SDLerner

Bitcoin design analyst

Homepage: https://bitslog.wordpress.com

The Bitcoin Freeze on Transaction Attack (FRONT)

Two month passed since my last post and the reason is I’ve been terribly busy working for Coinspect and also helping with Bitcoin Core security. A rainy Sunday evening is a great moment to write, so here is my new post, with some new thoughts. People are trying to understand the security guarantees Bitcoin provides. […]

, ,

3 Comments

Blockpad: Improved Proof-of-work function with decentralization incentives

A few posts ago I presented BlockPow, an example of a proof of work function that practically reduces the incentives for users to join mining pools. The shorter the block interval, the best it works. Let’s first summarize the idea behind BlockPow:¬† if a miner tries to join a pool, then he incur in overhead […]

, , ,

Leave a comment

Preventing Geographical Centralization of Cryptocurrency Mining with the LIMIO protocol

There has been much discussion recently about how to prevent mining pools. There are theoretical and practical¬†approaches. Nevertheless preventing mining pools is not the same as preventing geographical centralization. Mining pools incentives are: Reduce payoff variance. Reduce resource usage. Normally Bitcoin node would require more resources (memory,disk, bandwidth) than a pooled miner. Reduce exposition to […]

, , , ,

Leave a comment

Preview of Identiva PassKey: vote for us for the Cisco IoT Challenge

A friend of mine and me have developed a new technology and device that we think can be a game changer in web authentication. I’d like you take a look and vote for as for the Cisco IoT Challenge (you must register first to vote….#?@!) We’re launching a new company (Identiva Security) to develop the […]

Leave a comment

July 2009 Mystery Solved

A year ago I analyzed a mining pattern that suggested a correlation between Satoshi computer and another computer mining at the same time. This relation had been highlighted to me by a another user in the forums (I don’t remember who) . From this correlation I conjectured that the same computer was mining both patterns […]

, ,

Leave a comment

How you will not uncover Satoshi

Computer forensics is the science of finding evidence in computers and digital documents, and when a hacker perform forensics, better be prepared for the unknown. Satoshi did many things in order to try to stay anonymous: he used Tor, he used anonymous e-mail servers, he did not disclose personal information in posts and probably he […]

, ,

4 Comments

Theoretical and Practical Nonoutsourceable Puzzles

The fact that GHash.io has reached twice 51% of the Bitcoin hashing power this year has pushed scientist and alt-coin creators to find for other proof-of-work puzzles that discourage mining coalitions. Several months ago I read the foundations of Nonoutsourceable Puzzles as proposed by Andrew Miller, and now his paper (working with Elaine Shi, Jonathan […]

, , , ,

Leave a comment

Deterministic Signatures, Subliminal channels and Hardware wallets

A subliminal channel in a signature scheme allows a signing party to send a covert message to an authorized receiver of signed messages without anyone else noticing it. One property of ECDSA, DSA and many similar digital signature schemes (such as Schnorr) is that they need to produce, for each signature generation, a fresh random […]

, , ,

Leave a comment

NimbleCoin can be Bitcoin’s Best Friend

The debate of what will happen with Bitcoin hashing power when the reward is halved around August 2016 is starting to boil in the bitcointalk forums. Some questions have been risen about the security of CPU-friendly alt-coins, such as LiteCoin and DogeCoin in the long run. The problem was summarized in one sentence: If the […]

, ,

Leave a comment

DECOR+

In my previous post I presented the DECOR protocol. One of the assumptions I did was that the amount of coins each miner earned in competing blocks was approximately the same. This could be true for cryptocurrencies with never ending block subsidies (inflationary designs) because the block subsidy may be an order of magnitude higher […]

,

Leave a comment