Questions on: cryptography

Bitcoin uses two rounds of SHA256 on the entire contents of each block (which includes a reference to the previous block) as well as a randomly varied nonce. When the result of those calculations are below a network-determined threshold it is conside
Welcome to part four in our series on Elliptic Curve Cryptography. I this episode we dive into the development of the public key. In just 44 lines of code, with no special functions or imports, we produce the elliptic curve public key for use in Bitc
but there is no indication what kind of signature it checks! (What are opcodes in Bitcoin? Well it turns out that the protocol has a really neat scripting system built in for building transactions. You can read more about it here. ) So in fact, I man
Assume for a second that we found a proof of work algorithm that had all of the good properties of sha256, but was also useful for SETI and maintaining world peace. Now suppose a group of miners collectively have more than 51% of the hashing power. I
If you have a cryptographically secure random number generator, you don't need to hash it's output. In fact you don't want to. Just use $token = openssl_random_pseudo_bytes($BYTES,true) Where $BYTES is however many bytes of data you want
Dash Dash (originally known as Darkcoin) is a more secretive version of Bitcoin. Dash offers more anonymity as it works on a decentralized mastercode network that makes transactions almost untraceably. Launched in January 2014, Dash experienced an in
To the best of our knowledge, Bitcoin has not been made illegal by legislation in most jurisdictions. However, some jurisdictions (such as Argentina and Russia) severely restrict or ban foreign currencies. Other jurisdictions (such as Thailand) may l
Securing data using cryptography , public/private key encryption is common used system. the server part can encrypt the data using private key and the client can verify the data using the public key. now we test a verification using a public/private
This has nothing to do with RFC6979, but with ECDSA signing and public key recovery. The (r, s) is the normal output of an ECDSA signature, where r is computed as the X coordinate of a point R, modulo the curve order n. In Bitcoin, for message signat