Kripto 1

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| By Catherine Halcomb
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Catherine Halcomb
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Quizzes Created: 1453 | Total Attempts: 5,796,832
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Kripto 1 - Quiz


Questions and Answers
  • 1. 

    Sifarski sistem je bezbedan:

    • A.

      Ako je kljuc duzine 256 bita

    • B.

      Ako za njega garantuje treca strana od poverenja svojim sertifikacionim telom

    • C.

      Ako je nabolji moguci napad - potpuna pretraga kljuceva

    • D.

      Ako je algoritam nelinearan

    • E.

      Ako se za sifrovanje koriste mocni racunari

    Correct Answer
    C. Ako je nabolji moguci napad - potpuna pretraga kljuceva
    Explanation
    The given correct answer states that the sifarski sistem is secure if the best possible attack is a complete search of the keys. This implies that if the system is designed in such a way that it is not vulnerable to other types of attacks, such as brute force or cryptographic attacks, and the only feasible way to compromise the system is through a complete search of all possible keys, then it can be considered secure.

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  • 2. 

    Sifra A5/1 zasniva se na:

    • A.

      Tajnim kodovima

    • B.

      Promenljivim tabelama

    • C.

      Linearnim pomerackim registrima

    • D.

      Permutatorima

    • E.

      Kombinacionim linearnim mrezama

    • F.

      Invertorima

    Correct Answer
    C. Linearnim pomerackim registrima
    Explanation
    Sifra A5/1 se zasniva na linearnim pomerackim registrima. To znači da se koriste registri za pomeranje bitova kako bi se generisao ključ za šifrovanje. Ovi registri pomeraju bitove u određenom obrascu koji se koristi za kombinovanje sa podacima i stvaranje šifrovane poruke. Linearni pomeracki registri su ključni element u algoritmu A5/1 i omogućavaju generisanje sigurnih šifrovanih poruka.

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  • 3. 

    Karakteristike sesijskog kljuca kod sifarskih sistema sa GPSN:

    • A.

      Treba da ima dobre statisticke karakteristike

    • B.

      Obavezno je tajan

    • C.

      Inkremetira se u odnosu na prethodnu vrednost

    • D.

      Treba da bude promenljiv za svaku upotrebu

    • E.

      Ima duzinu kao i otvorena poruka

    • F.

      Ne mora da bude tajan

    Correct Answer(s)
    A. Treba da ima dobre statisticke karakteristike
    D. Treba da bude promenljiv za svaku upotrebu
    F. Ne mora da bude tajan
    Explanation
    The correct answer is that the session key in cipher systems with GPSN should have good statistical characteristics, should be variable for each use, and does not need to be secret. This means that the session key should have a random and unpredictable distribution of values, it should be changed for every new session or use, and it does not necessarily need to be kept secret from attackers. These characteristics help to ensure the security and effectiveness of the cipher system.

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  • 4. 

    Obeleziti kriticne propuste(slabe tacke) veb aplikacija:

    • A.

      SQL injection

    • B.

      Veliki broj korisnika

    • C.

      Socijalni inzenjering

    • D.

      Ogromna brzina prenosa podataka

    • E.

      Heterogena softverska okruzenja

    • F.

      Buffer overflow

    Correct Answer(s)
    A. SQL injection
    C. Socijalni inzenjering
    F. Buffer overflow
    Explanation
    The correct answer includes SQL injection, social engineering, and buffer overflow. These are critical vulnerabilities in web applications that can be exploited by attackers. SQL injection involves inserting malicious SQL code into input fields to manipulate the database. Social engineering is a technique used to manipulate people into revealing sensitive information. Buffer overflow occurs when a program tries to store more data in a buffer than it can handle, leading to potential security breaches. These vulnerabilities pose serious threats to the security and integrity of web applications.

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  • 5. 

    Neporecivost je servis koji oznacava:

    • A.

      Predajna strana ne moze da porekne da j eporuka ispravna

    • B.

      Prijemna strana ne moze da porekne da je primila poruku

    • C.

      Strana koja je primila poruku ne moze da porekne da je promenila poruku

    • D.

      Strana koja je poslala poruku ne moze da porekne da je to uradila

    Correct Answer
    D. Strana koja je poslala poruku ne moze da porekne da je to uradila
    Explanation
    The correct answer states that "Strana koja je poslala poruku ne moze da porekne da je to uradila" which translates to "The party that sent the message cannot deny having done so." This means that once a message has been sent, the sender cannot claim that they did not send it. This concept is known as non-repudiation, which ensures that the sender of a message cannot later deny their involvement or responsibility for the message.

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  • 6. 

    Obeleziti karakteristike prakticno tajnog sifarskog sistema:

    • A.

      Cena razbijanja sifrata pervazilazi vrednost otvorene informacije

    • B.

      Zasniva se na algoritmu i kljucu

    • C.

      Vreme za razbijanje sifrata je duze od vremena u kom informacija treba da bude tajna

    • D.

      Kljuc za sifrovanje se iz prakticnih razloga moze slati komunikacionim kanalom

    • E.

