Chapter 6 · XOR function in cryptography
This chapter focuses on the XOR function as the cryptographic primitive that enables mathematically provable secrecy in the one-time pad. It first explains XOR as a Boolean operation that is easy to implement in digital hardware and central both to encryption and to message-authentication mechanisms.
The chapter then discusses the one-time pad in detail. It explains the three classic conditions for absolute secrecy: the key must be truly random, at least as long as the plaintext, and never reused. Under those conditions, XOR-based encryption is information-theoretically secure. The text also links XOR to MAC constructions that support integrity and authenticity.
A further contribution of the chapter is its treatment of storage encryption. It reviews XTS mode and proposes extensions intended to move storage encryption closer to one-time-pad principles. These variants—XTSO, XTSC, and true OTP mode—are presented as ways to reconcile practical data storage requirements with the security logic of one-time-pad-like processing.
- Defines XOR as a core logical operation
- Explains why OTP achieves provable secrecy
- Connects XOR to integrity and authenticity tools
- Reviews XTS for storage encryption
- Introduces OTP-oriented XTS extensions