panduan


LONTAR KOMPUTER VOL. 9, NO. 1, APRIL 2018                 p-ISSN 2088-1541   
DOI : 10.24843/LKJITI.2018.v09.i01.p06  e-ISSN 2541-5832 
 

52 
 

Encoding the Record Database of Computer Based 
Test Exam Based on Spritz Algorithm 

 

 
Taronisokhi Zebua

 

 
AMIK STIEKOM North Sumatera, Indonesia 

taronizeb@gmail.com 
 
 

Abstract 
 

Computer utilization in the execution of the computer-based test is currently no strange. Almost 
all government agencies and companies at the time of conducting the test acceptance of new 
employees have been using computer-based test system online or often referred to as 
Computer Based Test (CBT). One of the important aspects to be considered and must be 
maintained in the execution of computer-based exams is the problem of question security and 
exam answers to abuse actions. One technique that can be done to solve the problems above 
is the use of cryptographic techniques. This research describes the use of spritz algorithm which 
is one of the cryptographic algorithms to encode the text database record of the computer-
based test. The results of the encoding process can make it harder for the attackers to know the 
original text of the exam, so as to minimize the abuse of the exam. 
  
Keywords: cryptography, CBT, database, exam, spritz. 
 
 
1. Introduction 

Implementation of computer-based exams online nowadays has been done by various agencies 
both government and private companies. This is done because the implementation process is 
more effective when compared with the Paper-Based Test (PBT) test or better known as a 
conventional test. Testing Computer-based or often known as Computer Based Test (CBT) is 
no longer excluded exams to come to the location of the exam or exam executive agencies, 
slowly can appear online anywhere or place that has been determined by the executive 
committee. One aspect that must be considered in making the test. Based on research 
conducted by Rejito and Setiana, who said things that must be considered in the 
implementation of CBT is the confidentiality of the exam database because it should not be 
published either from the side of the test participants (client) or database manager 
(administrator) [1]. 

Utilization of cryptographic algorithm techniques is one alternative solution to solve the above 
problems. Another study conducted by Setyaningsih say that the application of cryptographic 
techniques is one way that can be done to secure the data by encrypting it [2]. Text exam 
records that have been stored in the database can be encoded by the procedure or the 
cryptographic algorithm. It can have a significant impact on the business to minimize the abuses 
of the exam from a party other than the legitimate parties. Counterparts, aiming to avoid the 
misuse of information by other parties who are not eligible [3]. 

Spritz algorithm is a variant of the RC4 algorithm produces sponge-base construction in 
generating a key in the encryption and decryption process. This algorithm works based on the 
concept of a stream cipher that is encryption one by one. One of the advantages of this 
algorithm is the process of generating the keys used in the process of encryption and 
decryption. The next generated key always depends on the flow of the previous key [4]. The 
high complexity of the performance of the spritz algorithm led to the complexity of the 
cryptanalysts to find the key and solve this algorithm. 

This research describes how the security text records a computer-based exam conducted 
online. The safeguards do is minimize the abuses of the exam to encode the original text of 
exam questions are stored as database records based algorithm spritz. Records that have been 

mailto:1penulis@email.com


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encrypted is what will be accessed by the examinee (client) when accessing the exam. Exam 
encrypted will be decrypted automatically by the application test so that the original text of 
proficiency level exam questions can be understood by the examinee. 
 
2. Research Methodology 

The methodology that used in conducting this research is : 
a. Literature Review 

Search and study relevant literature or references to topics covered either through books 
or electronic journals. 

b. Analysis 
Analyzing the security problems in the implementation of the computer-based test, 
especially security exam on either the server or client computers. This is done to 
determine the solutions provided to solve problems that have been identified. 

c. Implementation 
Using spritz algorithm to encrypt the online test records computer-based database.  

