seperti satu perkongsian di media sosial internet baru baru ini, seorang wanita teleh meluahkan rasa kesal dan kecewanya apabila dia telah menjumpai gambar serta video bogel seorang remaja masih sekolah., Astaghfirullah..
itulah luahan wanita ini, yang di kenal sebagai NOR , apabila mendapati telefon bimbit yang di jumpai itu adalah dimiliki seorang yang di kenalinya.
tambahnya, hubungan bersama gadis tersebut sangat akrab bagaikan ibu dan anak
Blockchain[edit]
The validity of each cryptocurrency's coins is provided by a blockchain. A blockchain is a continuously growing list of records, called blocks, which are linked and secured using cryptography.[13][16] Each block typically contains a hash pointer as a link to a previous block,[16] a timestamp and transaction data.[17] By design, blockchains are inherently resistant to modification of the data. It is "an open, distributed ledger that can record transactions between two parties efficiently and in a verifiable and permanent way".[18] For use as a distributed ledger, a blockchain is typically managed by a peer-to-peer network collectively adhering to a protocol for validating new blocks. Once recorded, the data in any given block cannot be altered retroactively without the alteration of all subsequent blocks, which requires collusion of the network majority.
Blockchains are secure by design and are an example of a distributed computing system with high Byzantine fault tolerance. Decentralized consensus has therefore been achieved with a blockchain.[19] It solves the double spending problem without the need of a trusted authority or central server.
The block time is the average time it takes for the network to generate one extra block in the blockchain.[20] Some blockchains create a new block as frequently as every five seconds.[21] By the time of block completion, the included data becomes verifiable. This is practically when the money transaction takes place, so a shorter block time means faster transactions.[citation needed]
Timestamping[edit]
Cryptocurrencies use various timestamping schemes to avoid the need for a trusted third party to timestamp transactions added to the blockchain ledger.
Proof-of-work schemes[edit]
The first timestamping scheme invented was the proof-of-work scheme. The most widely used proof-of-work schemes are based on SHA-256 and scrypt.[22] The latter now dominates over the world of cryptocurrencies, with at least 480 confirmed implementations.[23]
Some other hashing algorithms that are used for proof-of-work include CryptoNight, Blake, SHA-3, and X11.
Proof-of-stake and combined schemes[edit]
Some cryptocurrencies use a combined proof-of-work/proof-of-stake scheme.[22] The proof-of-stake is a method of securing a cryptocurrency network and achieving distributed consensus through requesting users to show ownership of a certain amount of currency. It is different from proof-of-work systems that run difficult hashing algorithms to validate electronic transactions. The scheme is largely dependent on the coin, and there's currently no standard form of it.
Mining[edit]
In cryptocurrency networks, mining is a validation of transactions. For this effort, successful miners obtain new cryptocurrency as a reward. The reward decreases transaction fees by creating a complementary incentive to contribute to the processing power of the network. The rate of generating hashes, which validate any transaction, has been increased by the use of specialized machines such as FPGAs and ASICsrunning complex hashing algorithms like SHA-256 and Scrypt.[24] This arms race for cheaper-yet-efficient machines has been on since the day the first cryptocurrency, bitcoin, was introduced in 2009.[24] However, with more people venturing into the world of virtual currency, generating hashes for this validation has become far more complex over the years, with miners having to invest large sums of money on employing multiple high performance ASICs. Thus the value of the currency obtained for finding a hash often does not justify the amount of money spent on setting up the machines, the cooling facilities to overcome the enormous amount of heat they produce, and the electricity required to run them.[24][25]
Some miners pool resources, sharing their processing power over a network to split the reward equally, according to the amount of work they contributed to the probability of finding a block. A "share" is awarded to members of the mining pool who present a valid partial proof-of-work.
One company is operating data centers for mining operations at Canadian oil and gas field sites, due to low gas prices.[26]
Given the economic and environmental concerns associated with mining, various "minerless" cryptocurrencies are undergoing active development.[27][28][29] Unlike conventional blockchains, some directed acyclic graph cryptocurrencies utilise a pay-it-forward system, whereby each account performs minimally heavy computations on two previous transactions to verify. Others utilise a block-lattice structure whereby each individual account has its own blockchain. With each account controlling its own transactions, no traditional proof-of-work mining is required, allowing for free, instantaneous transactions.[30]
Wallets[edit]
A cryptocurrency wallet stores the public and private "keys" or "addresses" which can be used to receive or spend the cryptocurrency. With the private key, it is possible to write in the public ledger, effectively spending the associated cryptocurrency.[31] With the public key, it is possible for others to send currency to the wallet.
Anonymity[edit]
Cryptocurrency is pseudonymous rather than anonymous in that the cryptocurrency within a wallet is not tied to people, but rather to one or more specific keys (or "addresses").[32]Thereby, cryptocurrency owners are not identifiable, but all transactions are publicly available in the blockchain.[32] Still, cryptocurrency exchanges are often required by law to collect the personal information of their users.[32]
Additions such as Zerocoin have been suggested, which would allow for true anonymity. In recent years, anonymizing technologies like zero-knowledge proofs and ring signatures have been employed in the cryptocurrencies Zcash and Monero, respectively.
Economics[edit]
Cryptocurrencies are used primarily outside existing banking and governmental institutions and are exchanged over the Internet. While these alternative, decentralized modes of exchange are in the early stages of development, they have the unique potential to challenge existing systems of currency and payments. As of December 2017 total market capitalization of cryptocurrencies is bigger than 600 billion USD and record high daily volume is larger than 500 billion USD.[37