Certified: The Security+ Prepcast

In this episode, we are exploring three cryptographic tools that help preserve integrity, prove authenticity, and improve password security: hashing, salting, and digital signatures. Each of these techniques plays a critical role in modern cybersecurity. Whether it’s verifying a file, protecting stored passwords, or proving that a message was not altered in transit, these methods form the backbone of trust in digital communication.
Let’s begin with hashing fundamentals. Hashing is the process of converting any input—such as a file, password, or message—into a fixed-length string of characters known as a hash value. The key characteristic of hashing is that it is a one-way function. You can create a hash from data, but you cannot reverse the hash to recover the original content.
Hashing is used to validate the integrity of data. If even one character of the original input changes, the resulting hash value changes dramatically. This allows cybersecurity professionals to verify whether data has been altered. For example, if a file is downloaded from a trusted website, the site might also provide a hash value. After downloading the file, you can hash it locally and compare the result. If the values match, the file has not been tampered with.
Popular hashing algorithms include Secure Hash Algorithm variants like SHA One, SHA Two Fifty-Six, and SHA Five Twelve, as well as older algorithms like MD Five. Secure Hash Algorithm variants are considered stronger and more secure, while MD Five is largely outdated and vulnerable to collisions—meaning different inputs can produce the same hash, which defeats the purpose of uniqueness.
In practice, hashing is used in file verification, digital forensics, secure communication, and more. Email systems, operating systems, and antivirus software all use hashing to check whether data is authentic and unchanged.
Now let’s talk about salting techniques. Salting is a method used to improve the security of stored passwords. It works by adding a unique, random string—called a salt—to each password before hashing it. This ensures that even if two users have the same password, their stored hash values will be completely different.
Without salting, identical passwords produce identical hashes, which makes it easier for attackers to use precomputed tables—called rainbow tables—to crack multiple passwords at once. By salting the password first, each hash becomes unique, rendering those tables useless and dramatically slowing down brute-force attacks.
In a real-world scenario, consider two users who both choose the password “CyberTwentyTwentyFour.” If the system does not use salting, both hashes will be identical. But if the system generates a random salt for each user, even the same password results in completely different hashes. The salt value is stored alongside the hash and used during authentication to recreate and verify the hash when the user logs in.
Salting is especially important in environments with many users or in systems targeted by attackers. A well-designed salting system also uses long and unpredictable salt values, adding even more complexity for an attacker trying to reverse hashes or use stolen credentials.
Finally, let’s move to digital signatures. A digital signature is a cryptographic technique used to verify that a message or file was created by a specific sender and has not been altered. It supports two major goals in cybersecurity: non-repudiation and integrity.
Non-repudiation means the sender cannot deny having sent the message. Integrity means that the contents have not been changed since the message was signed. Digital signatures use asymmetric encryption, where the sender signs a hashed version of the message with their private key. The recipient uses the sender’s public key to verify the signature and confirm that the hash matches the received message.
This process ensures that the message was sent by someone in possession of the private key and that the message has not been tampered with in transit. Digital signatures are used in secure email, document signing, software distribution, and authentication protocols.
One common implementation is in email systems. When an executive sends a confidential message to their team, the email can be digitally signed. The recipients can then verify that it was indeed sent by the executive and that the message content has not been changed. In another example, software companies digitally sign their updates. When a user installs the update, their system verifies the signature to confirm that it was issued by the software provider and is safe to run.
Best practices for using digital signatures include protecting private keys with strong access controls, using secure cryptographic libraries, and validating all received signatures before acting on the associated data. Organizations often use certificate authorities to issue and manage digital certificates that tie public keys to real-world identities, strengthening trust in the signature process.
As you prepare for the Security Plus exam, focus on the unique purposes and behaviors of hashing, salting, and digital signatures. Understand that hashing ensures data integrity, salting protects passwords from rainbow table attacks, and digital signatures provide both integrity and non-repudiation using asymmetric encryption. You may see exam questions that ask you to identify the best tool for a specific security goal or to explain why a certain hashing or signing practice is necessary in a given situation.