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// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
import * as hex from "../../encoding/hex.ts";
type SpongePermutator = (data: Uint8Array) => void;
/** Sponge construction option */
export interface SpongeOption {
bitsize: number;
rate: number;
dsbyte: number;
permutator: SpongePermutator;
}
export type Message = string | ArrayBuffer;
const STATE_SIZE = 200;
const TYPE_ERROR_MSG = "sha3: `data` is invalid type";
/** Sponge construction */
export class Sponge {
#option: SpongeOption;
#state: Uint8Array;
#rp: number;
#absorbing: boolean;
constructor(option: SpongeOption) {
this.#option = option;
this.#state = new Uint8Array(STATE_SIZE);
this.#rp = 0;
this.#absorbing = true;
}
/** Applies padding to internal state */
private pad(): void {
this.#state[this.#rp] ^= this.#option.dsbyte;
this.#state[this.#option.rate - 1] ^= 0x80;
}
/** Squeezes internal state */
protected squeeze(length: number): Uint8Array {
if (length < 0) {
throw new Error("sha3: length cannot be negative");
}
this.pad();
const hash = new Uint8Array(length);
let pos = 0;
while (length > 0) {
const r = length > this.#option.rate ? this.#option.rate : length;
this.#option.permutator(this.#state);
hash.set(this.#state.slice(0, r), pos);
length -= r;
pos += r;
}
this.#absorbing = false;
return hash;
}
/** Updates internal state by absorbing */
update(data: Message): this {
if (!this.#absorbing) {
throw new Error("sha3: cannot update already finalized hash");
}
let msg: Uint8Array;
if (typeof data === "string") {
msg = new TextEncoder().encode(data as string);
} else if (typeof data === "object") {
if (data instanceof ArrayBuffer || ArrayBuffer.isView(data)) {
msg = new Uint8Array(data);
} else {
throw new Error(TYPE_ERROR_MSG);
}
} else {
throw new Error(TYPE_ERROR_MSG);
}
let rp = this.#rp;
for (let i = 0; i < msg.length; ++i) {
this.#state[rp++] ^= msg[i];
if (rp >= this.#option.rate) {
this.#option.permutator(this.#state);
rp = 0;
}
}
this.#rp = rp;
return this;
}
/** Returns the hash in ArrayBuffer */
digest(): ArrayBuffer {
return this.squeeze(this.#option.bitsize >> 3);
}
/** Returns the hash in given format */
toString(format: "hex" = "hex"): string {
const rawOutput = this.squeeze(this.#option.bitsize >> 3);
switch (format) {
case "hex":
return hex.encodeToString(rawOutput);
default:
throw new Error("sha3: invalid output format");
}
}
}
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