How to determine if a private key belongs to a public certificate

This document (7015500) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 10
SUSE Linux Enterprise Server 11
SUSE Linux Enterprise Server 12

Situation

How to determine if private key belongs to public certificate or key.
Determine key values mismatch of private and public keys.

Resolution

SSL Certificates have a key pair: a public and a private key. These keys work together to establish an encrypted connection. They are not interchangeable with other keys, thus it can be important to verify an existing public server certificate and a private key are a pair before attempting to use them for encrypting communication.

Follow the steps below in a terminal window to verify a public and private key are a pair:

  1. openssl x509 -noout -modulus -in <public.crt> | openssl md5 > /tmp/crt.pub
    Note: Replace <public.crt> with the filename of the public certificate.

  2. openssl rsa -noout -modulus -in <private.key> | openssl md5 > /tmp/key.pub
    Note: Replace <private.key> with the filename of the private key. Enter the password if prompted.

  3. diff /tmp/crt.pub /tmp/key.pub
    Note: If nothing is printed to the console, they were found to be a pair. Any differences are printed to the console in detail.

Disclaimer

This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.

  • Document ID:7015500
  • Creation Date: 08-Aug-2014
  • Modified Date:03-Mar-2020
    • SUSE Linux Enterprise Server

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