      Realizuje se softverski iz prakticnih razloga

    Correct Answer(s)
    A. Cena razbijanja sifrata pervazilazi vrednost otvorene informacije
    C. Vreme za razbijanje sifrata je duze od vremena u kom informacija treba da bude tajna
    Explanation
    The correct answer is that the cost of breaking the cipher exceeds the value of the open information, and the time it takes to break the cipher is longer than the time the information needs to remain secret. This means that the encryption system is practical because it provides a high level of security, as the cost and time required to break the cipher make it impractical for attackers to access the encrypted information. Additionally, the fact that the encryption is implemented through software adds to its practicality, as it allows for easy and efficient encryption and decryption processes.

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  • 7. 

    Rec "bit" moze da se skrembluje na:

    • A.

      3 nacina

    • B.

      6 nacina

    • C.

      8 nacina

    • D.

      9 nacina

    Correct Answer
    B. 6 nacina
    Explanation
    The word "bit" can be scrambled in 6 different ways.

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  • 8. 

    Kod sekvencijalnih sifara koristimo:

    • A.

      Radni kljuc za generisanje inicijalnog stanja algoritma

    • B.

      Oba kljuca u isto vreme

    • C.

      Digitalno potpisivanje simetricnih kljuceva

    • D.

      Sertifikat za prenos tajnih kljuceva

    • E.

      Unutrasnji kljuc za generisanje radnog kljuca

    Correct Answer
    E. Unutrasnji kljuc za generisanje radnog kljuca
    Explanation
    In sequential ciphers, we use an internal key to generate a working key. This internal key is used to determine the initial state of the algorithm and is essential for generating the working key. The working key is then used in the encryption or decryption process.

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  • 9. 

    Obelezite sta je karakteristicno za Cezarovu sifru:

    • A.

      Polialfabetska sifra

    • B.

      Monoalfabetska sifra

    • C.

      Sifra supstitucije

    • D.

      Sifra zamene

    • E.

      Homofona sifra

    Correct Answer(s)
    B. Monoalfabetska sifra
    C. Sifra supstitucije
    D. Sifra zamene
    Explanation
    The correct answer is "Monoalfabetska sifra, Sifra supstitucije, Sifra zamene". This means that the characteristic of Caesar cipher is that it is a monoalphabetic substitution cipher. In a monoalphabetic cipher, each letter in the plaintext is replaced by a corresponding letter in the ciphertext, using a fixed substitution method. In the case of Caesar cipher, this substitution is done by shifting the letters of the alphabet by a certain number of positions. Therefore, Caesar cipher is a type of substitution cipher where the substitution is done by replacing letters with other letters.

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  • 10. 

    Kod simetricnih sekvencijalnih sifarskih sistema:

    • A.

      Kljuc se moze sifrovati kao i otvorena poruka

    • B.

      Tajni kljuc ima jednokratnu upotrebu

    • C.

      Kljuc se ne sme dostavljati komunikacionim kanalom

    • D.

      Tajni kljuc se dostavlja komunikacionim kanalom

    • E.

      Predajnik i prijemnik imaju isti kljuc

    Correct Answer(s)
    C. Kljuc se ne sme dostavljati komunikacionim kanalom
    E. Predajnik i prijemnik imaju isti kljuc
    Explanation
    The correct answer is "Kljuc se ne sme dostavljati komunikacionim kanalom" which means "The key must not be delivered through the communication channel". This statement is true because in symmetric sequential cipher systems, the key should be kept secret and should not be transmitted through the same channel as the encrypted message. If the key is transmitted through the communication channel, it can be intercepted by unauthorized parties, compromising the security of the system. Additionally, the statement "Predajnik i prijemnik imaju isti kljuc" which means "The transmitter and receiver have the same key" is also true in symmetric sequential cipher systems, as both parties need to use the same key for encryption and decryption.

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  • 11. 

    Karakteristicno za one-time pad je:

    • A.

      Kljuc moze da se upotrebi samo jedanput za sifrovanje

    • B.

      Kljuc moze da se upotrebi vise puta za sifrovanje

    • C.

      Koristi se sifarski algoritam i kljuc

    • D.

      Sifrat je duzine kao i otvoreni tekst

    • E.

      Sifrat ima karakteristike slucajnog niza

    Correct Answer(s)
    A. Kljuc moze da se upotrebi samo jedanput za sifrovanje
    D. Sifrat je duzine kao i otvoreni tekst
    E. Sifrat ima karakteristike slucajnog niza
    Explanation
    The one-time pad encryption technique is characterized by the fact that the key can only be used once for encryption. This ensures a high level of security as it prevents any patterns or repetitions in the ciphertext that could be exploited by an attacker. Additionally, the length of the ciphertext is equal to the length of the plaintext, ensuring that no information is leaked through the length of the message. Lastly, the ciphertext produced by the one-time pad has the characteristics of a random sequence, making it difficult for an attacker to decipher any meaningful information from it.

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  • 12. 

    Ako je poruka sifrovana apsolutno tajnim sifarskim sistemom

    • A.

      Kljuc je poznat samo posiljaocu i primaocu

    • B.

      Integritet poruke je obezbedjen

    • C.

      Kljuc postoji samo kod posiljaoca

    • D.

      Integritet poruke se ne moze narusiti

    • E.

