Protecting Your Digital Signature: Tips for Keeping It Secure

A digital signature is a mathematical technique used to validate the authenticity and integrity of a message, software or digital document.

As the digital equivalent of a handwritten signature or stamped seal, a digital signature offers far more inherent security, and it is intended to solve the problem of tampering and impersonation in digital communications.

Digital signatures rely on certain types of encryption to ensure authentication. Encryption is the process of taking all the data that one computer is sending to another and encoding it into a form that only the other computer will be able to decode.

Authentication is the process of verifying that information is coming from a trusted source. These two processes work hand in hand for digital signatures.

Password – The use of a user name and password provide the most common form of authentication. You enter your name and password when prompted by the computer. It checks the pair against a secure file to confirm. If either the name or password do not match, then you are not allowed further access.

Checksum – Probably one of the oldest methods of ensuring that data is correct, checksums also provide a form of authentication since an invalid checksum suggests that the data has been compromised in some fashion.

A checksum is determined in one of two ways. Let’s say the checksum of a packet is 1 byte long, which means it can have a maximum value of 255. If the sum of the other bytes in the packet is 255 or less, then the checksum contains that exact value.

However, if the sum of the other bytes is more than 255, then the checksum is the remainder of the total value after it has been divided by 256. 

Digital signatures can provide the added assurances of evidence of origin, identity and status of an electronic document, transaction or message and can acknowledge informed consent by the signer.

In many countries, including the United States, digital signatures are considered legally binding in the same way as traditional document signatures.

Digital signature technology requires all the parties to trust that the individual creating the signature has been able to keep their own private key secret. If someone else has access to the signer’s private key, that party could create fraudulent digital signatures in the name of the private key holder.

What is digital signature example?

To create a digital signature, signing software — such as an email program — creates a one-way hash of the electronic data to be signed. The private key is then used to encrypt the hash. The encrypted hash — along with other information, such as the hashing algorithm — is the digital signature.

What are three uses for digital signatures?

Uses of digital signatures:

Digital signatures are used to meet three important goals of information security: integrity, authentication, and non-repudiation. Message or Data integrity is particularly crucial during data transfers.

How to create a digital signature:

To create a digital signature, signing software — such as an email program — creates a one-way hash of the electronic data to be signed. The private key is then used to encrypt the hash. The encrypted hash — along with other information, such as the hashing algorithm — is the digital signature.

The reason for encrypting the hash instead of the entire message or document is that a hash function can convert an arbitrary input into a fixed length value, which is usually much shorter. This saves time as hashing is much faster than signing.

The value of a hash is unique to the hashed data. Any change in the data, even a change in a single character, will result in a different value. This attribute enables others to validate the integrity of the data by using the signer’s public key to decrypt the hash.

If the decrypted hash matches a second computed hash of the same data, it proves that the data hasn’t changed since it was signed. If the two hashes don’t match, the data has either been tampered with in some way — integrity — or the signature was created with a private key that doesn’t correspond to the public key presented by the signer authentication.

A digital signature can be used with any kind of message — whether it is encrypted or not — simply so the receiver can be sure of the sender’s identity and that the message arrived intact.

Digital signatures make it difficult for the signer to deny having signed something — assuming their private key has not been compromised — as the digital signature is unique to both the document and the signer and it binds them together. This property is called nonrepudiation.

Digital certificates – To implement public key encryption on a large scale, such as a secure Web server might need, requires a different approach. This is where digital certificates come in. A digital certificate is essentially a bit of information that says the Web server is trusted by an independent source known as a Certificate Authority. The Certificate Authority acts as the middleman that both computers trust. It confirms that each computer is in fact who they say they are and then provides the public keys of each computer to the other.

The Digital Signature Standard (DSS) is based on a type of public key encryption method that uses the Digital Signature Algorithm (DSA). DSS is the format for digital signatures that has been endorsed by the US government. The DSA algorithm consists of a private key that only the originator of the document (signer) knows and a public key.