An MD5 value is always 22 (useful) characters long in Base64 notation. Many Base64 algorithms will also append 2 characters of padding when encoding an MD5 hash, bringing the total to 24 characters. The padding adds no useful information and can be discarded. Only the first 22 characters matter. Here’s why: An MD5 hash is … Read more
Since everyone until now has simply defined what a hash function was, I will bite. A one-way function is not just a hash function — a function that loses information — but a function f for which, given an image y (“SE” or 294 in existing answers), it is difficult to find a pre-image x … Read more
MD5 is designed to be cryptographically irreversible. In this case, the most important property is that it is computationally unfeasible to find the reverse of a hash, but it is easy to find the hash of any data. For example, let’s think about just operating on numbers (binary files after all, could be interpreted as … Read more
public static string ToHex(this byte[] bytes, bool upperCase) { StringBuilder result = new StringBuilder(bytes.Length*2); for (int i = 0; i < bytes.Length; i++) result.Append(bytes[i].ToString(upperCase ? “X2” : “x2”)); return result.ToString(); } You can then call it as an extension method: string hexString = byteArray.ToHex(false);
The input material can be an infinite length, where the output is always 128 bits long. This means that an infinite number of input strings will generate the same output. If you pick a random number and divide it by 2 but only write down the remainder, you’ll get either a 0 or 1 — … Read more
32 chars as hexdecimal representation, thats 2 chars per byte.
md5 is available on the iPhone and can be added as an addition for ie NSString and NSData like below. MyAdditions.h @interface NSString (MyAdditions) – (NSString *)md5; @end @interface NSData (MyAdditions) – (NSString*)md5; @end MyAdditions.m #import “MyAdditions.h” #import <CommonCrypto/CommonDigest.h> // Need to import for CC_MD5 access @implementation NSString (MyAdditions) – (NSString *)md5 { const char … Read more
SHA-256 isn’t an “encoding” – it’s a one-way hash. You’d basically convert the string into bytes (e.g. using text.getBytes(StandardCharsets.UTF_8)) and then hash the bytes. Note that the result of the hash would also be arbitrary binary data, and if you want to represent that in a string, you should use base64 or hex… don’t try … Read more
In cryptography, hash functions provide three separate functions. Collision resistance: How hard is it for someone to find two messages (any two messages) that hash the same. Preimage Resistance: Given a hash, how hard is it to find another message that hashes the same? Also known as a one way hash function. Second preimage resistance: … Read more