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1. H can be applied to a block of data of any size.

2. H produces a fixed-length output.

3. H(x) is relatively easy to compute for any given x, making both hardware and

software implementations practical.

4. For any given value h, it is computationally infeasible to find x such that H(x)

= h. This is sometimes referred to in the literature as the one-way property.

5. For any given block x, it is computationally infeasible to find y ≠ x with H(y) =

H(x).

6. It is computationally infeasible to find any pair (x, y) such that H(x) = H(y).

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Q: What characteristic are needed to secure hash function?
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How do you decyrpt the MD5 hash string?

The MD5 hash algorithm is a cryptographic hash function, not an encryption method. A cryptographic hash function converts a message of variable length to a fixed size of 'hash,' usually done to check the integrity and authenticity of the original message, and not transmit the message itself in a unreadable encrypted way. The message is also sent ALONG with the hash, usually to ensure that the original message has not been altered en route. Thus it does not have enough information to actually retrieve the message itself. (although it can if the size of the message is the size of the hash, it is never the case.) Decrypting the MD5 hash string will not yield the information that was used for its creation anyways.


What does MD5 encryption mean?

You are probably referring to the MD5 Message-Digest Algorithm which is a widely used cryptographic hash function that produces 128-bit (16-byte) hash values. A hash function is an algorithm that takes a block of data and creates a string of data (hash) of fixed length. By running the algorithm on a received block of data, a user should be able to detect whether the data has been altered because a given block of data should always yield the same hash unless it has been altered. Ideally a hash function will allow easy computation of the hash value for any given message but make it hard to start with the hash value and come up with a message that will yield that hash value. It should also be so difficult to modify a message without changing the hash that the time and effort necessary to do it exceeds the value of doing it and extremely difficult or impractical to find two different messages with the same hash. Note that by its nature the MD5 hash is not supposed to allow you to recover the message that was processed. Usually when we use the word "encryption" we are talking about a process where a message is converted to something called "cyphertext" which is unreadable unless you have the right algorithm and key to decrypt it and convert it back to the original message. In this respect it is more accurate to refer to "MD5 hashing" rather than MD5 encryption. See the attached link for more details on the MD5 hash.


Which of the following increases the collision resistance of a hash?

The collision resistance of a hash is proportional to the number of hash values that are stored, relative to the number of items that can be hashed, and it is proportional to the adequacy of the hash. The latter means that the hash should usually be of cryptographic quality.


Can you decrypt a hash of a message to get the original message?

yes


Is the lamport hash protocol vulnerable to server database disclosure?

No, it is safe. Even if the attacker would have seen the hashes he wouldn't be able to recreate the hash because the user's secret is still secret. Watch out for the small n attack though.

Related questions

What is the best way of referring to the output of a secure hash function?

The output from a hash function is referred to as the hash value, hash code, hash sum, checksum or just plain "hash" as in "the hash of the file is...". Generally a hash function is presumed to be secure or it wouldn't be used. If a hash is not secure it could be referred to as "worthless" or "false sense of security".


What is hash key?

hash key is an element in the hash table. it is the data that you will combine (mathematical) with hash function to produce the hash.


What is a hash function?

hash function is technique used in message authentication it is attached to the message for security purpose


Insert value into hash table?

Insertion in hash tables is based on a 'key' value which is calculated on the basis of a hash function. This hash function generates the key based on what type of data it is fed. For example hash function for an integer input might look like this : int hash(int val) { return (val%101); } where return value of hash function would become a key. Complete implementation can be found at: http://simplestcodings.blogspot.com/2010/07/hash-table.html


Advantages of Secure hash algorithm?

because it is more secure than any other algorithm.


What is double hashing in data structure?

if collision is occurred in hash function then we can solve this problem by using double hash function


What is a decryption of the hash string 108933322ed670db49b0141d10f6dbbe?

To decode a hash string you first need to know what hash function was used to encode it.


What is the standard for encryption currently recommended by NIST?

The secure hash standard


What code should you write in c plus plus that if the user enters a particular word then it further proceeds?

You're talking about password entry. For that you will need a one-way cryptographic hashing function. The hashing function converts a user's name and password into a hash value which can be openly stored on disk. Being a one-way function, even if an intruder knows the hash values, it is not possible for them to determine which user name and password combination was used to generate which hash value other than by brute force. The most widely used cryptographic hash functions are SHA-1 (Secure Hash algorithm 1) and MD5 (named after the Merkle-Damgård construction upon which it is based). However, SHA-1 implementations are being dropped due to well-funded intrusions which suggest it is no longer secure. It has since been replaced by SHA-2 and SHA-3.


Define hashing and describe briefly including types of hashing and where it is used and advantages and disadvantages of hashing?

Hashing is performed on arbitrary data by a hash function. A hash function is any function that can convert data to either a number or an alphanumeric code. There are possibly as many types of hashing as there are data. How precisely the hash function works depends on what data it is meant to generate a hash code from. Hashing is used for a variety of things. For example, a hash table is a data structure used for storing data in memory. Instead of iterating through the structure to find a specific item, we associate a key (hash code) to a particular item (data). A hash code can be generated from a file or disk image. If the data does not match the code, then the data is assumed to be corrupted. Hashing has the advantage of taking a larger amount of data and representing it as a smaller amount of data (hash code). The code generated is unique to the data it came from. Generating a hash code can take time however, depending on the function and the data. Some hash functions include Bernstein hash, Fowler-Noll-Vo hash, Jenkins hash, MurmurHash, Pearson hashing and Zobrist hashing.


What is the most insecure hash for storing passwords?

Of the conman ones in use today MD5 is the least secure.


What is the major advantage of a hash table?

The major advantage of a hash table is its speed. Because the hash function is to take a range of key values and transform them into index values in such a way that the key values are distributed randomly across all the indices of a hash table.