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What do you need to know about cryptographic hash?
If you want to use hashing for cryptographic purposes, there are several requirements the hash function has to meet to be considered secure. If you like fancy words – the cryptographic hash functions should be computationally efficient. That means the hashing function should be able to produce a hash in a fraction of a second.
How are cryptographic hashes used in DVCS tools?
Most DVCS tools, including Git, Mercurial, and Veracity, use cryptographic hashes. A cryptographic hash is an algorithm which constructs a short digest from a sequence of bytes of any length. There are many such hash algorithms. For the SHA-1 algorithm, the output digest is always 160 bits in length.
How are hashes used in a git repository?
Git uses hashes in two important ways. When you commit a file into your repository, Git calculates and remembers the hash of the contents of the file. When you later retrieve the file, Git can verify that the hash of the data being retrieved exactly matches the hash that was computed when it was stored.
How are hash functions used in computer systems?
Hash functions are commonly-used data structures in computing systems for tasks, such as checking integrity of messages and authenticating information. But they are considered cryptographically weak.
Which is the best hash function for storing passwords?
Update: Simply using a hash function is not strong enough for storing passwords. You should read the answer from Gilles on this thread for a more detailed explanation. For passwords, use a key-strengthening hash algorithm like Bcrypt or Argon2i. For example, in PHP, use the password_hash () function, which uses Bcrypt by default.
Is it OK to use MD5 for cryptographic hashes?
For some low-priority, relatively uncritical purposes, there is no problem with using MD5 or SHA-1 for generating cryptographic hashes, also known as “digests”. Most Unix-like operating systems include utilities for generating and comparing MD5 and SHA-1 hashes with their default, core toolsets.
How is a password hash different from a hash table?
A password hash has different properties from a hash table hash or a cryptographic hash. Never use an ordinary cryptographic hash such as MD5, SHA-256 or SHA-512 on a password. A password hashing algorithm uses a salt, which is unique (not used for any other user or in anybody else’s database).