## Introduction to Digital Signature Algorithm

When a person sends data through a document, it becomes important to identify his/her authenticity for security and safety reasons. Digital signatures are used for this identification. Authentication of the documents means to be aware of who created it and that it did not interfere during its transmission. These signatures are created using certain algorithms. The Digital Signature Algorithm (DSA) is one of these. DSA is a type of public-key encryption algorithm and it is used to generate an electronic signature.

### An Overview

As we have already seen, DSA is one of the many algorithms that are used to create digital signatures for data transmission. In DSA, a pair of numbers is created and used as a digital signature. These are generated using some specific algorithms. They allow the receiver to authenticate the origin of the message. The digital signature, created using DSA, is in private at the starting point of the data transmission, while ends in public. What this means is that only the person transmitting the data can make the signature, which is to be added to the message, but anyone can authenticate the signature at the other end.

### Understanding Digital Signature Algorithm

There are a number of algorithms that are used to create digital signatures. Most of these follow a simple method of using the private keys of a sender to sign the message digests. This is how the digital thumbprint is formed for the data to be sent. Take a note that it is the message digest that is signed and not the data. Therefore, the size of the signature is small. However, this is not the case with the digital signature algorithm. The procedure followed when using DSA is not as simple as using a private and public key at the start and end of the transmission, respectively. It, on the other hand, generates two digital signatures by applying complex and unique mathematical functions, about which we will know in detail in the later parts of this article.

So, as it can be understood, DSA is used only to create the signatures. They cannot be used for encryption of data. Due to this, it is not subjected to the restrictions of import and export, which is usually the case with RSA.

### The Working of Digital Signature Algorithm (DSA)

The DSA algorithm is standard for digital signature which is based on the algebraic properties of discrete logarithm problem and modular exponentiations and is based on the on public-key cryptosystems principal.

Digital signatures are work on the principle of two mutually authenticating cryptographic keys. Signatures are based on public/private key pairs. With public key algorithm like RSA, one can create a mathematically linked private key and public key. One can sign a digital message with his private key. Signature related data can be encrypted by a person with the use of a private key. The private key should always be with a person who wants to create a digital signature. The public and the private key, both can always be derived from one another as they are related mathematically. Signer’s public key is the only way to decrypt this data. One can give the public key to anyone who needs verification of the signer’s signature. It is vital to keep private key secret as one can generate your signature on a document with the help of this. In this manner, the authentication digital signature is done. In a digital signature, validly is only assured by public and private keys.

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On the other hand, the digital signature algorithm does not use a private key to encrypt data. Also, a digital signature algorithm does use a public key to decrypt this data. To create a digital signature with two 160-bit numbers, DSA works on the principle of a unique mathematical function. These two numbers are made by using the private key and the message digest.

As the public key is not used to authenticate the signature, the verification process is complex. Both keys are used to secure data in a special digital signature algorithm for further security assurance.

Now, a hash function is used to create a message digest. The generated message digest along with the DSA algorithm is what gives the digital signature. This signature is then sent along with the message. At the receiving end, the same hash function is used to authenticate the source and the data.

**To summarise-**

- Keys are generated with the help of the key generation algorithm. Created keys are used to sign a document.
- For generating a signature, digital signature algorithm is used.
- A hash function is used to make a message digest.
- Message digest with DSA gives the digital signature.
- The digital signature is then transmitted along with the data sent.
- The authentication of the signature is done using verification algorithms. For verification, the same hash function is used.

### Advantages of Digital Signature Algorithm

- Along with having strong strength levels, the length of the signature is smaller as compared to other digital signature standards.
- The signature computation speed is less.
- DSA requires less storage to work as compared to other digital standards.
- DSA is patent free so it can be used free of cost.

### Disadvantages of Digital Signature Algorithm

- It requires a lot of time to authenticate as the verification process includes complicated remainder operators. It requires a lot of time for computation.
- Data in DSA is not encrypted. We can only authenticate data in this.
- The digital signature algorithm firstly computes with SHA1 hash and signs it. Any drawbacks in cryptographic security of SHA1 are reflected in DSA because implicitly of DSA is dependent on it.
- With applications in both secret and non-secret communications, DSA is of the US National Standard.

### Conclusion

In the above script, we have come up with an essential point regarding digital signature algorithm. This article gives information about the digital signature algorithm, its way of working and advantages & disadvantages.

The digital signature is one of the best authentication tools for the electronic record. On account of its cost, security, time, and speed, digital signatures are popular nowadays. In today’s interconnected and digital world, the digital signature algorithm is a vital aspect for creating a safer and secure environment.

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