OpenSSL Command-Line Essentials
Master the essential OpenSSL commands for key generation, encryption, hashing, and certificate inspection.
OpenSSL Version and Build Info
The command "openssl version -a" displays the OpenSSL version, build date, compiler, and configured options. Verifying the version is important because cryptographic capabilities and defaults differ significantly between OpenSSL 1.0.x, 1.1.x, and 3.x. Many older algorithms are disabled by default in newer versions for security.
Generating RSA Keys
The command "openssl genrsa -out private.pem 4096" generates a 4096-bit RSA private key in PEM format. For production use, 2048-bit is the minimum, 3072-bit provides ~128-bit security, and 4096-bit provides additional margin. Keys can be AES-encrypted at rest by adding "-aes256" to the command, prompting for a passphrase.
All lessons in this course
- OpenSSL Command-Line Essentials
- Creating and Managing Certificate Chains
- OCSP Stapling and Certificate Transparency
- Let's Encrypt and ACME Protocol Automation