From the standardization of DES in the 1970's to the
design of AES, the research community has made great
strides in cryptanalysis and design of symmetric-key
ciphers. In this survey talk, I will review a number
of the most important techniques developed over the
past decades for analyzing block ciphers, including
some algebraic methods that may be of interest due
to the choice of Rijndael for the AES standard. No
prior knowledge of block ciphers will be assumed.