frequency analysis on a simple substitution type cypher should never fail. it was close. but the trick is the frequencies on short messages only give you proba

frequency analysis on a simple substitution type cypher should never fail. it was close. but the trick is the frequencies on short messages only give you probabilities that a certain mapping is true. but those probabilities are enough to shorten the potential mappings significantly (i.e. e is probably e or t, g is probably e or t). Combine that with a word match (does the result contain stop words such as - it not the etc) and bam, game over.