properties.py

import os, hashlib, hmac, base64

def loadcredentials():
    properties = {}
    with open(os.path.join(os.getenv('HOME'), '.s3dropbox')) as prop_file:
        for line in prop_file:
            text = line.strip()
            if len(text) > 0 and not text.startswith('#'):
                key, sep, val = text.partition('=')
                properties[key.strip()] = val.strip()
    access_key = properties['AMAZON_ACCESS_KEY_ID']
    secret_key = properties['AMAZON_SECRET_ACCESS_KEY']
    return Credentials(access_key, secret_key)

class Credentials:
    def __init__(self, access_key_id, secret_access_key):
        self.secret_access_key = secret_access_key
        self.access_key_id = access_key_id

    def sign(self, text):
        digest = hmac.new(self.secret_access_key, text, hashlib.sha1).digest()
        return base64.b64encode(digest)