3. Literature Review 

3.1. Computer Based Test 

The Computer-based test known as Computer Based Test (CBT) has been done since 1960 [5]. 
Until now, government agencies and companies are using CBT as a model of implementation of 
the various examination techniques or hiring new employees, because in addition to effectively 
and efficiently can reduce operating costs required in the implementation of the test. Computer-
based exams involve client-server systems. Computer servers to act as a provider of the exam 
as well as a central controller for the client implementation of the test. Implementation of 
computer-based test can give participants more accurate test results because everything is 
done by the system. In addition to this, the level of fraud participants in working on the test can 
be minimized. 

3.2. Cryptography 

Cryptography is a term of one of the commonly used data security techniques. This technique 
works by encoding data to be secured so it is not easy to fall into the hands of others who are 
not the real recipient [6]. Along with its development, the term cryptography is defined as a 
science that studies mathematical techniques relevant to data security aspects including 
confidentiality, integrity, authentication, and non-repudiation[9]. Cryptographic techniques have 
several algorithms such as GOST, TDES, RC4, Spritz, Triangle Chain Cipher and others. The 
application of cryptographic algorithms must achieve the principle of confusion 
(confusion/confusion) and diffusion (diffusion/melting)[7][10]. The basic functions of 
cryptographic algorithms are encryption, decryption, and keys. The elements of the 
cryptographic system are the original file/data (plaintext), the encrypted file (ciphertext), the 
encryption process, the process of converting ciphertext to plaintext (decryption) and key [6].  

Spritz algorithm is an update of the RC4 algorithm performed by Ron Rivest and Jacob Schultz 
in 2014. Spritz as a variant of encryption RC4 cows including messages or data one by one 
using relatively short time-dependent transformation encryption [4][8]. The addition of a 
relatively prime element to the N value of the pseudo-random generation algorithm is the 
difference with the RC4 algorithm. In addition to stream ciphers, the spritz algorithm can also be 
used as a hash function and the Message Authentication Code (MAC) by using the sponge 
function in securing data. The main procedure of the spritz algorithm as a stream cipher 
consists of three processes: Key Scheduling Algorithm (KSA), Pseudo-Random Generation 
Algorithm (PRGA) and encryption or decryption process. 

a. Key Scheduling Algorithm (KSA) 
The key scheduling process is a process that is done to make the S-Box table (array S) 
and table permutation in the array S. The length of the array that is required is 256 which 
starts from an index of 0 to 255. The purpose of KSA is the process of permutation array 
values as much as 256 times which is initialized with variables i and j with integer types. 
 
 



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Pseudo-code of KSA is: 

for  i  = 0 to N – 1  
S[i] = i 

next i 
i, j = 0 
for i = 0 to N – 1 

j = ( j + S[i] + K[i mod Key.length]) mod N 
swap ( S[ i ], S[ j ] ) 
j = j 

next i 
where N is the size of the array to be mutated, i.e. 0 – 255. 

b. Pseudo-Random Generation Algorithm (PRGA) 
The pseudo-random generator algorithm process is performed to derive a new key 
number of plain elements. The value of w is a new variable added to the spritz algorithm 
that corresponds to the RC4 algorithm. The value of the variable i, j, k and z starting at 0 
and will change according to results at each iteration. This process involves an array of S 
values that have been permuted in the KSA process. 
Pseudo-code PRGA is : 

for  i = 0 to plain.length 

 i = ( i + w ) mod N 

 j = (k + S[j + S[ i ]]) mod N 

 k = (i + k + S[ j ]) mod N 

 swap S[ i ], S[ j ] 

 z = ( S[ j + S[ i + S[ z + k ]]] ) mod N 

 output  z 

next i 

where w is a relatively prime value of integer with N and the value of i, j, k, z starts from 0. 

c. Encryption and Decryption 

The encryption and decryption process is done by XOR-binary each output z with each 

plain element in a stream. 

Formulation of the encryption process: 

           (1) 

Formulation of the decryption process: 

           (2) 

Description of the formula above: 

Pi = plain element 

Ci = cipher element 

zi = key element (the result of PRGA process) 

3.3. Database 

A database can simply be defined as a system that serves to store and process data into useful 
information. One of the data that should be maintained and maintained by the owner of the 
information system is the database. Information on a system can be updated by using the 
database management process [7]. A database is filled with one or more tables, and each table 
is filled with some record. These records which shall be processed and processed into 
information for the users of the system. MySQL is one of the applications that can be used to 
create and manage databases. Through commands (query) owned by MySQL, the 
management of the database to generate information do. 

