We use two levels of encryption.
The Passwordless vault is encrypted using Advanced Encryption Standard (AES), a symmetric algorithm used worldwide to protect sensitive data.
When you create a master password, a special key is automatically derived from it using the Password-Based Key Derivation Function 2 (PBKDF2) mechanism. Your storage is accessed using this key, which is encrypted using PBKDF2. The key is not known to anyone, including us.