Wednesday, January 24, 2018
For fun, I proposed a crossword puzzle-based signature scheme. It suffers a rather serious limitation. I expect one can securely sign a single bit of data in a one-time fashion with it, but security falls apart as you go above a few bits. Even a single bit likely requires two puzzles, one solved to indicate a 1 and the other solved to indicate a 0 (as partial solutions to the whole key degrade the key massively).
The attraction of NP complete problems is the idea that the difference in complexity of signing, versus complexity of forging, can be made arbitrarily large, and that we have very high assurance this is true. That by itself does not guarantee the system is practically secure with today's technology, nor does it (by itself) say what signing complexity must be chosen for the complexity of attack to exceed some target threshold, but it seems like a good first step. Any such problem can be used to sign one bit, but can any such problem be scaled to much more than that? For any given number of bits x, one can make a composite key out of 2x smaller keys, so if we fix X in advance (at any value!) the answer is yes. But again, simply being NP complete does not guarantee security in practical applications on today's hardware. It seems improbable that crosswords would be a good way to secure terabytes under this scheme.
Friday, January 12, 2018
Sunday, December 24, 2017
One often sees the false assertion that bitcoin has no intrinsic use in the sense that one can use gold to make jewelry (although such use a counts for a tiny percent of overall market cap in gold.)
Bitcoin does have intrinsic uses. For example, one can encode a hash value of arbitrary data in a transaction for purpose of depositing that hash on the blockchain, which is an immutable record. Thus, it is like a trustless spin on a public notary. There are other intrinsic uses which leverage the double spend protections to implement trustless mechanisms for tracking transfers and exchanges of physical or other virtual assets, via rigorous analogy to bitcoin - by encoding representations in literal bitcoin.
When seeing the assertion that there are no intrinsic uses, it may be worth asking how well researched the piece as a whole is likely to be. These uses have been recognized for some years now.
Thursday, December 21, 2017
Or... you can view a summary of the site, current as of 12/21/2017, here:
(Updated 12/8/2017 in response to a private email asking for clarification. I still intend to create a better description and analysis, with...
Asymmetric cryptography is a slightly dodgy proposition today, since all known asymmetric cryptosystems require introduction of at least one...
In 1976, Nobel laureate Friedrich Hayek proposed that money should be denationalized, such that privately issued moneys would compete over t...