Certified Bitcoin Professional Practice Exam

Can cryptographic hashes be reversed?

1. Yes, using advanced cryptography

2. No, they are designed to be irreversible

3. Only with permission from the original creator

4. Yes, but only for certain types of hashes

The correct answer is: No, they are designed to be irreversible

Cryptographic hashes are specifically designed to be irreversible, which is fundamental to their functionality and security. When data is processed through a cryptographic hash function, it is transformed into a fixed-length string of characters that does not reveal any information about the original data. This one-way nature ensures that it is computationally infeasible to take a hash and retrieve the original input. This design feature is crucial for various applications, including digital signatures, password storage, and data integrity verification. In contrast to the other options, which suggest that it might be possible to reverse a hash through various means, the security of cryptographic hashes lies in their resistance to such reversibility. This is accomplished through complex mathematical processes that do not allow for straightforward reverse engineering. Thus, saying that hashes can be reversed under any circumstances misrepresents their intended application in secure systems.