Generate signed URL for Amazon Associates

amazon-signed-url.py

from time import gmtime, strftime
import urllib2
import hmac
import hashlib
import base64

"""
Code to generate signed URL for Amazon Associate
I hope it is simple to understand

Don't forget to fill PUBLICKEY, SECRETKEY and ASSOCIATETAG
And also edit HOST and SEARCH


Good links
http://docs.aws.amazon.com/AWSECommerceService/latest/DG/rest-signature.html
http://associates-amazon.s3.amazonaws.com/signed-requests/helper/index.html

Amazon hash help from stackoverflow
http://stackoverflow.com/questions/1306550/calculating-a-sha-hash-with-a-string-secret-key-in-python
"""

# Keys
# Get AWS Security Credentials
# http://docs.aws.amazon.com/general/latest/gr/getting-aws-sec-creds.html
# Access keys (access key ID and secret access key)

PUBLICKEY = ""
SECRETKEY = ""

# Associate tag

ASSOCIATETAG = ""

# Host

HOST = 'webservices.amazon.com.br'

# Search term example

SEARCH = urllib2.quote("Harry Potter")

# Example data

time = strftime("%Y-%m-%dT%H:%M:%SZ", gmtime())
response_group = 'Large,EditorialReview,ItemAttributes,OfferFull,Offers'


# Unsigned URL

uri = 'Operation=ItemSearch&Condition=All&Availability=Available'
uri += '&ResponseGroup=' + urllib2.quote(response_group)
uri += '&Version=2011-08-01'
uri += '&Keywords=' + SEARCH
uri += '&SearchIndex=Books'
uri += "&AWSAccessKeyId=" + PUBLICKEY
uri += "&AssociateTag=" + ASSOCIATETAG
uri += "&Timestamp=" + urllib2.quote(time)
uri += "&Service=AWSECommerceService"
uri += "&Sort=relevancerank"

unsigned_url = "http://webservices.amazon.com.br/onca/xml?" + uri


# Signed URL

parameters = uri.split('&')
parameters.sort()
sorted_pairs = "\n".join(list(parameters))
uri = '&'.join(parameters)

get_request = """GET
%s
/onca/xml
%s""" % (HOST, uri)

string_to_sign = get_request


# Hash for Signature

dig = hmac.new(SECRETKEY, msg=get_request, digestmod=hashlib.sha256).digest()
signature = base64.b64encode(dig).decode()
signature = urllib2.quote(signature, '')

uri = "http://webservices.amazon.com.br/onca/xml?" + uri
uri += "&Signature=" + signature

signed_url = uri


# Data created
# Compare at
# http://associates-amazon.s3.amazonaws.com/signed-requests/helper/index.html

print "\nunsigned url"
print unsigned_url
print "\nsorted pairs"
print sorted_pairs
print "\nstring to sign"
print string_to_sign

# The most useful data
print "\nsigned url"
print signed_url