RSATool
A Python tool for calculating RSA and RSA-CRT cryptographic parameters and generating OpenSSL-compatible keys.
What is RSATool?
rsatool is a Python command-line utility for calculating RSA cryptographic parameters and generating OpenSSL-compatible private keys. It solves the problem of manually computing RSA values by automating the process of deriving all necessary parameters from either two primes or from modulus and private exponent inputs.
Security researchers, cryptography developers, and system administrators who need to generate RSA keys or work with RSA parameters in cryptographic implementations.
Developers choose rsatool for its simplicity and specificity—it does one thing well without the overhead of larger cryptographic libraries, and it produces keys that are immediately compatible with OpenSSL and other standard tools.
Overview
rsatool can be used to calculate RSA and RSA-CRT parameters
Use Cases
Best For
- Generating RSA private keys from known primes
- Converting between RSA parameter formats
- Creating OpenSSL-compatible keys for testing
- Educational purposes for learning RSA cryptography
- Scripting cryptographic key generation workflows
- Recovering RSA parameters from partial key information
Not Ideal For
- Projects requiring support for cryptographic algorithms beyond RSA, such as ECC or AES
- Environments that demand graphical user interfaces or web-based tools for key management
- Systems needing built-in key validation, auditing, or compliance with security standards like FIPS
- Applications that require integration with hardware security modules or real-time key generation
Pros & Cons
Pros
Calculates all RSA and RSA-CRT values from primes or modulus/exponent pairs, as demonstrated in the README examples for deriving p, q, n, d, e, dP, dQ, and qInv.
Generates DER or PEM encoded private keys that work seamlessly with OpenSSL, ensuring easy integration into standard cryptographic workflows.
Accepts input as two primes or as modulus and private exponent, providing versatility for different key derivation scenarios, as shown in usage examples.
Command-line interface allows for automation in scripts, with simple commands for outputting keys to files in various formats.
Cons
Relies on Python packages like pyasn1 and gmpy2, which can complicate installation and maintenance, especially in restricted environments.
Focuses solely on RSA parameter calculation and key generation, lacking features for other algorithms, key management, or security validations.
Does not verify input prime validity or key security, placing the onus on users to ensure correct and secure parameters, which could lead to errors.
Frequently Asked Questions
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