pure python GF(2^233) field arithmetic, binary curve point operations,
and ECDSA-SHA256 on sect233r1. verifies OTP CTCert against nintendo
root CA public key. zero dependencies. sign+verify round-trip tested,
n*G=O verified, wrong key/message rejection confirmed.
pure python RSA-2048 PKCS1v15 SHA256 for SecureInfo_A,
LocalFriendCodeSeed_B, movable.sed. AES-128-CBC + SHA256 for otp.bin.
keys extracted from azahar default_keys.h, added RSA/ECC sections
to aes_keys.txt. sect233r1 ECC not reproducible (binary field curve).