      Ne postoji integritet poruke

    Correct Answer(s)
    A. Kljuc je poznat samo posiljaocu i primaocu
    E. Ne postoji integritet poruke
    Explanation
    The correct answer is "Kljuc je poznat samo posiljaocu i primaocu" which means "The key is known only to the sender and receiver". This statement suggests that the encryption system used is based on a secret key known only to the sender and receiver. This ensures the confidentiality of the message and prevents unauthorized access. The other options are not relevant to the given information or contradict the statement.

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  • 13. 

    Obeleziti bezbednosne racunarske protokole:

    • A.

      IpSec

    • B.

      DNS

    • C.

      AES

    • D.

      SSL

    • E.

      HTTP

    • F.

      Kerberos

    Correct Answer(s)
    A. IpSec
    D. SSL
    F. Kerberos
    Explanation
    The correct answer includes the protocols IpSec, SSL, and Kerberos. These protocols are all related to computer security. IpSec is a protocol used for securing internet communications by encrypting and authenticating IP packets. SSL (Secure Sockets Layer) is a protocol that provides secure communication over the internet, commonly used for websites that require sensitive information. Kerberos is a network authentication protocol that provides secure authentication for client/server applications. Therefore, these protocols are all examples of security protocols used to protect computer systems and data.

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  • 14. 

    Napadi kod simetricnih sifara mogu biti realizovani na osnovu:

    • A.

      Poznatih parova: otvoreni tekst - sifrat

    • B.

      Statistickom analizom

    • C.

      Pretrage unazad

    • D.

      Poznatog algoritma

    • E.

      Poznatog otvorenog teksta

    • F.

      Poznatog sifrata

    Correct Answer(s)
    A. Poznatih parova: otvoreni tekst - sifrat
    E. Poznatog otvorenog teksta
    F. Poznatog sifrata
    Explanation
    The correct answer options all refer to methods that can be used to perform attacks on symmetric ciphers. "Poznatih parova: otvoreni tekst - sifrat" refers to known plaintext attacks, where the attacker has access to pairs of plaintext and corresponding ciphertext. "Poznatog otvorenog teksta" refers to known plaintext attacks where the attacker knows the plaintext but not the corresponding ciphertext. "Poznatog sifrata" refers to known ciphertext attacks, where the attacker knows the ciphertext but not the corresponding plaintext. These methods can be used to analyze the cipher and potentially break its encryption.

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  • 15. 

    Kod sifre transpozicije:

    • A.

      Sifrat je duzi od otvorenog teksta

    • B.

      Slova se premestaju

    • C.

      Slova se menjaju drugim slovima

    • D.

      Slova se menjaju kodnom reci

    • E.

      Utvrdjuje se korak zamne

    Correct Answer
    B. Slova se premestaju
    Explanation
    The correct answer is "Slova se premestaju" because the given information suggests that the code is using a transposition cipher, which involves rearranging the letters of the message. The other options mentioned, such as changing letters to other letters or using a keyword, are not directly related to transposition ciphers.

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  • 16. 

    Algoritmi koji vrse transformaciju nad jednim bitom ili bajtom nazivaju se:

    • A.

      Inicajlni algoritmi

    • B.

      Sekvencijalni algoritmi

    • C.

      Binarni algoritmi

    • D.

      Blokovski algoritmi

    • E.

      Bitski algoritmi

    Correct Answer
    B. Sekvencijalni algoritmi
    Explanation
    The correct answer is "Sekvencijalni algoritmi". This is because the question is asking for the name of algorithms that perform transformations on one bit or byte. "Sekvencijalni algoritmi" refers to sequential algorithms, which means that they process data one step at a time in a specific sequence. Therefore, it is the most appropriate answer in the context of the question.

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  • 17. 

    Sifarski sistem sa javnim kljucem koristi:

    • A.

      Privatni kljuc za sifrovanje, a javni za desiforvanje

    • B.

      Privatni kljuc za sifrovanje i desifrovanje

    • C.

      Javni kljuc za sifrovanje i desfirovanje

    • D.

      Javni za sifrovanje, a privatni za desiforvanje

    • E.

      Simetricni kljuc za desifrovanje

    Correct Answer
    D. Javni za sifrovanje, a privatni za desiforvanje
    Explanation
    The correct answer is "Javni za sifrovanje, a privatni za desiforvanje" which means that a public key is used for encryption and a private key is used for decryption. In a public key encryption system, anyone can use the public key to encrypt a message, but only the intended recipient with the corresponding private key can decrypt and read the message. This ensures that the message remains secure and only accessible to the intended recipient.

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  • 18. 

    Osnovni bezbednosni koncepti su:

    • A.

      Poverljivost

    • B.

      Ravnomernost

    • C.

      Integritet

    • D.

      Slozenost

    • E.

      Raspolozivost

    • F.

      Jednoznacnost

    • G.

      Nerazumljivost

    • H.

      Pouzdanost

    Correct Answer(s)
    A. Poverljivost
    C. Integritet
    E. Raspolozivost
    Explanation
    The correct answer is Poverljivost, Integritet, Raspolozivost. These three concepts are fundamental to security. Poverljivost refers to the protection of information from unauthorized access or disclosure. Integritet ensures that data remains accurate and unaltered. Raspolozivost means that information and resources are accessible and available when needed. These concepts form the basis of a secure system, ensuring that data is protected, accurate, and available to authorized users.

