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Search found 8 results on 1 pages for 'drelihan'.

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• Pohlig–Hellman algorithm for computing discrete logarithms

  - by drelihan

  Hi Folks, I'm working on coding the Pohlig-Hellman Algorithm but I am having problem understand the steps in the algorithm based on the definition of the algorithm. Going by the Wiki of the algorithm: http://en.wikipedia.org/wiki/Pohlig%E2%80%93Hellman_algorithm I know the first part 1) is to calculate the prime factor of p-1 - which is fine. Howeever, I am not sure what I need to do in steps 2) and 3). Can someone help with explaining this in plain english (i) - or pseudocode. I want to code the solution myself obviously but I cannot make any more progress unless i understand the algorithm. Note: I have done a lot of searching for this and I read S. Pohlig and M. Hellman (1978). "An Improved Algorithm for Computing Logarithms over GF(p) and its Cryptographic Significance but its still not really making sense to me. Thanks in advance

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• Member variable pointers to COM objects

  - by drelihan

  Hi Folks, Is there any problem with keeping member variable pointer refernces to COM objects and reussing the reference through out the class in C++. Is anybody aware of a reason why you would want to call .CreateInstance every time you wanted a to use the COM object i.e. you were getting a fresh instance each time. I cannot see any reason who you would want to do this, Thanks, (No is an acceptable answer!!!)

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• Refactoring a C# derived class with method dependancies

  - by drelihan

  Hi Folks, I want to get your opinion on this. I have a class which is derived from a base class. I don't have control over the code in the base class and it is critical to the system that I derive from it. In my class I inherite two methods that are critical to the system and are used in pretty much every function, many times. I intend to refactor this derived class and extract some classes from it - this won't be a problem. What I'm not sure about is, is it worth extracting class if I have to constantly make call backs to my main class to access the two methods (or public wrappers to the methods)??? Thanks

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• Career Plan: The one year plan. The three year plan.

  - by drelihan

  Hi Folks, I work as a developer however I only recently began developing full time having worked for 5 years in various roles. When it comes to career planning I think I pretty much agree with The Journeyman to Craftsman model coined in The Pragmatic Probrammer and used by Bob Martin. I see myself as a journeyman and I won't call myself a "good" (for want of a better word) until I re-evaluate my skills in 5 years time. However, as part of our careers we are encouraged to make one and three year plan with specific goals that we should hit. Unfortunately, my goal is this: Write clean code that solves a problem and is easy to maintain. From a technology point of view I want to know C++ and .net programming inside out(C#, WCF etc..) But that's it. That's my plan. Is this enough? So although there's a great discussion on what people should do with their career: http://stackoverflow.com/questions/11313/career-planning-any-tips My question is this: What's your one year plan? What's your three year plan? And am I being naive with my career? Thanks,

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• Mathematical attack on the Digital Signature Algorithm

  - by drelihan

  Does anybody know the mathematics behind an attack on DSA where modulus p has p-1 made up of only small factors. In reality, this would not happen as the key generator would guarantee that this is not so. There is much information on the web on generating good input paramters for DSA so that it is hard to crack but no information on how you find X if modulus p has p-1 made up of only small factors.

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• Worked Example of Digital Signature Algorithm

  - by drelihan

  Hi Folks, Does anybody have a DSA worked example with simple values on how to calculate r,s and verify v == r. As this standard has been around awhile and is implemented in librarys e.g. the Java Cryptography Extension I'm finding it very hard to find an example of how the algorithm works. Compute r=(gk mod p) mod q Compute s=(k-1 * (x * r + i)) mod q Verifying a signature; again i is the input, and (r,s) is the signature. u1 = (s-1 * i) mod q u2 = (s-1 * r) mod q v = ((gu1 * yu2) mod p) mod q If v equals r, the signature is valid. Thanks,

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• What is the Difference between a Hash and MAC (Message Authentication code)?

  - by drelihan

  Hi Folks, What is the Difference between a Hash and MAC (Message Authentication code)? By their definitions they seem to serve the same function. Can someone explain what the difference is? Thanks

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• Use Case diagrams as a requirements gathering tool for new functionality - particularly in systems t

  - by drelihan

  Hi Folks I'm interested in persuing the idea of using Use Case Diagrams as a tool for collecting user requirements. However, it will be for new features as opposed to developing a system from scratch. Also, the system only has a small level of user interaction - most of the actors will be external systems. I want to know what people's experiances have been with using this method of gathering requirements. How did your customers respond to the change and was it positive? Did it just not work for anybody? Thanks,

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