As a CHFI in a computer forensics lab, how can you prove that evidence has not changed since it entered the lab?

Calculating a hash of the evidence is a fundamental practice in computer forensics to ensure the integrity of digital data. When evidence is first received in the lab, a unique cryptographic hash function is applied to it. This hash produces a string of characters that effectively represents the data at that point in time.

If, at any subsequent time, you need to verify that the evidence has not changed, you can simply compute the hash again. If the newly calculated hash matches the original hash, this confirms that the data has remained unchanged. This approach is crucial in maintaining the chain of custody, as it provides a mathematically verifiable means of demonstrating data integrity.

Other methods, while important in the context of evidence handling and management, do not provide the same level of assurance regarding data integrity as hash calculations do. Documenting actions taken is necessary for maintaining a record but does not confirm data integrity by itself. Similarly, comparing timestamps can give some context about when data was created or modified but does not establish whether the data itself has been altered. Capturing video footage can enhance the documentation of procedures but does not directly relate to verifying the integrity of the evidence in a technical or quantitative manner. Thus, calculating a hash is highly regarded for its reliability and accuracy