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  • 19. 

    Supstitucija predstavlja:

    • A.

      Sifre transpozicije

    • B.

      Kodne knjige

    • C.

      Sifre zamene

    • D.

      Racunarski sigurne sifre

    • E.

      One-Time pad

    Correct Answer
    C. Sifre zamene
    Explanation
    The correct answer is "Sifre zamene" which translates to "Substitution ciphers" in English. Substitution ciphers are a type of encryption technique where each letter in the plaintext is replaced with another letter or symbol. This method of encryption involves replacing the original letters with different letters or symbols according to a predetermined substitution key. Substitution ciphers are commonly used in cryptography to protect sensitive information and ensure data security.

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  • 20. 

    Obeleziti sta cini dvostruku transpoziciju:

    • A.

      Transpozicija sifrata

    • B.

      Transpozicija redova

    • C.

      Transpozicija kolona

    • D.

      Transpozicija kljuceva

    • E.

      Transpozicija tabela

    • F.

      Transpozicija tabela

    Correct Answer(s)
    B. Transpozicija redova
    C. Transpozicija kolona
    Explanation
    The correct answer is "Transpozicija redova, Transpozicija kolona". This is because the given options are related to different types of transposition. "Transpozicija redova" refers to the transposition of rows, while "Transpozicija kolona" refers to the transposition of columns. These two operations are commonly used in cryptography and data manipulation to rearrange the order of rows and columns in a matrix or table.

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  • 21. 

    "Otvoren tekst" u kriptologiji moze da bude:

    • A.

      Poruka koja moze da se dodaje

    • B.

      Slika

    • C.

      Video signal

    • D.

      Govorni signal

    • E.

      Tekst

    • F.

      Hardver

    • G.

      Signal koji moze da se otvori

    Correct Answer(s)
    B. Slika
    C. Video signal
    D. Govorni signal
    E. Tekst
    Explanation
    In the field of cryptology, "otvoren tekst" refers to plaintext or unencrypted text. The given answer options - Slika (image), Video signal, Govorni signal (audio signal), and Tekst (text) - all represent different forms of data that can be considered as plaintext or unencrypted text. Therefore, all of these options can be classified as "otvoren tekst" in cryptology.

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  • 22. 

    Sifra je ekonomicna ako je E=N(ST)/N(OT):

    • A.

      E daleko manje od 1

    • B.

      E daleko vece od 1

    • C.

      E priblizno jedanko 1

    • D.

      E razlicito od 1

    Correct Answer
    C. E priblizno jedanko 1
    Explanation
    The correct answer is "E priblizno jedanko 1." This is because the equation states that E is economical if it is approximately equal to 1.

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  • 23. 

    Karakteristicno za Homofone sifre je:

    • A.

      Sifrat je duzi od otvorenog teksta

    • B.

      Sifrovanje se vrsi u grupama slova

    • C.

      Sifrat je iste duzine kao i otvoren tekst

    • D.

      Slova sa najvecom frekvencijom se sifruju na dva ili tri nacina

    Correct Answer(s)
    C. Sifrat je iste duzine kao i otvoren tekst
    D. Slova sa najvecom frekvencijom se sifruju na dva ili tri nacina
    Explanation
    Homofone sifre su karakteristične po tome što šifrat ima istu dužinu kao i otvoreni tekst, što znači da se svako slovo iz otvorenog teksta zamenjuje odgovarajućim šifrovanim slovom. Takođe, slova sa najvećom frekvencijom se šifruju na dva ili tri načina, što dodatno otežava dešifrovanje poruke.

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  • 24. 

    Integritet moze biti narusen u slucaju npada:

    • A.

      Neovlascenih korisnika

    • B.

      Autentifikovanih i autorizovanih korisnika

    • C.

      Ovlascenih korisnika koji zloupotrebljavaju svoja prava

    Correct Answer(s)
    A. Neovlascenih korisnika
    C. Ovlascenih korisnika koji zloupotrebljavaju svoja prava
    Explanation
    Integrity can be compromised by unauthorized users and authorized users who misuse their privileges. Unauthorized users may gain access to sensitive information or systems, leading to potential data breaches or unauthorized modifications. On the other hand, authorized users who abuse their privileges can intentionally or unintentionally alter or delete data, jeopardizing the integrity of the system. Both scenarios pose a risk to the integrity of the system and can result in data corruption or loss.

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  • 25. 

    Nelinearnost kod sifre A5/1 se postize:

    • A.

      Povremenim permutovanjem LPR

    • B.

      Povratnom spregom koja je nelinearna

    • C.

      Neuniformnim taktovanjem LPR

    • D.

      Primenom funkcije ADD na izlazu iz registara

    • E.

      Nelinearnim invertovanjem LPR

    Correct Answer
    C. Neuniformnim taktovanjem LPR
    Explanation
    The correct answer is "Neuniformnim taktovanjem LPR". This means that the nonlinearity of the A5/1 cipher is achieved through nonuniform clocking of the Linear Feedback Shift Register (LPR). This technique introduces randomness and complexity into the cipher, making it more resistant to cryptographic attacks.

