RSA encryption, decryption and prime calculator
This RSA calculator supports prime generation, encryption, and decryption.
About RSA encryption, decryption and prime calculator
This website provides a tool to calculate prime numbers, encrypt plain-text messages using RSA, and attempt brute-force decryption of RSA messages. Encryption uses two primes and a chosen e value, while decryption uses the public key values N and e plus the message. It also includes example messages with N, e, and encoded bits for use in the other tabs.
Generated primes are preserved only until the page reloads. The optional explanation for prime results can cause severe lag or unresponsiveness with large ranges.
Key features
- Calculate primes between a specified lower and upper bound
- Show explanations for why numbers are not prime
- Encrypt plain-text messages using two primes and e
- Brute-force decrypt RSA messages from N, e, and message
- Provide example messages with N, e, and encoded bits
- Generate additional primes kept until page reloads
Best for: Students learning RSA who want to practice prime calculation and simple encryption and decryption tasks.
Good for
- Covers prime calculation, encryption, and decryption in one tool
- Includes examples with N, e, and encoded bits for testing
- Offers optional explanations for non-prime results
Watch out for
- Generated primes are lost when the page reloads
- Explanation option can cause lag with large ranges
RSA encryption, decryption and prime calculator at a glance
- Category
- Privacy & Security › Security Tools
- Type
- Website
- Pricing
- Not confirmed. Check the site
- Platforms
- Web
- Open source
- Not stated
- Last checked
- Oct 5, 2026 · Online when checked
- Listed
- Oct 5, 2026
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RSA encryption, decryption and prime calculator FAQ
What do I need to decrypt a message?
The public key values N and e, plus the message to decrypt.
What do I need to encrypt a message?
A first prime, a second prime, a chosen e value, and the plain-text message.
What happens to primes I generate?
They are preserved only until the page reloads.
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