func evpBytesToKey(password:String, keyLen:Int, ivLen:Int) -> ([UInt8], [UInt8]) {
        var m = [Data]()
        guard let passwd = password.data(using: String.Encoding.utf8) else {
            return ([], []);
        }
        while m.reduce(0, {$0 + $1.count}) < keyLen + ivLen {
            let data = m.count > 0 ? m.last! + passwd : passwd
            m.append(data.md5Digest())
        }
        let final = m.reduce(Data(), +)
        return (Array(final.bytes[0...(keyLen - 1)]), Array(final.bytes[keyLen...(keyLen + ivLen - 1)]))
    }

/*def EVP_BytesToKey(password, key_len, iv_len):
    # equivalent to OpenSSL's EVP_BytesToKey() with count 1
    # so that we make the same key and iv as nodejs version
    password = str(password)
    m = []
    i = 0
    while len(''.join(m)) < (key_len + iv_len):
        md5 = hashlib.md5()
        data = password
        if i > 0:
            data = m[i - 1] + password
        md5.update(data)
        m.append(md5.digest())
        i += 1
    ms = ''.join(m)

    key = ms[:key_len]
    iv = ms[key_len:key_len + iv_len]
    return (key, iv)*/