• Hamming codes

    April 22, 2014

    The Huffman Code is a family of error correcting codes. To the information bits is added parity bits that depend fully and uniquely on the information bits. If there are bit errors in transmission, the balance between the information bits and parity bits, in fact, the balance between any of the bits, will be disturbed [...]

  • Chaum’s E-cash

    April 21, 2014

    This follow the exposition by Mira Belenkiy in The Handbook of Financial Cryptography, edited by Burton Rosenberg. E-cash is one of many forms of financial instruments, an alternative to cash. Cash itself isn’t well understood. There are those that think of cash as an easy form of gold transfer, called the gold standard, and those [...]

  • Information and stuff

    April 16, 2014

    Last time we went over the Shannon-Hartley theorem. I’d like to summarize in simpler terms. Communication is the transport of information. Information is measured in bits, and is the measurement of the least number of yes-no questions whose answer will identify a message from among a fixed set of possible messages. For instance, if the [...]

  • Bit security for DLOG

    April 5, 2014

    The DLOG assumption is that given a prime p, and a generator α of the group of units mod p, <α>=Zpx, that the map αi → i is not polynomial-time computable. However it is not true that every bit of information about i is unattainable. Most notably, the parity of i is easily determined. If [...]

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