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8

No, because even SHA-512 was considered overkill from a security perspective. It has 256-bit collision resistance, which is unbreakable. (The link is about keys but a similar argument applies.) If you think large quantum computers will be efficient, a 512-bit hash makes some sense, but even then a 1024-bit one wouldn't. A quantum computer requires ...


6

The main thing that makes HMAC secure in typical use even with MD5 is that it is used with a secret key. That means only preimage attacks are really relevant, since finding a collision is always an online attack if you don't know the key. With known attacks the preimage resistance of both MD5 and SHA-1 is > 100 bits. Additionally, HMAC may be secure even ...


5

What you are describing is essentially the same things as a hash list. A hash list is a sequence of hashes over which another hash is calculated. Your scheme does the same thing after sorting. The sorting won't matter for the security of the scheme; it won't increase the chance of collisions. Hash lists are also used for a well known structure called a ...


5

The Secure Hash Standard and corresponding FIPS-180/202 do not specify any hash to meet a security requirement above 256-bits (using a 512-bit hash). This is unlikely to change. SHA-2 was built with state and word sizes to meet the security requirements on commodity computers (x86 and Alpha), which use 32 and 64-bit maximum CPU word sizes for general ...


5

You can't say SHA-2 has a security level of half its hash length without any given context. 128 bit against what type of attack? What is the attacker trying to do? Perform a collision? Ok yes it has 128 bit against collisions. Perform a preimage? Nope it has 256 bit security against preimage attacks. Any algorithm is considered n bit strength if the ...


4

There is no known exploitable relationships between the words (32/64 bit "chunks") of SHA-2 but this is always a source of cryptanalysis. There are some academic weaknesses against reduced round variants of SHA-2 but nothing against the full cipher. Still hashes are cheap so why not just use multiple hash functions? Seed = HASH(secret) <- This should ...


3

I know SHAKE128 and 256 are part of the SHA-3 standard but is the SHA3 standard officially released yet? i can only find a draft of the publication, does this mean it's not official and therefor not proven to be secure? No, SHA-3 has not been formally approved. On the other hand, what do you mean "not proved to be secure"? Do you really thing that ...


2

So your idea is to effectively turn the password authentication into a key-based authentication by deriving the machine passwords from a single random key stored elsewhere. Assuming key storage is secure (probably encrypted with a strong password), this is sound. It would be better to just use the asymmetric key-based authentication built into most remote ...


2

There is none. Conjunctive normal form is for Boolean formulas, which have a single truth value. SHA-256 is not a Boolean formula (SHA-256(x) is not "true" or "false.") Furthermore, CNF is only applicable if you have a fixed number of variables; this is not true for SHA-256, which has variable-length input. At best you could have 256 different formulas, each ...


2

SHA is related to AES in that they are both US government standards. They are not similar algorithmically. SHA and AES are cryptographic primitives, TLS is a protocol. As the name describes SHA is a family of hash algorithms. AES is a block cipher. TLS uses many encryption algorithms, including AES in various modes, and several hash algorithms, including ...


2

Actually, it's there on the list, just with a different name -- the approved algorithm you want is listed as "SHS" (Secure Hashing Standard). Now, the term "SHS" doesn't distinguish between the various flavors of SHA-2 (and SHA-1, which is still approved for some uses); however if you look at this more detailed list, that gives details on what vendors have ...


1

It depends. If you have full control over the whole system, all components and can use whatever algorithm you want to deploy, you can stick to the one giving you the best efficiency which fulfills your security requirements. In this case, it would be Tiger. However, Tiger has a 192 bit output. If that is not enough for you, go for SHA256. However, if the ...


1

It is extremely likely to be either RSA with PSS padding or RSA with PKCS#1 v1.5 padding, the latter being the most likely. If you sign two times and the output is twice the same then it is not PSS and PKCS#1 v1.5 would be the prime suspect (that was my brain making fun of me, pun not intended). RSASSA-PSS is different from other RSA-based signature ...



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