---
page_title: sha1 function reference
description: |-
  The `sha1` function computes the SHA1 hash of a given string and encodes it
  with hexadecimal digits. Learn how to use the `sha1` function in Packer templates.
---

# `sha1` Function

`sha1` computes the SHA1 hash of a given string and encodes it with
hexadecimal digits.

The given string is first encoded as UTF-8 and then the SHA1 algorithm is applied
as defined in [RFC 3174](https://tools.ietf.org/html/rfc3174). The raw hash is
then encoded to lowercase hexadecimal digits before returning.

Collision attacks have been successfully performed against this hashing
function. Before using this function for anything security-sensitive, review
relevant literature to understand the security implications.

## Examples

```shell-session
> sha1("hello world")
2aae6c35c94fcfb415dbe95f408b9ce91ee846ed
```
