Shared secret vault for applications with single sign on

Some aspects of the disclosure generally relate to providing single sign on features in mobile applications in a secure environment using a shared vault. An application may prompt a user to provide user entropy such as a passcode (e.g. a password and/or PIN). The application may use the user entropy to decrypt a user-entropy-encrypted vault key. Once the vault key is decrypted, the application may decrypt a vault database of the shared vault. The shared vault may store shared secrets, such as server credentials, and an unlock key. The application may store the unlock key, generate an unlock-key-encrypted vault key, and cause the shared vault to store the unlock-key-encrypted vault key, thereby "unlocking" the vault. The application may then use the unlock key to decrypt the vault database without prompting the user to provide user entropy again.