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Questions tagged [cryptography]

Concerning the broad subject of cryptography and its narrow application in Bitcoin protocol and applications.

61
votes
4answers
21k views

What is a compressed Bitcoin key?

The standard Bitcoin client in version 0.6 apparently introduces compressed keys. What are they? Are there any drawbacks to using them? Any incompatibilities with older software? Reductions in ...
33
votes
5answers
11k views

Bitcoin Mining ASICs used for cryptographic application? Rainbow tables?

What is the potential that the ASICs being developed for mining could be used for other cryptographic applications such as building rainbow tables? I know that for instance those that crack GSM with ...
54
votes
4answers
6k views

Have any cryptography experts vetted the bitcoin source code?

Theoretically, bitcoin's open source nature makes it more resistant to bugs and exploits. However, due to the specialized nature of the code, even many programmers don't fully understand the ...
17
votes
2answers
9k views

ECDSA: (v, r, s), what is v?

Deterministically signing a Tx with RFC6979 returns v, r, s, where r and s are the 2 values used in standard ECDSA signatures. v = 27 + (y % 2), so 27 + the parity of r, as pybitcointools indicates. ...
12
votes
3answers
1k views

Can the Bitcoin network be used for cracking?

I'm assuming that the Bitcoin economy is rapidly building a computing cluster capable of unprecedented amount of hash searching. Would it be possible for an attacker to leverage this to crack other ...
8
votes
4answers
4k views

What exactly is generator G in Bitcoin's elliptical curve algorithm?

What exactly is the generator G in elliptical curve math? It is typically described as a point on the curve. Is this a tuple of values? What properties does it have?
8
votes
4answers
735 views

How can a bitcoin exchange prove its solvency while maintaining privacy?

What methods can an exchange website use to prove that it actually has all its users' bitcoins? These are the requirements: User privacy is a must. No one should be able to tell how many bitcoins an ...
7
votes
2answers
2k views

If SHA256 and/or RIPEMD-160 were broken, would all bitcoin addresses be compromised?

If not, what else would be needed to steal all funds from all people and completely break bitcoin? I bet some will say ECSDA gives bitcoin an additional layer of protection. I counter this by saying ...
6
votes
2answers
928 views

Bitcoin Blockchain in the Quantum computing era

The design and the evolution of quantum computers has been one of the "hot" topics during the last 20 years. My question is about the possible consequences of the rise of quantum computers (through ...
46
votes
2answers
23k views

What does the curve used in Bitcoin, secp256k1, look like?

I'm reading up on ECC curves and on many of them I see an illustration that looks like this What does the comparable curve in Bitcoin look like, or are all curves generally the same?
15
votes
6answers
3k views

Which Bitcoin-powered gambling sites are “provably fair”?

Through the spread of Bitcoin for the purposes of online gambling, the concept of "provably fair" games came more into the limelight. Which of the Bitcoin-powered gambling websites are provably fair? ...
6
votes
3answers
993 views

How do you derive the lambda and beta values for endomorphism on the secp256k1 curve?

You can see a little background about this on this bitcointalk post by the late Hal Finney. Beta and lambda are the values on the secp256k1 curve where: λ^3 (mod N) = 1 β^3 (mod P) = 1 As seen ...
9
votes
2answers
15k views

How to generate a Bitcoin Private Key Checksum

I want to understand how a bitcoin private key is made up. Looking at this graphical generator https://royalforkblog.github.io/2014/08/11/graphical-address-generator/#hello I understand step 1, how ...
2
votes
3answers
3k views

How proof of work prevents double spend

One article I am reading said that proof of work system is used in Bitcoin to prevent double spending. More particularly: Imagine we are protecting against double spending in following way. When Bob ...
4
votes
2answers
3k views

How to generate Ed25519 public key from private key using libsodium?

Not all crypto currencies are using secp256k1 technology for keypair generation and digital signatures. Curve25519 technology (frequently used to support ECDH key exchanges) is being used by a few ...
4
votes
1answer
392 views

What are the weakest cryptographic guarantees in Bitcoin?

I read in this Github pull that Bitcoin relies on weaker cryptographic guarantees than SHA256. What are the weaker cryptographic guarantees being referred to? Could it be that RipeMD is 160 bits? ......
3
votes
1answer
580 views

The compressed public key byte header

I've noticed that compressed public keys are always either 0x02 or 0x03, but what exactly determines whether it's 0x02 or 0x03? I can go look at the OpenSSL code to answer this, but I'm hoping someone ...
-1
votes
2answers
506 views

Litecoin formal description

Is there a paper with a formal description of a Litecoin? And a paper explaining what a miner does? I would like to understand how to mine "manually", I mean I dont need a tutorial on how to install ...
4
votes
1answer
250 views

Why is a chain code needed for entropy in HD wallets?

In the documents and articles I have read, it is stated that the "chain code" in HD wallets exists to provide entropy to the derivation of child public/private keys. If I understand the process ...
3
votes
1answer
154 views

Anonymous transactions technology for a cryptocoin? [duplicate]

I’m thinking of investing in a cryptocoin with anonymous transactions feature. So far there are 3 well-known technologies for that: coinjoin (Bitcoin), masternodes (Darkcoin) and CryptoNote (Bytecoin)....
1
vote
1answer
335 views

Why are blocks hashed?

Am I correct that addresses are hashed to compress a huge text-represented coprime into something of manageable size? Am I also correct that transactions are hashed for the same reason and also ...