---
type: concept
title: Certificate Fingerprint Verification
tags: [security, pki, xmpp]
related: [xmpp-configuration, pidgin]
created: 2026-06-30
updated: 2026-06-30
sources: ["output/rz_uni_greifswald_de_dienste_allgemein_instant_messaging_chat_client_konfigurier.md"]
---

# Certificate Fingerprint Verification

**Certificate Fingerprint Verification** is a security technique used to verify the authenticity of a server's SSL/TLS certificate. A "fingerprint" is a unique cryptographic hash (such as SHA1 or SHA256) of the certificate.

## Purpose
The primary goal is to prevent **Man-in-the-Middle (MitM)** attacks. Even if a client accepts a certificate as "valid" (e.g., signed by a trusted CA), verifying the specific fingerprint ensures that the certificate is exactly the one issued to the intended server.

## Application in URZ XMPP
For the university's XMPP server (`jabber.uni-greifswald.de`), users are encouraged to manually check the fingerprints in their client's certificate manager.

### Valid Fingerprints (until 2026-10-17)
- **SHA1**: `02:30:12:29:f9:b2:eb:9f:8b:28:7d:6a:97:4d:f1:42:7f:7d:60:f6`
- **SHA256**: `f3:c9:c7:5a:d7:6f:29:52:44:3d:b3:a7:b3:b5:62:98:e5:05:f5:d3:a6:18:7c:c6:4c:8d:d2:6b:0c:89:79:7f`