4. Results and Discussion 

Based on the description of the background above, the problem being analyzed is the issue of 
security text database record computer-based exam. One important aspect to be considered in 
the implementation of the computer-based test is the security of the exam. If the analogy 
database security exam conducted without securing the database, then it is very easy to be 



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attacked by the other party, because if an attacker manages to get the exam can access the 
database, it is clear the record about the exam can be easily manipulated or leaked. 

This study describes how the security database records are secured by encryption of the text 
record exam questions are then stored into the database exam application. 
 
 
 
 
 
 
 
 
 
 
 

Figure 1. Encryption Process Scheme CBT Exam 
 

A Based on the figure 1 above, it is known that the process is carried out starting with the 
process of encryption (encryption) exam conducted by the maker of the exam committee. The 
exam that was encrypted stored in the database exam application (server). That is, the text of 
records stored in the database password from the exam is about the original text. This database 
to be accessed by the client (examinees). Exam application that is accessed by the participants 
automatically perform the decryption process (returns cipher into a plain), so the exam can be 
understood by the client. 

4.1. The process of Computer Based Test Database Encryption 

The process of encrypting the computer-based test database is done by the test team and then 
stored into the exam application database (server). The encryption process is based on the 
spritz algorithm to generate exam ciphers. The schema of encryption process can be illustrated 
in Figure 2 below. 
 
 
 
 
 
 
 
 
 
 
 
 
 

Figure 2. Schema of Encryption Process 
 

The following database records will serve as an example of the encryption process in this 
research. Database created using MySQL application. 
 

Table 1. Table of Record Database CBT Exam 

Id Text of Exam 

1 Kepanjangan KSA adalah.... 

2 Defenisi dari kriptografi yang benar adalah..... 

 
 
Encryption Key : CRYPTEx 

Key Schedule Algorithm (KSA) 

Pseudo-Random Generator Algorithm (PRGA) 

Text of CBT Exam 

Cipher of CBT 
Examination 

 

Database  
of  

CBT Exam 

save in 

Computer 
Based Test 
Application 

(server) 

Database      
of CBT Exam 

CBT Application 
(client) will decrypt 
the CBT question 

 

Encrypt the  
CBT Exam Text 

Cipher of CBT 
text 

Text of CBT 
Exam 

Store into 
database 



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a. KSA Process 
Based on the KSA process algorithm, it appears that there are two main processes that 
are done, namely, generate an array S and do permutations of the contents of the S array 
that has been formed. The contents of the Permuted S Array will be used in the PRGA 
process to generate a random key element. The value of i, j, in this case, start from 0 to 
255, while the value of N is 256. 
 

The initial step is the formation of an array of initial key: 

K[0] = C (dec 67) K[2] = Y (dec 89) K[4] = T (dec 84) K[6] = x (dec 120) 

K[1] = R (dec 82) K[3] = P (dec 80) K[5] = E (dec 69) 

 

The next is the manufacture of the array S, by following the KSA's pseudo-code array S, 
so that the resulting table array with integer values ranging from 0-255. 
 

Table 2. Initial array S value 

index 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 

 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 

index 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 

 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 

index 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 

 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 

..... 

..... 

..... 

..... 

..... 

..... 

..... 

..... 

..... 

..... 

..... 

..... 

..... 

..... 

..... 

..... 

..... 

Index 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 

 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 
 

The text colored red is the index of the array S. 
 

Based on table 2 above, it appears that the value of N is 256, since the number of arrays 
generated is 256 integer values. 
The next step is to permutate the initial array S values (table 2 values) based on pseudo-
code KSA. 
 

