Crypto lab one way hash function solution

Young and Tim J. Hudson obiwanbd, After that, I use sudo. I then can execute the rest of the commands: sudo make sudo make install 1. GHex In this lab, we need to be able to view and modify files of binary format. It allows the user to load data from any file, view and edit it in either hex or ascii. A hex editor uses these two-digit representations to provide a simple grid that can be easily navigated, something that would be harder with 3 digit decimal numbers.

These tools can be very powerful, but it is also easy to corrupt binary files, so please use them with care. Encryption using different ciphers and modes The algorithm seems to follow the pattern: Algorithm name - key size - encryption mode Noted: If the key size is omitted or excluded then it means there is only one key-size for that algorithm.

Algorithm name: Sometimes there is number included in the algorithm name whose usage is to distinguish the version of the algorithm; for instance, RC2 and RC4. Key size: key size is in bit. The longer the key the stronger your encryption is, but the slower operation it takes. Encryption mode — ECB vs. The resulting sequence of output blocks is the cipher text. In ECB decryption, the inverse cipher function is applied directly and independently to each block of the cipher text.

Even a slight change in an input string should cause the hash value to change drastically. Even if 1 bit is flipped in the input string, at least half of the bits in the hash value will flip as a result. This is called an avalanche effect. Since it is computationally infeasible to produce a document that would hash to a given value or find two documents that hash to the same value, a document's hash can serve as a cryptographic equivalent of the document. This makes a one-way hash function a central notion in public-key cryptography.

When producing a digital signature for a document, we no longer need to encrypt the entire document with a sender's private key which can be extremely slow. It is sufficient to encrypt the document's hash value instead. Although a one-way hash function is used mostly for generating digital signatures, it can have other practical applications as well, such as secure password storage, file identification and message authentication code MAC.

See Chapter 3 of the User Manual for more information.

From cara menggunakan robot forex simply does

We can use the -hmac option this option is currently undocumented, but it is supported by openssl. The string following the -hmac option is the key. Please try several keys with different length. Do we have to use a key with a fixed size in HMAC?

If so, what is the key size? If not, why? Create a text file of any length. Generate the hash value H1 for this file using a specific hash algorithm. Flip one bit of the input file. You can achieve this modification using ghex or Bless. Generate the hash value H2 for the modified file. Please observe whether H1 and H2 are similar or not. Please describe your observations in the lab report.

You can write a short program to count how many bits are the same between H1 and H2. We will use the brute-force method to see how long it takes to break each of these properties. Please get familiar with this sample code. Since most of the hash functions are quite strong against the brute-force attack on those two properties, it will take us years to break them using the brute-force method.

To make the task feasible, we reduce the length of the hash value to 24 bits. We can use any one-way hash function, but we only use the first 24 bits of the hash value in this task. Namely, we are using a modified one-way hash function. Here we're interested in a subset of hash functions which are suitable for cryptographic purposes. Cryptographic hash functions are designed to be one-way: functions that are practically impossible to invert. This is in contrast to the functions used in asymmetric cryptography, where trapdoor functions are infeasible to invert unless some additional secret knowledge is known.

Cryptographic hash functions are used to verify message integrity, compute digital signatures, and safely store passwords in databases. In asymmetric cryptography, hash functions are particularly useful in compressing arbitrary length messages to a value which has a smaller bit-length than the modulus when signing messages with RSA or protocols such as EC DSA or Elgamal.

This is another way of saying that the hash must be a one-way function. Note the difference to the second pre-image attack, in that we can vary both m1 and m2. We can think of this as a linked set of dependencies, if a pre-image attack is known, so are second pre-image attacks and collision attacks.