🔐 OpenSSL Command Generator – Build CLI Commands Instantly
OpenSSL is the de-facto standard toolkit for working with TLS/SSL certificates, private keys, cryptographic digests, and secure file encryption. It is powerful, but its command-line interface has hundreds of flags, subcommands, and options that are difficult to memorize. The OpenSSL Command Generator eliminates that friction by providing an interactive form where you select an operation, fill in your parameters, and instantly receive the correct, copy-ready openssl command.
🎯 Who Is This Tool For?
This tool is designed for developers, DevOps and platform engineers, system administrators, and security professionals who work with TLS certificates, PKI infrastructure, or encrypted data on a regular basis. Whether you are setting up a self-signed certificate for local development, provisioning a CSR for a production domain, or verifying a certificate chain before a deployment, this tool generates the exact command you need without requiring you to consult the man page every time.
⚙️ Supported Operations
The tool covers the eight most commonly performed OpenSSL operations:
| Operation | OpenSSL Subcommand | Use Case |
|---|---|---|
| Generate Private Key | genpkey / genrsa / ecparam | Create RSA, EC, Ed25519, or DSA keys |
| Generate CSR | req -new | Create a Certificate Signing Request for a CA to sign |
| Self-Signed Certificate | req -x509 | Local development, internal services, testing |
| Sign CSR with CA | x509 -req | Issue a certificate from your own CA |
| Inspect Certificate / Key | x509 / pkey / req / pkcs12 | Decode and read a certificate, key, or CSR |
| Convert Format | x509 / pkcs12 | Convert between PEM, DER, and PKCS#12 bundles |
| Generate Digest / Hash | dgst | Compute SHA-256, SHA-512, and other file hashes |
| Encrypt / Decrypt File | enc | Symmetric encryption with AES-256-CBC and others |
🔑 Private Key Generation
The tool supports four key algorithms: RSA, Elliptic Curve (EC), Ed25519, and DSA. For RSA keys, you can choose from key sizes of 2048, 3072, or 4096 bits (2048 is the current industry minimum; 4096 offers stronger security at the cost of slightly slower operations). For EC keys, the tool exposes the most widely used named curves: prime256v1 (NIST P-256), secp384r1 (P-384), and secp521r1 (P-521). Ed25519 is a modern, fast, and secure choice for authentication keys and SSH certificates.
OpenSSL 3.x introduced the unified genpkey subcommand for all key types and added -addext for inline SAN entries in req commands. The tool generates the appropriate syntax for each version — select your version in the dropdown.
📝 Certificate Signing Requests (CSRs)
A CSR is a message you send to a Certificate Authority (CA) to request a signed TLS certificate. It contains your public key and identity information (CN, O, C, etc.) but NOT your private key. The tool builds the complete openssl req -new command including the -subj string from your subject field inputs and the subjectAltName extension from your SAN entries. Modern TLS requires SANs — the CN field alone is no longer sufficient for browser trust.
🔏 Subject Alternative Names (SANs)
SANs specify the hostnames, IP addresses, email addresses, or URIs that the certificate should be valid for. Use the SAN builder to add entries in the format DNS:example.com, IP:192.168.1.1, email:[email protected], or URI:https://example.com. For OpenSSL 3.x, the tool uses the -addext flag; for 1.x it notes the requirement to use an external extension file.
🛡️ Security Warnings
The tool embeds inline security validation so you don't accidentally use weak parameters in production:
- RSA < 2048 bits — flagged as insecure. NIST recommends 2048 as the minimum and 3072+ for long-lived certificates.
- MD5 and SHA-1 digests — deprecated and broken for certificate signing. Modern CAs and browsers reject SHA-1 certificates.
- DES and RC4 ciphers — removed from modern TLS and considered insecure for key encryption.
- Validity > 825 days — Apple, Google, and Mozilla have capped browser-trusted certificate lifetimes.
📦 Format Conversion (PEM, DER, PKCS#12)
Different systems expect certificates in different formats. PEM is the most common format (Base64-encoded with -----BEGIN headers) and is used by Apache, Nginx, and most Linux tools. DER is a binary format commonly required by Java keystores and some Windows tools. PKCS#12 (also called PFX) bundles a certificate, its private key, and optionally the CA chain into a single password-protected archive — commonly used by IIS and Azure.
🔢 File Digest / Hash Verification
The openssl dgst command computes a cryptographic hash of any file, which is useful for verifying file integrity. The tool supports SHA-256, SHA-384, SHA-512, SHA3-256, and SHA3-512. MD5 and SHA-1 are available but flagged as deprecated — use them only when required by legacy systems.
🔒 File Encryption with AES
The openssl enc command provides symmetric file encryption using a passphrase-derived key. The tool generates commands that include the -pbkdf2 flag (Password-Based Key Derivation Function 2), which is much stronger than the legacy default key derivation and is recommended for all new encrypted files. AES-256-CBC is the recommended cipher choice for compatibility and security.
💡 Tips for Common Workflows
- Local HTTPS dev server: Use Self-Signed Certificate with
CN=localhostand aDNS:localhostSAN entry. - Production certificate: Generate a key → generate a CSR with SANs → submit the CSR to your CA (e.g., Let's Encrypt).
- Internal CA: Create a self-signed root CA cert → generate server CSRs → sign them with the Sign CSR with CA operation.
- Verify certificate before deployment: Use the Inspect operation to confirm the SANs, validity dates, and signature algorithm before deploying.