What cryptographic technique underlies the security of Bitcoin?

Hashing algorithms are fundamental to Bitcoin's security because they govern how transactions are hashed into a blockchain. Specifically, Bitcoin uses the SHA-256 hashing algorithm to create a secure and unique hash for every block of transactions, ensuring that any alteration in the transaction data would result in a completely different hash. This makes it virtually impossible to manipulate previous transactions, as any hash change would require recalculating the entire blockchain, which would require enormous computational resources.

Additionally, hashing enables the process of mining, where miners use computational power to solve complex mathematical problems, thereby verifying and adding new blocks to the blockchain. The proof-of-work mechanism ensures that valid blocks are added in a manner that reinforces network security and disincentivizes malicious attempts to alter recorded transactions.

While public-key cryptography, digital signatures, and symmetric encryption all play roles in enhancing transaction security and user identity verification within the Bitcoin network, hashing algorithms serve as the backbone of the blockchain's structure, making them crucial for the integrity and security of Bitcoin’s ecosystem.