If your 17 characters are distributed equally along just the letters a-z, no one can build a useful codebook during their lifetime. If your 17 characters are 3

If your 17 characters are distributed equally along just the letters a-z, no one can build a useful codebook during their lifetime. If your 17 characters are 3 lowercase non-archaic English words, maybe with two digits at the end, then a codebook for them already exists in MD5.