Criptografia

Criptografia.cat is an educational resource focused on explaining cryptography, the science of protecting information through secret writing. Its central offering is La criptografia que et cal saber, a structured book that introduces readers to the foundations, history, mathematics, and practical techniques of modern cryptography. The material is organized into chapters and made available for download, with chapter descriptions that help readers explore the topics covered.

The book progresses from historical ciphers and modular arithmetic to stream and block ciphers, including AES, hash functions such as SHA-256, public-key systems such as RSA and ElGamal, and digital signatures. Further chapters cover public-key infrastructures and digital certificates, elliptic-curve cryptography, pairings, and cryptographic protocols. The resource also introduces cryptanalysis and explains its role in evaluating the security of cryptographic systems. By combining conceptual explanations, mathematical foundations, and descriptions of widely used algorithms, Criptografia.cat offers a reference for people seeking a systematic introduction to the subject. The site includes navigation for its chapters, downloads, information about the project, and contact details.