Memory stick file encryption

I am having trouble trying to sort out various encryption software available. I want to carry my .txt password file with me on a memory stick and, of course, want to protect it. I could put it in a .rar file but if the machine I am using doesn't have WinRAR or something I'm not helped. And, finally, I don't understand most of this encrypting stuff.

I think I need a very small program, self-contained like old DOZ programs, so that it doesn't have to be installed on the temporary computer. Doesn't have to be freeware.

Any suggestions?

Thank you.

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