Seamless Transition to Post-Quantum Resistant: Implementing Digital Signatures for PDF Documents Using PQ Algorithms.

During these past years, the internet has had an enormous importance in current society. Large amounts of information are shared on this virtual agora, in which people interacts all across the globe at full speed. Nevertheless, not only it is crucial to guarantee this communication, but also its security an truthfulness.

For this reason, some algorithms, for both Digital Signature and Encryption purposes, have been conceived. Since now, RSA, DSA or ECC have guaranteed this security. These systems, based on complex problems in which classical computers cannot solve, have been useful for most applications. Nevertheless, these communications will not be longer secure. These algorithms have been proof to be broken using Quantum Computers. Even though these computers will not be available until a couple of decades, a change in the long term should be done. In order to solve this problem, the mathematical community has investigated and conceived a large amount of algorithms, in which some of them are still under test and analysis.

Nonetheless, not only is the security of communications uncertain, but also its integrity. Digital Signatures Schemes, which enable to demonstrate the identity of a person or a group, are based on these algorithms. For example, Personal Identity Cards or PDF Documents as a property deed will be impossible on the long term.

Although some advancements have been done, due to the newness and constant development of this field, not too much implementation has been done.

The main aim of this thesis is to study, create, develop and analyse a program which enables Digital Signature Scheme on PDFs using different Post Quantum (PQ) Algorithms, mainly CRYSTALS-Dilithium, Falcon and SPHINCS+. This implementations will be done based on different standards and technologies used for standard algorithms. Moreover, other multiple signature schemes as Composite or multiple signerInfos are going to be implemented and studied.