RSA is a public-key cryptographic algorithm based on the difficulty of factoring large integers. One key (public) encrypts, the other key (private) decrypts.

Is this tool production-grade security?

No. This in-browser tool uses small demonstration primes for educational purposes. For real security, use well-reviewed cryptographic libraries and large key sizes (2048 bits or higher).

Can I see n, e, and d?

Yes. After generating a key pair, the tool shows the modulus n, the public exponent e, and the private exponent d so you can follow the math.

RSA Encryption / Decryption

A browser-based, educational RSA lab: generate small demo keys, encrypt a short message with the public key, and decrypt with the private key. Good for learning the algorithm, not for real-world security.

⚠️ Educational only — uses small primes and naïve randomization. Do not send secrets.

1. Generate / enter keys

Click “Generate demo keys” to let the tool pick two primes and compute n, φ(n), e and d. Or paste your own n, e, d below.

Modulus n

φ(n) (optional)

Public exponent e

Private exponent d

Status

2. Encrypt

We convert your message to UTF-16 code units and encrypt each unit separately: simple, visible, educational.

Ciphertext (array of big integers):

3. Decrypt

Paste the ciphertext array exactly as produced above, then decrypt with the private key d.

Decrypted message:

How RSA works (short)

RSA is based on modular arithmetic and the difficulty of factoring a large number \( n = p \times q \):


                1. Choose two primes p, q

                2. n = p · q

                3. φ(n) = (p − 1)(q − 1)

                4. Choose e s.t. 1 < e < φ(n) and gcd(e, φ(n)) = 1 (common: 65537)

                5. Compute d ≡ e⁻¹ (mod φ(n))

                6. Public key = (n, e), Private key = (n, d)

To encrypt a number \(m\): \( c = m^e \bmod n \). To decrypt: \( m = c^d \bmod n \).

Note: Real implementations use padding schemes (like OAEP) and big key sizes (2048+ bits). This page is intentionally simplified.