oPenGP is a mobile and web-based application that provides users with secure access to their personal data. It enables users to store and manage their personal data securely and privately, and to control who can access it. With oPenGP, users can easily store and access their medical records, financial accounts, and other sensitive information. The app uses a combination of encryption, authentication, and access control to ensure that user data is kept safe and secure. oPenGP also provides users with an easy-to-use interface for creating and managing secure data stores. Additionally, the app provides users with the ability to track their data usage, and to control who can access the data. oPenGP also provides users with the ability to manage their data backups, and to store their data in the cloud in a secure manner.
iGPMail works and seems to be supported, while oPenGP seems to be no longer supported on iOS 12.
GnuPG
GPG4Win
AES Crypt
Axcrypt
Kleopatra
Encrypto
GPG Suite
APG
FreeOTFE
DCrypt
iGPMail
Fort
Drag'n'Crypt ULTRA
OneTime
Steadycrypt
Challenger
Kruptos
FileWall
Cryptext
Cryptix
Discontinued Discontinued by Wikipedia page (https://en.wikipedia.org/wiki/FreeOTFE)