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import { SHA1, SHA256, SHA512, encode } from "./deps.ts";
const SHA1_REGEX: RegExp = /^\s*sha-?1\s*$/i;const SHA256_REGEX: RegExp = /^\s*sha-?256\s*$/i;const SHA512_REGEX: RegExp = /^\s*sha-?512\s*$/i;
/** An interface representation of a hash algorithm implementation. */export interface Hash {  hashSize: number;  init(): Hash;  update(msg: string | Uint8Array, inputEncoding?: string): Hash;  digest(outputEncoding?: string): string | Uint8Array;}
/** A class representation of the HMAC algorithm. */export class HMAC {  readonly hashSize: number;  readonly B: number;  readonly iPad: number;  readonly oPad: number;
  private iKeyPad!: Uint8Array;  private oKeyPad!: Uint8Array;  private hasher: Hash;
  /** Creates a new HMAC instance. */  constructor(hasher: Hash, key?: string | Uint8Array) {    this.hashSize = hasher.hashSize;    this.hasher = hasher;    this.B = this.hashSize <= 32 ? 64 : 128; // according to RFC4868    this.iPad = 0x36;    this.oPad = 0x5c;
    if (key) {      this.init(key);    }  }
  /** Initializes an HMAC instance. */  init(key: string | Uint8Array, inputEncoding?: string): HMAC {    if (!key) {      key = new Uint8Array(0);    } else if (typeof key === "string") {      key = encode(key, inputEncoding) as Uint8Array;    }
    // process the key    let _key: Uint8Array = new Uint8Array(key);
    if (_key.length > this.B) {      // keys longer than blocksize are shortened      this.hasher.init();      _key = this.hasher.update(key).digest() as Uint8Array;    }
    // zeropadr    if (_key.byteLength < this.B) {      const tmp: Uint8Array = new Uint8Array(this.B);      tmp.set(_key, 0);      _key = tmp;    }
    // setup the key pads    this.iKeyPad = new Uint8Array(this.B);    this.oKeyPad = new Uint8Array(this.B);
    for (let i: number = 0; i < this.B; ++i) {      this.iKeyPad[i] = this.iPad ^ _key[i];      this.oKeyPad[i] = this.oPad ^ _key[i];    }
    // blackout key    _key.fill(0);
    // initial hash    this.hasher.init();    this.hasher.update(this.iKeyPad);
    return this;  }
  /** Update the HMAC with additional message data. */  update(    msg: string | Uint8Array = new Uint8Array(0),    inputEncoding?: string  ): HMAC {    if (typeof msg === "string") {      msg = encode(msg, inputEncoding) as Uint8Array;    }
    this.hasher.update(msg);
    return this;  }
  /** Finalize the HMAC with additional message data. */  digest(outputEncoding?: string): string | Uint8Array {    const sum1: Uint8Array = this.hasher.digest() as Uint8Array; // get sum 1
    this.hasher.init();
    return this.hasher      .update(this.oKeyPad)      .update(sum1)      .digest(outputEncoding);  }}
/** Returns a HMAC of the given msg and key using the indicated hash. */export function hmac(  hash: string,  key: string | Uint8Array,  msg?: string | Uint8Array,  inputEncoding?: string,  outputEncoding?: string): string | Uint8Array {  if (SHA1_REGEX.test(hash)) {    return new HMAC(new SHA1())      .init(key, inputEncoding)      .update(msg, inputEncoding)      .digest(outputEncoding);  } else if (SHA256_REGEX.test(hash)) {    return new HMAC(new SHA256())      .init(key, inputEncoding)      .update(msg, inputEncoding)      .digest(outputEncoding);  } else if (SHA512_REGEX.test(hash)) {    return new HMAC(new SHA512())      .init(key, inputEncoding)      .update(msg, inputEncoding)      .digest(outputEncoding);  } else {    throw new TypeError(      `Unsupported hash ${hash}. Must be one of SHA(1|256|512).`    );  }}