0
16 (48-bit)
subkey
are derived from the main key using key schedule.
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What is the definition of an encryption key?
The definition of an encryption key is a way to transform information using an algorithm. By doing this, not anyone can read the transformed scripts, but only those who know the algorithm can solve the scripts.
What pseudo-random block stream is generated by 64-bit OFB with a weak DES key?
With (OFB) output feed back, a random 64-bit number, known as the IV is encrypted with the weak secret key to create the one-time pad. A weak DES secret key is one which is either all 1's, 0's or alternating ones and zeros. The plain text is XOred with as many bits of the generated one-time pad. If a weak key patterns will emerge in the ciphertext. - Eric Appelboom
What is a zero bit key?
It's a blank, uncut key.
Using a 20-bit key is how many times more secure than using a 18-bit key?
four times. adding 1 bit to an encryption key makes it twice as hard to crack.
Which algorithm do you use to exchange shared private keys?
The diffie hellman key exchange uses prime numbers to generate an asymmetric key pair which is used to create a secure channel over which a privet symmetric key can be sent.
Which algorithm has the smallest key space?
DES Data Encryption Standard 56 bit
What are the difference between DES and RSA algorithm?
DES is a symmetric cryptographic algorithm, while RSA is an asymmetric (or public key) cryptographic algorithm. Encryption and decryption is done with a single key in DES, while you use separate keys (public and private keys) in RSA. DES uses 56-bit keys for encryption while RSA uses 2600-bits of KEY
Why 48 bit key is USED in des algorithm?
The total key length for single DES is 56 bits. At the time, it was felt that was adequate so that someone could not easily guess what the key was. With automated approaches that has been shown to be too weak for good cryptoanalysis.
What performs three rounds of encryption using three different 56-bit keys giving an effective key length of 168 bits?
It sounds like you are describing Triple DES.The Triple-DES variant of DES (Data Encryption Standard) was developed after it became clear that DES by itself was too easy to crack. It uses three 56-bit DES keys, giving a total key length of 168 bits. Encryption using Triple-DES is simplyencryption using DES with the first 56-bit keydecryption using DES with the second 56-bit keyencryption using DES with the third 56-bit keyIn practice, Triple DES is sometimes executed using just two keys, with the 1st key being reused in step 3, i.e. 3rd key = 1st key.Decryption is done in the reverse of encryption.decryption using DES with the third 56-bit keyencryption using DES with the second 56-bit keydecryption using DES with the first 56-bit keyA couple notes here:The effective security of TripleDES is equivalent to 112-bit key (two 56-bit keys), rather than a 168-bit key. The algorithm has certain redundancies which weaken the overall strength, so use of three keys yields only the one more key's worth of strength, not the expected 3-keys.The common usage of reusing the 1st key as the 3rd key is proven to weaken TripleDES significantly to modern attacks. In fact, it reduces the strength of the algorithm back down to no stronger than ordinary 1-key DES. DON'T DO IT.Also, be careful when you say "rounds". This is different that you think. DES itself has multiple rounds of work in its implementation. That is, for DES, you don't just take the key and the plaintext, and perform some one operation on it. Rather, multiple rounds of operations are done, each using the preceding's output as its input. I mention this, because the term "round" has a specific meaning in the world of cryptography, which is different than the layman's usage.
What kind of algorithm is Saville?
A Saville algorithm is a classified NSA (National Security Agency) Type 1 encryption algorithm. Due to the nature of this algorithm little is known publicly, however some military documentation and personal have stated that it has a 128 bit key.
Why the DES is currently considered insecure?
DES is now considered to be insecure for many applications. This is chiefly due to the 56-bit key size being too small; in January, 1999, distributed.net and the Electronic Frontier Foundation collaborated to publicly break a DES key in 22 hours and 15 minutes (see chronology). There are also some analytical results which demonstrate theoretical weaknesses in the cipher, although they are infeasible to mount in practice. The algorithm is believed to be practically secure in the form of Triple DES, although there are theoretical attacks. In recent years, the cipher has been superseded by the Advanced Encryption Standard (AES). Furthermore, DES has been withdrawn as a standard by the National Institute of Standards and Technology (formerly the National Bureau of Standards).In some documentation, a distinction is made between DES as a standard and DES the algorithm which is referred to as the DEA (the Data Encryption Algorithm). When spoken, "DES" is either spelled out as an abbreviation (/ˌdiːˌiːˈɛs/), or pronounced as a one-syllable acronym (/ˈdɛz/).
Is knapsack algorithm is a public key encryption algorithm?
yes
What is the best public-key cryptography algorithm and why?
RSA (Rivest, Shamir, and Adelman) is the best public key algorithm.
What is the difference between AES and RSA?
AES is a symmetric cryptographic algorithm, while RSA is an asymmetric (or public key) cryptographic algorithm. Encryption and decryption is done with a single key in AES, while you use separate keys (public and private keys) in RSA. The strength of a 128-bit AES key is roughly equivalent to 2600-bits RSA key.
What are the drawbacks of des algorithm?
The Data Encryption Standard (DES) is a block cipher that uses a symmetric key (shared secret) algorithm. DES is now considered to be insecure for many applications. This is chiefly due to the 56-bit key size being too small; in January, 1999, a group of computer experts collaborated to publicly break a DES key in 22 hours and 15 minutes. There are also some analytical results which demonstrate theoretical weaknesses in the cipher, although they are infeasible to mount in practice. The algorithm is believed to be practically secure in the form of "Triple DES". Triple DES uses a "key bundle" which comprises three DES keys, K1, K2 and K3, each of 56 bits (excluding parity bits).The encryption algorithm is: ciphertext = EK3(DK2(EK1(plaintext)))in other words, DES encrypt with K1, DES decrypt with K2, then DES encrypt with K3.Decryption is the reverse: plaintext = DK1(EK2(DK3(ciphertext)))in other words, decrypt with K3, encrypt with K2, then decrypt with K1.Each triple encryption encrypts one block of 64 bits of data. The strongest application of Triple DES is to use 3 independent keys so that you get 3 x 56 = 168 independent key bits, but it is not uncommon to simplify the operation by just using two keys, making K1 and K3 the same but making sure K2 is independent of K1. This second Keying option provides less security than using 3 independent keys, with 2 x 56 = 112 key bits. This second option is stronger than simply DES encrypting twice, e.g. with K1 and K2, because it protects against meet-in-the-middle attacks.In recent years, the DES cipher has been superseded by the Advanced Encryption Standard (AES). Furthermore, DES has been withdrawn as a standard by NIST (previously known as NBS).
How many different keys are possible in the DES scheme?
i also confused about that！ but I search the answer on google. it shows that "DES uses a 56-bit key, so there are 256 possible keys"
Which key is often used to securely distribute symmetric algorithm keys?
Session key
