Percy Reyes

PhD Candidate in Computer Science (Cryptography) 

Loughborough University, England, UK 

Systems Engineer & Computer Scientist

Owner/Founder at SQLEngineers

"As within so without..."

Research Areas: Cryptographic Boolean functions, planar functions, APN functions, number theory, finite fields, stream ciphers, algebraic aspects of cryptography. Also, database query processing, distributed database systems, database security, database performance, database reliability engineering. 


  • PhD candidate in Computer Science (cryptography) at Loughborough University, England, UK
  • DR Representative for Computer Science & the DR Representative Lead for School of Science at Loughborough University, UK (2020–2021)
  • Master (with distinction) in Advanced Computer Science at Loughborough University, England, UK (2018–2019); I won the MSc project prize with the highest mark
  • Bachelor degree (with distinction) in Systems Engineering at National University of Trujillo, Peru (2003–2007)
  • Senior Microsoft SQL Server database administrator for over 15+ years
  • Owner/founder of SQLEngineers – a company that provides 24x7 remote SQL DBA services, based in Lima, Peru
  • Certified database professional since 2005 (official transcript is here — transcript ID: 710696, access code: 71069600)
  • Three-time awarded Microsoft Data Platform MVP (Jan 2015 – Jul 2018)
  • International Speaker and Technical Writer of SQL Server Administration tips for over 12+ years
  • Contributor and Author at MSSQLTips.com
I hold the following Microsoft certificates:
  • MCSE Data Management and Analytics (issued Aug 2018)
  • MCSA SQL 2016 Database Administration (issued Aug 2018)
  • MCSA SQL 2016 Database Development (issued Aug 2018)
  • MCP Microsoft Certified Professional (renewed 2012, issued Apr 2012)
  • MCITP Database Developer on SQL Server 2005 (issued Oct 2008)
  • MCTS SQL Server 2008, Implementation and Maintenance (issued Jul 2008)
  • MCITP Database Administrator on SQL Server 2005 (issued Dec 2007)
  • MCTS SQL Server 2005 (issued Oct 2006)
  • MCP Microsoft Certified Professional (issued Sep 2005)

My experience as a Sr. database administrator

I am a senior SQL Server database administrator (DBA) with over 15+ years of extensive experience managing critical database servers running on SQL Server [versions 6.5, 7.0, 2000, 2005, 2008, 2008 R2, 2012, 2014, 2016, 2017, 2019]. Most importantly, I have an excellent command of all SQL Server database administration topics and, even more so, I am very passionate about SQL Server internals. Moreover, I am used to working with all sizes of databases for many multinational companies. So, I will make your database run significantly better resulting in your mission-critical business applications running smoothly – it all means your business will be more productive.  

Additionally, I am the owner of SQLEngineers, a company to provide 24x7 Remote SQL Server DBA services, which represents the best way to manage your databases proactively, cutting costs and improving the performance. (For more information in detail, you can have a look at DBA Services.)

My key skills as a database administrator:
  • in-depth knowledge and strong experience in database administration of SQL Server including: 
    • installation/upgrade of the database engine and client tools
    • allocation system storage and planning future storage requirements for the database system
    • database maintenance — indexing, statistics, integrity checks, database deduction
    • storage engine, backup/restore operations, FileStream, partitioning very large tables
    • optimization/performance tuning, in-memory OLTP 
    • security and compliance, monitoring 
    • high availability/disaster recovery — replication, log shipping, mirroring, Always-On, failover clustering 
    • troubleshooting/internals issues
  • in-depth knowledge of database theory, Structured Query Language (SQL), T-SQL, and SQL Server internals
  • good understanding of distributed computing architectures (client/server, internet/intranet), underlying Windows operating systems, memory management, storage technologies, disk arrays, NAS/SAN, TCP/IP networking
  • great object-oriented programming skills
  • excellent communications and teamwork skills
  • ability to handle pressure and conflict
  • experience leading and mentoring technical staff
  • innate ability to take initiative
  • a proactive approach to work without close supervision
  • high-performance working under the pressure of demanding deadlines
  • ability to simplify complex problems and resolve them quickly
  • good experience working with ITIL
  • good documentation skills.

