Password / Passphrase

Password manager For iOS

AuthPass – Password Manager

KeePassium (KeePass passwords‪)‬
Strongbox – KeePass & PwSafe

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2FA (2-factor Authentication)

Forced password disclosure

In some countries the law forces citizens to give up their passwords under threat of jail (UK, Australia, Iran, etc), if you are at that level of risk, you will be better off running the OS as a live DVD and never installing anything. When something runs in RAM it is not possible to recover the data regardless of threats.