IBM Blockchain Certification Practice Exam

The primary method used for securing blockchain data is hashing, often utilizing algorithms like SHA-256. Hashing transforms input data into a fixed-size string of characters, which appears random. This process ensures that even the slightest change in the input will result in a completely different hash output.

In the context of blockchain, hashing serves several critical purposes. It maintains the integrity of the data by allowing users to verify that a block of transactions has not been altered; if even a single bit changes, the hash will differ dramatically. This property makes it easy to detect tampering, as any modifications would produce a new hash that does not match the original.

Using SHA-256, which is a cryptographic hash function, also provides a high level of security as it is designed to be computationally infeasible to reverse (i.e., derive the original input from the hash) and resistant to collision attacks (where two different inputs produce the same hash).

While symmetric and asymmetric encryption are important for securing data during transmission and access control, they are not the primary means of securing the integrity and authenticity of the transaction data recorded on the blockchain itself. Double encryption protocols may enhance security in certain scenarios, but they do not fundamentally pertain to how blockchain data is typically secured