rc4 not standard implementation

rc4.rb

#!/usr/bin/env ruby

# simple RC4 implementation
# NO WARRANTY, IT COULD BE WRONG

def rc4 (str_key, str_plaintext)

	## KSA

	#holding key and plaintext
	key = str_key.bytes
	plaintext = str_plaintext.bytes


	# create output
	output = Array.new(plaintext.length)

	#sbox initialized with 0..255 values
	sbox = Array.new(256) { |i| i+1}

	#input length
	kl = key.length
	tl = plaintext.length

	#j index
	j = 0

	# so preparation
	255.times do | i |
		#such shifting
		j = (j + sbox[i] +  key[i % kl])	% 256
		#so swap
		sbox[i], sbox[j] = sbox[j], sbox[i]
	end

	## /KSA
	## PRGA
	
	i = 0
	j = 0

	tl.times do | v |
		i = (i + 1) % 256
		j = (j + sbox[i]) % 256

		sbox[i], sbox[j] = sbox[j], sbox[i]

		output[v] = sbox[(sbox[i] + sbox[j]) % 256] ^ plaintext[v]

	end

	## /PRGA

	out_string = ""
	key_string = ""

	output.each do | v |
		out_string = out_string + sprintf("%X", v)
	end
	return out_string
end