Principles of Evidence Preservation and Integrity

Preserving the integrity of digital evidence means being able to mathematically prove that the data analyzed in court is identical to what was collected at the original scene, without any intermediate alteration. This is achieved through cryptographic hash functions such as SHA-256, which generate a unique fingerprint of the data at the time of acquisition; if that fingerprint matches years later when the evidence is presented at trial, integrity is proven without having to rely solely on the investigator's testimony. In practice, this principle also requires always working on forensic copies and never on the original, storing media under controlled conditions that prevent physical degradation, and documenting any event, however minor it seems, that could raise doubts about the data's integrity. Neglecting this aspect, even with the best intentions, can turn a technically flawless investigation into useless evidence in the face of any serious legal challenge.