Hashing Encryption

Hashing Encryption.

Encryption. Encryption is the process of encrypting messages or information in such a way that only authorized people can read it A process that converts real information, also called blank text into a difficult translation form called ciphertext The encryption itself does not block access, but refuses the content of the message on the connector It is made using an encryption algorithm, a formula used to convert plain text into ciphertext text..

Types. Symmetric Key Encryption Asymmetric Key Encryption.

Symmetric Key Encryption. A private key, used in message text to modify content in a certain way It uses the same keys for both explicit encryption and decryption The keys may be the same or there may be a simple transition between the two keys. Keys, in fact, represent a shared secret between two or more parties that can be used to maintain a secret information link.

Asymmetric Key Encryption. Known as private key encryption or public key encryption Uses pairs of keys for encryption or decrypting data Public key is used for encryption and private key is used for encrypting data It has same public key. Able to share private data without sharing the same encryption key.

Hashing Algorithm. The hash algorithm is a one-way operation that converts a data unit to a output unit of a fixed length. The output character unit is usually much smaller than the original data. So it is also called message or message compression algorithm. Hash algorithms are designed to be contradictory, meaning they are less likely to have the same series created for different data. Two common hash algorithms are MD5 (Message-Digest algorithm 5) and SHA-1 (Secure Hash Algorithm). MD5 Message Digest checks are often used to verify data integrity when digital files are transferred or stored..

Hashing Algorithms. The 64-bit Hash functions are too small to survive a birthday attack. Many active single-mode hash functions produce 128-bit hashs . This forces anyone trying to attack a birthday party to hasten 264 random documents to get two with the same hash value, which is not enough for permanent security. NIST, in Secure Hash Standard (SHS), uses a 160-bit hash value. This makes birthday attacks even more difficult, requiring 280 random hashes. One-way Hash length Thash one-way Hash function.

Applications of hashing. Hashing passwords: It is a bad idea for computer systems to keep passwords in plain text (in their original form), because if a bad person does not know where they are stored, you get all the passwords. Knowing how many people foolishly use a password on many sites, getting a stash on one program may give them access to others. A more secure way to store a hash password, than the actual password. Since these horses cannot be undone, there is no way to find out for sure "which password generated this hash?" - and the effect of consensus is very low..

Hashing vs encryption. Encryption Hashing The purpose of encryption is to modify the data so that it is kept confidential to others. Hashing serves the purpose of ensuring integrity Encryption converts data into another format in such a way that only a specific person / persons can undo the change. The same input will always produce the same output. Examples: AES, Blowfish, RSA Examples: SHA-3, MD5.

Snefru. Snefru is a cryptographic hash project developed by Ralph Merkle in 1990 while working at Xerox PARC. The function supports 128-bit and 256-bit output. It was named after the Egyptian Pharaoh Sneferu , continuing the tradition of Khufu and Khafre block ciphers..

Snefru hash algo. Hash Algorithm Snefru is a cryptographic hash function invented by Ralph Merkle in 1990 while working at Xerox PARC. The original design of Snefru was shown to be insecure by Eli Biham and Adi Shamir who were able to use differential cryptanalysis to find hash collisions. Snefru was soon broken by the newly introduced differential cryptanalysis, while MD4 remained unbroken for several more years. As a result, newer functions based on MD4, e.g., MD5 and SHA-1, became the de-facto and international standards. Following recent techniques of differential cryptanalysis for hash function, today we know that MD4 is even weaker than Snefru..

Explination. Snefru is a recurring hash function that follows the construction of Merkle-Damg˚ard . It is designed to be a cryptographic hash function that transmits unwanted length messages into 128-bit values ​​(256-bit variations based on the same design are also introduced). Snefru is using an attachment scheme for that always add an extra clip with message length..

Explanation…. Messages are divided into 384-bit blocks, M1, ..., Mn − 1, where the last block is grouped by ‘0’s. An additional Mn block containing only message length (in bits) has been added. Each block is then connected to a binding value (originally used IV = 0) for press function C. Press C takes a 512-bit input connected to the binding value and the current block, and calculates the new binding value. Officially, hi = C (hi − 1Mi) of any 1 ≤ i ≤ n, where ‘’ concatenation operator for bit vectors, Mi is block number i , and h0 = 0. The last hash is hn..

Mod of operation of snefru.

Compression Function of Snefru. This attack involves a collision attacks and attacks of the first second image. Some previous attacks are effective if the attacker does not know the details of the S boxes. At this stage we explain the main ideas and basic strategies for attack, focusing a variant with 128-bit hash values. The first second image attack is as follows: select a random message size block then configure the provided 128-bit component for integration to create a 512-bit input modification of the pressure function. We create a second message to the first by changing two or more bytes 5–11 words, which are used as input..

Compression Function of Snefru …. in the S boxes in rounds 53–59 (i.e., those bytes do not touch the count before the fourth quarter). We are hash both messages with a press function then compare the results of the two executions. A fraction of 2−40 of these pairs messages are rushed to the same value. Therefore, immediately 241 messages we can find the second picture. As described later in this section, a number can greatly reduced through systematic messaging..

Compression Function of Snefru.

Preimage of Snefru. We have carefully examined the definition of Snefru, and especially the definition of padding block. There is no limit to the size of the message, as long as the length is equal to the last block. Therefore, the attacker can fully control the latter block, at the expense of creating messages with a large number of blocks. There is no difficulty in creating such large messages, as can be found in editing areas and repeated as many times as necessary..

Preimage of Snefru. On the other hand, the first picture of the oppressive work described in Table 1 represents 384 repetitions, and repair area. Therefore, if this block is repeated 79F6A75E CB8E7368 A8532FD9 81175859 CCE2C60C 734D51CF 5E8B7F23 F48893F9 EE56676D 6E565530 9864E5B1 A 2322E00x / 384≈ 2 374 times. It becomes a zero hash value! This the main message is the first image of 2-pass Snefru.

Table 1 The Block Used for the Preimage of Snefru.