What AES-256 does
AES-256 is a standard way to encrypt data. Encryption changes a readable file, message or photo into data that looks like random noise. The right secret key turns it back into something readable.
AES means Advanced Encryption Standard. It is public, heavily studied and widely used in phones, password managers and financial services. Security comes from keeping the key secret, not from hiding the algorithm.
Think of a locked suitcase with a unique key. Anyone can see the suitcase; only a person with the key can open it. AES-256 is the lock. Your encryption key is what opens it.
What the “256” means
The number 256 is the key length in bits. It means AES-256 has 2256 possible keys—a number so large it has 78 digits.
To open encrypted data by brute force, an attacker would try keys until one worked. Even with vast computing power, trying enough AES-256 keys is beyond practical reach.
That does not make every encrypted file automatically safe. A thief does not need to guess a key if they can get your password, use your already-unlocked phone or find an unencrypted copy.
Where attacks really happen
When protected data is exposed, the encryption algorithm is rarely the failure. Attackers usually go around it.
Weak passwords. If a password helps unlock the encryption, a short or reused one may be guessed. The attacker then has a legitimate way in; AES-256 has not been cracked.
Unlocked devices. If someone can use your open phone, or malware is running while a file is open, it may see the readable data directly.
Unsafe handling. A careless app might store a key or a plain copy of a file where it should not. That weaker copy becomes the target.
Why your password matters
A password is often the human-sized door to an encryption key. If it is easy to guess or reused after a breach, an attacker may try the password instead of AES-256 keys.
Use a long, unique passphrase or a password-manager-generated password. Keep your device updated and lock it when you are not using it.
Practical takeaway: choose a unique passphrase and protect the device that holds the key. AES-256 then does the job it was designed to do.
How Sealby uses AES-256
Sealby encrypts files with AES-256-GCM. GCM adds an integrity check, so changes to encrypted data can be detected. Every file gets its own key, limiting what any one key can open.
Keys are created on your iPhone and protected by its hardware. Your PIN or passphrase goes through a deliberately slow process before it can unlock a vault, making password guesses more costly. Strong encryption works best when the key, password and device are all protected.