Questions tagged [cryptography]

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

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6
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3answers
1k 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 ...
6
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3answers
673 views

Papers/Books on how bitcoin works from a mathematical perspective?

I'm a math student interested in Cryptography. Is there any paper or book which explains, in mathematics and cryptography terms, how bitcoin (more general, a digital cryptocurrency system) works? In ...
7
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1answer
469 views

Is there a fallback plan if bitcoin's underlying cryptography is cracked?

Lets say someone started making real viable quantum computers that were affordable enough that large companies could buy one. And lets say a quantum algorithm was devised to crack the private keys of ...
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2answers
217 views

Hash property resistance

I'm experimenting with some self study cryptography and I was curious about the two following scenarios (simple answers and/or in relation to bitcoin) If SHA256 was found to lack pre-image resistance,...
2
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1answer
151 views

What is the algorithm used to sign data within Nxt?

I understand that Nxt uses Curve25519 to generate pubkeys for user accounts, however, I can't find a reference that states what which signing algorithm/process is used for transactions and blocks. (...
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4answers
5k 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?
3
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1answer
155 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)....
4
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2answers
146 views

Which cryptocurrencies deviate significantly from Bitcoin?

There's been dozens of alternate cryptocurrencies but I don't believe many of them did much other than find/replace some strings. We see Bitcoin as made up of the blockchain and proof-of-work via ...
-2
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1answer
172 views

Bitcoin related research areas [closed]

I have a one year research project in my MSc curriculum. So i was suppose to address a existing issue in bitcoin protocol. Highly appreciate if someone can advise me and give me some ideas. Thank you....
3
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2answers
771 views

Are Bitcoin Block Hashes Predictable

to create the block chain, the Bitcoin network runs hashing algorithms for each block, is it mathematically possible to predict the hash value of say, the 100th block from the last block currently in ...
2
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1answer
72 views

Should I use a large random value for i in BIP 32 instead of sequential?

BIP32 doesn't have any guidance on how to choose the i value for child keys. Is there any benefit to using a random value for i ? Other than documenting and saving the value of I for various ...
4
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1answer
425 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? ......
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4answers
752 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 ...
5
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2answers
688 views

Is Electrum Cryptographically Secure?

Electrum seems very user friendly, thin and convenient, but is it cryptographically secure? One of the ways to attack any cryptographic system is to exploit weaknesses in the key generation algorithm....
2
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1answer
348 views

ECIES - When is it bad to sign and encrypt using the same keys?

Suppose I have a public key for a particular user (perhaps extracted when using the new public key recovery format included in P2SH, and BIP32 transactions). Is it OK the same key for both signing ...
2
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3answers
2k views

Why is Bitcoin better than other cryptocurrency? [duplicate]

If there too many types of such kind of currency, will them be very cheap? I have 4 BTC and since the current BTC price waves a lot, I am wondering this. Thanks,
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1answer
161 views

Is there a signature format, or cryptography has *only one* possible S value?

EDIT: This question is not specific to Bitcoin. It's applicable to any other crypto currency that is interested in using a different signature scheme than Bitcoin or the QT reference client. One ...
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2answers
28k 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?
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0answers
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Does Amit Sahai's indistinguishability obfuscator enable Autonomous Virtual Corporations or “Agents”?

Given that an "Agent" is described as Agents are autonomous programs that maintain their own wallet, which they use to buy server time. Money is obtained by the agent selling services. If demand ...
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2answers
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How does this OpenCL BTC private-key cracker work? Is it a real threat to bitcoins?

I am specifically referring to this over at bitcointalk.org. The general consensus I gathered from reading the thread is that this is not a hoax. There seems to be a group of generated bitcoin ...
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2answers
224 views

Multibit: Using the same passphrase for both my wallet and exported private keys

I have a password-protected wallet in Multibit that I have backed up in multiple locations. I have exported the private keys from this wallet. The private keys are password-protected using the same ...
1
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1answer
531 views

Are transactions still tamper-proof if blocks are hashed without nonces?

If an alt were to forgo difficulty and timed release of new supply by removing the nonce from blocks therefore the whole difficulty/target system, is hashing without nonces still providing the same ...
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1answer
375 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 ...
2
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1answer
713 views

What is the Elliptic Curve algorithm used in Ripple to generate public / private key pairs?

The algorithm used by bitcoin to generate keys is secp256k1, is it the same for ripple?
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2answers
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Is it possible to use a PGP key as a bitcoin address?

Both bitcoin and encrypted emailing are based on public key cryptography. However, they use different implementations, so I assume that a public PGP key cannot be used as a bitcoin address directly. ...
3
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1answer
2k views

Step by Step - how does sending 1 bitcoin work?