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  • 26. 

    Sifarski sistem sa simetricnim kljucem koriste:

    • A.

      Jedan tajni kljuc

    • B.

      Jedan tajni privatni kljuc

    • C.

      Jedan javni privatni kljuc

    • D.

      Jedan simetricni javni kljuc

    • E.

      Jedan javni kljuc i jedan privatan

    Correct Answer
    A. Jedan tajni kljuc
    Explanation
    The correct answer is "Jedan tajni kljuc" which translates to "One secret key" in English. In a symmetric key system, the same key is used for both encryption and decryption. This means that there is only one secret key that is known by both the sender and the receiver. This key is used to encrypt the data by the sender and decrypt it by the receiver, ensuring secure communication between them.

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  • 27. 

    Sifre zamene dele se na:

    • A.

      Alfabetske

    • B.

      Polialfabetske

    • C.

      Asinhrone

    • D.

      Transpozicione

    • E.

      Numericke

    • F.

      Monoalfabetske

    Correct Answer(s)
    B. Polialfabetske
    F. Monoalfabetske
    Explanation
    The given answer suggests that the substitution cipher can be classified as both polialphabetic and monoalphabetic. A polialphabetic cipher is a cipher that uses multiple cipher alphabets, while a monoalphabetic cipher uses only one cipher alphabet. Therefore, the cipher in question involves the use of multiple cipher alphabets (polialphabetic) as well as the use of a single cipher alphabet (monoalphabetic).

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  • 28. 

    Karakteristika "tajnih algoritama":

    • A.

      Tesko ostaju tajna duzi period

    • B.

      Danasnji algoritmi su tajni algoritmi

    • C.

      Kada se otvore za javnost, najcesce imaju slabosti

    • D.

      Ostaju tajni zauvek

    Correct Answer(s)
    A. Tesko ostaju tajna duzi period
    C. Kada se otvore za javnost, najcesce imaju slabosti
    Explanation
    The characteristics of "secret algorithms" are that they are difficult to remain secret for a long period of time and when they are made public, they often have weaknesses.

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  • 29. 

    Za apsolutno tajni sifarski sistem karakteristika kljuca je:

    • A.

      Dvostruki niz

    • B.

      Slucajni niz

    • C.

      Deterministicki niz

    • D.

      Jedinstveni niz

    • E.

      Prirodni niz

    Correct Answer
    B. Slucajni niz
    Explanation
    The correct answer is "Slucajni niz" which translates to "Random sequence" in English. This means that the key characteristics of an absolutely secret cryptographic system are based on a random sequence. Randomness is crucial in cryptography as it adds unpredictability and makes it difficult for attackers to decipher the encrypted information. Therefore, using a random sequence as a key helps to enhance the security and confidentiality of the system.

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  • 30. 

    Sifarski sistem je bezuslovno bezbedan ako:

    • A.

      Ako je sifrat nastao na nepoznatkom jeziku

    • B.

      Ako je sifrat nelinearan

    • C.

      Svi otvoreni tekstovi su jednako verovatni

    • D.

      Ako je algoritam javan, a kljuc tajan

    • E.

      Ne moze da bude razbijen ni uz primenu neogranicenih racunarskih resursa

    Correct Answer(s)
    C. Svi otvoreni tekstovi su jednako verovatni
    E. Ne moze da bude razbijen ni uz primenu neogranicenih racunarskih resursa
    Explanation
    The correct answer is "Svi otvoreni tekstovi su jednako verovatni" (All plaintexts are equally probable) and "Ne moze da bude razbijen ni uz primenu neogranicenih racunarskih resursa" (It cannot be broken even with unlimited computing resources). These two conditions ensure the unconditional security of the cipher system. If all plaintexts are equally probable, it means that there is no pattern or information leakage in the ciphertext that can be exploited to decrypt the message. Additionally, if the cipher cannot be broken even with unlimited computing resources, it means that the algorithm used is strong and resistant to any computational attacks.

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  • 31. 

    Ulazni parametri u sifarski sistem su:

    • A.

      Smart kartica

    • B.

      Otvoreni tekst

    • C.

      Linearni pomeracki registri

    • D.

      Ugovoreni vid tajnog pisanja

    • E.

      Kljuc za sifrovanje

    Correct Answer(s)
    B. Otvoreni tekst
    E. Kljuc za sifrovanje
    Explanation
    The correct answer is "Otvoreni tekst, Kljuc za sifrovanje". This means that the input parameters in the cipher system are the plaintext and the encryption key. The plaintext refers to the original message that needs to be encrypted, while the encryption key is the secret information used to perform the encryption process. These two parameters are crucial in the cipher system as they determine the encryption and decryption process. The other mentioned parameters, such as the smart card, linear shift registers, and agreed mode of secret writing, may also be important components in the cipher system, but they are not specifically mentioned as input parameters in this question.

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  • 32. 

    Osnovni uslovi kod One-time pad:

    • A.

      Kljuc se ne sme ponavljati

    • B.

      Kljuc mora biti iste duzine kao i poruka

    • C.

      Kljuc mora da bude pravi slucajni niz

    • D.

      Nista od ponudjenog

    • E.

