# Questions tagged [collision-resistance]

Difficulty of finding two different inputs that hash to the same value

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### Challenging $O(2^{n/2})$ for hash collisions using quantum computers

In "Finding Hash Collisions with Quantum Computers by Using Differential Trails with Smaller Probability than Birthday Bound" the authors Akinori Hosoyamada and Yu Sasaki state that it may ...
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### What are other good attack examples that use the hash collision?

When we consider the security of a cryptographic hash function with $n$ bit output we simply say that it must have at least $\mathcal{O}(2^{n/2})$-time security against the (generic) collision attack ...
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### Bits of security vs collision resistance?

I have been doing some research on security, and I am confused on the bits of security vs collision resistance, and I was wondering if someone could clarify my understanding. For instance, if you have ...
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### Application of cryptographic hash functions which do not require collision resistance property

I can not understand why collision resistance of a cryptographic hash function is not required for some applications. for example, if we store the trusted hash of a file or program, and later when we ...
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### What are the “costs” to find a pre-image, weak collision, or strong collision?

For a secure, n-bit hash function, what are the “costs” to find a pre-image, weak collision, or strong collision?
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### Is this modification in Merkle-Damgård collision-resistant?

We modify Merkle-Damgård construction by setting $z_0:=L$ (the length of the message), computing $z_i:=h(z_{i-1}||x_i)$ for $i=1,...,B$ and defining $H(x):=z_B.$ Is this construction collision-...
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### Time and Space complexity of MiniAES

I am currently doing my masters research on security of wireless sensor networks, the topic is "ENHANCING THE SECURITY OF WIRLESS SENSOR NETWORKS BY COMBINING GEOENCRYPTION AND LIGHT WEIGHT ...
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### How much brute forcing efforts needed to find 2 or more inputs that generating same SHA256 outputs

Say I have SHA256 hash result that produced from 2000 bits inputs. For example, 0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef (64 bit hex representation) is the SHA256 output. ...
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### How secure is a hash based signature scheme after signing assuming quantum computers?

Consider a hash based signature scheme that requires taking the $k$-bit hash of an arbitrary length message to be signed (e.g. Lamport one-time signature scheme). My understanding is, assuming that ...
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### Hash function construction

I recently studied a Hash function and its security requirement. I have studied that simple hash construction from XOR is weak. My question is, based on Xor property the following Hash based on RSA Mi&...
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### Do hash functions for digital signatures need to be preimage resistant?

I understand that hash functions used for hashing a document or some data before signing it, needs to be collision resistant and 2nd pre-image resistance. Otherwise an adversary could "look" ...