Wasn’t +256 bit encryption restricted in the US for communication services because the NSA would have to invest in computational power of several orders higher magnitude, to be able to crack the encryption?
Yup, no text encryption software (on the iPhone) with better than AES 256-bit. Two examples of encrypting apps...
Text Encrypter is a unique encryption app that lets you encrypt and decrypt any text. It is designed to use AES 256-bit encryption algorithm with Base64 character encoding scheme.