Hiding a salt is unnecessary. A different salt should be used for every hash. In practice, this is easy to achieve by getting 8 or more bytes from cryptographic quality random number generator. From a previous answer of mine: Salt helps to thwart pre-computed dictionary attacks. Suppose an attacker has a list of likely passwords. … Read more
The magic number is supposed to be 32 random bits, where each is equally likely to be 0 or 1, and with no simple correlation between the bits. A common way to find a string of such bits is to use the binary expansion of an irrational number; in this case, that number is the … Read more
If you have a hash, you can add items to it by referencing them by key: hash = { } hash[:a] = ‘a’ hash[:a] # => ‘a’ Here, like [ ] creates an empty array, { } will create a empty hash. Arrays have zero or more elements in a specific order, where elements may … Read more
As none of the answers provide you with a random string consisting of characters 0-9, a-z, A-Z: Here is a working solution which will give you one of approx. 62^16 = 4.76724 e+28 keys: import random, string x = ”.join(random.choice(string.ascii_uppercase + string.ascii_lowercase + string.digits) for _ in range(16)) print(x) It is also very readable without … Read more
Python’s dict class is an implementation of what the Python documentation informally calls “mapping types”. Internally, dict is implemented using a hashtable. Java’s HashMap class is an implementation of the Map interface. Internally, HashMap is implemented using a hashtable. There are a few minor differences in syntax, and I believe the implementations are tuned slightly … Read more
This is a little bit late, but I succeeded in implementing a compile-time CRC32 function with the use of constexpr. The problem with it is that at the time of writing, it only works with GCC and not MSVC nor Intel compiler. Here is the code snippet: // CRC32 Table (zlib polynomial) static constexpr uint32_t … Read more
every javascript object is a simple hashmap which accepts a string or a Symbol as its key, so you could write your code as: var map = {}; // add a item map[key1] = value1; // or remove it delete map[key1]; // or determine whether a key exists key1 in map; javascript object is a … Read more
First, note that this behavior applies to any default value that is subsequently mutated (e.g. hashes and strings), not just arrays. It also applies similarly to the populated elements in Array.new(3, []). TL;DR: Use Hash.new { |h, k| h[k] = [] } if you want the most idiomatic solution and don’t care why. What doesn’t … Read more
Here is everything about Python dicts that I was able to put together (probably more than anyone would like to know; but the answer is comprehensive). A shout out to Duncan for pointing out that Python dicts use slots and leading me down this rabbit hole. Python dictionaries are implemented as hash tables. Hash tables … Read more
From the docs: Here are the rules governing implicit creation of a __hash__() method: […] If eq and frozen are both true, by default dataclass() will generate a __hash__() method for you. If eq is true and frozen is false, __hash__() will be set to None, marking it unhashable (which it is, since it is … Read more