---
title: digest.hash_crc32b
summary: null
url: >-
  https://www.fastly.com/documentation/reference/vcl/functions/cryptographic/digest-hash-crc32b
---

```
STRING digest.hash_crc32b(STRING s)
```

**Available in:** all subroutines

Returns a CRC-32b digest for the string `s`. CRC-32b is not a cryptographic
hash and is typically used as a fast error-detecting code for detecting
changes in raw data. This function is a different algorithm than `hash_crc32`
and is not likely to return the same results given the same input string.

This algorithm is known as `PKZip CRC-32 (ITU V.42)`, or more commonly `CRC-32`.

## Example

```vcl
declare local var.crc32b STRING;
set var.crc32b = digest.hash_crc32b("123456789");
# var.crc32b is now "2639f4cb"
```