---
title: cf.tls_client_auth.cert_fingerprint_sha1 · Cloudflare Ruleset Engine docs
description: The SHA-1 fingerprint of the certificate in the request.
source_url:
  html: https://a74404c8.preview.developers.cloudflare.com/ruleset-engine/rules-language/fields/reference/cf.tls_client_auth.cert_fingerprint_sha1/index.md
  md: https://a74404c8.preview.developers.cloudflare.com/ruleset-engine/rules-language/fields/reference/cf.tls_client_auth.cert_fingerprint_sha1/
---

# cf.tls\_client\_auth.cert\_fingerprint\_sha1

`cf.tls_client_auth.cert_fingerprint_sha1` String

The SHA-1 fingerprint of the certificate in the request.

This field is only filled in if the request includes a client certificate for [mTLS authentication](https://developers.cloudflare.com/ssl/client-certificates/enable-mtls/).

Example value:

```txt
"933ad5282c560ae3f482a43ecd73bc9de878a190"
```

Categories:

* Request
* mTLS
