Guide to OpenSSL Commands: Securing Your Digital Conversations
A list of useful OpenSSL commands
"Security is always excessive until it's not enough." - Robbie Sinclair
Opening our conversation with this insightful quote captures the essence of OpenSSL and its importance. OpenSSL, a full-featured and robust toolkit, handles SSL and TLS protocols. A widely-used tool, it allows you to create, manage, convert, verify, and test SSL certificates.
- Crafting the 'Keymaker': Generating a New Private Key and CSR
A CSR or Certificate Signing Request is like a 'keymaker'. The following command helps you generate a new private key (myserver.key
) and CSR (myserver.csr
):
openssl req -new -newkey rsa:2048 -nodes -keyout myserver.key -out myserver.csr
- Self-Signed Certificates: The 'Locksmith's Proof'
A self-signed certificate is akin to a 'locksmith's proof', showcasing their proficiency. Generate one from the private key (myserver.key
) and CSR (myserver.csr
) with this command:
openssl x509 -signkey myserver.key -in myserver.csr -req -days 365 -out myserver.crt
- Transforming Certificates: Various Formats
OpenSSL also allows you to transform or convert certificates into different formats:
- PEM to DER
openssl x509 -outform der -in myserver.pem -out myserver.der
- DER to PEM
openssl x509 -inform der -in myserver.der -out myserver.pem
- PEM to PKCS#7
openssl crl2pkcs7 -nocrl -certfile myserver.pem -out myserver.p7b -certfile CACert.pem
- PKCS#7 to PEM
openssl pkcs7 -print_certs -in myserver.p7b -out myserver.pem
- Scrutinizing the 'Digital Conversation': SSL/TLS Configuration
OpenSSL allows you to check the SSL/TLS configuration of a server, providing an overview of each step in the SSL/TLS handshake.
openssl s_client -connect www.example.com:443
- Diffie-Hellman Parameters: Creating a 'Secret Code'
Diffie-Hellman parameters, used for DHE or ECDHE ciphers, can be likened to a 'secret code' in a conversation. Generate a new DH parameters file with:
openssl dhparam -out dhparam.pem 2048
- Encryption and Decryption: 'Code Breakers'
OpenSSL allows you to encrypt and decrypt, acting as a 'code breaker':
- Encryption
openssl enc -aes-256-cbc -salt -in file.txt -out file.txt.enc
- Decryption
openssl enc -d -aes-256-cbc -in file.txt.enc -out file.txt
To quote Edward Snowden,
"Arguing that you don't care about the right to privacy because you have nothing to hide is no different than saying you don't care about free speech because you have nothing to say."
OpenSSL helps maintain this right to privacy in our digital world.

As we conclude this enhanced guide to OpenSSL commands, take a moment to reflect on your own digital security practices. Are there aspects you could improve? Could OpenSSL play a role in strengthening your digital security?
Our action item for you is simple yet impactful: identify one area where OpenSSL could enhance your digital privacy and take the first step in implementing it. This practical step not only improves your understanding of OpenSSL but also reinforces its importance in maintaining digital privacy. By leveraging your consistency bias, this action will create a change that you'll easily recall and apply in the future.