Hashing

Understanding cryptographic hash functions

Cryptographic hash functions are key tools in the development of blockchain and smart contracts. These functions accept arbitrary-sized input data and generate a fixed-size hash value using an encryption technique. This hash value, which is frequently represented as a hexadecimal string, performs several important functions in blockchain technology:

• Data integrity: Hashes are used to validate the data’s integrity. Even tiny changes in the input data result in a radically altered hash value, making any tampering or corruption easy to detect.

• Cryptographic signatures: Hashes are an important part of digital signatures. When a user signs a message, they’re effectively signing the message’s hash. Verifying the signature entails comparing the hash to the sender’s public key.

• Mining and proof of work: In blockchain networks such as Bitcoin and Ethereum, miners compete to find a nonce value that, when coupled with the data to be hashed, results in a hash value that’s less than a particular threshold. Proof of work is a fundamental procedure for network security and consensus.

A cryptographic hash function, known for its encryption algorithm, generates encrypted text of a fixed size using input data of any size. The output can be dramatically altered by even a little change in the input.

Keccak and Ethereum

Ethereum uses the Keccak-256 hashing algorithm, which is related to SHA-256 but distinct from it. Keccak-256 is used in various aspects of Ethereum, including:

• Address generation: Ethereum addresses are derived from the public key, which is hashed with Keccak-256 to produce a 256-bit hash. The last 20 bytes (160 bits) of this hash are used to generate the Ethereum address.

• Transaction signatures: When a user signs an Ethereum transaction, the transaction data is hashed with Keccak-256, and the resulting hash is signed by the user’s private key.

• Smart contracts: Hashes are utilized in contract generation and function calls in smart contracts. In a smart contract, function selectors (the first four bytes of the hash) are utilized to choose which function to execute.

Solidity cryptographic operations

Solidity, the Ethereum smart contract programming language, has cryptographic functions that can be used in contract building. Some of these operations are given in the following table: