Can we use block ciphers as hash functions? Iterated hash functions based on block ciphers are treated. Five attacks on an iterated hash function and on its round function are formulated. The wisdom of strengthening
Can we use block ciphers as hash functions?
Iterated hash functions based on block ciphers are treated. Five attacks on an iterated hash function and on its round function are formulated. The wisdom of strengthening such hash functions by constraining the last block of the message to be hashed is stressed.
Is compression a property of hash function?
A proper hash function should meet the following requirements and properties [1]: Compression. Hash function h(x) produces a fixed-length output string s with bit-length n for any given input string k of any arbitrary finite length. Ease of computation.
What are the requirements of cryptographic hash functions?
A cryptographic hash function must satisfy three criteria: Preimage resistance. Second preimage resistance (weak collision resistance) Strong collision resistance.
Is MD5 a block cipher?
Many well-known hash functions, including MD4, MD5, SHA-1 and SHA-2, are built from block-cipher-like components designed for the purpose, with feedback to ensure that the resulting function is not invertible.
Which block is cipher?
A block cipher is an encryption method that applies a deterministic algorithm along with a symmetric key to encrypt a block of text, rather than encrypting one bit at a time as in stream ciphers. For example, a common block cipher, AES, encrypts 128 bit blocks with a key of predetermined length: 128, 192, or 256 bits.
Which is not a good property of hash function?
Explanation: As the hash functions are irreversible and has pre-image resistance property, therefore it is almost impossible to obtain the original data form its hash value. Therefore, it is not possible to retrieve data in its original form from its hash value.
Which is not a hash function?
Explanation: A scheme in which the hash of the password is stored by an operating system rather than the password itself is the one-way password file system. 6. Which one of the following is not an application hash functions? Explanation: Key wrapping is a separate algorithm and not an application of hash fuctions.
What are two requirements for a hash function?
The basic requirements for a cryptographic hash function are:
- the input can be of any length,
- the output has a fixed length,
- H(x) is relatively easy to compute for any given x ,
- H(x) is one-way,
- H(x) is collision-free.
Why is MD5 still used?
Although MD5 was initially designed to be used as a cryptographic hash function, it has been found to suffer from extensive vulnerabilities. It can still be used as a checksum to verify data integrity, but only against unintentional corruption….MD5.
| General | |
|---|---|
| Rounds | 4 |
| Best public cryptanalysis |