2. Tools for Safe guarding Web Resources
Digital Signature
Encryption
Watermarking etc.
Dr. Irfan ul Haq Akhoon
3. Digital Signature
A digital signature is a mathematical scheme for verifying the authenticity of digital messages or
documents.
A representation of assuring that the document meets all legal formalities and is authentic in its
framework.
A digital signature can be used with any kind of message, whether it is encrypted or not, so that the
receiver can be sure of the sender's identity and that the message arrived intact.
It is commonly used for software distribution, financial transactions, contract management software,
and in other cases where it is important to detect forgery or tampering.
Dr. Irfan ul Haq Akhoon
4. Advantages
Makes a document a legal one.
Authentication, identification of the person that signs.
Integrity of data, every change will be detected.
Non repudiation, because the author cannot be denied of his work (created and sent).
Imposter prevention, Elimination of possibility of committing fraud by an imposter
Dr. Irfan ul Haq Akhoon
5. Disadvantages
Its advantages are hampered by lost or theft of keys and use of vulnerable storage facilities.
A number of Digital Signature standard exist which are incompatible with each other and
There is a strong need of a standard through which these different methods (keys) can interact.
Dr. Irfan ul Haq Akhoon
6. Encryption
Encryption is the conversion of data into a form, called a CIPHER Text.
The use of encryption/decryption is as old as the art of communication.
It is especially important when carrying out any kind of sensitive transaction in
wireless communications.
Ex: A credit-card purchase online, or the discussion of a company secret between
different departments in the organization.
Dr. Irfan ul Haq Akhoon
7. Example
Encryption depends on modifying or scrambling messages.
So a key is necessary to understand the message.
If the original message is
ALLAHA IS GREAT
Then the encrypted version depends on the key as follows:
(key = 1) BMMBIB JT HSFBU
(key = 2) CNNCJC KU ITGCV
(key = 3) DOODKD LV JSHDW
Dr. Irfan ul Haq Akhoon
8. Watermark
A distinguishing mark impressed on paper during manufacture; visible when paper is held up to
the light (e.g. $ Bill)
Dr. Irfan ul Haq Akhoon
9. Digital Watermarking
Digital Watermarking: Application of Information hiding (Hiding Watermarks in digital Media, such as images)
Digital Watermarking can be ?
- Perceptible (e.g. author information in .doc)
- Imperceptible (e.g. author information in images)
Dr. Irfan ul Haq Akhoon
10. Applications
Copyright Protection: To prove the ownership of digital media
Tamper proofing: To find out if data was tampered.
Quality Assessment: Degradation of Visual Quality
Authenticity: To authenticate the facts
Dr. Irfan ul Haq Akhoon
