A Daraja consumer key and secret are effectively the keys to a business's M-Pesa Till. If PesaLoop's database were ever exposed, plaintext credentials would mean every connected business's Till is exposed with it.
PesaLoop encrypts Daraja credentials with AES-256-GCM before they touch the database, using a key held outside the database itself. GCM mode was chosen specifically because it's authenticated encryption — a tampered ciphertext fails to decrypt rather than silently returning garbage, which matters when the decrypted value is about to authenticate a live payment API call.
This is table-stakes for anything handling financial credentials, not a novel idea — but it's worth stating plainly, because a lot of early-stage fintech tools skip it under time pressure.