Your Master Password keeps your 1Password data safe. If someone gets ahold of your data, your Master Password is all that is stopping them from decrypting it.
Password-Based Key Derivation Function 2 (PBKDF2) makes it harder for someone to determine your Master Password by making repeated guesses in a brute force attack. 1Password uses PBKDF2 in the process of deriving encryption keys from your Master Password. PBKDF2 requires many computations to get from the Master Password to the key. Anyone trying to automatically guess a Master Password has to perform those same calculations.
PBKDF2 prevents password cracking tools from making optimal use of graphics processing units (GPUs), thus reducing guess rates from hundreds of thousands of guesses per second to less than a few tens of thousands of guesses per second. Learn more about why crackers report great news for 1Password 4.
How 1Password uses PBKDF2
1Password has always used PBKDF2, but the implementation is different depending on whether you use a 1Password account or a standalone vault.
1Password accounts use PBKDF2-HMAC-SHA256 for key derivation. All accounts are created using 100,000 iterations.
However, password cracking attempts are effectively rendered impossible because your Master Password is combined with your Secret Key which is only on your own devices. A good Master Password is still needed to protect you from an attacker who acquires your encrypted 1Password data from your own device. Learn how to choose a good Master Password.
Learn more about the key derivation process in 1Password Security Design White Paper .
OPVault uses PBKDF2-HMAC-SHA512 for key derivation. The number of iterations depends on the processing power of your machine and is calibrated when you create a vault or change its Master Password. The minimum number of iterations is 10,000 but may be much higher.
Learn more about the derivation process in OPVault Design.
The retired Agile Keychain format uses PBKDF2-HMAC-SHA1 for key derivation. The number of iterations depends on the version of 1Password used to create the vault and the processing power of the machine where it was created.
History of PBKDF2 in 1Password
- 1Password introduced the Agile Keychain format with PBKDF2-HMAC-SHA1 in Autumn 2007.
- 1Password for Mac 2.5.0 (October 2007) – 3.8.10: Keychains created with 1,000 PBKDF2 iterations.
- 1Password for Windows 18.104.22.168 (April 2010) – 22.214.171.1246: Keychains created with 1,000 PBKDF2 iterations.
- 1Password for Mac 3.9 (September 2011): All versions of 1Password for Mac from the Mac App Store calibrate the number of PBKDF2 iterations on initial setup and on Master Password change. A minimum of 10,000 iterations is used.
- 1Password for Mac 3.8.11 (December 2011) – 3.8.20: Keychains created with 10,000 PBKDF2 iterations. Changing the Master Password did not change iterations.
- 1Password for Windows 126.96.36.1999 (October 2012) – 1Password 188.8.131.527: Keychains created with 10,000 PBKDF2 iterations. Master Password change did not increase number of iterations.
- 1Password for Mac 3.8.21 (April 2013): Keychains created with 10,000 PBKDF2 iterations. On a Master Password change, iterations will be increased from 1,000 to 10,000 if necessary.
- 1Password for Mac 4 (October, 2013) will still create Agile Keychain format data under some circumstances. For both OPVault and Agile Keychain it will calibrate the number of PBKDF2 iteration on initial setup and on Master Password change. A minimum of 10,000 iterations is used.
- 1Password for Mac 4.2 (March 2014): Keychains created with a minimum of 25,000 iterations and a maximum of 100,000. On a Master Password change, iterations will be re-calibrated.
- 1Password for Mac 5 (October 2014): Keychains created with a minimum of 40,000 iterations and a maximum of 100,000. On Master Password change, iterations will be re-calibrated.
- 1Password for Windows 4.1 (November 2014) Keychains created with 40,000 iterations.
- 1Password Accounts (February 2016) All accounts are created using 100,000 iterations.
- 1Password for Windows 6 (September 2016) Accounts are created with 100,000 iterations.
Depending on the number of PBKDF2 iterations and the power of the device you’re using, there may be a small, but noticeable, delay when unlocking a vault on some systems.