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Importance of Hash Values in Computer Forensics

Written by Anuraag Singh ~ Modified: 09-03-2022 ~ Cyber Tip ~ 5 Minutes Reading

hash values in computer forensics

In most civil and criminal cases, along with normal evidence, shreds of electronic evidence whether stored in computers or other hard drives are also considered admissible evidence in courts of law. Hence, examining, discovering, and authenticating that digital evidence becomes crucial before placing them in front of the court. For that, the importance of hash value in computer forensics comes into the picture.

Before entering into the world of the hash value, let’s understand its meaning.

What is Hash Value?

With the increase in the use of social media platforms, everyone misunderstands the meaning of hash value with the meaning of hash-tag(#). In reality, these two are completely different things.

Generally, you can say that hash values represent the DNA of electronic evidence.

Now, let’s dive deeper and understand the technical meaning of hash value.

Typically, a hash value is a string of hexadecimal values ranging from 32 to 64 characters long. The hash algorithm may be the deciding factor for the same.

Also, in the world of cryptography and computer forensics, experts use the hash value for doing the analysis of a particular digital file.

So, how do the hash value look like? Let’s look into an example.

For instance, consider a sample string of characters

‘Sam is eating Apple’

Using the MD5 hashing algorithm (will discuss later on), the hash value of the above string will look like this ‘387f51d0ccbab6be677275c9933c250e’.

In addition to that, the file format matters while generating hash values. That is even if a word file and PDF contain the same content, after running the algorithm they will produce different hash values.

Now, let’s discuss the hash algorithms that generate hash values.

Types of Hash Algorithms in Computer Forensics Giving rise to Hash Values

There are many hash algorithms present. However, the Digital Forensics Professionals adopt the below two most common hash algorithms.

1. MD5

It is the short form of Message Digest, developed by professor Ronald Rivest. MD5 is the latest version of the MD hashing algorithm.

This algorithm is less complex and the length of the hash value is 128 bits that make it faster to process the algorithm.

Moreover, its common use is to verify the integrity of the digital files.

2. SHA1

SHA1 or Secure Hash Algorithm 1 is comparatively more powerful and secure than MD5.

In this algorithm, the length of the hash value is 160 bits. The algorithm is a bit complex.

It is generally used to verify that the files have been untampered.

Although the algorithms have been updated from time to time to give more accurate and non-collision hash values.

Basically, the above two algorithms allow computer forensic professionals to protect electronic evidence from tampering once they acquire it.

Hash Values in Discovering Electronic Evidence in Computer Forensics

As you already know different file formats produce different hash values. Similarly, a single change in character in the character string will generate a different hash value.

This shows the uniqueness of the hash value.

Now the use of hash value in e-discovery is also vital. It helps in identifying duplicate files. Thus, it ensures that after collecting data, files are unaltered and forensically okay.

Secondly, you can equivalent the hash value with ‘digital fingerprint’ to represent an electronic file. Due to its uniqueness, hash value plays an important role in presenting electronic evidence in courts of law.

Before presenting any electronic evidence in court, you must check for its authenticity. And hash value helps in achieving the same.

Four Characteristics of Hash Values that justifies its Authenticity

  • It is Unique- that is when you enter a specific input into the algorithm, every time the output has the same hash value. If two people try to find the hash value of the same input string independently then they are going to receive the same hash value. Hence, finding the authenticity of a file becomes easy.
  • The Chances of Collision are Low. When two different input string generates the same output(hash value) then a collision occurs. Since a change in a single character produces a different hash value, the odds of getting a hash collision are negligible.
  • Hash Value Calculation is Quick. With the right tools, you can obtain hash values in no time. Whatever may be the size of a file, generating a hash value is very simple.
  • A Change in the Input will Result in a Change in Output. Even a minor alteration in the input will completely change the output. As a result, after collecting a piece of digital evidence if someone tries to tamper with the same then you can easily recognize the change.

Hence, the above-mentioned characteristics increase the importance of hash value in the field of computer forensics.

Hash Value in Different Phases of Computer Forensics Process

  • In forensics examination, when digital evidence is collected, the Cyber Expert of India, Anuraag Singh, doesn’t conduct any examination on the original evidence at first. He captures an image to retain the original evidence. After that, he obtains the hash value of the imaged copy and matches the same with the original evidence. If the result of both is the same then you can consider the copy as the original.
  • After calculating the hash value, the authenticity, and integrity of the same will be evaluated so that it can be admissible in court. Once the authentication process is complete, then you can present the electronic evidence without any hesitation.

What is the best way to calculate Hash Value?

The File Hash Calculator allows you to compute the cryptographic hash value of a text or file using a variety of methods, including MD5, SHA1, SHA2, CRC32, and others. It is the world’s simplest Hash calculator for Forensicators. This tool calculates all checksums in a single location, allowing you to complete your task more rapidly. Simply browse your file and the hash value will be calculated in a few simple steps. Therefore, click the button below to download the tool.