Difference between Direct and Arbitrated Digital Signature

Prerequisite – Digital Signatures

The Direct Digital Signature is only included two parties one to send a message and the other one to receive it. According to the direct digital signature both parties trust each other and know their public key. The message is prone to get corrupted and the sender can decline the message sent by him at any time. 

Advantages:

• Simplicity: Direct digital signatures are simple and straightforward to implement, requiring only the use of digital certificates and a secure private key.
• Speed: Direct digital signatures are fast and efficient, allowing for quick signing of electronic documents.
• Security: Direct digital signatures are secured using strong cryptographic techniques, making it difficult for unauthorized parties to access or alter the signature.

Disadvantages:

• Limited scope: Direct digital signatures can only be used for documents that are exchanged between two parties, making it less suitable for situations that require multiple signatures.
• Lack of impartiality: Direct digital signatures may be seen as less impartial than arbitrated digital signatures, as they do not require a third-party to verify the identity of the signer.

The Arbitrated Digital Signature includes three parties in which one is the sender, the second is a receiver and the third is the arbiter who will become the medium for sending and receiving messages between them. The message is less prone to get corrupted because a timestamp is included by default.

Advantages:

• Impartiality: Arbitrated digital signatures require a trusted third-party to verify the identity of the signer, providing greater impartiality and validity to the signature.
• Multiple signatures: Arbitrated digital signatures can be used for documents that require multiple signatures, such as contracts and agreements.
• Legal recognition: Arbitrated digital signatures are often legally recognized, making it easier to comply with legal requirements for electronic signatures.

Disadvantages:

• Complexity: Arbitrated digital signatures can be more complex to implement and use compared to direct digital signatures, requiring the involvement of a trusted third-party and compliance with certain regulations.
• Cost: Arbitrated digital signatures can be more expensive than direct digital signatures due to the involvement of a trusted third-party and the need for compliance with certain regulations.
• Dependence on third-party: Arbitrated digital signatures require a trusted third-party to verify the identity of the signer, making it important to choose a reliable and trustworthy third-party.

Similarities :

• Both are digital signatures used to sign electronic documents.
• Both are secure and use strong cryptographic techniques to ensure the authenticity and integrity of the signature.
• Both can be used to comply with legal requirements for electronic signatures.
• Both can be used to verify the identity of the signer.
• Both can be used for a wide range of applications, including business contracts, financial transactions, and legal documents.
• Both require the use of digital certificates and a secure private key to sign the document.
• Both can help to reduce the risk of fraud and unauthorized access to signed documents.
• Both can be used to sign documents remotely, allowing individuals and businesses to sign documents from any location.
• Both can be used to provide a time-stamp, providing a record of the date and time of signing.
• Both are widely used in the digital age, as more and more transactions and communications are conducted online.

Difference between Direct and Arbitrated Digital Signature:

S No.	Direct Digital Signature	Arbitrated Digital Signature
1.	It only requires the communicating parties.	It requires an arbiter along with communicating parties to send or receive messages.
2.	In this the digital signature encrypts the whole plain text with the sending party’s private key.	The encrypted message is send by X to arbiter Z with Y’s id, timestamp and some random number PQ.
3.	The message is directly transmitted between both parties without any help from an intermediate.	An arbiter is needed to transmit the message.
4.	The timestamp is not maintained by both sides.	The timestamp is maintained by all three members by default.
5.	In case the confidentiality is needed the message will be encrypt with receiver’s public key or a shared key.	The arbiter provides confidentiality of the message.
6.	Vulnerable to any kind of replay attack.	The timestamp is used to protect the message from any kind of replay attack.
7.	It clocks a processing speed of 16 MHz.	While Raspberry Pi clocks a processing speed of 1.4 GHz.
8.	It is implemented using public key.	It is implemented using private key.
9.	Drawbacks- Trust is needed between sender and receiver because of the absence of an independent verification process. Requirement of private key to be held by sender and public key by both sender and receiver and incase the sender lost the key then he asserts that signature is forged. Having the private key stolen and then falsifying signatures is a potential security risk when utilizing a direct digital signature.	Drawbacks- When using an arbitrator, the sender and the receiver must have trust that the arbitrator will not only time-stamp and send the document as directed, but also take care that there should not be any kind of modification in the data. There is possibility of biasing that an arbiter will be biased in favor of one party or the other if any discretion is used.

Conclusion :

Direct and arbitrated digital signatures are two different types of digital signatures used for signing electronic documents. While direct digital signatures are simple and easy to use, they may not be suitable for high-risk transactions. Arbitrated digital signatures, on the other hand, provide a higher level of security and legal enforceability, particularly for high-value transactions. Understanding the differences between these two types of signatures is important for businesses and individuals who need to sign electronic documents and want to ensure the highest level of security and legal enforceability.