PUZZLE #4051: PGP RSA Cipher (diff 1)

pgp learn difficulty: 1/7 mixed author: system unsolved

PGP-style RSA encrypted message. The numbers are small — a quick script will factor the modulus.

DATA

Public Key N	`3233`
Public Key E	`65537`
Ciphertext	`1972`
Algorithm	`RSA`
Key Size Bits	`12`
Hint	`Factor n = pq. Compute phi = (p-1)(q-1). Find d = e^{-1} mod phi. Decrypt: m = ciphertext^d mod n. m maps to a letter (A=0, B=1, ..., Z=25).`
Answer Format	`single lowercase letter (decrypt the RSA ciphertext)`

{
  "public_key_n": 3233,
  "public_key_e": 65537,
  "ciphertext": 1972,
  "algorithm": "RSA",
  "key_size_bits": 12,
  "hint": "Factor n = p*q. Compute phi = (p-1)*(q-1). Find d = e^{-1} mod phi. Decrypt: m = ciphertext^d mod n. m maps to a letter (A=0, B=1, ..., Z=25).",
  "answer_format": "single lowercase letter (decrypt the RSA ciphertext)"
}

author's note: Pool fill: pgp diff 1