Introduction to Cryptography
Cryptography one of the most important means of maintaining privacy and secrecy. Strong cryptography may protect your information against industrial espionage, unlawful surveillance and similar threats.
To a company, inventor or scientist information theft may cause huge financial losses. To an individual, it may result in a major private intrusion.
There is no single solution for protection against governments, authorities, companies or individuals who at a certain time decide it is their right to take away yours. But there are tools to aid you in an unjust world. Cryptography is one of them. Cryptography is the science of how you can tell your friend what you want, in a room full of untrusted, unknown people, and knowing that only your friend can understand what you say. Cryptography is also to know that the letter your friend has written to you truly comes from your friend and not someone else. Cryptography is the science about securing your data and data flows.
Some nations have intentionally attempted to distribute weak cryptography; cryptography with back doors (hidden weaknesses) or with escrow technologies which allows intelligence agencies and law enforcements to decrypt them as they wish. This weak cryptography offers little if any supervision by public or court of law. With weak cryptography, you cannot know if your rights are violated.
Your have few ways to protect yourself against weak cryptography but the general rule is that if possible only use Open Source software, where the code is open for public examination, Open standards where it’s publicly documented how a program is supposed to work, and well known algorithms which have been around for years without weaknesses found.
Cryptography basics
The base for understanding cryptography and it’s applications is to understand the different kinds of cryptography and what usages it has. Also, you must be aware of that it takes time (years) and public analyzes of algorithms before an algorithm can be considered secure. Thus, we list some (but not all) of the strong algorithms available.
Cryptoanalysis
You cannot prove an algorithm secure, thus cryptographers talk about “strong” algorithms, and “weak” algorithms. A “weak” algorithms does not survive public and professional analysis for years, but a “strong” algorithm has survived at least a few years without serious flaws being found. Strength of an algorithm can be supported by proofs that it withstands certain attacks, but it alone is not enough to consider an algorithm strong.
A cryptographer must thus also be a “cryptoanalyst”, someone who knows how algorithms are being broken. He must not only design his algorithms and implementations to withstand known attacks, but he must also attempt to anticipate mathematical advances, new ideas, and improved computing power which may make new attacks possible. He should document the reason why he thinks his algorithm would survive the present and future threats – why he thinks cryptoanalysts will fail to break his algorithm in, say, the next 50 years.
As you can imagine, to protect yourself against cryptoanalysis is one of the hardest possible tasks. We will not describe how as it is beyond our skills, but we sum up with a table of possible exploits cryptoanalysis may result in, and a page about cryptoanalysis of trivial cryptographic algorithms.
Further referenceses
For more reading on cryptography, read “Applied Cryptography” by Bruce Schneier. It has been a great aid for a lot of people to understand cryptography, and has been used partly used to fresh up my memory (any error is on my side). The book also contains academic references.
Further referenceses, links
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Counterpane Systems — meet Bruce Schneier and his co-workers on a cryptography company.
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RSA Data Security — one of the most famous cryptography companies, the creators of the RSA algorithm and several other well known cryptoalgorithms.
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National Security Agency (NSA) — visit the American organization who works with making the world secure and unsecure at the same time!
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Jya’s Cryptome — has the latest about security (NSA is actually reported monitoring this site regularly!)
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ScramDisk – cryptographic softwares and source codes for Borland Delphi.
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FreeS/WAN – is a solution for encrypted TCP/IP networking.
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SSH – offers solutions for encrypted TCP/IP networking. Most famous for ssh/sshd, the de facto standard for encrypted Unix logins.
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The end of privacy: The surveillance society from the economist.
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Press release from the Swedish Foreign Department, about Swedish cryptopolicy.
- Leif Pagrotsky’s response and clarification of Swedish policies. (Pagrotsky is the minister of commerce)