for each output block pair
   get file index from block_indices
   if it is not chaff
      read a data block for this file
      package transform the data block
      write the transformed block to the output file
      compute the HMAC of the transformed block
      write the HMAC of the transformed block to the output file
   else
      write out fake block-HMAC bytes
   end
end

Example 2: Pseudocode implementation of encryption process.