QUIZ CMPE-552 17.01.2014 (90 min, 100 points)
St. Name, Surname______________________________________ St.Id#_____________
Calculators are allowed
Instructor Alexander Chefranov
Task 1. (20 points) Consider Fig. 26.7 below.
Figure 26.7. An encrypted element within an XML document
<PaymentInfo xmlns = “http://...”>
<Name> John Doe </Name>
<EncryptedData Type =
“http://www.w3.org/2001/04/xmlenc#Element”
xmlns=”http://www.w3.org/2001/04/xmlenc#”/>
<EncryptionMethod Algorithm =
“http://www.w3.org/2001/04/xmlenc#tripledes-cbc”/>
<ds:KeyInfo xmlns:ds =
“http://www.w3.org/2000/09/xmldsig#“>
<ds:KeyName>keyABC</ds:KeyName>
</ds:KeyInfo>
<CipherData>
<CipherValue>Zx23XAbc4..</CipherValue>
</CipherData>
</EncryptedData>
</PaymentInfo>
What is encrypted, by what encryption method, with what key, and what is the result of
the encryption?
Payment information is encrypted, with tripledes-cbc method, using the key named
keyABC, and result of encryption is Zx23XAbc4..
1
Task 2. (20 points) Consider X.509 certificate in Fig. 14.3 below
Explain contents of the Signature part of the certificate: what is the meaning of each of its
three parts (algorithms, parameters, encrypted), give particular examples of their possible
values or how they might be calculated.
Signature parts are:
- Algorithms – specifies an asymmetric encryption algorithm and hash function
(e.g., RSA, MD5);
- Parameters – specify parameters of the algorithms above (e.g., keylength of RSA,
initial value IV for MD5);
- Encrypted – specifies result of signing (hash of the certificate is calculated,
followed by encryption with the private key of a signer).
2
Task 3. (20 points) Consider Fig. 14.5 below
What is the aim of message 2 in the two-way X.509 strong authentication. Describe the
message as a whole and each its component in particular. What is the aim of each its
part?
The aim of the message 2 is to confirm of the authentication of A to B, and requesting
authentication of B to A
Message 2 contains some data signed with the private key of B
tB is a timestamp generated by B
rB is a nonce generated by B, they both are to counter replay attack
IDA is identifier of A, shows the recipient of the message
sgnData is a data signed by B
EKUa[Kba] is a key for communication between B and A encrypted with the public key
of A for hiding
3
Task 4. (20 points) Let h(x)=(2x+3)mod10. Calculate h4(5). Show your intermediate
calculations.
h4(5)= h3(h((5))= h2(h(3))= h(h(9))=h(1)=5
4
Task 5. (20 points) Consider the table Employee below
Name
Smith U
Brown C
(a) Employee – the original tuples
Salary
JobPerformance
40000 C
Fair TS
80000 S
Good C
TC
TS
S
What result set will be obtained if
Select * from employee
is invoked by a user of S (Secret) level? Show resulting table and explain the result
Name
Smith U
Brown C
Salary
40000 C
80000 S
JobPerformance
Null S
Good C
TC
S
S
As far as the user’s level is S, according to no read-up rule, he can’t see higher level
information, replaced by Null in the display
5