leonardodino/basic-crypto

'use strict'

var crypto = require('crypto')

function constantTimeCompare(val1, val2){
    var sentinel

    if(val1.length !== val2.length){
        return false
    }

    for(var i = 0; i < val1.length; i++){
        sentinel |= val1.charCodeAt(i) ^ val2.charCodeAt(i)
    }

    return sentinel === 0
}

var newBuffer = function(_string, _encoding){
    var string = '' + _string
    var encoding = _encoding || 'utf8'
    return new Buffer(string, encoding)
}

function truncateTo(size){
    return function(string){
        return string.substring(0, size)
    }
}

function pseudoKeyStrech(key, len){
    // Intended only as a consistent way to derive a fixed length buffer,
    // from any length string. For use on server supplyed keys only.

    // for use with user supplied passwords, use real key stretching:
    // pbkdf2, bcrypt, scrypt, etc.
    return newBuffer(truncateTo(len)(crypto.createHash('sha256').update(key).digest('base64')))
}

function fallback(v, d){
    return (typeof v === 'undefined') ? d : v
}

function isObject(thing){
    return Object.prototype.toString.call(thing) === '[object Object]'
}
function isString(thing){
    return typeof thing === 'string'
}

module.exports = {
    constantTimeCompare: constantTimeCompare,
    newBuffer: newBuffer,
    truncateTo: truncateTo,
    pseudoKeyStrech: pseudoKeyStrech,
    fallback: fallback,
    isObject: isObject,
    isString: isString,
}