Kripto 1

XOR (exclusive OR) is the correct answer for the question. XOR is a logical operation that returns true if the inputs are different and false if they are the same. In the context of encryption and decryption in absolutely secret cipher systems, XOR is commonly used as it provides a high level of security. XORing a message with a secret key produces the encrypted message, and XORing the encrypted message with the same key retrieves the original message. This operation is reversible and ensures that the encrypted message cannot be easily deciphered without the key.

The given question provides the ciphertext (C) as 1001 and the key (K) as 1111. The plaintext (P) is given as four different possibilities: 0110, 1100, 1111, and 0010. To decrypt the ciphertext using a one-time pad, we perform an XOR operation between the ciphertext and the key. In this case, 1001 XOR 1111 results in 0110, which matches one of the given plaintext options. Therefore, the correct answer is P=0110.

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.

The correct answer is "Confidentiality, Integrity and Availability." In the field of information security, CIA stands for these three fundamental principles. Confidentiality ensures that information is only accessible to authorized individuals, integrity ensures that information is accurate and unaltered, and availability ensures that information is accessible and usable when needed. These principles help protect sensitive information and ensure its reliability and accessibility.

If two ciphertexts obtained from the One-time pad cipher are XORed, the result will not reveal the secret key.

Autentifikacija obezbeđuje proveru identiteta. This means that authentication ensures that the identity of the user or entity trying to access a system or resource is verified. It helps in confirming that the user is who they claim to be, preventing unauthorized access and protecting against identity theft or impersonation.

The correct answer is "Ovlascenih korisnika koji zloupotrebljavaju svoja prava, Neovlascenih korisnika" which translates to "Authorized users who abuse their privileges, Unauthorized users" in English. This answer suggests that integrity can be compromised when authorized users misuse their rights and when unauthorized users gain access to the system. Both scenarios can lead to unauthorized modifications, deletions, or alterations of data, thus compromising its integrity.

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.

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.

In block ciphers, a key determines a specific codebook or code table that is used for encryption and decryption. Each key corresponds to a unique codebook, which is a collection of mappings between plaintext and ciphertext. By using different keys, different codebooks are generated, introducing uncertainty and making it difficult for an attacker to decipher the encrypted message without the correct key. Therefore, the statement "Svaki kljuc odredjuje novu kodnu knjigu" (Each key determines a new codebook) is a correct explanation of the concept of block ciphers.

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.

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.

The word "bit" can be scrambled in 6 different ways.

The correct answer is "Broj kolona." In classical column transposition ciphers, the key is determined by the number of columns used to rearrange the letters of the message. The number of columns determines the order in which the letters are written out to form the ciphertext. Therefore, the number of columns is an essential element in decrypting the message correctly.

Steganografija je proces skrivanja informacija unutar drugih oblika medija, kao što su slike, zvukovi ili tekstovi, na način da se promene ili sakriju tako da ne budu primetne. Ova tehnika se koristi kako bi se poruke ili podaci tajno preneli, a da ne izazovu sumnju ili privuku pažnju. Steganografija se razlikuje od kriptografije jer se ne bavi šifrovanjem samih podataka, već njihovim skrivanjem unutar drugih medija.

The given correct answer states that the one-time pad cipher is used in places where the highest level of secrecy is required and it is highly impractical for use in computer networks. This implies that the one-time pad cipher provides a high level of security and confidentiality, making it suitable for sensitive information. However, it is not practical for use in computer networks due to its limitations, such as the need for a pre-shared key of the same length as the message and the challenge of securely distributing and managing the keys.

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.

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.

The given answer "Slova se premestaju" is correct because the phrase "Kod sifre transpozicije" translates to "Transposition cipher" in English. In a transposition cipher, the letters of the plaintext are rearranged or shuffled to form the ciphertext. This means that the letters are indeed being moved or shifted, which aligns with the answer "Slova se premestaju."

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.

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.

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.

