semaphore/packages/identity/src/utils.ts

import { BigNumber } from "@ethersproject/bignumber"
import { randomBytes } from "@ethersproject/random"
import { sha256 as _sha256 } from "@ethersproject/sha2"
import { toUtf8Bytes } from "@ethersproject/strings"

/**
 * Returns an hexadecimal sha256 hash of the message passed as parameter.
 * @param message The string to hash.
 * @returns The hexadecimal hash of the message.
 */
export function sha256(message: string): string {
    const hash = _sha256(toUtf8Bytes(message))

    return hash
}

/**
 * Generates a random big number.
 * @param numberOfBytes The number of bytes of the number.
 * @returns The generated random number.
 */
export function genRandomNumber(numberOfBytes = 31): bigint {
    return BigNumber.from(randomBytes(numberOfBytes)).toBigInt()
}

/**
 * Checks if a string is a JSON.
 * @param jsonString The JSON string.
 * @returns True or false.
 */
export function isJsonArray(jsonString: string) {
    try {
        return Array.isArray(JSON.parse(jsonString))
    } catch (error) {
        return false
    }
}