How can an analyst show that the original digital evidence is unmodified?

An analyst can demonstrate that the original digital evidence is unmodified by creating a cryptographic hash (e.g., SHA-256) of the evidence at the time of acquisition and storing it securely. This hash value serves as a unique digital fingerprint of the data. Later, the analyst can re-calculate the hash of the original evidence and compare it to the original hash; if they match, it confirms that the data has not been altered. Additionally, documenting the entire chain of custody and using write-blocking tools during acquisition further ensures the integrity of the original evidence.