# RSA Key Pair Generator Generate an RSA key pair (2048/3072/4096-bit) as PEM-encoded public and private keys. Optionally encrypt the private key with a passphrase. PKCS#8 (recommended) or PKCS#1 private key format. Everything runs locally. > Canonical page: https://elysiatools.com/en/tools/rsa-key-generator - **Category:** Security - **Keywords:** rsa, key pair, public key, private key, pem, pkcs8, pkcs1, asymmetric, cryptography, generate ## Overview Produces a matching RSA public/private key pair using Node's `crypto.generateKeyPairSync()`. - **Key size**: 2048 (the modern baseline), 3072, or 4096 bits. Larger = more security but slower. 2048 is fine for most uses; use 4096 for long-term protection. - **Private key format**: - **PKCS#8** (recommended) — generic format, works everywhere, supports passphrase encryption. - **PKCS#1** — RSA-specific (older), label `RSA PRIVATE KEY`. Cannot be encrypted with a passphrase in this tool. - **Passphrase**: if provided, the private key is encrypted (AES-256-CBC) and cannot be used without it. The public key is always SPKI format (`PUBLIC KEY`). Use cases: setting up HTTPS, JWT signing keys, SSH from RSA, learning asymmetric crypto. The keys are generated locally and never transmitted. ## Inputs - **Key size** (select) - **Private key format** (select) - **Passphrase (optional, encrypts private key)** (text): Leave empty for an unencrypted key… ## When to use - When you need to generate secure SSH keys or SSL/TLS certificates for server authentication. - When setting up token-based authentication systems that require RSA public/private key pairs for JWT signing and verification. - When you need to quickly generate cryptographic keys for local development or testing without exposing sensitive data to external servers. ## How it works - Select your desired key size (2048, 3072, or 4096 bits) and choose between the PKCS#8 or PKCS#1 private key format. - Optionally enter a passphrase to encrypt the private key using AES-256-CBC. - Click generate to run the cryptographic function locally in your browser and instantly view the copy-ready PEM-encoded public and private keys. ## Use cases - Generating RSA key pairs for signing and verifying JSON Web Tokens (JWT) in web applications. - Creating public and private key pairs to configure secure SSH access to remote servers. - Setting up local SSL/TLS certificates for development environments requiring HTTPS. ## Frequently asked questions ### Are my generated keys secure? Yes. The keys are generated entirely in your browser using local cryptographic APIs and are never sent to any server. ### What is the difference between PKCS#8 and PKCS#1? PKCS#8 is a modern, generic standard that supports passphrase encryption in this tool, while PKCS#1 is an older, RSA-specific format. ### Which key size should I choose? 2048 bits is the standard baseline for most applications, while 4096 bits offers stronger, long-term security at the cost of slower performance. ### Can I encrypt a PKCS#1 private key with a passphrase here? No, passphrase encryption in this tool is only supported for the PKCS#8 format. ### What format is the generated public key? The public key is always generated in the standard SPKI format, labeled as 'PUBLIC KEY'. ## Related tools - [Env File Secret Rotation Planner](https://elysiatools.com/en/tools/env-file-secret-rotation-planner): Paste a .env file and get a staged secret-rotation plan. Detects database URLs, API keys, auth tokens, private keys, cloud credentials, payment keys and encryption secrets, scores each by exposure and age, and schedules them across a 4-week rotation timeline with a dual-key checklist and a generated .env.example. Optional last-rotated dates and a configurable cadence (30/90/180/365 days) drive compliance scoring. - [AGEX Keypair Generator](https://elysiatools.com/en/tools/agex-keypair-generator): Generate an Ed25519 keypair for AGEX bundle signing and verification - [Key Pair Generator](https://elysiatools.com/en/tools/key-pair-generator): Generate public/private key pairs for various cryptographic algorithms - [SSH Key Pair Generator](https://elysiatools.com/en/tools/ssh-key-generator): Generate an SSH key pair (Ed25519 recommended, RSA 4096, or ECDSA P-256) with an OpenSSH-format public key ready for ~/.ssh/authorized_keys, a SHA256 fingerprint, and a PEM private key. Optional passphrase encryption. 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