If  i = 0; j = 0, then: 
j   = (0 + S[0] + K[0 mod 7]) mod 256 
  i = 0; j = 0; S[0] is array S value on index-0; K[0 mod 7] is value of array key on index 

0 modulus 7 (number of initial key characters) 
 = (0 + 0 + K[67 mod 7]) mod 256 
 = (0 + 0 + 4) mod 256 
j = 4 
 

swap ( S[0], S[4] ) 
 

j = 4 
 exchange (swap) the array S there is at index 0 to the value of the array S at  index 4 

and conversely. The result of this iteration produces a value j as 4. 
 

Table 3. Value of Array S at Iteration 0 (i = 0) 

Inde
x 

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 

 4 1 2 3 0 5 6 7 8 9 10 11 12 13 14 15 

..... 

..... 

..... 

..... 

..... 

..... 

..... 

..... 

..... 

..... 

..... 

..... 

..... 

..... 

..... 

..... 

..... 

Index 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 

 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 

 

If  i = 1; j = 4 (j value taken from the value of the previous j), then: 



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j   = (4 + S[1] + K[1 mod 7]) mod 256 
  i = 1; j = 4; S[1] is array S value at index 1; K[1 mod 7] is key array value at index 1 

modulus 7 (number of initial key) 
 = (4 + 1 + K[82 mod 7]) mod 256 
 = (4 + 1 + 5) mod 256 
j = 10 
swap ( S[1], S[7] ) 
 exchange (swap) the value of the array S in the index with a value 1 results 

permutation array S at index 10, and conversely, the results are shown in Table 4. 
 

Table 4. Value of Array S Tabel in Iteration 1 (i = 1) 

Inde
x 

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 

 4 10 2 3 0 5 6 7 8 9 1 11 12 13 14 15 

..... 

..... 

..... 

..... 

..... 

..... 

..... 

..... 

..... 

..... 

..... 

..... 

..... 

..... 

..... 

..... 

..... 

Index 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 

 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 
 

This process will be done up to the value of i = N - 1 or equal to 255 (255th iteration). 
During the iteration process, there are times when the contents of an array experiencing a 
process swap (exchange) more than once. The array S values that are permuted in the 
next process are the values of array S  that has resulted from the previous permutation. 
The result of the key scheduling process (array S) as a whole is shown in table 5. 
 
Table 5. The Result of Key Scheduling Algorithm (KSA) Process 

56 64 17 245 201 118 45 56 107 83 244 228 167 139 196 47 

219 180 206 164 26 243 84 106 100 95 78 52 242 161 63 97 

129 168 173 242 27 87 134 227 195 143 241 75 124 172 218 15 

218 187 158 228 27 200 240 211 0 176 61 187 112 183 121 188 

1 239 72 207 25 95 195 98 66 142 216 41 118 238 26 110 

145 217 106 155 22 112 138 179 110 93 225 237 247 89 186 210 

127 225 71 175 166 128 169 83 188 41 152 8 163 236 88 204 

186 178 190 125 224 142 5 128 160 127 147 235 245 115 245 121 

254 182 194 141 175 155 38 178 61 209 86 226 114 4 151 41 

234 80 227 122 157 173 70 221 123 21 179 215 244 148 203 215 

120 29 196 233 178 184 100 12 184 102 21 195 111 34 209 189 

222 239 164 87 17 232 185 208 250 182 193 49 238 175 214 54 

249 186 130 70 14 216 163 109 231 4 207 158 221 65 18 225 

183 137 95 55 16 232 190 155 116 81 48 16 239 230 176 144 

116 90 65 39 11 246 221 200 181 163 252 123 253 91 250 254 

54 255 28 21 10 248 254 250 245 238 238 234 234 236 239 241 
 

b. PRGA Process 

The pseudo-random process will generate a new key at random which is equal to the 
number of plain elements. 
The value of i, j, k, z = 0 and the value w is selected one of the relatively prime values 
with 256, for example, w = 29. Suppose, PRGA process to encrypt exam number 1. 
 

The text of the test (plain): Kepanjangan KSA adalah .... 
 

The number of text characters about the test is 26 characters, meaning that the key will 
be raised as much as 26. The key value obtained will be used to perform the encryption 
process of each text character on the exam in a stream. 
 
