Page 208 - Cyber Defense eMagazine Annual RSA Edition for 2024

There are theoretical ways to reverse a hash function, but they require immense computing power and
are not practical for real-world scenarios. This makes hashing a valuable tool for cybersecurity tasks
where you need to verify data integrity without storing the original data in a recoverable format.

How and Who uses “hashing” in the real world?

Here are some real-world examples of how hashing is used in cybersecurity:

• Verifying Software Downloads: When you download a program or update from the internet,
there’s a good chance it comes with a hash value. The software provider usually publishes this
hash on their website. Before running the downloaded file, you can use a hashing tool to calculate
its hash and compare it to the published value. If they match, you can be confident the download
hasn’t been tampered with during transfer.
• Securing Password Storage: Websites never store your actual password. Instead, they
leverage hashing. When you create an account or log in, your password goes through a hashing
algorithm, and the resulting hash is stored in their database. When you log in again, the website
hashes the password you enter and compares it to the stored hash. If they match, you’re granted
access. This way, even if a hacker breaches the database, they steal only a bunch of nonsensical
hashes, not your actual passwords.
• Protecting File Integrity: Hashing is crucial for ensuring the integrity of files at rest and in transit.
For example, backup systems might calculate a hash for each file before storing it. Later, during
verification, they can recalculate the hash and compare it to the stored one. This ensures the
backup hasn’t been corrupted over time. Similarly, some file transfer protocols use hashing to
detect any alterations to the data during transmission.
• Digital Signatures: Digital signatures are like electronic stamps of approval for documents. They
use hashing to ensure the authenticity and integrity of a document. Here’s the process:
1. The sender creates a hash of the document.
2. The sender uses their private key to encrypt the hash, creating a digital signature.
3. The recipient receives the document and the signature.
4. The recipient uses the sender’s public key (which is publicly available) to decrypt the
signature and retrieve the original hash.
5. The recipient then calculates a new hash of the document and compares it to the
decrypted hash from the signature.

If the hashes match, the recipient can be confident that the document is authentic and hasn’t been
tampered with since it was signed.

• Malware Detection: Anti-virus and anti-malware software often use hashing to identify malicious
files. They maintain databases of known malware hashes. When they scan a file on your system,
they calculate its hash and compare it to the database. If there’s a match, it flags the file as
potentially harmful.

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