LGNSCOE, Anjaneri
Department of Computer Engineering
(GR: B)
ASSIGNMENT NO:
Write a program for identifying the tampering of digital signature
using Python Programming .
TE Comp (SEMESTER I)
1
Programming Laboratory-II
LGNSCOE, Anjaneri
Department of Computer Engineering
Title: Write a program for identifying the tampering of digital signature using Python
Programming.
Learning Objective:
1. To learn about concept of tampering.
2. To understand and implement the tampering digital signature.
1. Theory
Digital Signatures:
Digital signatures are commonly used for software distribution, financial transactions,
and in other cases where it is important to detect forgery or tampering. so digital
signatures ("digital thumbprints") are commonly used to identify electronic entities for
online transactions. A digital signature uniquely identifies the originator of digitally
signed data and also ensures the integrity of the signed data against tampering or
corruption.
One possible method for creating a digital signature is for the originator of data to create
the signature by encrypting all of the data with the originator's private key and enclosing
the signature with the original data. Anyone with the originator's public key can decrypt
the signature and compare the decrypted message to the original message. Because only
someone with the private key can create the signature, the integrity of the message is
verified when the decrypted message matches the original. If an intruder alters
the
original message during transit, the intruder cannot also create a new valid
signature.
If an intruder alters the signature during transit, the signature does not verify properly
and is invalid.
However, encrypting all data to provide a digital signature is impractical for three
reasons:
TE Comp (SEMESTER I)
2
Programming Laboratory-II
LGNSCOE, Anjaneri
•
Department of Computer Engineering
The ciphertext signature is the same size as the corresponding plaintext, so message
sizes are doubled, consuming large amounts of bandwidth and storage space.
•
Public key encryption is slow and places heavy computational loads on computer
processors, so network and computer performance can be significantly degraded.
•
Encrypting the entire contents of information produces large amounts of ciphertext,
which can be used for cryptanalysis attacks, especially known plaintext attacks
(where certain parts of the encrypted data, such as e-mail headers, are known
beforehand to the attacker).
Tampering of digital signature:
An electronic signature is only as good as the security that protects it. Some electronic
signature services
-offer a feature called “tamper evidence.”If someone tries to change any part of the
document (even Something as simple as deleting a space or capitalizing a word) there’s
proof that tampering took place. Dealing with important documents or high-value
transactions, advanced tamper evidence is vital. In fact
-many banks and credit unions require this kind of tamper evidence to protect their
customers.
Intuitively, a signature scheme is tamper-evident if there is only a single valid signature
for any given message and any given transcript. Note that in practice a verifier (whom we
call observer) must check the validity and covert-validity of all the signatures output by
the signer. If the signer refuses to engage in the Verify protocol with the observer, or (in
the non-interactive case which we focus on), if it does not output a proof of covertvalidity, the observer announces that the signer failed the test of covert -validity and is
thus untrustworthy.
2. Student supposed to write a mathematical modeling for above problem
definition
TE Comp (SEMESTER I)
3
Programming Laboratory-II
LGNSCOE, Anjaneri
Department of Computer Engineering
3. Steps in Algorithm
Students supposed to write steps in algorithm
4. Program
Student should develop program for above problem definition
5. Output:
Students supposed to attach output of implemented program
6. Conclusion
Hence, we have successfully studied concept of identifying the tampering of digital
signature.
TE Comp (SEMESTER I)
4
Programming Laboratory-II