs

(ESM port) Misuse resistant symmetric encryption library providing AES-SIV (RFC 5297), AES-PMAC-SIV, and STREAM constructions

import {select} from "./constant-time.dist.mjs";
import {wipe} from "./wipe.dist.mjs";
export default class Block {
  static SIZE = 16;
  static R = 0x87;
  data;
  constructor() {
    this.data = new Uint8Array(Block.SIZE);
  }
  clear() {
    wipe(this.data);
  }
  clone() {
    const ret = new Block();
    ret.copy(this);
    return ret;
  }
  copy(other) {
    this.data.set(other.data);
  }
  dbl() {
    let carry = 0;
    for (let i = Block.SIZE - 1; i >= 0; i--) {
      const b = this.data[i] >>> 7 & 0xff;
      this.data[i] = this.data[i] << 1 | carry;
      carry = b;
    }
    this.data[Block.SIZE - 1] ^= select(carry, Block.R, 0);
    carry = 0;
  }
}