      Kljuc se sme ponavljati

    Correct Answer(s)
    A. Kljuc se ne sme ponavljati
    B. Kljuc mora biti iste duzine kao i poruka
    C. Kljuc mora da bude pravi slucajni niz
    Explanation
    The correct answer states that the key must not be repeated, it must be the same length as the message, and it must be a truly random sequence. This is because the one-time pad encryption method relies on each character of the message being combined with a unique character from the key, using a bitwise XOR operation. If the key is repeated, it introduces patterns that can be exploited by attackers. If the key is not the same length as the message, encryption and decryption become impossible. And if the key is not truly random, it can be predicted or guessed, compromising the security of the encryption.

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  • 33. 

    One-time pad sifra:

    • A.

      Veoma je prakticna za upotrebu

    • B.

      Koristi se za zastitu brzih racunarskih komunikacija

    • C.

      Koristi se na mestima gde se zahteva najvisi nivo tajnosti

    • D.

      Veoma je neprakticna za upotrebu u racunarskim mrezama

    Correct Answer(s)
    C. Koristi se na mestima gde se zahteva najvisi nivo tajnosti
    D. Veoma je neprakticna za upotrebu u racunarskim mrezama
    Explanation
    The correct answer states that the one-time pad cipher is used in places where the highest level of secrecy is required and that it is very impractical for use in computer networks. This means that the one-time pad cipher is highly secure and effective for protecting sensitive information in certain contexts. However, it is not suitable for use in computer networks due to its impracticality, possibly because it requires a large amount of resources and is difficult to implement and manage in such systems.

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  • 34. 

    Cilj servisa raspolozivosti je:

    • A.

      Da omoguci distribuciju zasticenih podataka samo on-line korisnicima

    • B.

      Da nesmetano pruza ulusgu ovlascenom korisniku

    • C.

      Da u svakom momentu stiti integritet poruke

    • D.

      Da se postigne robusnost prenete poruke u odnosu na sum u komunikacionom kanalu

    • E.

      Da obezbedi jednoznacno sifrovanje-desifrovanje neke poruke

    Correct Answer
    B. Da nesmetano pruza ulusgu ovlascenom korisniku
    Explanation
    The purpose of the availability service is to ensure uninterrupted service to authorized users.

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  • 35. 

    Servis kontrole pristupa obuhvata:

    • A.

      Autoritet

    • B.

      Integritet

    • C.

      Autorizaciju

    • D.

      Neporecivost

    • E.

      Modifikaciju

    • F.

      Autentifikaciju

    Correct Answer(s)
    C. Autorizaciju
    F. Autentifikaciju
    Explanation
    The correct answer includes two components: autorizacija (authorization) and autentifikacija (authentication). Authorization refers to the process of granting or denying access to resources based on the user's identity and privileges. Authentication, on the other hand, is the process of verifying the identity of a user or entity. Together, these two components ensure that only authorized and authenticated individuals or entities are granted access to the system or resources.

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  • 36. 

    Izlaz iz linearnog pomerackog registra (LPR) ima sledece karakteristike:

    • A.

      Dobijeni niz je stabilan

    • B.

      Dobijeni niz je pseudoslucajan

    • C.

      Dobijeni niz je priodican

    • D.

      Dobijeni niz je slucajan

    • E.

      Dobijeni niz je stohasticki

    • F.

      Dobijeni niz je nepredvidiv

    Correct Answer
    B. Dobijeni niz je pseudoslucajan
    Explanation
    The correct answer is "Dobijeni niz je pseudoslucajan" which means "The resulting sequence is pseudorandom". This means that the output sequence appears to be random, but it is actually generated by an algorithm that follows a specific pattern or formula. Pseudorandom sequences are often used in simulations, cryptography, and other applications where true randomness is not necessary but a high level of unpredictability is desired.

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  • 37. 

    Blokovske sifre su zasnovane na konceptu kodnih knjiga gde:

    • A.

      Svaka strana predstavlja novu kodnu knjigu

    • B.

      Kodne knjige stvaraju neodredjenost sifrata

    • C.

      Svaki kljuc odredjuje novu kodnu knjigu

    Correct Answer
    C. Svaki kljuc odredjuje novu kodnu knjigu
    Explanation
    In block ciphers, each key determines a new codebook. This means that for each different key used, a different codebook is generated, which is used for encryption and decryption. The codebook creates uncertainty in the cipher, making it difficult for an attacker to decipher the encrypted message without knowing the key. Therefore, the statement "Svaki kljuc odredjuje novu kodnu knjigu" (Each key determines a new codebook) is a correct explanation of how block ciphers work.

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  • 38. 

    Osnovne pretpostavke simetricnog sifarskog sistema su:

    • A.

      Kljuc se cuva kod trece osobe od poverenja

    • B.

      Kljuc je javan

    • C.

      Kljuc je tajan

    • D.

      Algoritam i kljuc su nepoznati

    • E.

      Algoritam je javan

    • F.

