Temporarily read an encrypted file

I want to store an encrypted .txt file (encrypted with a password, with AES for example) in the interal SD memory or µSD card of my phone. I want to be able to read it every now and then, but:

• I don't want the unencrypted plain text file to be extracted and stored in the SD card (even as a temp file).




• I don't want the unencrypted plain text file to transit via network (internet, etc.)

Is there a solution / app that would display an encrypted text file?

PS: I already tried full encryption of the phone, it's not what I'm looking for (other reasons, off topic here)

PS2: I don't want to use an online service