I want to anonymise the initials of experiment participants by giving each a pseudonymic set of initials, by encrypting their true initials. Their initials are only two or three letters in length.
These are data from individual human experiment participants that I publish online and in scientific journals. The convention (from a more innocent time) is to inset each participant's initials in a graph of their data. Using Github I will publish all the code and anonymised data, excepting the key (more background: https://plus.google.com/+AlexHolcombe/posts/1sNgTnnAtYz). Symmetric encryption seems fine.
Is there a suitable algorithm simple enough to quickly implement in the R statistical language? I came across the Vignere cipher, which seems to be exactly what I need, but I know almost nothing about cryptography so perhaps that is naive. http://www.counton.org/explorer/codebreaking/vigenere-cipher.php