Cryptography for network security

Cryptography for network security: failures, successes and challenges

FREE-DOWNLOADB Preneel – Computer Network Security, 2010 –
The first boom in cryptography can be attributed to the introduction of wirelessdata communications at the beginning of the 20th century ]: it is clear thatwireless communications are as easy to read for an adversary as for the legitimatereceiver. There is also the mistaken perception that intercepting wired commu-nications is really dicult; while the introduction of optical communicationshas raised the threshold, a well motivated opponent can also bypass this hur-dle. From the 1960s, dedicated or switched wired networks were introduced forcomputer networks. Only military, governmental and nancial communicationswere encrypted; until the early 1990s this encryption was mostly implementedin expensive hardware at the data link layer. The development of the worldwide web resulted in broad use of cryptography for e-commerce and businessapplications. The underlying enabling technologies are inexpensive fast softwarecryptography and open security protocols such as TLS (SSL), SSH and IPsecas introduced in the second half of the 1990s. In spite of this development, onlya small fraction of the Internet trac is encrypted. Most of this encryption issituated at the network or transport layer; the communication is protected end-to-end (e.g., from the browser in the client to the web server), from gateway togateway (for a VPN based on IPsec using tunnel mode) or from client to gate-way (e.g., a VPN for remote access to company networks).