The correct answer is "Sifre zamene" which translates to "Substitution ciphers" in English. Substitution ciphers are a type of encryption method where each letter in the plaintext is replaced by a different letter or symbol in the ciphertext. This method is commonly used in cryptography to protect sensitive information.

The correct answer is "Korišćenje tajnih mastila". This refers to the use of invisible ink, which is a type of secret writing technique. Invisible ink is a substance that is not visible to the naked eye, but can be revealed by applying heat, chemicals, or special light. It was historically used for covert communication or to hide sensitive information. By using invisible ink, messages can be written in plain sight without anyone knowing the true content unless they possess the means to reveal it.

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.

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.

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.

Sequential ciphers are pseudo generators whose output key is approximately random, similar to the one-time pad. These ciphers, such as DES, JDES, and AES, generate a sequence of blocks that are used to encrypt and decrypt data. The output key is not truly random like the one-time pad, but it is designed to be unpredictable and provide a high level of security.

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.

The correct answer is "Sequential codes." Sequential codes are a type of encryption that generates a sequence of numbers or characters based on a predetermined algorithm. These codes are used in various applications, such as generating unique identification numbers or in cryptographic systems. They are called "sequential" because the next code in the sequence can be easily determined from the previous one. This makes them less secure compared to other encryption methods, such as block ciphers or public-key cryptography.

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.

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.

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.

The correct answer is "Predstavlja proces sifrovanja." The given text mentions "Procedura C = E(P, K)" which indicates a process of encryption (sifrovanja). Therefore, the correct answer is that it represents the process of encryption.

The correct answer suggests that the message is divided into blocks of fixed length. This means that the message is broken down into equal-sized chunks, each containing a specific number of characters or bits. This approach allows for easier processing and manipulation of the message data.

The correct answer is One-Time Pad. The One-Time Pad is a type of encryption where a random key is used only once to encrypt a message. It is considered to be one of the most secure encryption methods because it provides perfect secrecy if used correctly. The other options mentioned, such as substitution ciphers, Vigenere cipher, and Caesar cipher, are all different types of encryption methods but do not provide the same level of security as the One-Time Pad. Transposition ciphers involve rearranging the letters of a message, but they also do not provide the same level of security as the One-Time Pad.

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.

The purpose of the availability service is to ensure uninterrupted service to authorized users.

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.

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).

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.

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.

By using a frequency test, it is easy to break the Caesar cipher. The Caesar cipher is a simple substitution cipher where each letter in the plaintext is shifted a certain number of places down or up the alphabet. Since the frequency of letters in any given language is not evenly distributed, a frequency analysis can be used to determine the shift used in the Caesar cipher. This makes it vulnerable to decryption.

In sequential ciphers, the inner key is used to generate the working key. This means that the inner key is responsible for generating the key that will be used in the encryption or decryption process. The working key is derived from the inner key and is used to initialize the algorithm's initial state. Therefore, the inner key plays a crucial role in generating the working key, which is essential for the functioning of sequential ciphers.

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.

The correct answer includes three options: "Onom što jesmo" (based on who we are), "Onom što se poseduje" (based on what we possess), and "Onom što znamo" (based on what we know). These options suggest different ways in which authentication can be established. "Onom što jesmo" refers to biometric authentication, where individuals are authenticated based on unique physical or behavioral characteristics. "Onom što se poseduje" refers to possession-based authentication, where individuals are authenticated based on something they possess, such as a token or a smart card. "Onom što znamo" refers to knowledge-based authentication, where individuals are authenticated based on something they know, such as a password or a PIN.

The given answer states that the well-known cryptographic methods for the Vigenère cipher are the Kasiski test and the Friedman test. The Kasiski test is used to find the length of the keyword used in the Vigenère cipher by analyzing the repeated patterns in the ciphertext. The Friedman test is used to determine the length of the keyword by analyzing the index of coincidence in the ciphertext. Both of these tests are commonly used in cryptanalysis to break the Vigenère cipher.

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.

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.

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.