Following my new passion for cryptography

Besides my passion for database systems, I am keen on cryptography, that's, algorithmic cryptanalysis, cryptographic Boolean functions, planar functions, APN functions, number theory, finite fields, stream ciphers, and other algebraic aspects of cryptography. Since I am more interested in the mathematical side of cryptography, I did my dissertation on cryptography, as part of my Master in Advanced Computer Science at Loughborough University in 2018, namely, research on cryptographic Boolean functions to prevent algebraic attacks. I am currently doing a PhD in Computer Science (cryptography) at Loughborough University, UK.

Boolean functions are used as components in the design of many symmetric ciphers (for example, S-boxes for block ciphers like AES, or the non-linear component of stream ciphers). These functions have to satisfy certain properties to resist known cryptographic attacks. More precisely, block ciphers and stream ciphers have to face multiple types of attacks such as differential attacks and algebraic attacks, respectively. These attacks exploit vulnerabilities in some properties of Boolean functions. 

Therefore, my PhD studies are intended to work out some solutions to make cryptography Boolean function properties resistant to certain attacks. Also, in this project, I consider a family of such properties, called PN (Perfect Non-linear), APN (Almost Perfect Non-linear) and GAPN (Generalised APN). There are some well-known functions with these properties, but recently new methods of constructing such functions have been proposed, involving a combination of theoretical results and computer search. I aim to further develop these methods and obtain new such functions.

I make massive use of C programming language for cryptography.

How I am living my best life

To begin with, I am a very happy man, and I live my best life evolving and growing each day, feeling stronger than ever, developing myself from within. I am very spiritual but not religious — as within so without. I am a down-to-earth man with a great personality and youthful enthusiasm, a bit chatty every so often and happy-go-lucky as well. Above all, I have got principles, and my most important attributes are integrity, honesty and trustworthiness. 

I am always willing to do my best to achieve all my goals since I strongly believe in the beauty of my dreams. I have no fear of failure; I always try to go beyond fears as I believe better things are on the other side. Also, I am single-minded and sold on the idea of everything one can achieve depends on our determination and dedication. "Believe and you will find your own way" is my most inspiring quote.

Particularly, I am most comfortable in environments where things are constantly changing, evolving, and personal freedom are emphasised. Likewise, my approach to work and life is driven by advancement, curiosity and solutions since I am an optimistic thinker who constantly adapts to new expectations. Thinking big, going global, and being open to change is part of my personality. 

I deeply love reading books — I spend most of my time reading maths and computer science books — and therefore doing research, but I always make time for home workouts (particularly like kettlebell workouts), meditation, and playing the electronic keyboard. Despite not being very interested in movies, The Lord of the Rings and The Hobbit are my favourite ones.

I find enjoyment in travelling the world; my favourite place ever visited was England where I had unforgettable and life-changing experiences. I have been there twice; I lived in Manchester, London, and Loughborough. I've been to Scotland, Northern Ireland, Wales, Colombia, and Brazil as well.

My love for books

I have a special place in my heart for books. I cannot imagine living my life without reading books; it is just something I have always been doing almost every day — I can't help but reading! I hold a special pile of books on different topics — such as database management, philosophy, mathematics, physics, and cryptography. What's more, I hold almost a bit more than two hundred books in my personal library at home; I am sure this number will increase in the coming years. So, I call myself a book lover. 

I started buying some of these books when I was in England in 2016, then I carried on buying the rest of them while doing my Master at Loughborough University in 2018. You're not going to believe this! — I bought almost one hundred books at that time – Yes, I know, I just got carried away; I do love reading paper books and therefore being in England for me was a golden opportunity to let my passion fly! I cannot regret that moment now; I have never done it and I will undoubtedly buy more books in the foreseeable future. It is just so exciting to live among lots of books! — can you believe it?

My favourite book is Alan Turing: The Enigma, while my favourite author is Bruce Schneier, whose books are completely engrossing — I did read them all — which are highly recommendable for those of you interested in computer security, cryptography, code-breaking, and security issues.