Bitcoin Is No Paradise for Criminals

This brief article helps to clear up a common misconception about Bitcoin. Bitcoin is frequently portrayed as the chosen currency of crooks. There is no doubt that criminal activity has been associated with the Bitcoin ecosystem, but I would argue that cash is still king in the underworld. Jason Bloomberg writes in his recent Forbes article [1]: “Professional criminals’ number one requirement is a secure, anonymous way to move and store money, and Bitcoin fits the bill perfectly.” There’s a really big problem with that statement: it is simply and provably not true. It displays ignorance in how Bitcoin really works. In fact, Bitcoin is a potential nightmare for criminals. If they want to minimize getting caught, they’ll stick with

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Ripple vs. Bitcoin (security and privacy)

by Albert Szmigielski Fairness Bitcoin’s public ledger, the blockchain, allows any entity to check the transactions in the system. Furthermore, as long as 66.7% of the miners are honest no entity can change the history of transactions. Both of those properties ensure fairness. However in light of recent research into attacks on the Bitcoin network, several double-spending attacks have been identified. Such attacks negate the fairness property. Ripple has not been studied as extensively as Bitcoin. Ripple relies on ledgers that can be inspected. However, Ripple’s validating nodes are currently run and therefore controlled by Ripple labs, it seems that there are not sufficient incentives to run a Ripple validating node. Double spending attacks have not been identified in Ripple

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Countermeasures to information leakage of Bloom Filters in Bitcoin lightweight clients

by Albert Szmigielski Keep the state about the seed. When a device restarts and uses a different seed (as well as other filter information) to create a new bloom filter, the probability of having the same false positives is very low. Therefore an adversary with access to two bloom filters from the same client, created with different seeds can easily check if addresses appear in both filters. If so, they are addresses of the SPV client, otherwise they are false positives. Keeping the state about the seed would not give that advantage to the adversary. When an SPV client restarts it will create the exact same filter. Disadvantages The need to store a seed and some other information about the

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Bitcoin Security and Privacy

Bitcoin Security and Privacy By Albert Szmigielski Bitcoin is a decentralized currency and payment system. In order to be an effective and secure payment system it should satisfy several security requirements. The first of these requirements is fairness. On the surface Bitcoin meets the property as users can only sign for coins that they control. However, upon further examination of recent research we do see that several double-spend attacks have been performed that would negate the fairness property of Bitcoin. On the other hand Bitcoin does satisfy resistance to impersonation attacks very well. No one can obtain the private keys (assuming they are stored properly and securely) of another person in the system to sign their transactions. As a result

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