Droplock is probably the best encryption app you can find. It supports the iOS 'Open in' feature, allowing you to encrypt files from other applications or decrypt .droplock files sent to you through Mail.
Open a file, enter the password and, voilà, your file is either encrypted and safe for storage or decrypted and ready to be read.
After encryption or decryption, you will be offered three choices. For decrypted documents, 'Preview' briefs you on the file contents, 'Open in' allows you to export your file and 'Email' enables you to share the file with colleagues, friends and family.
Droplock is powered by a custom enhanced AES-256 algorithm. Working with Droplock is secure, simple and speedy.