One emerging threat to Public Key Infrastructures is the possible development of large-scale quantum computers, which would be able to break the public-key cryptosystems used today. Several possibly post-quantum secure cryptographic algorithms have been proposed but so far they have not been used in many practical settings. The purpose of this thesis was to find post-quantum digital signature algorithms that might be suitable for use in Public Key Infrastructures today. To answer the research question, an extensive literature study was conducted where relevant algorithms were surveyed. Algorithms with high-grade implementations in different cryptographic libraries were benchmarked for performance. Hash-based XMSS and SPHINCS, multivariate-based Rainbow and lattice-based BLISS-B were benchmarked and the results showed that BLISS-B offered the best performance, on par with RSA and ECDSA. All the algorithms did however have relatively large signature sizes and/or key sizes. Support for post-quantum digital signature algorithms in Public Key Infrastructure products could easily be achieved since many algorithms are implemented in cryptographic libraries. The algorithms that could be recommended for use today were SPHINCS for high-security applications and possibly BLISS-B for lower security applications requiring higher efficiency. The biggest obstacles to widespread deployment of post-quantum algorithms was deemed to be lack of standardisation and either inefficient operations compared to classical algorithms, uncertain security levels, or both. / Ett nytt hot mot Public Key Infrastructures är den möjliga utvecklingen av storskaliga kvantdatorer som kan knäcka de asymmetriska kryptosystem som används idag. Ett flertal eventuellt kvantsäkra algoritmer har presenterats men de har än så länge inte sett mycket praktisk användning. Målet med detta examensarbete var att försöka identifiera eventuellt kvantsäkra signaturalgoritmer som skulle kunna lämpa sig för användning i Public Key Infrastructures idag. För att besvara forskningsfrågan gjordes en utredande litteraturstudie där relevanta signaturalgoritmer identifierades. Därefter prestandatestades de algoritmer som var implementerade i kryptografiska bibliotek. De algoritmer som prestandatestades var de hash-baserade algoritmerna XMSS och SPHINCS, flervariabel-baserade Rainbow och gitter-baserade BLISS-B. Resultaten visade att BLISS-B hade bäst prestanda och att prestandan var i nivå med RSA och ECDSA. Samtliga algoritmer hade emellertid relativt stora signatur- och/eller nyckelstorlekar. Eventuellt kvantsäkra algoritmer skulle redan idag kunna stödjas i Public Key Infrastructures eftersom många algoritmer finns implementerade i kryptografiska bibliotek. SPHINCS kunde rekommenderas när hög säkerhet krävs medan BLISS-B möjligtvis skulle kunna användas när lägre säkerhet kan tolereras i utbyte mot bättre prestanda. Största hindren för utbredd användning ansågs vara en brist på standardisering samt ineffektiva operationer jämfört med klassiska algoritmer och/eller tveksamma säkerhetsnivåer.

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Submitted by Valdinei Souza (neisouza@hotmail.com) on 2015-10-06T20:49:45Z No. of bitstreams: 1 DISSERTACAO LEONARDO COM CAPA.pdf: 1273238 bytes, checksum: 45cf92815aa55e73d2858f881116bc64 (MD5) / Approved for entry into archive by Urania Araujo (urania@ufba.br) on 2015-11-13T17:59:16Z (GMT) No. of bitstreams: 1 DISSERTACAO LEONARDO COM CAPA.pdf: 1273238 bytes, checksum: 45cf92815aa55e73d2858f881116bc64 (MD5) / Made available in DSpace on 2015-11-13T17:59:16Z (GMT). No. of bitstreams: 1 DISSERTACAO LEONARDO COM CAPA.pdf: 1273238 bytes, checksum: 45cf92815aa55e73d2858f881116bc64 (MD5) / Esta dissertação buscou explorar a validação jurídica dos processos de informação jurídica ou juridicisada pelo referido processo. São dois, portanto, os objetivos: conceituar os processos de informação jurídica e conceituar os processos de sua validação jurídica. Buscou-se, pois, recompor ponto a ponto o itinerário do surgimento à validação jurídica das tecnologias de validação da informação desde as marcas pessoais pré-históricas até a tecnologia criptográfica assimétrica que proporcionou o advento da assinatura digital. Os conceitos de forma, de norma e de padrão são analisados com o fulcro na problematização do tema da validação nos processos humanos de comunicação da informação. / Abstract- This paper means to explore legal validation of information processes, wether the information is legal or legalized by its validation process. It had, thus, two main objectives, i.e.: to conceptualize legal information processes and to conceptualize legal validation processes pursuant to the latter. A step-by-step trace of the path from the advent to the legal validation of information processes – since the beginning of it as pre-historical personal marks, up to the latest asymmetric cryptographic technologies that allow the upcoming of digital signatures. The concepts of norm, form, pattern and standard are thus analyzed, meaning to further comprehend the ever-evolving quest for validation in human information communication processes.