#!/usr/bin/python
#
#	http://tools.ietf.org/html/draft-ietf-hybi-thewebsocketprotocol-06#section-1.2
#

#	Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ==
#
#	For this header, the server has to take the value (as present in the
#   header, e.g. the base64-encoded version), and concatenate this with
#	the GUID "258EAFA5-E914-47DA-95CA-C5AB0DC85B11" in string form, which
#   is unlikely to be used by network endpoints that do not understand
#	the WebSocket protocol.  A SHA-1 hash, base64-encoded, of this
#   concatenation is then returned in the server's handshake
#	[FIPS.180-2.2002].
#
#	Concretely, if as in the example above, header |Sec-WebSocket-Key|
#   had the value "dGhlIHNhbXBsZSBub25jZQ==", the server would
#	concatenate the string "258EAFA5-E914-47DA-95CA-C5AB0DC85B11" to form
#   the string "dGhlIHNhbXBsZSBub25jZQ==258EAFA5-E914-47DA-95CA-
#	C5AB0DC85B11".  The server would then take the SHA-1 hash of this,
#   giving the value 0xb3 0x7a 0x4f 0x2c 0xc0 0x62 0x4f 0x16 0x90 0xf6
#	0x46 0x06 0xcf 0x38 0x59 0x45 0xb2 0xbe 0xc4 0xea.  This value is
#   then base64-encoded, to give the value "s3pPLMBiTxaQ9kYGzzhZRbK+xOo=".  This value would then be echoed in the header |Sec-WebSocket-
#   Accept|.


from hashlib import *
from base64 import *
catStr = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11" 

def getServerSecWebSocketKey(clientKey):
	buffer = clientKey + catStr
	buffer = sha1(buffer)
	return b64encode(buffer.digest())

	
if __name__ == '__main__':
	import string
	headerStr = "Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ=="
	#Splitting, and remowing whitespace
	clientKey = string.join(
		headerStr.split("Sec-WebSocket-Key:")[1].split(),
		""
	)
	print ( getServerSecWebSocketKey(clientKey) )
	print ("s3pPLMBiTxaQ9kYGzzhZRbK+xOo=")
	raw_input('wait for the key...')