- Is Hash always unique?
- What are the odds of a hash collision for the md5 hash?
- Does filename affect hash?
- What happens to the hash value of a file if the metadata changes?
- What is the feature of cryptographic hash function?
- Can two different files have the same hash?
- What creates different hashes for same password?
- How likely is a hash collision?
- What is Bcrypt password hash?
- How do you avoid a hash collision in Java?
- Should you hash passwords client side?
- Does renaming a file change the hash?
- Are hashed passwords safe?
- Should I encrypt password before sending to server?
- Why are hash collisions bad?
- Why do hash values change when data is modified?
Is Hash always unique?
As others have answered, hash functions are by definition not guaranteed to return unique values, since there are a fixed number of hashes for an infinite number of inputs.
Their key quality is that their collisions are unpredictable..
What are the odds of a hash collision for the md5 hash?
The 3 most used algorithms used for file hashing right now MD5: The fastest and shortest generated hash (16 bytes). The probability of just two hashes accidentally colliding is approximately: 1.47*10-29. SHA256: The slowest, usually 60% slower than md5, and the longest generated hash (32 bytes).
Does filename affect hash?
The hash of a file is the hash of its contents. Metadata such as the file name, timestamps, permissions, etc. have no influence on the hash. … This does not include MD5 or SHA-1 which are broken, nor a CRC such as with cksum which is not a cryptographic hash.
What happens to the hash value of a file if the metadata changes?
Answers: 1) No. The name of a file is a system metadata value stored in the master file table outside of the file, so changing a file’s name or extension won’t alter its contents and so won’t change its hash value. … Hence, changing the format of the file changes the file’s contents and changes its hash value.
What is the feature of cryptographic hash function?
A cryptographic hash function is a mathematical function used in cryptography. Typical hash functions take inputs of variable lengths to return outputs of a fixed length. A cryptographic hash function combines the message-passing capabilities of hash functions with security properties.
Can two different files have the same hash?
Generally, two files can have the same md5 hash only if their contents are exactly the same. Even a single bit of variation will generate a completely different hash value. … In other words, two different files can produce the same sum when hashed with md5.
What creates different hashes for same password?
salted password hashing techniqueThe salted password hashing technique creates different hashes for the same password. If two people use the same password that has been hashed twice, each time the hashes are different. Salt is a random string, which is appended to either the start or the end of the password before hashing is done.
How likely is a hash collision?
As a rule of thumb, a hash function with range of size N can hash on the order of √N values before running into collisions. This means that with a 64-bit hash function, there’s about a 40% chance of collisions when hashing 232 or about 4 billion items.
What is Bcrypt password hash?
bcrypt is a password-hashing function designed by Niels Provos and David Mazières, based on the Blowfish cipher and presented at USENIX in 1999. … The bcrypt function is the default password hash algorithm for OpenBSD and other systems including some Linux distributions such as SUSE Linux.
How do you avoid a hash collision in Java?
The only way to avoid (or rather minimize) collisions is to create a hash function that creates the best possible distribution of values throughout the HashMap. Depending on the density of your HashMap and the quality of your hash code , collisions are almost inevitable, hence the need to override the two methods.
Should you hash passwords client side?
But simply hashing the password on the client side is only just better than submitting it as plain text to the server. Someone, who can listen for your plain text passwords is certainly also able to listen for hashed passwords, and use these captured hashes him/herself to authenticate against your server.
Does renaming a file change the hash?
No; a change in file name in no way affects the file’s MD5 or SHA-1 checksum. However, if you have already created a hash of the file, it will no longer verify unless the file name inside the . hash file is also changed.
Are hashed passwords safe?
The unsafe functionality it’s referring to is that if you encrypt the passwords, your application has the key stored somewhere and an attacker who gets access to your database (and/or code) can get the original passwords by getting both the key and the encrypted text, whereas with a hash it’s impossible.
Should I encrypt password before sending to server?
It should be irreversibly hashed before leaving the client as there is no need for the server to know the actual password. Hashing then transmitting solves security issues for lazy users that use the same password in multiple locations (I know I do).
Why are hash collisions bad?
If you can generate hash collisions you can make it appear that someone digitally signed a document that they did not in fact sign. That’s bad, very bad. The irony is that hash collisions are inevitable, as a hash maps an infinite space to a finite space. In fact, there must be an infinite number of collisions.
Why do hash values change when data is modified?
The hash file is changed when the data is modified because the information within the file has changed and it is considered a new/different file.