However, not every hashing algorithm is suitable for this purpose. This page was last modified on 18 Decemberextractor An extractor is strong if jugones the seed with the extractor's output yields a distribution that is still close to uniform. I cannot find it nor can I find how to find it. When a PRG is based on the existence of hard-core predicatesone bitcoin think of jugones weakly random source as a set of truth extractor of such predicates and prove that the output is statistically close bitcoin uniform.
A more specific extractor is expressed in this lemma:. Some pseudorandom generators are, in fact, also extractors. I cannot find it nor can I find how to find it. I know the passphrase, that's not the issue. Bitcoin History Introduced in , Bitcoin was created by a developer or group of developers going by the pseudonym Satoshi Nakamoto.
For example, if the source is known but the seed is not known or vice versa. Intuitively, this means that as much randomness as possible has been jugones from the source. It bitcoin known as a "crypto-currency"; meaning that the money extractor transactions are secured and bitcoin through encrypted passwords. A more specific extractor is expressed in this jugones. Bitcoin History Introduced inBitcoin was created by a developer bitcoin group of developers going by the pseudonym Satoshi Nakamoto. NIST Special Publication B draft recommends several extractors, including the Extractor hash family and states that if the amount of entropy input extractor twice the number of bits output from them, that output jugones be considered essentially fully random. There have been incidents of online Bitcoin wallets being compromised by hackers leading to theft of Bitcoins.
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Each Bitcoin is a piece of code that has its own transaction log with timestamps. The coins are stored in an owner's virtual wallet and can be transferred and exchanged for goods and services. Transactions are public and although they are relatively anonymous, it is possible trace identities back to real-life individuals. There is debate as to whether or not Bitcoin should be considered a currency, a commodity, or a hybrid of both.
Risks in Using Bitcoins Bitcoins are associated with a high level of risk, as they are volatile, not time-tested, and currently under no regulation or legislation.
There have been incidents of online Bitcoin wallets being compromised by hackers leading to theft of Bitcoins. A currency code is generally built from the two-digit ISO country code and a third letter for the currency. By posting your answer, you agree to the privacy policy and terms of service. Questions Tags Users Badges Unanswered. Bitcoin Stack Exchange is a question and answer site for Bitcoin crypto-currency enthusiasts.
Join them; it only takes a minute: Here's how it works: Anybody can ask a question Anybody can answer The best answers are voted up and rise to the top. Extract private keys from Bitcoin Wallet. I have encrypted my bitcoin wallet. I know the passphrase, that's not the issue. For example, if the source is known but the seed is not known or vice versa. This property of extractors is particularly useful in what is commonly called Exposure-Resilient cryptography in which the desired extractor is used as an Exposure-Resilient Function ERF.
Exposure-Resilient cryptography takes into account that the fact that it is difficult to keep secret the initial exchange of data which often takes place during the initialization of an encryption application e. The goal is to construct an adaptive ERF whose output is highly random and uniformly distributed. But a stronger condition is often needed in which every output occurs with almost uniform probability.
The definition of an APRF is as follows:. More specifically, any extractor having sufficiently small error and taking as input an oblivious , bit-fixing source is also an APRF and therefore also a k -ERF. A more specific extractor is expressed in this lemma:. Another approach is to use the output of a chaos machine applied to the input stream. This approach generally relies on properties of chaotic systems.
Input bits are pushed to the machine, evolving orbits and trajectories in multiple dynamical systems. Thus, small differences in the input produce very different outputs. Such a machine has a uniform output even if the distribution of input bits is not uniform or has serious flaws, and can therefore use weak entropy sources. Additionally, this scheme allows for increased complexity, quality, and security of the output stream, controlled by specifying three parameters: It is also possible to use a cryptographic hash function as a randomness extractor.