I have read that basic replacement ciphers, such as replacing one byte with another specific byte at each location, are far less effective with non-randomized data. My question is, can this problem be mitigated to the point where basic ciphers can be effective on structured data by encrypting the data with other methods before passing it through the basic cipher?
For encrypting exclusively highly structured data, are basic substitution ciphers useful from early on in the encryption process, such as directly after something simple like a single XOR, or only after heavy encryption or should such basic replacements be avoided for this purpose all together?