 

The iteration process when the value of i, j and k = 0, then: 



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i   = (0 + 29) mod 256 
i   = 29 
j   = (0 + S[0 + S[29]]) mod 256 
 let's see index 29 value on permutation of array S values (table 5), then we get : 
 = (0 + S[0 + 161]) mod 256 
 = (0 + S[161]) mod 256 
 See index 161 value on permutation of array S (table 5), then we get :   
= (0 + 120) mod 256 
j = 120 
k = (0 + 0 + S[120]) mod 256 
 let’s see array 120 (j) value on permutation of array S (table 5), then we get : 
 = ( 0 + 0 + 160) mod 256 
k = 160 
swap S[29], S[160] 
exchange the array S value in index 29 with the value of the array S index 160, then the 
contents of the array S that has been permutated based on KSA process will be 
recovered based on the swap value. 
z = (S[10 + S[29 + S[0 + 160]]]) mod 256 
 = (S[10 + (S[29 + 160] mod 256)) mod 256 
 = (S[10 + S[189]) mod 256 
 let's see index 10 and index 189 on the result of array S permutation table (table 5), 

then we get: 
= S[10 + 175] mod 256 
 = S[185], see array S value in index 185, then we get: 
z1=185 (The key used to encrypt the first character of the exam question is the binary of 

the decimal 185). 

 

The process of iteration when the value of i = 29, j = 120, k = 160, z = 185 (value i, j, k 
and z taken from the previous process value) then: 
 

i  = (29 + 29) mod 256 
i  = 58 
 

j  = (160 + S[120 + S[58]]) mod 256 
 = (160 + S[120 + 61]) mod 256 
 = (160 + S[181]) mod 256 
 = (160 + 232) mod 256 
j = 136 
 

k = (58 + 160 + S[136]) mod 256 
 = ((( 58 + 160) mod 256) + 160) mod 256 
 = (218 + 160) mod 256 
k =122 
 

 swap S[58], S[136] 
 

z = (S[136 + S[58 + S[185 + 122]]]) mod 256 
 = (S[136 + (S[58 + S[51] mod 256)]]) mod 256 
 = (S[136 + (S[58 + 228] mod 256)]) mod 256 

 = (S[136 + S[30]]) mod 256 
 = (S[136 + 63]) mod 256 
 = S[199] 

z2 =109 (the key used to encrypt the second character of the exam question is the binary 
of the decimal 109). 

 

This process is done until the 26th iteration (corresponding to the number of exam text). 
 

c. Encryption Process 
The process of encrypting text characters the exam is done based on equation (1) so that 
the cipher is obtained as follows: 
 

Exam Question (plain): Kepanjangan KSA adalah :.... 



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Key Schedule Algorithm (KSA) 

Pseudo-Random Generator 
Algorithm (PRGA) 

Plainteks of 
CBT Exam 

Decryption Key 

CBT exam application that is 
accessed by the participants 
automatically generates the 

decryption key 

Plaintext of CBT Exam 

Cipher of 
CBT  

Exam 

Server of CBT Exam 

Exam 
Participants 

(Client) 

Cipher of CBT Exam 

P1 = K  01001011 P2 = e  01100101 

z1 = 185 10111001  z2 = 109 01101101  
C1 = 11110010 = char  ò C2 = 00001000 = char 
 

Ciphertext of the exam that resulted from both of this process is ò and 
This process will be done until the entire text character of the exam is encoded.                     
 
The result of the whole process of encoding the text of exam is shown in table 6. 
 

Table 6. The Text of Record Database that Resulted from Encryption Process 

 

Based on table 6 above, it appears that stored in the database is a text record that has 
been encoded so that anyone who gets this record cannot easily understand the original 
meaning of the question. 

