Small-key RSA demonstration with public and private keys.
RSA is a public-key cipher built from two prime numbers. You pick primes
p and q, multiply them to get the modulus n, and
derive a public exponent e and a private exponent d. Anyone can
encrypt with the public pair (e, n), but only the private exponent d can decrypt.
See more at
Wikipedia.
This is an educational demonstration with small keys. It is meant for learning and
puzzle solving, not for protecting real secrets. Real RSA uses primes hundreds of
digits long plus padding schemes that this demo does not implement.
Text mode encrypts each character's Unicode code point as its own ciphertext
block. Number mode encrypts one integer m where 0 is less than or equal to m and
m is less than n.