ECB is safe in this context because it's encrypting one-time messages
using a one-time key. All input data going through encryptAes() is
either random or partially random and passed through a secure hashing
function (SHA-256 on modern GFE versions).
Message authentication is not a concern either, because it is performed
by the pairing process itself via RSA signature verification. Any
ciphertext tampering would cause signature verification to fail later in
the pairing process.
Cameron Gutman
6a34ff2728