---
type: concept
title: Asymmetric Encryption
tags: [cryptography, security, pki]
related: [smime, dfn-pki-zertifikate]
created: 2026-07-01
updated: 2026-07-01
sources: ["output/rz_uni_greifswald_de_dienste_webdienste_groupware_module_email_smime_emails_vers.md"]
---

# Asymmetric Encryption

Asymmetric encryption is a cryptographic method that uses a pair of related keys: a **public key** and a **private key**.

## Mechanism in S/MIME
In the context of [[smime]] and the URZ Groupware email module:
- **Encryption**: To send an encrypted message, the sender must use the recipient's **public key** (contained within their certificate). This ensures that only the holder of the corresponding **private key** (the recipient) can decrypt and read the message.
- **Requirement**: Because of this asymmetric nature, a sender cannot encrypt an email to a recipient unless they have first acquired that recipient's public certificate (typically by receiving a signed email from them).
