Security

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A password manager asks for trust. This page says how EasyKeys encrypts, and shows a way to check it without our code.

The algorithms

EasyKeys does not invent its own encryption. It uses two publicly standardised algorithms:

AES-256-GCM encrypts the whole vault file, not just the passwords. Titles, usernames, notes, tags and attachments cannot be read from outside. GCM also notices every change: a file in which even a single bit was flipped cannot be opened.
Argon2id turns your master password into the key. It is expensive on purpose (64 MiB of memory, 3 passes), so that trying out passwords stays slow.

Both building blocks are checked against the published test values of their standards every time the app is built (RFC 9106 for Argon2id, the GCM specification for AES-256-GCM).

Where the key comes from

The key is derived from your master password alone. The password is not stored anywhere and not sent anywhere; the app does not hold the internet permission. There is no second key and no way back: without the master password nobody opens the vault, not even us.

If you switch on the fingerprint, the app puts a copy of the key into a locker that Android opens only after your fingerprint. That copy is expendable: if someone adds another finger on the device, it becomes worthless and the master password applies again.

Check it yourself

You do not have to take our word for it. The program tresor_nachbau.py (about 80 lines of Python, comments in German) opens a vault file without a single line of code from the app. It knows only the format description below and two independent, widely used libraries: the Argon2 reference implementation and OpenSSL. If it opens your file, the file is encrypted exactly as described here.

Save a backup in the app and bring it to a computer. The backup is the vault file itself.
Install the two libraries: pip install argon2-cffi cryptography
Run python3 tresor_nachbau.py tresor-….pwm and enter your master password.

The program names the algorithms from the file header and the number of entries; with --json it prints the whole content in plain text. With a wrong password or a modified file it stops.

Do this on a computer you trust, and delete the output afterwards: it contains your passwords.

The file format

The file starts with 48 bytes that are not encrypted but protected against modification. All numbers are stored most significant byte first.

From byte	Length	Content
0	8	Marker `PWMGRVLT`
8	2	Format version (1)
10	1	Key derivation (1 = Argon2id, version 1.3)
11	4	Argon2: memory in KiB
15	4	Argon2: passes
19	1	Argon2: lanes
20	16	Salt
36	12	Nonce for AES-GCM, new on every save
48	rest	AES-256-GCM over the content (JSON, UTF-8), with a 16-byte tag at the end

The master password goes into Argon2id as UTF-8 and yields a 32-byte key. The first 48 bytes enter GCM as additional data.

What this does not do

No outside audit. EasyKeys has not yet been reviewed by an independent party. The program above shows what is in the file, not that the app is free of errors.
The vault is as strong as your master password. A short or guessable password does not protect you, Argon2id or not.
An unlocked device is open. Encryption protects the file, not the unlocked vault from someone holding your phone.
The CSV export is plain text, and a copied password stays in the clipboard until you copy something else.

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