cryptography Archivi - Page 2 of 3

One-Way and Trapdoor Functions: The Heart Of Modern Encryption

Introduction By definition, a one-way function is easy to compute but hard to invert. In other words, inverting a one-way function is equivalent to solving an intractable mathematical problem for...

Quantum Key Distribution (QKD) and Post-Quantum Cryptography (PQC)

14 Nov

Today the quantum attacks threat is a real danger. The protection of data and communications is linked to technologies that give future-proof answers, capable of thwarting threats with still partially...

Digital signature algorithms: present and future

21 Oct

Introduction and general structure In many ways, digital signatures are the digital equivalent of the handwritten signatures we all use every day. However, the main difference between the two is...

Key Negotiation in the Post-Quantum Era

09 Sep

Introduction Cryptography, understood as the set of schemes for protecting information, is typically divided into symmetric or private key cryptography and asymmetric or public key cryptography. Symmetric encryption involves schemes...

Cryptophones: what they are and how they work

05 Sep

The issue of mobile communication security highlights one of the weak links in the security chain of organizations. It is often the behavior of individual employees, not necessarily malicious but...

Leon Battista Alberti’s cipher disk

18 Jul

Leon Battista Alberti’s cipher disk, described in “De cifris” around 1467, is the first polyalphabetic encryption system. The device consists of two concentric discs, rotating relative to each other, containing...

Post-Quantum Cryptography (PQC): a classical solution to the quantum threat

13 Jul

Introduction Public key cryptography (or asymmetric cryptography) is one of the foundations on which all communication protocols are based. Starting from an insecure channel, these protocols must achieve multiple security...

The Caesar cipher

07 Feb

In cryptography, the Caesar cipher is one of the oldest cryptographic algorithms of which there is a historical trace. It is a mono-alphabetic substitution cipher, in which each letter of...

History of cryptography: the scitala

29 Nov

The scitala or scital (in ancient Greek: σκυτάλη, skytàlē, “stick”) is traditionally considered an encrypted and secret message that was sent by the ephors, the five supreme magistrates of Sparta,...

RSA Cryptography: history and uses

26 May

The RSA encryption is a public-key-based cryptosystem, named after Ron Rivest, Adi Shamir and Len Adleman who invented it in 1977. Clifford Cock had previously invented an equivalent system for...