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-3

For multiple word/phrase resulting in same hash value,the term coined for it is Collision. Hence because of the mathematical flaw which results in multiple collision the MD5(hashing algorithm) is no longer used. So, now MD5 is superseded with SHA-1, SHA 2, SHA-3. Theoretically SHA-1 has found collision but SHA-2 and SHA-3 is still secure. To make sure ...


1

Funnily enough, all of your questions are answered by the same word: salt A salt is typically a large (128bit) random value. First, a unique salt is generated for each password. Now, instead of hashing the password and storing it, we append the salt to the password and then hash the result of that. Now, we store the salt and hash in the database. ...


3

True All members with the same password have the same hash, unless the hash has been salted with a random value. In fact the hash value for "password1" is always the same regardless of the web application


4

Yes, sort of. Ideally two values are stored. A unique salt, and a hash of the salt+password. A globally unique salt is generated and stored for each password. Again, sort of. First the salt for that user account is retrieved from the database, then the salt+password is hashed and compared to the hash value sotred in the database. No, because the salt ...


0

Under some conditions, your hashes might leak sensitive information. This depends on whether or not an attacker can guess the content of specific files. As a trivialized example, let's say your files are memos from your boss which say which employee they are going to fire. They are always simple ASCII text files in the form of The next employee we fire is ...


1

SHA-1 produces a 160 bit hash. Hashing any file longer than 160 bits (20 octets) will therefore necessarily lose information and makes reconstruction impossible. In theory, that is. On the other hand, hashing files shorter than 20 octets is highly likely (practically guaranteed) to produce a 1:1 mapping. A 1:1 mapping means that without salt, it is trivial ...


0

Question: Do you want to publish the sensitive file names on the internet? Your approach above seems to imply that you will be publishing your file names on the internet. You may not want your file names published on the internet. brain@brain-laptop:~/Secret Files$ sha256sum * c988f4a50da6021fc70f618faeb5e27891b5de7162fb395b1dfd5b42f76a8070 Blueprints ...


2

The security you are thinking of with regards to the hash strength and the security you are talking about with the hashes on the internet are two different things. Hashes like SHA* are designed to work quickly so that files you send and the file you receive can be verified to be the same, however, this makes it easier brute force, due to this speed. What it ...


6

This attack is not about generating a modified SHA-1 that makes collisions easier, it's about generating a modified SHA-1 as part of the process of generating one specific collision. The modified hash function so produced is only useful for creating the single collision used in the generation process; it is no more vulnerable to collisions in general than ...


1

I think this question is opinionated, but here's my take. SHA-1 is standardized. The constants used are described in RFC3174. That article describes modifying the constants of a SHA-1 implementation to induce collisions. Now your question, were the constants in RFC3174 chosen in a way that NSA could produce collisions? You could ask this same question ...


1

I cannot say if this method was used anywhere. That is probably hard to find out. However, it is not possible to use this technique to exploit already existing implementations of SHA-1 that have not been designed to be weak by purpose. SHA-1 is still safe to use (as safe as it was before). The paper you refer to only shows how, by using certain constants, ...


2

Your main assumption that key size is directly related to the format of the keys, parameters or output size does not hold. Normally the attacker would only have access to a public EC key, which is (usually) not 256 bit, but a point on the curve. This point consists of two coordinate values prefixed with an indicator (compressed or uncompressed points). ...


8

Cryptographic hash functions must have several properties: Resistance to preimages: given x, it should be infeasible to find m such that h(m) = x. Resistance to second-preimages: given m, it should be infeasible to find m' such that h(m) = h(m'). Resistance to collisions: it should be infeasible to find m and m' such that m ≠ m' and h(m) = h(m'). These ...


4

The assessment of any strong 256 bit cryptographic hash as having a security level of either 128 or 256 bit depends entirely on how it is used. In an application where an attacker can succeed simply by finding any hash collision, the security level cannot exceed 128 bit since a simple birthday attack will (probabilistically) succeed after 2^128 random ...


3

No. In the context of a hash, "bits of security" is a measure of how many possible outputs a hash function has, and thus, how hard it is to find an input with a given output. It's on a logarithmic scale, so each additional bit doubles the security. You can't compare the security of SHA-256, AES-128, and ECC-256. They're totally different things: SHA-256 ...



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