openssl-rsa: RSA Key Management

Overview

openssl-rsa is part of the OpenSSL toolkit, specialized for handling private and public keys used in RSA encryption. It provides a range of functionalities from key generation to format conversion, encryption/decryption, and key information verification, making it essential for building and managing RSA-based security systems.

Key Features

Generate RSA private keys
Extract public keys from private keys
Convert key file formats (DER, PEM)
Encrypt and decrypt private keys
View and verify key information

Key Options

The openssl-rsa command allows for fine-grained control over the generation, conversion, and management of RSA keys through various options.

Input/Output and Format

Key Generation and Encryption

Generated command:

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Description:

`openssl-rsa` Executes the command.

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Usage Examples

Learn how to perform RSA key management tasks through various usage examples of the openssl-rsa command.

Generate RSA Private Key (2048-bit)

openssl-rsa -out private_key.pem 2048

Generates a 2048-bit RSA private key and saves it to the file `private_key.pem`.

Extract Public Key from Private Key

openssl-rsa -in private_key.pem -pubout -out public_key.pem

Extracts the public key from the generated private key file (`private_key.pem`) and saves it to `public_key.pem`.

View Private Key Information

openssl-rsa -in private_key.pem -text -noout

Outputs detailed information of the private key file (`private_key.pem`) in text format. The key itself is not outputted.

Generate Encrypted Private Key (AES256)

openssl-rsa -out private_key_enc.pem -aes256 2048

Generates a 2048-bit RSA private key encrypted with the AES256 algorithm. You will be prompted to enter a password.

Decrypt Encrypted Private Key

openssl-rsa -in private_key_enc.pem -out private_key_dec.pem -passin pass:your_password

Decrypts the encrypted private key (`private_key_enc.pem`) and saves it to a new file (`private_key_dec.pem`). You can specify the password directly using the `-passin` option.

Tips & Precautions

RSA keys are critical for system security, so always consider the following tips and precautions when generating and managing them.

Security Tips

**Private Key Security:** Private keys should never be exposed externally. Minimize access permissions and store them in a secure location.
**Use Strong Passwords:** When encrypting private keys, use strong, long passwords that are difficult to guess.
**Choose Appropriate Key Length:** Generally, 2048-bit or 4096-bit RSA keys are recommended. Select based on your security requirements and performance considerations.

Precautions

File permissions for key files are very important. Private key files should be set so that only the owner can read or write them, for example, using `chmod 400` or `chmod 600`. Also, if you lose your key, recovery may be impossible, so it is advisable to back them up in a safe place.