"""
AWSSigner.py
Copyright (c) 2006 Ansel Halliburton
This is free, public domain software!
"""
import hmac, sha, base64

class AWSSigner:
	"""
	Provides HMAC/SHA-1/base64 signatures for Amazon Web Services requests
	Methods:
		__init__
			Parameters:
				secret_key: your AWS 'Secret Access Key'
		sign
			Parameters:
				service
				operation
				timestamp: NOTE: must be in proper format!
	Returns: string
	"""
	
	def __init__(self, secret_key):
		self.secret_key = secret_key
	
	def sign(self, service, operation, timestamp):
		h = hmac.new(self.secret_key, str(service) + str(operation) + str(timestamp), sha)
		digest = h.digest()
		return base64.b64encode(digest)