4.2. Decryption Process of CBT Exam Database 

The process of decrypting the text of a database record of an encrypted test is done in the same 
way as in the encryption process. Beginning with the KSA process, then the PRGA process and 
the last is the process of decryption. Decryption is performed based on the formulation in 
equation (2), which perform the XOR operation between the binary elements with a binary 
cipher each generated key to the process resulting PRGA to the original text of the record 
exam. The decryption process is done automatically by the application exam already available 
on the client computer when accessing a matter examinees. The decryption process scheme is 
shown in Figure 3. 
 
 

 

 

 

 

 

 

 

 

 

 

 

   

 

 

 

 

 

 

Figure 3. Schema of Decryption Process 



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If examinees legitimate access the exam, then the exam application will automatically generate 
the decryption key to the process of KSA and PRGA based on the initial key used in the 
encryption process. KSA and PRGA process in the decryption process carried out in the same 
manner as in the encryption process, because of this algorithm including the symmetric key 
algorithms (the same key). Keys are generated from the process PRGA (equal the number of 
records about the ciphertext) is used as a key in the decryption process. Decryption process 
performed by equation (2), which perform XOR process between the cipher key element to 
element test database records. 

First Key= CRYPTEx 
The key generated from the PRGA process is 185  109  ..... 
 

Biner of key is: 
K1 = 185 (in biner is 10111001) 
K2 = 109 (in biner is 01101101) 
 

If we assume, the decrypted cipher is ò  then the decryption process is:  
C1 = ò (decimal is 242  or in biner is 11110010) 
C2 =    (decimal is 8 or in biner is 00001000) 
 

The next step is to XOR binary ciphers with binary keys generated from KSA and PRGA 
processes based on equation (2), so: 
 

C1  = 11110010   

K1 = 10111001    
P1 = 01001011  (char  K)  
 

C2  = 00001000 

K2  = 01101101  
P2  = 01100101  (char  e) 
 

The same process will be done to decrypt other record characters, so get the record database 
exam that same as the original. The overall result of the decryption process is shown in table 7. 

Table 7. Record of Database Exam After Decrypted 

Id Soal 

1 Kepanjangan KSA adalah.... 

2 Defenisi dari kriptografi yang benar adalah..... 

 
Computing performance measurement results from the key generation process, the decryption 
process encryption and obtained the following results:  

a. Key Generation Performance  
Based on the tests performed, the key characters generated by the spritz algorithm are 
very random, since the keys generated for the encryption and decryption process are 
no longer the same as the initial key characters but will generate new key characters 
equal to the number text character test record. But the process of generation of key 
characters that many would take a long time. This is one of the weaknesses of this 
algorithm. This occurs because of the number of key characters that are raised to be 
equal to the number of text characters exam. 
 
Tabel 8. Key Generation Performance Level 

Early Key 
Number of 
Character 

Exam 

Number of 
Character New Key 

(PRGA Result) 

Number of 
same key 
characters 

Processing 
Time 

(second) 

CRYPTEx 15 char 15 char 0 0,253 

AMIK_STIEKOM 80 char 80 char 1 1,087 

StiekomSU 150 char 150 char 3 1,460 

STIEKOM 180 char 180 char 3 5,435 

Sumatera 200 char 200 char 5 6,157 



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According to the table 8 above, it appears that more and more about the encrypted text 
characters, so the more time it takes to generate the key. Based on the generated key, 
it appears that the repetition of the same character with a very little initial key character 
that occurs at intervals that are not adjacent letters.  
 
The performance level of the key generation graph shown in figure 4 below.  
 

 
Figure 4. Key Generation Performance Testing 

 
Based on figure 4 above, it appears that the more the number of text characters exam 
questions are encrypted, the higher the time needed in the key generation process, but 
the character is getting randomly generated key. 
 

b. Computing Performance of Encryption and Decryption Process 
Performance computing process of encryption and decryption based on spritz algorithm 
in this research, conducted by measuring the time of encryption process and decryption 
of five database record about an exam. The measurement results are shown in table 9 
below. 
 
