Pick a 8 or 9 digit number at random, say 839712541. Then, take your order number’s binary representation (for this example, I’m not using 2’s complement), pad it out to the same number of bits (30), reverse it, and xor the flipped order number and the magic number. For example: 1 = 000000000000000000000000000001 Flip = … Read more
From the VIM documentation: The algorithm used is breakable. A 4 character key in about one hour, a 6 character key in one day (on a Pentium 133 PC). This requires that you know some text that must appear in the file. An expert can break it for any key. When the text has been … Read more
As others have said, AES is a symmetric algorithm (private-key cryptography). This involves a single key which is a shared secret between the sender and recipient. An analogy is a locked mailbox without a mail slot. Anybody who wants to leave or read a message needs to have a key to the mailbox. If you … Read more
Hashing is a technique of creating semi-unique keys based on larger pieces of data. In a given hash you will eventually have “collisions” (e.g. two different pieces of data calculating to the same hash value) and when you do, you typically create a larger hash key size. obfuscation generally involves trying to remove helpful clues … Read more
Repent, 13 7 chars (No file support), 14 char (With file support) Repent is an esoteric stack-based toy language of my own, with inspiration from J, APL, Golfscript and Python. Here is a short solution. I will explain it, but is very late and this is doing my head in, so I’ll explain it and … Read more
CTR security requires that you never reuse an IV for two message encryptions with the same key. Actually it is even stricter: CTR mode works by encrypting successive values of a counter (the IV is just the initial value for that counter) and proper security is achieved only if the same counter value is not … Read more
AES itself does not directly use a salt (or indeed, an IV). A situation when you might use a salt in combination with AES is when you are using Password Based Encryption (PBE). In this scheme, a human-memorizable password is used, in combination with a salt, to generate an AES key. A salt is used … Read more
This is based on the NewCFBEncrypter / NewCFBDecrypter examples and seems to do what you require: EDIT: Based on Kluyg’s comment regarding IV creation I’ve modified the example code to use the recommended method of creating the IV from the ciphertext same method as the linked example to create the IV from the ciphertext. (In … Read more
An IV is essential when the same key might ever be used to encrypt more than one message. The reason is because, under most encryption modes, two messages encrypted with the same key can be analyzed together. In a simple stream cipher, for instance, XORing two ciphertexts encrypted with the same key results in the … Read more
The point of the salt is to be unique. The salt is meant to prevent attack cost sharing, i.e. an attacker trying to attack two hashed passwords for less than the twice the cost of attacking one. One solution to ensure uniqueness is to generate a random salt in a wide enough space. Therefore, getting … Read more