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

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Signing data with ECDSA

I was reading about the math behind bitcoins in this article, and one thing I can't seem to wrap my head around is how the said algorithm is used to sign "data". What exactly is this "data"? Is it my ...
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1answer
30 views

Get uncompressed public key from compressed form

A similar question has an answer in Python which links to the bitcointalk forum: How can I get the uncompressed public key from the compressed public key in openssl? ...
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1answer
17 views

Are Hashed Timelock Contracts and Zero-Knowledge Contingent Payments the same thing?

This answer to How is a node in the middle prohibited from keeping the money in a routed Payment in Lightning network? describes how a Hashed Timelock Contract would be used to exchange the "secret" ...
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74 views

Is Bitcoin mining chance based?

This answer says that Bitcoin is not chance based, may I know how it is deterministic and does not have any associated probability of mining a coin?
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193 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 ...
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1answer
55 views

Proving collisions on Bitcoin addresses without discovery of the private key?

If there is a private key that leads to a collision on an address, it is possible to show that the private key is not the one used previously, even though they have a collision on the address? ...
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Looking for a Project Ideas [closed]

Im a student at Sri Lanka institute of information technology and I am reading for cyber security BSc. I'm supposed to do a research project with a group of four people within an year. We are ...
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52 views

Cryptocurrencies based on RSA instead of ECDSA

Bitcoin is based on ECDSA. Does anyone know of cryptocurrencies based on RSA for authentication?
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42 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 ...
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57 views

Bitcoin's Cryptographic Integrity

A few people I know compare bitcoin and gold regarding currencies with integrity; Martin Armstrong on Zero Hedge compared both in a recent post. One advantage I currently see that bitcoin has over ...
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151 views

Using a Bitcoin or Litecoin miner for attacking PBKDF2 / SHA-256 [duplicate]

I'm wondering if it would be possible to utilize a Bitcoin or Litecoin miner to attack, say, a password database that uses PKBDF2 with HMAC / SHA-256. PBKDF2 uses multiple iterations of a PRF - ...
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130 views

What level of mathematical understanding do I need in order to contribute or to understand the crypto behind bitcoin?

My mathematical knowledge is up to CALC II (college level.) Is this enough mathematical maturity in order to understand the crypto in bitcoin or do I need more knowledge? If I do indeed need more ...
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67 views

Getting bitcoin globe data

I just saw this bitcoin globe https://blockchain.info/nodes-globe?series=topBlockRelay It has two modes,"Online Now" and "Miners". I wanted to ask if anyone knows what the bars and colors stand for ...
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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. ...
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Is it possible to discover the set of bitcoin addresses from a public key?

I'm trying to find the set of bitcoin addresses from a public key associated with a user just to analyse this user transaction. Is there any way to derive/find all the addresses that have been ...
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1answer
135 views

Ramifications of creating Electrum 2.x seeds which are not BIP39

Electrum 2.0 seeds (mnemonic phrases) are created with a checksum based algorithm (such that the hmac_sha512 starts with 01. It's usually a 13 word seed, but can be 12 in some circumstances. If all ...
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36 views

Authentication and key distribution in bitcoin

After going through the bitcoin protocol documentation it is still unclear to me how the bitcoin client is authenticated. Where can I find an overview of what the client sends and receives on the wire ...
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40 views

Electrum 2 validation: how is the HMAC always 01…?

Electrum version 2 creates a seed from a random number which is then encoded as a mnemonic. The seed is validated by checking that the hmac begins with the bytes 01 or 101 for standard and 2fa types, ...
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127 views

HMAC “Bitcoin Seed” for BIP32

Pybitcointools uses the following code for calculating a master private key (BIP32) from a seed: def bip32_master_key(seed, vbytes=MAINNET_PRIVATE): I = hmac.new(from_string_to_bytes("Bitcoin ...
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Error While making windows.exe using gitian build?

Actually I'm making a logos windows exe (logosd and logos-qt) following the release process, which is mention on below path on any coin you can find that path, I'm working logos LGS Coin that's why ...
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111 views

How do I create release build of my new bitcoin wallet?

I have created a new alt coin, and now I want to create a executable of my wallet in ubuntu. I don't know how to create a release build wallet with all its dependencies. How I can build my wallet ...
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Signing data with a namecoin private key?

Consider the following scenario User A stores an image on a DHT and receives a SHA-256 hash in return. User A wants to prove ownership of the data has, so he registers a username on the namecoin ...
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412 views

Problems with deterministic ECDSA based on RFC6979 in Bitcoin

Generating random number k in elliptic curve is crucial and in any transactions signature in Bitcoin, random number k is required to compute a point k*G. If this k is chosen not randomly, it instantly ...
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244 views

How to generate a Litecoin Private key and correspondent Public Address in C#

I found this C# tool to generate addresses for Bitcoin (compressed and uncompressed): https://en.bitcoin.it/wiki/Bitcoin_Address_Utility https://github.com/casascius/Bitcoin-Address-Utility It ...
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Bitcoin-qt doesn't get a server connection?

I have created a new altcoin, and I run a server on one machine and connect bitcoin-qt on another machine. In this case it's blink the network connection, sometimes it shows one connection and after ...
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241 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 ...
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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 ...
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234 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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82 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 ...
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1answer
63 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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407 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?
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1answer
118 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 ...
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2answers
118 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 ...
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125 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 ...
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135 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 ...
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1answer
65 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 ...
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1answer
197 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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3answers
495 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 ...
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1answer
358 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 ...
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1answer
159 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 ...
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705 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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114 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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1answer
2k 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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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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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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91 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 ...
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1answer
162 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
154 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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298 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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540 views

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. ...