shortest alphanumeric reversible encryption

bsgrules

What can I use to obtain a short alphanumeric reversible encryption?

When I say alphanumeric, i mean strictly [0-9a-zA-Z] only.

Weedpacket

base64_encode($string) is pretty short, str_rot13($string) is shorter still, but strrev($string) is even shorter than that.

"Short" isn't a sensible measure of encryption algorithms.

bsgrules

those aren't really encryptions...I wanted something along the lines of mcrypt.

laserlight

What do you mean by short?
Why must the ciphertext be alphanumeric? Or is the restriction for the plaintext to be alphanumeric?

Weedpacket

What do you mean by "really encryptions"?

bsgrules

laserlight wrote:
1. What do you mean by short?

Well, I don't know what i'm talking about so forget about that whole short thing. I thought different encryptions would make a strings larger than the original. For example converting something into base64 takes about 33% more space than the original data.

laserlight wrote:
2. Why must the ciphertext be alphanumeric? Or is the restriction for the plaintext to be alphanumeric?

Well, I planned on transferring this via url, and I didn't want any special characters in it.

Weedpacket wrote:
What do you mean by "really encryptions"?

Well, something thats actually secure, and requires a key to decode like mcrypt.

So let me rephrase my entire question, cause I don't know crap about encryption.

I need a moderately secure way of transferring data via url.

laserlight

Well, I planned on transferring this via url, and I didn't want any special characters in it.

Then a solution is to use mcrypt, then [man]urlencode/man or [man]rawurlencode/man the ciphertext - though I'm not entirely sure if urlencoding handles all possible special characters properly.