      Algoritam je tajan

    Correct Answer(s)
    C. Kljuc je tajan
    E. Algoritam je javan
    Explanation
    The basic assumptions of a symmetric cipher system are that the key is kept secret and the algorithm is publicly known. This means that the key used for encryption and decryption is only known to the authorized parties, while the algorithm used for encryption and decryption is openly available to everyone. This allows for secure communication between parties, as the secrecy of the key ensures that only authorized individuals can decrypt the encrypted messages, while the public knowledge of the algorithm allows for transparency and verification of the encryption process.

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  • 39. 

    Kod sekvencijalnih sifara softverska realizacija je:

    • A.

      Linearnija od hardverske realizacije

    • B.

      Fleksibilnija od hardverske realizacije

    • C.

      Sporija od hardverske realizacije

    • D.

      Brza od hardverske reazlicaije

    Correct Answer(s)
    B. Fleksibilnija od hardverske realizacije
    D. Brza od hardverske reazlicaije
    Explanation
    The correct answer is "Fleksibilnija od hardverske realizacije" which means "More flexible than hardware implementation". This means that a software implementation of sequential ciphers allows for more flexibility in terms of customization and modification compared to a hardware implementation. Additionally, the answer "Brza od hardverske realizacije" which means "Faster than hardware implementation" implies that a software implementation of sequential ciphers can be faster in terms of processing speed compared to a hardware implementation.

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  • 40. 

    Racunarski bezbedan sifarski sistem ili:

    • A.

      Maksimalno tajan sistem

    • B.

      Apsoloutno tajan sistem

    • C.

      Prakticno tajan sistem

    • D.

      Digitalno potpisan sistem

    Correct Answer
    C. Prakticno tajan sistem
    Explanation
    The correct answer is "Prakticno tajan sistem." This means "Practically secret system" in English. This term refers to a computer security system that is designed to be as secret as possible, but not necessarily completely secret. It implies that while the system may have measures in place to protect sensitive information, it acknowledges that achieving absolute secrecy is difficult or impractical.

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  • 41. 

    Primena klasicne sifre tipa SUPSTITUCIJE odgovara:

    • A.

      Shanon-ovom principu KONFUZIJE

    • B.

      Shanon-ovom principu CENTRALIZACIJE

    • C.

      Shanon-ovom principu DIFUZIJE

    • D.

      Shanon-ovom principu LEVITACIJE

    • E.

      Shanon-ovom principu FREKVENCIJE

    • F.

      Shanon-ovom principu FREKVENCIJE

    Correct Answer
    A. Shanon-ovom principu KONFUZIJE
    Explanation
    The correct answer is "Shanon-ovom principu KONFUZIJE." This is because the principle of confusion in Shannon's theory of cryptography refers to the idea of making the relationship between the plaintext and the ciphertext as complex and random as possible. Substitution ciphers, such as the classical substitution cipher mentioned in the question, aim to achieve this confusion by replacing each letter in the plaintext with a different letter in the ciphertext.

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  • 42. 

    Cezarova sifra predstavlja:

    • A.

      Sifru zamene

    • B.

      Apsolutno tajnu sifru

    • C.

      Alfabetsko preslikavanje

    • D.

      Sifru transpozicije

    • E.

      Supstituciju

    Correct Answer(s)
    A. Sifru zamene
    C. Alfabetsko preslikavanje
    E. Supstituciju
    Explanation
    The correct answer is "Sifru zamene, Alfabetsko preslikavanje, Supstituciju". This is because the Cezarova sifra, also known as the Caesar cipher, is a substitution cipher where each letter in the plaintext is shifted a certain number of places down or up the alphabet. It involves replacing each letter with another letter in the alphabet, hence it is a form of substitution. This process can be seen as an alphabet mapping, where each letter is mapped to another letter in the alphabet. Therefore, the correct answer includes "Sifru zamene", "Alfabetsko preslikavanje", and "Supstituciju".

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  • 43. 

    Cilj bezbednosnog servisa zastite "poverljivosti" je:

    • A.

      Da obezbedi tajnost prenetih podataka u odnosu na prisluskivanje

    • B.

      Da zastiti poruku od laznog predstavljanja

    • C.

      Skrivanje informacija

    • D.

      Ucini servis raspoloziv svim legitimnim korisnicima

    • E.

      Da zastiti poruku od promene njenih sadrzaja i drugih zloupotreba

    • F.

      Da obezbedi poverljivu autentifikaciju i autorizaciju prenetih podataka

    Correct Answer
    A. Da obezbedi tajnost prenetih podataka u odnosu na prisluskivanje
    Explanation
    The goal of the security service of "confidentiality" is to ensure the secrecy of transmitted data from eavesdropping. This means that the service aims to prevent unauthorized individuals from intercepting and accessing the information being transmitted. By providing confidentiality, the service ensures that only the intended recipients can access the data, protecting it from potential threats.

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  • 44. 

    Obeleziti sta je tacno za softver zatvorenog koda:

    • A.

      Moguce je da sadrzi tzv. "tajna vrata"

    • B.

      Ako je softver skup garantuje kvalitetnu zastitu

    • C.

      To je odlicna osnova za gradnju kriptografskih resenja

    • D.

      Obezbedjuje visok kvaliet zastite

    • E.

      Ako je proizvodjac renomiran, softver je bezbedan

    • F.

