xahau.js/packages/ripple-binary-codec/src/hashes.ts

import { HashPrefix } from './hash-prefixes'
import createHash = require('create-hash')
import { Hash256 } from './types/hash-256'
import { BytesList } from './serdes/binary-serializer'
import { Buffer } from 'buffer/'

/**
 * Class for hashing with SHA512
 * @extends BytesList So SerializedTypes can write bytes to a Sha512Half
 */
class Sha512Half extends BytesList {
  private hash = createHash('sha512')

  /**
   * Construct a new Sha512Hash and write bytes this.hash
   *
   * @param bytes bytes to write to this.hash
   * @returns the new Sha512Hash object
   */
  static put(bytes: Buffer): Sha512Half {
    return new Sha512Half().put(bytes)
  }

  /**
   * Write bytes to an existing Sha512Hash
   *
   * @param bytes bytes to write to object
   * @returns the Sha512 object
   */
  put(bytes: Buffer): Sha512Half {
    this.hash.update(bytes)
    return this
  }

  /**
   * Compute SHA512 hash and slice in half
   *
   * @returns half of a SHA512 hash
   */
  finish256(): Buffer {
    return Buffer.from(this.hash.digest().slice(0, 32))
  }

  /**
   * Constructs a Hash256 from the Sha512Half object
   *
   * @returns a Hash256 object
   */
  finish(): Hash256 {
    return new Hash256(this.finish256())
  }
}

/**
 * compute SHA512 hash of a list of bytes
 *
 * @param args zero or more arguments to hash
 * @returns the sha512half hash of the arguments.
 */
function sha512Half(...args: Buffer[]): Buffer {
  const hash = new Sha512Half()
  args.forEach((a) => hash.put(a))
  return hash.finish256()
}

/**
 * Construct a transactionID from a Serialized Transaction
 *
 * @param serialized bytes to hash
 * @returns a Hash256 object
 */
function transactionID(serialized: Buffer): Hash256 {
  return new Hash256(sha512Half(HashPrefix.transactionID, serialized))
}

export { Sha512Half, sha512Half, transactionID }