Alice, Cathy and Delta are using the following “textbook”
RSA-4096 digital signature scheme: sig =
(msg)𝑑 mod 𝑁 for message authentication.
Answer the following questions.
Task 1a) (5 marks)
Given Alice’s private key (𝑁𝑎, 𝑑𝑎) and the
message msg given here, compute Alice’s signature sig and
enter the resulting signature value below. In the explanation text
box, briefly explain the method and give the code you used to
compute the answer. Enter below the hash value of
the signature value sig by using the following sagemath
code and upload the value sig
(in decimal format) in a text file at
the end of the Moodle quiz:
import hashlib
h=hashlib.sha256(sig.str(base=10).encode())
hm=Integer(h.hexdigest(),16)
print(hm % (10^8))
Sig: Answer
Task 1b) (4 marks)
Given Alice’s public key (e𝑎, 𝑁𝑎) where
𝑁𝑎 is given in the Moodle quiz
(called 𝑁 in the text file downloadable from the
Moodle quiz in task 1a) and e𝑎 = 65537, and
the two message/signature pairs (msg1, sig1) and (msg2, sig2) which
Bob received from Alice and are given in your Moodle quiz, verify
both as Bob would, and choose the results (accept or reject) you
got for both below. In Task 1a&b (Explanation) text box,
briefly explain the method you used to verify and give the code
you used to compute the answers.
Msg 1:
Msg 2:
Reject
- Task 1a B Computation Alice Cathy And Delta Are Using The Following Textbook Rsa 4096 Digital Signature Scheme Si 1 (54.74 KiB) Viewed 55 times