11. A method of tokenization, comprising: accessing a string of characters; producing, by a processor, an intermediate string of characters by replacing a first portion of the string of characters with a first token mapped to a value of the first portion of the string of characters by a first token table; and producing a tokenized string of characters by replacing a second portion of the intermediate string of characters with a second token mapped to a value of the second portion of the intermediate string of characters by a second token table, wherein the second portion of the intermediate string of characters includes at least one character replaced by the first token.
12. The method of claim 11 , further comprising one or more of: modifying the first portion of the string of characters before replacing the first portion, and modifying the second portion of the string of characters before replacing the second portion.