Table 9. Testing Time of Encryption and Decryption Process 

No 
Number of 
early key 

characters 

Number of 
exam text 
character 

Key 
Processing 

Time 
(second) 

Time of 
Encryption/ 
Decryption  

Process (Second) 

Total 
Processing 

Time 
(Second) 

1 7 char 15 char 0,253 1,405 1,658 

2 12 char 80 char 1,087 4,455 5,542 

3 9 char 150 char 1,460 4,673 6,133 

4 7 char 180 char 5,435 8,246 13,681 

5 8 char 200 char 6,157 12,159 18,316 

 
Based on table 9 above, it appears that the processing time required to perform both 
encryption and decryption is the same because the process is the same. Time 
measurement process performed in this research does not include the time required to 
access the exam by the participant (client) on online question bank server. Based on 
the measurement results obtained, it was concluded that the more the number of 
characters exam encrypted or decrypted, the more time the process takes. This has 
become one of the characteristics of the algorithms that work on the principle of stream 
cipher (encryption or decryption on an individual basis) include spritz this algorithm. 

 

15 char 80 char 150 char 180 char 200 char 

0,253 
1,087 1,46 

5,435 
6,157 

Measurement of Key Generation Process Time 



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62 
 

5. Conclusion 

Based on the description of the results and discussion of this research, it was concluded that 
the text encoding database record exam computer-based algorithm based spritz can minimize 
the abuses of the exam by parties who are not responsible for cipher generated by this 
algorithm is able to obscure the meaning of the exam original, so the principle of confusion and 
diffusion can be realized. Performance algorithms spritz in a random key generation process are 
quite reliable but requires a long processing time both encryption and decryption. Simple 
operation in the process of encryption and decryption in spritz algorithm becomes one of the 
weaknesses of this algorithm of attack types such as know-plain attack or cipher-only attack. 

 
References 
 
[1] A. Hangga and E.  rabowo, “Mod f kas  L near  ongruent al Generator untuk Sistem 

Pengacakan Soal pada Computer Based Test (CBT),” Jurnal Teknik Elektro, vol. 8, no. 2, 
pp. 47–49, 2016. 

[2] E. Setyan ngs h, “ enyand an   tra Menggunakan Metode  layfa r   pher,” Jurnal 
Teknologi, vol. 2, no. 2, pp. 213–219, 2009. 

[3] T. Zebua and E. Ndruru, “ engamanan   tra D g tal Berdasarkan Mod f kas  Algor tma 
R 4,” J. Teknol. Infomasi dan Ilmu Komput., vol. 4, no. 4, pp. 275–282, 2017. 

[4] S. Ban k and T. Isobe, “ ryptanalys s of the full Spr t  stream c pher,” in Lecture Notes in 
Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture 
Notes in Bioinformatics), 2016, vol. 9783, pp. 63–77. 

[5] R.G. J moh,“Students'  ercept on of  omputer Based Test ( BT) for Exam n ng 
Undergraduate  hem stry  ourses”, Journal of Emerging Trends in Computing and 
Information Sciences, vol. 3, no. 2, pp. 125-134. 

[6] Susanto, “Implementas  Keamanan Data S stem Informas  Inventory Stock Barang  T. 
Wings Food Menggunakan Algoritma Riverst  ode 4 (R 4),” Lontar Komputer: Jurnal 
Ilmiah Teknologi Informasi, vol. 8, no. 2, pp. 77–88, 2017. 

[7] T. Zebua, “Anal sa dan Implementas  Algor tma Tr angle  ha n  ada Penyandian Record 
Database,” Jurnal Pelita Informatika, vol. 3, no. 2, pp. 37–49, 2013. 

[8] R. L. R vest and J.  . N. Schuldt, “Spr t  — a spongy RC4-like stream cipher and hash 
funct on,”  n CRYPTO 2014 Rump Session, 2014, pp. 1–30. 

[9] T. Zebua, “ enerapan Metode LSB-2 Untuk Menyembunyikan Ciphertext Pada Citra 
D g tal,” Jurnal Pelita Informatika, vol. 10, no. 3, pp. 135–140, 2015. 

[10] E. Setyan ngs h, “Kr ptograf  dan Implementas  Menggunakan Matlab,” Yogyakarta: And , 
2015.