Errata Additions Adam Back suggested a pointer to "Covert Channels in the TCP/IP Protocol Suite", Craig H Rowland (http://www.firstmonday.dk/issues/issue2_5/rowland/). The paper describes how to replace random numbers in the TCP/IP protocol with encrypted data. Errors If I find any errors in the book, I'll post a note here. If you find any mistakes, please let me know. Thank you for your help. In the bibliography reference MBR99, the third author is "C. Retter" not "J. Retter". On page 30, the equation should be \rho(pq)=\rho(p)\rho(q). (Thanks to Salvador Sosa) On page 47, the bit stream should read: ...01010 0 01010 1 11001 1 01111 1 00011 1 ...".(Thanks to Salvador Sosa) On page 51, the sentence should be " If the right 11 are put together, then the original secret is unveiled."(Thanks to Salvador Sosa)