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Cryptographic Foundations of Blockchain Technology
Published in Rajdeep Chakraborty, Anupam Ghosh, Valentina Emilia Bălaş, Ahmed A Elngar, Blockchain, 2023
Initially, Bitcoin miners used CPUs and then moved on to GPUs. However, today it is almost impossible to mine Bitcoin using CPUs, GPUs, or FPGAs because ASICs outperform these devices in Bitcoin mining. This is somewhat against the decentralization idea behind the Bitcoin because only the nodes with special devices now have the control of the Bitcoin network. For this reason, many cryptocurrencies tried to obtain hash puzzles that are ASIC-resistant. Initial designs like scrypt [17] focused on puzzles that require a lot of memory which was assumed to slow down ASICs. Scrypt requires the miner to store successive hash values in the memory. Litecoin is an example for a cryptocurrency that uses scrypt and it aimed for ASIC-resistance. However, many ASICs for scrypt were produced in the past years that outperform GPU miners. The memory requirement of scrypt algorithm can be increased for better ASIC-resistance but this would slow down the verification of the hash puzzle solution, rendering the blockchain unusable.
A Review on Blockchain-Based Device Authentication Schemes for IoT
Published in Debarka Mukhopadhyay, Siddhartha Bhattacharyya, Balachandran Krishnan, Sudipta Roy, Blockchain for IoT, 2023
G. Megala, Prabu Sevugan, P. Swarnalatha
An important function involved in Blockchain-based authentication is using hash operations while signing every transaction present in the Blockchain. As a result, several applications of IoT deploying hash functions must remain stable; meanwhile it must be fast and use as little energy as possible without producing any conflicts [21]. Cryptocurrencies such as Bitcoin and name coin use the most popular SHA-256d hash function; Emercoin also uses SHA-256 hash function, whereas Litecoin and Dodgecoin uses Scrypt for authentication purpose. SHA-256’s output has been tested in a variety of IoT products, including wearables. Researchers who looked at the fingerprint and resource demands of SHA-256 in ASICs concluded that the advanced encryption standard (AES)is more effective for low-power protected communications. Other authors recommended using ciphers because of their power limitations, and several applications require analytical assessments of Blockchain-based IoT.
Security and privacy issues of blockchain-enabled fog and edge computing
Published in Muhammad Maaz Rehan, Mubashir Husain Rehmani, Blockchain-enabled Fog and Edge Computing, 2020
Imane Ameli, Nabil Benamar, Abdelhakim Senhaji Hafid
Cryptographic hashing [33] is a mechanism used to encrypt data transactions before broadcasting it in the network by its issuer. Secure hash algorithm (SHA256) is the famous hash algorithm implemented in several cryptosystems which relies on hashing an input parameter and converting it to an output with a size of 256 bit. It is a one-way function; that is, each input has one and only hash target as a result, and also there is no way to predict and to divine the input just based on the hash. Additionally, SHA-256d (SHA256 function is applied two times on data) is used for enhancing the complexity and the mining time (Bitcoin, Peercoin implement the SHA-256d). Also Scrypt (implemented by Litecoin) and EtHash (implemented by Ethereum) are other algorithms as a hashing function [34].
Energy-efficient distributed password hash computation on heterogeneous embedded system
Published in Automatika, 2022
Branimir Pervan, Josip Knezović, Emanuel Guberović
The three most common password hashing algorithms are PBKDF2 [8], bcrypt [9] and scrypt [10], with PBKDF2 and bcrypt (with reasonable settings of the cost parameter) being recommended by both OWASP [11] and IETF [12]. The process of updating or changing hash algorithms that are used is not completely trivial. One option, albeit very user-unfriendly, is to simply expire old user passwords and require users to enter new password values. Another option is to use the old hashed value as an input to the new hashing algorithm until the next time user successfully signs in when the new hash value is exchanged. Our research focuses on bcrypt algorithm, mostly because of its popularity in password hashing for web-based systems, and the legacy code base that will not be updated with the aforementioned algorithm update process and will use bcrypt for many years to come.
Proxy re-encryption architect for storing and sharing of cloud contents
Published in International Journal of Parallel, Emergent and Distributed Systems, 2020
File-Encryption (Pwd,Fi): To encrypt a file named Fi and store it in the cloud, the user has to derive a file based key. The inputs are the password Pwd and the file name Fi. E operator represents encryption function.Choose two 256-bit random numbers Ki and Ri. The number Ki is to be used as the key to encrypt the file content. The number Ri is a random number used to randomize the ciphertext.Use a password-based key derivation function such as PBKDF1 or SCRYPT to derive a unique key encryption key KEK from the password PWD and the random number Ri. Let us assume that this application uses SCRYPT [4] for password-based key derivation.
Rain Drop Service and Biometric Verification Based Blockchain Technology for Securing the Bank Transactions from Cyber Crimes Using Weighted Fair Blockchain (WFB) Algorithm
Published in Cybernetics and Systems, 2023
Bitcoin is a cryptocurrency that is used for digital trading assets online. Each transaction is protected through a digital signature. Every consumer in the bitcoin network has two keys. One is the public key. Here, the public key is the address that everyone inside the network is aware of; another is the private key. The Private Key depends on the specific description. The different Cryptocurrencies have been incorporated with the corresponding and different hashing Algorithms. For example, Bitcoin uses the Secure Hash Algorithm (SHA)-256 hashing algorithm, Ethereum uses Ethash and Litecoin uses Scrypt.