CRC For Node.js

To compute CRC values by providing the length of bits, expression, reflection, an initial value and a final xor value. It has many built-in CRC functions.

Requirements and Installation

Node.js 24 or later and Rust 1.88 or later are required. Install Rust with rustup and the native linker for your platform (a C compiler on Linux/macOS or the MSVC build tools on Windows).

npm install node-crc

Installation compiles the native module from source using the included Cargo.lock. There are no prebuilt platform packages. Package managers that block dependency build scripts must allow the node-crc install script; for pnpm, approve node-crc with pnpm approve-builds and rebuild it with pnpm rebuild node-crc. If npm requires script approval, use npm install-scripts approve node-crc followed by npm rebuild node-crc.

Usage

Built-in CRC Functions

To simplify the usage, there are several common versions of CRC whose computing functions are already built-in.

• crc3gsm
• crc4itu
• crc4interlaken
• crc5epc
• crc5itu
• crc5usb
• crc6cdma2000_a
• crc6cdma2000_b
• crc6darc
• crc6gsm
• crc6itu
• crc7
• crc7umts
• crc8
• crc8cdma2000
• crc8darc
• crc8dvb_s2
• crc8ebu
• crc8icode
• crc8itu
• crc8maxim
• crc8rohc
• crc8wcdma
• crc10
• crc10cdma2000
• crc10gsm
• crc11
• crc12
• crc12cdma2000
• crc12gsm
• crc13bbc
• crc14darc
• crc14gsm
• crc15can
• crc15mpt1327
• crc16
• crc16ccitt_false
• crc16aug_ccitt
• crc16buypass
• crc16cdma2000
• crc16dds_110
• crc16dect_r
• crc16dect_x
• crc16dnp
• crc16en_13757
• crc16genibus
• crc16maxim
• crc16mcrf4cc
• crc16riello
• crc16t10_dif
• crc16teledisk
• crc16tms37157
  • crc16tms13157 is still available but deprecated, because the old name has a typo.
• crc16usb
• crc_a
• crc16kermit
• crc16modbus
• crc16_x25
• crc16xmodem
• crc17can
• crc21can
• crc24
• crc24ble
• crc24flexray_a
• crc24flexray_b
• crc24lte_a
• crc24lte_b
• crc24os9
• crc30cdma
• crc32
  • It is also called crc32b in mhash.
• crc32mhash
  • mhash is a common library which has two weird versions of CRC32 called crc32 and crc32b. crc32 and crc32mhash in this module are crc32b and crc32 in mhash respectively.
• crc32bzip2
• crc32c
• crc32d
• crc32mpeg2
• crc32posix
• crc32q
• crc32jamcrc
• crc32xfer
• crc40gsm
• crc64
• crc64iso
• crc64we
• crc64jones
  • This is CRC-64/REDIS, which uses the Jones polynomial with an initial value of zero.

The input data can be a Buffer or a Uint8Array. The output is a Buffer which contains the CRC value in big-endian byte order. Its length is the number of bits of the CRC divided by 8, rounded up.

For instance,

import { crc32, crc64 } from "node-crc";

const result = crc32(Buffer.from("hello", "utf8")).toString("hex");
const result2 = crc64(new TextEncoder().encode("world")).toString("hex");

Custom CRC

You can use the crc function to compute a CRC value by providing the length of bits, expression, reflection, an initial value and a final xor value. For example, if you want to compute a CRC-24 value,

import { crc } from "node-crc";

const result = crc(
    { bits: 24, poly: 0x864cfb, initial: 0xb704ce },
    Buffer.from("hello", "utf8"),
).toString("hex");

The options are,

• bits: The width of the CRC in bits. It must be between 1 and 64.
• poly: The polynomial. When reflect is true, pass the reversed polynomial (for example, 0xEDB88320 for CRC-32).
• initial: The initial value. Pass it as it is listed in CRC catalogs, even when reflect is true. The default value is 0.
• finalXor: The value to XOR with the final result. The default value is 0.
• reflect: Whether to reflect both the input bytes and the final result. The default value is false.

The values of poly, initial and finalXor can be numbers or bigints. Use bigints if they are larger than Number.MAX_SAFE_INTEGER, such as the values of a 64-bit CRC. Invalid options throw an error.

Compute Large Data

The CRC class can compute a CRC value chunk by chunk, so you do not need to load all the data into memory. Every built-in CRC has a static method of the same name to create a CRC instance, and the constructor takes the same options as the crc function.

import { createReadStream } from "node:fs";

import { CRC } from "node-crc";

const crc32 = CRC.crc32();

for await (const chunk of createReadStream("/path/to/file")) {
    crc32.update(chunk);
}

const result = crc32.digest().toString("hex");

The update and reset methods return the instance itself, so calls can be chained. You can call digest many times, and call update again after calling digest. Call reset to compute another CRC value with the same instance.

License

MIT