I see a lot of confusion between hashes and encryption algorithms and I would like to hear some more expert advice about: When to use hashes vs encryptions What makes a hash or encryption algorithm different (from a theoretical/mathematical level) i.e. what makes hashes irreversible (without aid of a rainbow tree) Here are some similar … Read more
Per the Java documentation, the hash code for a String object is computed as: s[0]*31^(n-1) + s[1]*31^(n-2) + … + s[n-1] using int arithmetic, where s[i] is the ith character of the string, n is the length of the string, and ^ indicates exponentiation. Why is 31 used as a multiplier? I understand that the … Read more
Coda Hale’s article “How To Safely Store a Password” claims that: bcrypt has salts built-in to prevent rainbow table attacks. He cites this paper, which says that in OpenBSD’s implementation of bcrypt: OpenBSD generates the 128-bit bcrypt salt from an arcfour (arc4random(3)) key stream, seeded with random data the kernel collects from device timings. I … Read more
I need to convert strings to some form of hash. Is this possible in JavaScript? I’m not utilizing a server-side language so I can’t do it that way. 24 s 24 String.prototype.hashCode = function() { var hash = 0, i, chr; if (this.length === 0) return hash; for (i = 0; i < this.length; i++) … Read more
Is there any method to generate MD5 hash of a string in Java? 33 s 33
It is currently said that MD5 is partially unsafe. Taking this into consideration, I’d like to know which mechanism to use for password protection. This question, Is “double hashing” a password less secure than just hashing it once? suggests that hashing multiple times may be a good idea, whereas How to implement password protection for … Read more
SHA-256 is a cryptographic (one-way) hash function, so there is no direct way to decode it. The entire purpose of a cryptographic hash function is that you can’t undo it. One thing you can do is a brute-force strategy, where you guess what was hashed, then hash it with the same function and see if … Read more
Usually hashes wouldn’t do sums, otherwise stop and pots will have the same hash. and you wouldn’t limit it to the first n characters because otherwise house and houses would have the same hash. Generally hashs take values and multiply it by a prime number (makes it more likely to generate unique hashes) So you … Read more
This whileloop is strange: while (scanner.hasNextLine()) { String line = scanner.nextLine(); while (line != null) { String word = scanner.next(); addWord(word, linecount); } linecount++; } If your input file is: Then scanner.nextLine() would be return a, then scanner.next() would return b, because nextLine returns the next end-line delimited String, and next returns the next token … Read more
