Difference Between Digital Signature and Digital Certificate

People get a little confused between a digital signature and a digital certificate because both of them provide security measures and sound similar. This might be the reason that people think both of them are similar. The computations that are impossible to break by using the latest fastest computers are known as public-key cryptography. It is also called asymmetric encryption. But problems occur while using the encryption with the help of private and public keys. As per assumption, public keys are open and anyone can access these keys.

Encryption is the process of converting electronic information into some other form which is known as ciphertext. This text cannot easily understandable by anyone except the authorized parties. This will provide surety to data security. The process of translating the code to data is called decryption. 

What is a Digital Signature?

The tool that helps to verify a received document or transaction has been created and sent by the sender without any third-parties interference is known as a digital signature. It is considered as an authenticity guarantor which assures the receiver that the document which they received has not been tampered with. Basically, a digital signature is a mathematical technique that has been used for validating the authenticity and integrity of a message, software, or digital signature. 

How a Digital Signature Performed?

The tool which is used for performing the digital signatures is Digital Signature Standard (DSS). National Institute of Standards and Technology (NIST) issued the DSS standard and referred to as the Federal Information Processing Standard (FIPS) PUB 186 in 1991. Two primary techniques are used for performing a digital signature.

1. For computing the message digest against the original message, the SHA-1 algorithm is used by DSS. It helps to utilize the message digest in digital signature generation. Digital Signature Algorithm (DSA) is used for performing the above process and this in turn based on asymmetric key cryptography. The security and encryption of the messages are not provided by this process.
2. RSA algorithm can also be used for performing the digital signature. When the encryption and security of the message are needed then this method is used. 

Reasons to Use a Digital Signature

There are some reasons due to people use digital signature:

• Authenticity – The surety to the receiver is given by the digital signature about the correct sender of the message. At the time of financial transactions, this assurance is highly important. 
• Integrity – The malicious third parties can tamper with the message which is sent by someone by altering or changing the original meaning. If the digital signature is used, then any alteration in the message makes the signature invalid. This will give the receiver assurance that no alteration has been done to the message. 
• Accountability – The sender will not be able to claim on sending the message after using the digital signature to transmit a message or document. Non-repudiation of origin is a guarantee by the digital signature. 

Steps for Creating Digital Signatures

There are various steps that you need to follow for creating a digital signature are:

1. After applying the hash function on the message then the message digest can be computed. The private key of the sender is used for encrypting the message digest to form the digital signature. 
2. The transmission of digital signature occurs with the message.
3. By using the public key of the sender, the receiver can decrypt the digital signature. 
4. The message digest is with the receiver now.
5. The message digest can be computed by the receiver from the message.
6. The receiver computes message digest and this message digest need to be similar for ensuring integrity.

What is a Digital Certificate?

The important digital identification cards are known as Digital Certificates. The certificate authorities (CAs) and particular government bodies issue the digital certificates after doing complete verification of the individual’s identity. The purchaser of the digital certificate needs to meet all the requirements for the certificate. It is very important for the digital certificates to verify the identity of the owner which will be displayed to others. The relying party gives the authenticity guarantee when the digital certificate is signed by the document. 

Digital Certificate Consists of:

• Certificate holder name.
• Serial number which helps to identify a certificate.
• Date of expiration.
• Copy of public key certificate holder.
• Digital signature of the authority that issues the certificate.

Reasons to Use a Digital Certificate

There are several reasons due to which people use a digital certificate:

• The owner’s identity can be verified with the personal information present in the digital certificate.
• People can contact the issuing authority.
• It is difficult to tamper with a digital certificate.
• The issuing authority can revoke the certificate if identification is misused.
• After contacting the issuing authority, the revocation can be checked easily.

Digital Signature Vs Digital Certificate