Colin Percival, originally for the Tarsnap online backup service. The scrypt function is designed to hinder such ripemd160 bitcoin miner by raising the resource demands of the algorithm. Specifically, the algorithm is designed to use a large amount of memory compared to other password-based KDFs, making the size and the cost of a hardware implementation much more expensive, and therefore limiting the amount of parallelism an attacker can use, for a given amount of financial resources. The large memory requirements of scrypt come from a large vector of pseudorandom bit strings that are generated as part of the algorithm.
Once the vector is generated, the elements of it are accessed in a pseudo-random order and combined to produce the derived key. A straightforward implementation would need to keep the entire vector in RAM so that it can be accessed as needed. Because the elements of the vector are generated algorithmically, each element could be generated on the fly as needed, only storing one element in memory at a time and therefore cutting the memory requirements significantly. However, the generation of each element is intended to be computationally expensive, and the elements are expected to be accessed many times throughout the execution of the function. The idea behind scrypt is to deliberately make this trade-off costly in either direction.
Passphrase – The string of characters to be hashed. The blocksize parameter, which fine-tunes sequential memory read size and performance. 8 is the 8-round version of Salsa20. Scrypt is used in many cryptocurrencies as a proof-of-work algorithm. As of May 2014, specialized ASIC mining hardware is available for scrypt-based cryptocurrencies. In 2013 a Password Hashing Competition was held to develop an improved key derivation function. Beyond Bitcoin: A Guide to the Most Promising Cryptocurrencies”.
Litecoin Scrypt Mining Configurations for Radeon 7950. Massive surge in Litecoin mining leads to graphics card shortage”. Zeusminer Delivers Lightning, Thunder, and Cyclone Scrypt ASICs For Litecoin And Dogecoin Mining”. The scrypt page on the Tarsnap website. This page was last edited on 9 May 2018, at 03:30. This page summarises some of the benefits of those features. Unfortunately, the way the txid is calculated allows anyone to make small modifications to the transaction that will not change its meaning, but will change the txid.
More generally, if one or more of the signers of the transaction revise their signatures then the transaction remains valid and pays the same amounts to the same addresses, but the txid changes completely because it incorporates the signatures. Wallet authors tracking spent bitcoins: it’s easiest to monitor the status of your own outgoing transactions by simply looking them up by txid. But in a system with third-party malleability, wallets must implement extra code to be able to deal with changed txids. Anyone spending unconfirmed transactions: if Alice pays Bob in transaction 1, Bob uses that payment to pay Charlie in transaction 2, and then Alice’s payment gets malleated and confirmed with a different txid, then transaction 2 is now invalid and Charlie has not been paid. Anyone using the block chain: smart contracts today, such as micropayment channels, and anticipated new smart contracts, become less complicated to design, understand, and monitor. Linear scaling of sighash operations A major problem with simple approaches to increasing the Bitcoin blocksize is that for certain transactions, signature-hashing scales quadratically rather than linearly.