Monday, 18 February 2013

What is a Digital Signature

After talking about the Basic Cryptography its the time to learn about the Digital signatures...!!!

A Digital Signature Certificate, like hand written signature, establishes the identity of the sender filing the documents through internet which sender can not revoke or deny. Accordingly, Digital Signature Certificate is a digital equivalent of a hand written signature which has an extra data attached electronically to any message or a document.
Digital Signature also ensures that no alterations are made to the data once the document has been digitally signed. A DSC is normally valid for 1 or 3 years, after which it can be renewed
A Digital Signature is a method of verifying the authenticity of an electronic document.

What is a Digital Signature Certificate...?

Digital signature certificates (DSC) are the digital equivalent (that is electronic format) of physical or paper certificates. Examples of physical certificates are drivers' licenses, passports or membership cards. Certificates serve as a proof of identity of an individual for a certain purpose; for example a driver's license identifies someone who can legally drive in a particular country. Likewise, a digital certificate can be presented electronically to prove your identity, to access information or services on the Internet or to sign certain documents digitally, properly implemented digital signatures are more difficult to forge than the handwritten type.

To digitally sign a document, you must have a digital ID. This unique identifier can obtained from various Certification Authorities on the Web, such as VeriSign and EchoSign. Once you have a digital ID, you can add register it with programs that support digital signatures, such as Adobe Acrobat and Microsoft Outlook. Then you can use the program's "Sign" feature to add your digital signature to documents.
The digital signature is simply a small block of data that is attached to documents you sign. It is generated from your digital ID, which includes both a private and public key. The private key is used to apply the signature to the document, while the public key is sent with the file. The public key contains encrypted code, also called a "hash," that verifies your identity.
Digital signatures can be used to certify or approve documents. Certifying signatures verify the document's creator and show that the document has not been altered since it was signed. Therefore, only the original creator of a document can add a certifying signature. Approval signatures can be added by anyone with a digital ID and are used to approve documents, track changes, and accept terms stated with a document.

                                                         Digitally Signed Word Document

            So if a document is once digitally signed then its difficult to tamper it by others...!
A digital signature scheme typically consists of three algorithms:
  • A key generation algorithm that selects a private key uniformly at random from a set of possible private keys. The algorithm outputs the private key and a corresponding public key.
  • A signing algorithm that, given a message and a private key, produces a signature.
  • A signature verifying algorithm that, given a message, public key and a signature, either accepts or rejects the message's claim to authenticity.
Two main properties are required. First, a signature generated from a fixed message and fixed private key should verify the authenticity of that message by using the corresponding public key. Secondly, it should be computationally infeasible to generate a valid signature for a party who does not possess the private key.

How Digital Signatures works...?

 Assume you were going to send the draft of a certain contract to your client in another town. You want to give your client the assurance that it was unchanged from what you sent and that it is really from you. Here then would be the process:
1. You copy-and-paste the contract (it’s a short one!) into an e-mail note.
2. Using special software, you obtain a message hash (mathematical summary) of the contract.
3. You then use a private key that you have previously obtained from a public-private key authority to encrypt the hash.
4. The encrypted hash becomes your digital signature of the message. (Note that it will be different each time you send a message.)

The disadvantages of using digital signatures involve the primary avenue for any business: money. This is because the business may have to spend more money than usual to work with digital signatures including buying certificates from certification authorities and getting the verification software..., any how nothing in this world is for free.... :)

Types of Digital Signatures :

Class 1: The use of digital ID’s for secure email enables the user to digitally sign and encrypt digital communication. The best way to secure and validate your email address is by using Class I Digital Signature. The recipient of the email will know that the content was kept confidential during transmission.

Class 2: Safe Solutions provides LRA (Local Registration Authority) for commencement of service, Class 2 certificate from the IT Department and ROC department. The Class 2 Digital certificates are electronic files that are used to identify people and resources over networks such as the internet.

Class 3: Class 3 Digital Signature recognizes people and resources over network and ensures encrypted communication between two parties. Safe Solutions provides LRA (Local Registration Authority) for commencement of service. The class 3 Digital Signature certificate recognizes people at E- procurement, E-Tender & E-actions.
The list of licensed CAs along with their contact information is available on the MCA porta...
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  1. Great idea! Thanks for sharing What is a Digital Signature. Nice! Your curtains look beautiful, too! And loll at tutorial on removing black spray paint from garage floor. Awesome!!! I’m your newest follower from Creative Bloggers Hop. Please follow

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  2. Digital Signature Certificate, like hand written signature, establishes the identity of the sender filing the documents through internet which sender can not revoke or deny.

    These certificates are accepted for IFFCO, Northern Railway, MCA 21, E-filing, E -tendering etc...

    There are basically 3 types of Digital Signature Certificates Class-1, Class-2 & Class-3 each having different level of security.

    All the authorized signatories of company under MCA21 require Class-2 Digital Signature Certificate.

    Similarly any document filed by CA/CS/CWA & TAX PRACTIONERS under MCA21 require Class-2 Digital Signature Certificate.

    1. This comment has been removed by the author.

  3. That was very useful and interesting information Digital signature3 . A valid Digital signature for Tender offers a recipient reason to believe that the message was created by an authorized person of Coal India Company; such that he or she cannot refute having sent the document or and that the message was not modified in transit. A Digital signature for Tender is commonly used for conducting various tenders through electronically by the company, and in other cases where it is significant to identify tampering or forgery

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  5. This comment has been removed by a blog administrator.


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