慣用 かんよう暗号 あんごうシステムじゃなかったです
kan'yōangōshisutemujanakattadesu

Noun
Desu Copula

The polite, past negative form of 慣用暗号システム

1. Wasn't a conventional cipher.; Wasn't a customary code system.

Past/Perfective
Negative
Polite
Casual Register
Computing