What Are Digital Signatures?
A digital signature is exactly what it sounds like a modern alternative to signing documents with paper and pen.
It uses an advanced mathematical technique to check the authenticity and integrity of digital messages and documents. Every time when you receive any message or document that is digitally signed, you can be almost 100% sure that the message or document has not been altered when it was in-transit. It is guaranteed that the message or document has been sent by the original sender only (i.e., Origin of the message).
In addition to digital document signing, they are also used for financial transactions, email service providers, and software distribution, areas where the authenticity and integrity of digital communications are crucial.
There is an industry-standard technology that called 'Public Key Infrastructure (PKI)' which ensures a digital signature's data authenticity and integrity.
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How Do Digital Signatures Work?Digital signatures, at the most fundamental level, are mathematical algorithms used to validate the authenticity and integrity of an electronic message. This "message" could be an email, a credit card transaction, a macro, or a digital document.
These digital signatures create a virtual "fingerprint" that is completely unique to a person, or an entity. That's why these can therefore be used not just to protect the contents of messages, but also to ensure that they were written by 'who' they claim to have been.
If we are interest in looking at digital signature from a deeper level, then you need to know one thing that -- digital signatures work by applying a hash function to a message.
In most cases, a user's private key will be used to create a "hash," which is a fixed-length string of numbers and letters. And this string (hash) is totally unique to the message being hashed, or document being signed, for example.
Also know that these hash functions are also one-way functions — a computed hash CANNOT BE REVERESED to find other files that may generate the same hash value. The most popular hashing algorithms in use today are SHA-1, SHA-2 and SHA-256, and MD5.
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Why Are Digital Signatures So Important?They are highly important because they help you verify 3-things:
1. Authentication
Since in most cases, digital signatures are created using the sender's private encryption key, it is possible for you to verify the identity of the message source or sender of the message.
2. Data Integrity
Remember, hash functions produce a digital signature by looking at the ENTIRITY of a particular message. It means that--if any part of the message changes, so does the hash function; you would immediately know this. It also means that if a message is intercepted in-transit and changed before it reaches you, when you will verify the digital certification, it will fail. You would be sure to know that the data or message has lost its integrity.
3. Non-repudiation
You should also know that one is advised never to share one's PRIVATE KEY with anybody or any entity. This is the foundation of non-repudiation that it cannot be duplicated by anybody else, the sender's identity is verified and fully-established...it makes the document or message totally permissible as a proof, in any court of law. In most parts of the world, digital signatures are considered legally binding and hold the same value as traditional document signatures. Fully acceptable in the courts of law!
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However, it's important to recognize that newly-trained security analysts often overlook the importance and centrality of digital signatures to cybersecurity.
Though technologies like VPN with real-time encryption may ensure the security of data when it is in-transit, but they cannot authenticate the identity of the creator of a message in the same way that a digital signature can.
Other security technologies have their own place in the scheme of things, but never forget that digital signatures still cover a lot of grounds of your risk management approach.
NOTE:
Using digital signatures does not encrypt the message itself.
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