This book is an absolutely updated and comprehensive introduction to cryptography, network security applications, and system security.

The new topics in the third American edition include extended coverage of the Public Key Infrastructure (PKI) infrastructure, a new presentation of stream encoders, including the widely used RC4 algorithm, extensive coverage of the Advanced Encryption Standard (AES), a detailed introduction to Distributed Denial of Service (DDoS) attacks, as well as new references to the international security evaluation criteria initiative (Common Criteria).

Among many other things, the book includes the following:
- Symmetric encryption and confidentiality of messages (symmetric encryption algorithms, stream encoders and RC4, key distribution)
- Public key cryptography and message authentication (secure hash functions and HMAC, principles and algorithms of public key cryptography, digital signatures)
- Authentication certification applications (Kerberos, X.509 certification service, public key infrastructure, Kerberos encryption techniques)
- Email security (Pretty Good Privacy - PGP, S/MIME, data compression using ZIP, radix-64 conversion, random number generation in PGP)
- IP security (IPSEC overview and architecture, certification header, security payload encapsulation, security associations combination, key management, internetworking and Internet protocols)
- World Wide Web security (host and transport level security, secure electronic transaction)
- Network management security (SNMP protocol, SNMPv1 community service, SNMPv3 protocol)
- Intruders (intrusion detection and password management, the fallacy of the base rate)
- Malicious software (viruses and related threats, countermeasures, distributed denial of service attacks)
- Firewalls (design, trusted systems, security evaluation criteria)