crypto-helper

• crypto-helper
  • Install
  • Remarks
  • Usage
    • Encryption
    • Secret Sharing
    • Utilities

Install

Clone the repository and run:

npm i <path>/crypto --save

It can then be imported as:

var crypto = require('crypto-helper')

Remarks

Since we never work with UTF-8 strings, except for hashing, all string inputs and outputs mentioned below are hexadecimal strings.

Usage

Encryption

encrypt(key: string, plaintext: string) -> Object

• Encrypts the plaintext using the given key, both as hexadecimal strings using AES. Key length should be 128, 192, or 256 bits.
• Returns an object with two fields: iv and ciphertext, both as hexadecimal strings. iv is the initialization vector required for decryption.

decrypt(key: string, iv: string, ciphertext: string) -> string

• Returns the plaintext output of decryption, as a hexadecimal string, with the given key and IV.

Secret Sharing

These methods simply wrap the secrets.js library. See that for more details.

share(secret: string, t: int, n: int) -> [string]

• Generates n shares such that t of them are enough to reconstruct the secret. Outputs an array of hexadecimal strings.

combine(shares: [string]) -> string

• Takes an array of shares in hexadecimal form and returns their reconstruction of the secret. Does not explicitly warn if given fewer shares than the threshold.

newShare(id: int, shares: [string]) -> string

• Adds a new share with the given id. The number of shares given must match the threshold, otherwise the new share will not be valid.

Utilities

random(bits: int) -> string

• Returns random hexadecimal string of bits bits.
• It is secure, i.e. it can be used to generate keys etc.

hash(input) -> string

• Returns hexadecimal string obtained by hashing (SHA-256) the input. The input format does not matter.