      Ne sme se imati povrenja u softver zatvorenog koda

    Correct Answer(s)
    A. Moguce je da sadrzi tzv. "tajna vrata"
    F. Ne sme se imati povrenja u softver zatvorenog koda
    Explanation
    The correct answer states that closed-source software may contain "backdoors" and that one should not trust closed-source software. This means that closed-source software has the potential to have hidden vulnerabilities or malicious code that can be exploited by unauthorized individuals. Therefore, it is important to be cautious and skeptical when using closed-source software, as its security cannot be guaranteed.

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  • 45. 

    Obeleziti tipican primer napada na servis "raspolozivost":

    • A.

      Frekvencijaska analiza

    • B.

      Kasicki ispitivanje

    • C.

      Denial of Servise

    • D.

      Man in the Middle

    • E.

      Brute Force napad

    Correct Answer
    C. Denial of Servise
    Explanation
    Denial of Service (DoS) attack is a typical example of an attack on the "availability" of a service. In a DoS attack, the attacker overwhelms a system or network with an excessive amount of traffic or requests, causing it to become unavailable to legitimate users. This type of attack aims to disrupt the normal functioning of a service by exhausting its resources, such as bandwidth, processing power, or memory. By targeting the availability of a service, the attacker aims to prevent users from accessing or using the service effectively.

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  • 46. 

    Kod sifarskih sistema sa generatorima pseudoslucajnog niza, pored tajnog kljuca, koristi se obavezno:

    • A.

      Javni kljuc

    • B.

      Sesijski kljuc

    • C.

      Privatni kljuc

    • D.

      Jednokratni kljuc

    • E.

      Sigurni kljuc

    Correct Answer
    B. Sesijski kljuc
    Explanation
    In cryptographic systems with pseudorandom number generators, in addition to the secret key, a session key is used. The session key is a temporary key that is generated for a specific session or communication session between two parties. It is used to encrypt and decrypt the data exchanged during that session, providing security and confidentiality. The session key is different for each session, making it more secure than using a single key for all communications.

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  • 47. 

    Kod sifara zamene kljuc je:

    • A.

      Sabiranje po modulu

    • B.

      XORovanje

    • C.

      Sabiranje po modu 2

    • D.

      Nacin premestanja

    • E.

      Alfabetsko preslikavanje

    Correct Answer
    E. Alfabetsko preslikavanje
    Explanation
    The correct answer is "Alfabetsko preslikavanje." This means that the key substitution code is based on mapping letters of the alphabet to different letters or characters. In this method, each letter in the plaintext is replaced by a corresponding letter or character in the ciphertext according to a predetermined mapping. This type of substitution cipher is commonly used in cryptography to encrypt messages.

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  • 48. 

    Ukoliko napadac poznaje jedan od kljuceva sifarskog sistema sa javnim kljucevima:

    • A.

      Ne moze da izracuna drugi kljuc

    • B.

      Moze da desifruje poruku

    • C.

      Moze da izracuna drugi kljuc

    • D.

      Moze da izracuna kljuc ako je entropija sifrata manja od 1

    • E.

      Nista od ponudjenog

    Correct Answer
    A. Ne moze da izracuna drugi kljuc
    Explanation
    If an attacker knows one of the keys of a public key encryption system, they cannot calculate the other key. This is because public key encryption relies on the use of a pair of keys - a public key for encryption and a private key for decryption. The keys are mathematically related, but it is computationally infeasible to calculate one key based on the knowledge of the other key. Therefore, the attacker cannot calculate the second key if they only know one of the keys.

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  • 49. 

    Karakteristicno za sifre proste zamene duzine kljuca N, sa permutacijom kljuca:

    • A.

      Moguc je napad frekvencijskom analizom slova

    • B.

      Kljuc je tesko dostaviti primaocu

    • C.

      Veliki prostor kljuceva(N!)

    • D.

      Standardno se vrsi napad totalnom pretragom

    • E.

      Sifra je apsolutno tajna

    • F.

      Duzina sifrata je znacajno veca od duzine otvorenog teksta

    Correct Answer(s)
    A. Moguc je napad frekvencijskom analizom slova
    C. Veliki prostor kljuceva(N!)
    Explanation
    The correct answer is "Moguc je napad frekvencijskom analizom slova, Veliki prostor kljuceva(N!)". This is because the given statement implies that with a substitution cipher of key length N and key permutation, it is possible to perform a frequency analysis attack on the letters in the ciphertext. Additionally, the statement mentions that the key space is large, specifically N!, which means there are many possible keys to consider.

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  • 50. 

    Karakteristicna raspodela funkcije gustine verovatnoce za tajni simetricni kljuc je:

    • A.

      Normalna Gausova raspodela

    • B.

      Laplasova raspodela

    • C.

      Konfuzna raspodela

    • D.

      Slucajna raspodela

    • E.

      Difuzna raspodela

    • F.

      Uniformna raspodela

    Correct Answer
    F. Uniformna raspodela
    Explanation
    The correct answer for the given question is "Uniformna raspodela" (Uniform distribution). This suggests that the probability density function for the secret symmetric key follows a uniform distribution, meaning that all possible values of the key have equal probability of being chosen. In other words, there is no preference or bias towards any particular value of the key, making it uniformly distributed.

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