Basics of MD5: How to know hash bit length and symmetry?

Question

I'm curious about some basics of MD5 encryption I couldn't get from Google, Java questions here nor a dense law paper:

1-How to measure, in bytes, an MD5 hash string? And does it depends if the string is UNICODE or ANSI?

2-Is MD5 an assymetric algorythm?

Example: If my app talks (http) to a REST webservice using a key (MD5_128 hash string, ANSI made of 9 chars) to unencrypt received data, does that account for 9x8=72 bytes in an assymetric algorithm?

I'm using Windevs 25 in Windows, using functions like Encrypt and HashString, but I lack knowledge about encryption.

Edit: Not asnwered yet, but it seems like I need to know more about charsets before jumping to hashes and encryption. https://www.joelonsoftware.com/2003/10/08/the-absolute-minimum-every-software-developer-absolutely-positively-must-know-about-unicode-and-character-sets-no-excuses/

Answer 1

An MD5 hash is 128 bits, 16 bytes. The result is binary, not text, so it is neither "ANSI" nor "Unicode". Like all hashes, it is asymmetric, which should be obvious from the fact that you can hash inputs which are longer than 128 bits. Since it is asymmetric, you cannot "unencrypt" (decrypt) it. This is by design and intentional.