From fad2d26358addd73753ffde575e572199c290ac6 Mon Sep 17 00:00:00 2001 From: Bill Buchanan Date: Mon, 1 Mar 2021 18:17:09 +0000 Subject: [PATCH] Update mock_01.md --- z_assessments/test01/mock_01.md | 69 +++++++++++++++++++++++++++++---- 1 file changed, 62 insertions(+), 7 deletions(-) diff --git a/z_assessments/test01/mock_01.md b/z_assessments/test01/mock_01.md index 10af962..b9b2e77 100644 --- a/z_assessments/test01/mock_01.md +++ b/z_assessments/test01/mock_01.md @@ -1,15 +1,70 @@ ![esecurity](https://raw.githubusercontent.com/billbuchanan/esecurity/master/z_associated/esecurity_graphics.jpg) # Assessments -The module has two core learning outcomes: +The test will have short answer/essay questions. Here is a tutorial for the test and to test your knowledge an MCQ test is [here]. Make sure you can complete the following test examples. Any questions, ask Bill? +Q1. Diffie-Hellman -* LO1: Explain and demonstrate a critical understanding of specific cryptographic algorithms and cryptosystems. -* LO2: Implement, critically analyse and evaluate fundamental areas related to state-of-the-art cryptography related area, including current literature, practical implementation and evaluation. +1. G=2351, N=5683, x=7, y=14. What is the shared key? -The first test accounts for 40% of the overall grant, and the coursework accounts for 60%. The assessments are: +Q2. Key Entropy -* Test 1 [here](https://github.com/billbuchanan/appliedcrypto/tree/master/z_assessments/test01). -* C/W [here](https://github.com/billbuchanan/appliedcrypto/tree/master/z_assessments/coursework). +2. If we have a 16-bit key, but only use 200 phrases. What is the key entropy? - +Q3. Key Cracking + +3. If it takes 10ns to test an encryption key. How long will it take to crack a 20-bit key? + +Q4. Public key + +4. Outline how Bob proves his identity to Alice using public key. + +Q5. Public key generation + +5. With RSA, Bob selects two prime numbers of: p=3, q=5. What are the encryption and decryption keys? For a message of 4, prove that the decrypted value is the same of the message. + +Q6. Encoding + +6. What is the Base-64 encoding for "test"? + +Q7. Salting + +7. On a Linux system, using APR1, how is the salt defined in the password file? + +Answers +Q1. + +A=(2351^7) mod 5683 = 4612 +B=(2351^14) mod 5683 = 4758 +Key = 4758^7 mod 5683 = 4614 + +Q2. + +Key entropy = log (phases) / log (2) +Key entropy = log (200) / log (2) = 7.6 bits + +Q.3. + +Max time to crack = 10e-9 x 2^20 +Max time to crack = 0.01 seconds + +Q.5. + +N=p x q = 3 x 5 = 15 +PHI = (p-1)(q-1) = 8 +Pick e for no factors of PHI (1, 2, 4). So let's pick 3. +(3 x d) mod 8 = 1 +d = 3 + +encryption key [15,3] +Decryption key [15,3] + +Message = 4 +Encrypt: 4^3 mod 15 = 4 +Decrypt: 4^3 mod 15 = 4 + +Q6. + +test -> 01110100 01100101 01110011 01110100 +test -> 011101 000110 010101 110011 011101 00 +test -> d G V z d A ==