# Tag Info

22

There are several uses of cryptographic algorithms in the protocol. Accounts/Transactions To move money from one account to another, you need to collect some data (the previous transaction(s) which got you the money, the target account, the amount you want to transfer) and sign them, using the private key which belongs to your account. For this signature ...

20

For such a scheme to work, if I have some currency, I have to be able to give it to Abel and I have to be able to give it to Beth, but I have to be unable to give it to both Abel and Beth. This means that giving the currency to Abel has to somehow make me unable to give the currency to Beth even though I previously could do that. There are three mechanisms ...

18

I don't believe that there's any way to generate the vanity hashes without iterating. In base 58, there's $\log_2(58) \approx 5.858$ bits per letter, so fixing 8 letters would need in average $58^8/2 = 2^{\log_2(58)·8}/2 \approx 2^{46}$ iterations. Note that Bitcoin addresses always start with a 1 by convention (this comes from the version field), and the ...

5

Most of what the bitcoin system does consists of using well-known algorithms for their intended purposes. It is unlikely that there will be a fundamental or algorithmic problem in these parts of the system. There may be a software bug in the reference client, of course. There once was such a bug -- an overflow bug that allowed people to create transactions ...

5

Designing such signature schemes from scratch without having strong experience is very likely to fail and very dangerous (see the tons of bad papers out there being accepted to "dubious" conferences and journals). Your proposed scheme Your verification relation is to check if: $sP - Q + R \stackrel{?}{=} zP + mP$ where $Q$ is the public key of the signer ...

3

Depends on what you mean by secure. If you merely want the ability to detect and then presumably punish double spending, you can do that in a way that is secure and anonymous: double spending reveals enough information to provably identify the user. Since honest users don't double spend, they are still anonymous. This is used in Camenisch et al.'s Compact E-...

2

Blind signatures are online by definition. They involve at least two independent parties that interact during the signature generation process. A protocol is "online" if a successful execution of the protocol requires an exchange of messages between two or more independent parties. Consequently, no application of blind signatures, including a digital cash ...

2

The first google-entry brought up this paper. To answer your questions: An anonymous signature is a signature that is unforgeable in the classic sense. But without the message no informations about the signer can be extracted from the signature even if brute-force of all public keys is possible. If I'm understanding things correctly, a blind signature ...

2

It may be an interesting avenue to explore. I've read the highlight reel of the digital cash literature but I do not know it well enough to know how well these issues have been addressed. A few things to consider for #2: In a quick read of Lucre, it seems that the payee does no verification before passing the coin onto the mint. It seems, if the mint has ...

2

Zerocash is such a decentralized currency scheme. A Zerocash transaction completely hides the origin, amount, and destination of the transaction. It achieves this via a cryptographic tool called a zkSNARK, which effectively allows you to prove the validity of a statement in "zero knowledge", i.e. you leak nothing more than the truth of the statement. In ...

1

http://faircash.org/technology/teleportation.html Due to the Digital Coin concept, a value transfer between payer and payee is realized by transferring ownership of the eCoin. An essential part is the way how this transfer is conducted: Following the cash paradigm, it needs to be done peer-to-peer and offline in a repeatable way. Such a transfer is ...

1

There are a number of known attacks that can occur right at the point of block formation. The most recent one, transaction malleability, wasn't really the reason for Mt Gox's demise, but it surely created some problems (and for the most part has been fixed). Unfortunately there is a theoretical, but pretty convincing theory, about what has been called cartel ...

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