---
title: cf.tls_client_auth.cert_fingerprint_sha1
description: The SHA-1 fingerprint of the mTLS client certificate.
image: https://developers.cloudflare.com/core-services-preview.png
---

> Documentation Index  
> Fetch the complete documentation index at: https://developers.cloudflare.com/ruleset-engine/llms.txt  
> Use this file to discover all available pages before exploring further. 

[Skip to content](#%5Ftop) 

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

`cf.tls_client_auth.cert_fingerprint_sha1` ` String ` 

The SHA-1 fingerprint of the mTLS client certificate.

This field defaults to `""` if the connection does not use [mTLS authentication](https://developers.cloudflare.com/ssl/client-certificates/enable-mtls/).

Example value:

```
"933ad5282c560ae3f482a43ecd73bc9de878a190"
```

Categories: 
* Request
* mTLS

```json
{"@context":"https://schema.org","@type":"TechArticle","@id":"https://developers.cloudflare.com/ruleset-engine/rules-language/fields/reference/cf.tls_client_auth.cert_fingerprint_sha1/#page","headline":"cf.tls_client_auth.cert_fingerprint_sha1 · Cloudflare Ruleset Engine docs","description":"The SHA-1 fingerprint of the mTLS client certificate.","url":"https://developers.cloudflare.com/ruleset-engine/rules-language/fields/reference/cf.tls_client_auth.cert_fingerprint_sha1/","inLanguage":"en","image":"https://developers.cloudflare.com/core-services-preview.png","publisher":{"@type":"Organization","name":"Cloudflare","url":"https://www.cloudflare.com/"},"isPartOf":{"@type":"WebSite","@id":"https://developers.cloudflare.com/#website","name":"Cloudflare Docs","url":"https://developers.cloudflare.com/"}}
{"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"/directory/","name":"Directory"}},{"@type":"ListItem","position":2,"item":{"@id":"/ruleset-engine/","name":"Ruleset Engine"}},{"@type":"ListItem","position":3,"item":{"@id":"/ruleset-engine/rules-language/","name":"Rules language"}},{"@type":"ListItem","position":4,"item":{"@id":"/ruleset-engine/rules-language/fields/","name":"Fields"}},{"@type":"ListItem","position":5,"item":{"@id":"/ruleset-engine/rules-language/fields/reference/","name":"Fields reference"}}]}
```