What is a Digital Signature?

How do digital signatures work?

Digital signatures rely on the principles of asymmetric cryptography, which uses two mathematically linked keys—a private key and a public key. Here’s a step-by-step explanation suitable for a grade 12 reader:

1. Key Generation: When you sign up for a digital signature service, you generate a pair of keys. The private key, which you keep secret, is used to create the signature. The public key, which you share openly, is used by others to verify your signature.
   
2. Document Hashing: Before signing, the document is run through a hash function. Think of a hash function like a digital fingerprint; it takes the content of the document and produces a fixed-size string of characters. Even a tiny change in the document will result in a completely different hash value.
   
3. Signing: The hash of the document is then encrypted with your private key. This encrypted hash is the digital signature. Because it’s based on the unique hash of the document, any alteration in the document after signing will be detected.
4. Verification: When someone receives the digitally signed document, they use your public key to decrypt the signature and retrieve the hash. They also hash the document on their end. If the two hashes match, the document is verified as authentic and unaltered.

When do I need a digital signature?

Digital signatures offer extra layers of security and verification, making them ideal for situations where tamper-proof and legally robust documentation is required. However, it's important to note that for the vast majority of documents—especially everyday transactions and agreements—the electronic signatures provided by Sign.Plus are more than sufficient. They are secure, legally compliant, and user-friendly.