Digital signature algorithm in cryptography - A digitalsignature is a mathematical scheme used to prove the authenticity of a digital message or document. This scheme is a guarantee that the data and information really come from the correct source.
A digital signature consists of a series of hash functions generated from a certain hash function algorithm process which is then encoded (encrypted) with asymmetric key cryptography algorithms. To verify it, the public key of the algorithm is used.
Digital signatures are one of many ways to keep digital data secure. Digital signatures are made by affixing a "sign" in the form of codes that are placed at the end of the document. These codes are generated from the message encryption process with a cryptographic algorithm.
With the existence of this digital signature, a recipient of the message can be assured that the document he receives is true and genuine from the original sender of the message and that there is no modification in the document by unauthorized parties or intruders.
History
The idea of creating a digital signature scheme was originally in 1976. At that time Whitfield Diffie and Martin Hellman described the idea, but it was only an idea that had not been implemented.
Then a year later, in 1977, the RSA algorithm was born, which was discovered by Ronald Rivest, Adi Shamir and Len Adleman. This algorithm can actually be implemented to create a digital signature.
The year 1988 became a new beginning for digital signatures to be known, when it was born Lotus Notes 1.0 is software that uses the RSA algorithm. This software offers digital signatures. In 1999 digital signatures could be embedded in PDF documents.
It doesn't stop here, in 2000 digital signatures were legally available and in 2002 SIGNiX (cloud based digital signature software) was very widely used. Finally, in 2008 digital signatures became an ISO (International Organization for Standardization) standard.
Work Process
The digital signature process is as follows:
- The sender of the message first calculates the Message Digest (MD) of the message. MD is obtained by transforming message M with a one-way hash function.
- MD is encrypted with a private key cryptographic algorithm such as the RSA algorithm. The result of this encryption is called a digital signature (S).
- The digital signature (S) is placed on the M message.
- Then message M is sent through the communication channel, message M has been signed with S
When message M has reached the recipient, the verification process to prove the authenticity of the message is as follows:
- The digital signature (S) is decrypted with the public key that has been assigned to the recipient. This process will produce an MD (Message Digest).
- The receiver converts M to MD' with the same one-way hash function as the hash function used by the sender.
- If MD'=MD, then the digital signature received is authentic and comes from the correct sender.
Security Aspect
Digital signatures provide security services for users both on data sent on the network and on data stored on the device. The security aspects of digital signatures are as follows:
- Authentication: This is the aspect where the recipient of the information can ensure the authenticity of the message, that is, in other words, the data and information really come from the correct source. For example, when logging in using a certain username and password, the system will authenticate in a way that the system tries to ensure that the username and password are valid.
- Integrity: This is the aspect where the authenticity of the message is maintained even though it is sent through a network that is vulnerable to attacks, but it can be ensured that the data or information sent is not altered by unauthorized persons.
- Non-repudiation: Is an aspect related to the authenticity of the sender of the message, it can be ensured that the sender is the person who is actually expected to send the data.
Everyone involved in digital signatures has an obligation to provide security for the digital signatures used. At least the digital signature safeguards used include:
- the system cannot be accessed by other unauthorized persons
- must apply the precautionary principle to avoid unauthorized use
- delaying the use of digital signatures or using other means if it is known that the Electronic Signature creation data has been compromised or the conditions are known by the signer to pose a significant risk.
Use
The use of digital signatures has been widely used in this modern era. As for some examples of the use of digital signatures, namely, digital signatures are used for security in sending e-mails by encrypting and then affixing a digital signature to e-mails sent.
This is so that the email sent cannot be modified by unauthorized parties, and the recipient can be sure of the authenticity of the email because if the email has been modified, the digital signature will not match.
In addition, digital signatures are also used to secure online transactions and identify participants involved in transactions. This is important so that transaction actors are guaranteed data security.
Digital signatures can also be used to sign and ensure the authenticity of documents such as Word, Excel, and PDF document formats. Furthermore, digital signatures are used in companies with legally enforceable certificates.
The advantages of using digital signatures include being more efficient, faster, and more environmentally friendly because they save paper usage.
Based on The Total Economic Impact Of AdobeSign Study by Forrester in 2019 the benefits of digital signatures are to provide a better consumer experience, reduce costs, speed up deals and increase revenue.
While the advantages of digital signatures in the business world are saving resources and time, faster implementation of decisions, increasing productivity, reducing costs, minimizing risk, being more secure, improving customer experience, increasing environmental credentials.
Functionally, digital signatures serve as a tool to verify and authenticate the identity of the signer as well as to ensure the integrity and authenticity of the document.[Digital signatures are also capable of presenting a uniquely created signing identity that refers only to the signing.
Similar to manual signatures, digital signatures are unique in that one person will be different from other people's signatures.
Algorithm
- Some of the algorithms that can be used to build digital signatures are:
- RSA
- DSA (Digital Signature Alghoritm)
- SHA. Either SHA1, SHA2, or SHA3.
- ElGamal
- RSA combination SHA
- Schnorr signature
- Pointcheval–Stern signature algorithm
- Rabin signature
