Questions tagged [cryptography]

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

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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 ...
Thilo's user avatar
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34 votes
5 answers
12k 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 ...
gesell's user avatar
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57 votes
4 answers
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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 ...
lemonginger's user avatar
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48 votes
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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. ...
Wizard Of Ozzie's user avatar
13 votes
3 answers
2k 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 ...
John Nilsson's user avatar
80 votes
3 answers
61k 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?
makerofthings7's user avatar
11 votes
2 answers
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How is the generator point G chosen in the secp256k1 curve used in Bitcoin?

The generator point G in the secp256k1 curve used in Bitcoin is a known constant: Gx = 0x79BE667EF9DCBBAC55A06295CE870B07029BFCDB2DCE28D959F2815B16F81798 Gy = ...
RocketNuts's user avatar
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2 votes
3 answers
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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 ...
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12 votes
5 answers
14k 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?
Eric S's user avatar
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9 votes
2 answers
4k views

Is a bitcoin address collision possible if generating 90 million addresses every 4 hours?

I am running a test to see if I can obtain a successful bitcoin address collision after generating billions of addresses. I am not entirely sure how I would check them yet. Basically I have an extra ...
Anonymous's user avatar
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2 answers
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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 ...
John Smith's user avatar
8 votes
4 answers
787 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 ...
Pacerier's user avatar
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6 votes
2 answers
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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 ...
KonKan's user avatar
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5 votes
1 answer
306 views

Elliptic Curve Point at Infinity

Let's take into account the Bitcoin curve. My questions are: What exactly is the "point at infinity"? Is there more than one "point at infinity" How can I identify if my EC generated x and y are the "...
Allan Romanato's user avatar
3 votes
2 answers
356 views

To what extent does asymmetric cryptography secure bitcoin transactions?

Is there a specific attack or bug which asymmetric cryptography prevents during bitcoin transactions?
The Decoder's user avatar
2 votes
1 answer
158 views

What is the current computing speed of performing an elliptic curve multiplication?

Hi I was just looking for some information on how long it would take to crack a private key in bitcoin using a brute force approach and I couldn't find a very good answer for how long it takes to ...
Matt's user avatar
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2 answers
275 views

Can we have multiple possible nonce making same number of leading zeroes in the hash?

Is it possible to have different nonce which are satisfying the same condition of having let's say 4 leading zeroes in the hash? Is it possible that one node suggests 89123 nonce and other node ...
Mathew Pitcher's user avatar
15 votes
6 answers
4k 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? ...
ThePiachu's user avatar
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8 votes
3 answers
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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 ...
Jimmy Song's user avatar
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8 votes
2 answers
19k 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 ...
Will-In-China's user avatar
7 votes
1 answer
878 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 ...
Stephen's user avatar
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5 votes
2 answers
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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 ...
skaht's user avatar
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4 votes
1 answer
599 views

Is BIP 32 Technology Cryptographic Curve Agnostic?

Does BIP 32 always implicitly assume secp256k1 elliptic curve cryptography (ECC) is to be applied, or can BIP 32 technology also be applied to create extended public or private keys that can readily ...
skaht's user avatar
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3 votes
2 answers
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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 ...
user2387532's user avatar
3 votes
1 answer
614 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? ......
makerofthings7's user avatar
3 votes
1 answer
172 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)....
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1 vote
1 answer
256 views

Explanation of "Timestamp Server" section in original bitcoin paper

I'm trying to understand the "Timestamp Server" section in the original bitcoin paper. It feels overly short for someone without an understanding of cryptography. Is it saying? A block ...
tim_xyz's user avatar
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1 vote
1 answer
452 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 ...
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