I've been reading about how BitCoin works for a few weeks now - and I'm trying to understand under-the-hood how the cryptography works. So i'll explain what I know at the moment - and if someone ...
4
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2answers
596 views

What are the advantages of using Secp256k1?

Bitcoin uses secp256k1 as the specification for it's address system (https://en.bitcoin.it/wiki/Secp256k1). What are the advantages (and disadvantages) of using this over other specifications such as ...
3
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1answer
184 views

What is the ECC key length for OpenCoin's implementation of Ripple?

http://www.reddit.com/r/Bitcoin/comments/1lubl1/wired_oped_worries_that_elliptic_curve/cc2vhos suggests that key lengths < 500 bits are no longer considered secure from the NSA. What key length is ...
3
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1answer
639 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 ...
6
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1answer
648 views

Recovering the last few digits of a Litecoin private key

Is it possible to recover the last few lost digits (10) of my Litecoin wallet private key? Are there any recovery tools available? Or will I have to try and roll my own? Crucially, what crypto ...
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2answers
2k views

Economics of Bitcoin Mining [duplicate]

I thought I understood the gist of what "bitcoins" are: electronic currency tokens representing $X USD that could be used to trade, buy or sell online items. But recently I heard the term "mining for ...
5
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1answer
1k views

Address Public Private key verification [duplicate]

Apologies if this question has been asked before, but when a bitcoin client wishes to send funds to an address, does the bitcoin protocol force the client to verify that the address has a ...
6
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1answer
259 views

What standard is used for the ECDSA to verify transactions?

Bitcoin used Elliptic Curve Digital Signature Algorithm. (see here). I'm wondering what standard is actually used for this Algorithm: which curve? which prime? Can anybody give me a reference? (Wiki ...
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2answers
230 views

When will the public key of an address used in the network?

On block explorer there are some address with public key available, and some without. (e.g. this one has public key: http://blockexplorer.com/address/1HBheYzvX7NDtcwVrMS7gxReNRVezYS7w2 , and this ...
12
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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 ...
2
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1answer
5k views

How does bitcoin work from a technical computer science cryptography perspective?

How does the cryptography science behind bitcoins work to make it robust(reliable , scalable). I am interested in technical explanation with cryptography math and not just conceptual explanation.
3
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0answers
66 views

Can there be Bitcoin-like network that also works as whatever@home? [duplicate]

There are Bitcoin-like network that performs calculations that are not locally useful, but interesting for peers. There are {SETI,folding,...}@home networks that calculates something that is (...
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2answers
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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 ...
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1answer
1k views

Could mining calculations be used to crack private key? [duplicate]

Could mining calculations be used to crack private key, in addition to mining for checking against few million accounts with positive balances? If that possible, at the current mining rate (30TH/s) ...
2
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1answer
334 views

How can I use message signing to prove that I have private keys for many different accounts?

I want to prove the total sum of BTC I have access to. Therefore I think if I use message signing to assert "owned by makerofthings7" in each address, then anyone can compute the total coins in my ...
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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 ...
5
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1answer
332 views

Does a Vanity Address reduce the randomness / entropy of the private key? Is there cryptographic proof?

Since a vanity address discards many "valid" keys in order to find one that matches a pre-determined string, I think that the "randomness" of the data would be reduced, thus weakening the key. Is ...
7
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1answer
551 views

What OpenCL video cards (or FPGAs) are best for multiplication?

I'm benchmarking some Bitcoin related software and am looking for cards that are better at parallel multiplication vs parallel addition. Is there any prior work that may have this information? ...
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2answers
611 views

Do vanity addresses lower the security of my key? (reduced complexity)

Do vanity addresses somehow decrease the security of my private key?
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1answer
604 views

What mathematical property links the Armory chain to the public/private keys?

According to the Armory site the Public Keys needed for the Bitcoin addresses can be generated without having access to the Private Keys, which ideally are stored on a completely different computer. ...
15
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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
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1answer
1k views

Where and how is secp256k1 used within Bitcoin?

Bitcoin is unique that is uses secp256k1 to secure it's transactions; and any cryptographic attack against this algorithm is probably going to be percieved as an attack against the bitcoin network. ...
6
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1answer
440 views

Bitcoin Research

I have recently been assigned to advise a student on a senior thesis in math. She has taken linear algebra, introductory real analysis, basic cryptography, and abstract algebra. Her interest is in ...
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0answers
69 views

How secure is a private key? [duplicate]

Possible Duplicate: Is it possible to brute force bitcoin address creation in order to steal money? I've tried brainwallet.org and now I wonder, what happens if someone starts to generate a lot ...
64
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4answers
23k 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 ...