AES-256-GCM is the Advanced Encryption Standard with a 256-bit key in Galois/Counter Mode. It provides confidentiality and integrity: tampered ciphertext should fail authentication instead of decrypting to silent garbage.
Role in a vault
After a KDF produces a key, AES-GCM protects item payloads and related structures. Nonces/IVs must be handled carefully by the implementation � never reused with the same key.
In AzAd Vault
Vault contents are encrypted on device with AES-256-GCM after Argon2id derivation. Optional sync uploads ciphertext to your Drive app folder. See security and Argon2id.
Related reading
Are password managers safe? � Zero-knowledge
Why authenticated encryption matters
Older modes could encrypt without detecting bit flips. GCM’s authentication tag helps ensure ciphertext was not altered in transit or at rest. Combined with Argon2id-derived keys, this is the backbone of AzAd Vault’s on-device protection before any optional sync.
Key length intuition
AES-256 means a 256-bit key. In password managers, that key comes from a KDF output sized appropriately — not from typing 256 bits by hand. GCM mode streams efficiently on modern CPUs and mobile chips, which matters when vaults grow to hundreds of items and attachments.
Attachments in AzAd Vault are also encrypted rather than stored as plaintext sidecar files. Sync may move ciphertext blobs through Drive when enabled. See security for the product summary.
Practical takeaway
You do not configure AES-GCM by hand in AzAd Vault. The app applies it when saving items. Your responsibility is master password strength, device hygiene, and verifying you open the correct backup file after migrations.
Pair this term with Argon2id and zero-knowledge entries for a complete mental model of how confidentiality and integrity meet on device.