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### Is SHA-256 a one way permutation when restricting the domain to {0,1}^256? [duplicate]

Suppose we consider the space of $\lbrace 0,1 \rbrace^{256}$ as the domain and SHA-256 as our hash function. Does SHA-256 become a one way permutation? Has anyone tried to prove this? Or can it be ...
790 views

### If I compute the SHA-1 of all possible 40 digits hexadecimal strings, will I get all possible sha1 hashes? [duplicate]

Wikipedia says sha1 produces a 160-bit (20-byte) hash value. So if I compute the SHA-1 of all possible SHA-1 values, which as far as I understand is at current time impossible both to calculate and ...
124 views

### Is SHA-1 collision free on data up to 20 bytes long? [duplicate]

Is SHA-1 collision free on data up to 20 bytes long (lenght of hash / internal state)? That means that every input produce unique output, but you surely know that, i just write it in order my question ...
69 views

### SHA-512 hash collisions [duplicate]

Possible Duplicate: Is SHA-512 bijective when hashing a single 512-bit block? Is there any guarantee that there are no collisions for all 512-bit input values for SHA-512 (every 512-bit input has ...
41 views

### Number of unique outputs in hash function (SHA256) against all possible inputs [duplicate]

If I use SHA256 as a hash function, and I try all inputs starting from 0 to 2^256 (means all possible combination of 256-bit), then will it give me 2^256 unique output without any collision? Or ...
16 views

### Does every 256 bit number have a distinct sha256 result? [duplicate]

If I were some how able to create a table of all 256 bit inputs and outputs of sha256, would each of the inputs have a distinct output?
2k views

### Cycles in SHA-256

Let's say I start with a particular 256 bit value. Call this $v$. I then hash that value, and get another 256 bit value. Call this $\text{SHA256}(v)$. I take this value and get another 256 bit value. ...
3k views

### Is it theoretically possible to construct a string that contains its own hash value?

After saw the xkcd comic Self-Description, I wonder if it is theoretically possible to construct a self-descriptive string that contains its own hash value? Let's say the string's MD5 value is ...
3k views

### Is every output of a hash function possible?

Is every output of a hash function (e.g. SHA1, MD5, etc) guaranteed to be possible, or, conversely, are there any output values that cannot possibly be created from any input? In other words, are hash ...
5k views

### What alphanumeric string length can be used to guarantee no hash collisions from CRC-64? [closed]

If I'm hashing alphanumeric strings (chars in the set 0-9, a-...
1k views

### Determine whether bit sequence is hash?

I would like to know whether it is possible to determine whether a value of for example 256 bit length is a SHA-256 hash or a random, equally distributed value. Is ...
3k views

### Is Base64(SHA1(GUID)) still unique like the original GUID?

Basically what the title is; GUIDs are unique by design. If you run the GUID through SHA1 and then Base64 the hash, will the resulting string have the same guaranteed uniqueness as the GUID, or not?
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### How many recursive md5 hashes are needed to always get same string

If we start with a set of possible input values, and apply the md5 algorithm to all elements of this set and then filter out the unique results (a.k.a. filter out ...