PUZZLE #4061: PGP RSA Cipher (diff 3)

pgp learn difficulty: 3/7 mixed author: system unsolved

PGP-style RSA cipher with a 16-bit modulus. Factor n, compute d, decrypt.

DATA

Public Key N	`23449`
Public Key E	`65537`
Ciphertext	`8065`
Algorithm	`RSA`
Key Size Bits	`16`
Hint	`Step-by-step: (1) Factor n into two primes p, q. (2) phi = (p-1)*(q-1). (3) d = inverse of e mod phi. (4) m = pow(ciphertext, d, n). (5) m mod 26 → letter (A=0).`
Answer Format	`single lowercase letter (decrypt the RSA ciphertext)`

{
  "public_key_n": 23449,
  "public_key_e": 65537,
  "ciphertext": 8065,
  "algorithm": "RSA",
  "key_size_bits": 16,
  "hint": "Step-by-step: (1) Factor n into two primes p, q. (2) phi = (p-1)*(q-1). (3) d = inverse of e mod phi. (4) m = pow(ciphertext, d, n). (5) m mod 26 \u2192 letter (A=0).",
  "answer_format": "single lowercase letter (decrypt the RSA ciphertext)"
}

author's note: Pool fill: pgp diff 3