Font creation - programmatic

Need a font that I can select that if chosen replaces the current font with "lorem ipsum" words. So the idea is this. Input: The quick brown fox jumped over the lazy dog. Output: Sit amet, lorem vel lectus cras lit ante tur. So it is more of a word replacement font then a character replacement. Where the latin word/gibberish word must match the amount of letters from the input. The latin words are thus selected at random from groups of 1-letter words, 2-letter words, 3-letter words, up to 30 letter words (longest word in english language). Must work in mac.