aws_reko.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

import base64
import datetime
import hashlib
import hmac
import simplejson as json
import requests

# Key derivation functions
# http://docs.aws.amazon.com/general/latest/gr/signature-v4-examples.html#signature-v4-examples-python
import sys


def sign(key, msg):
	return hmac.new(key, msg.encode('utf-8'), hashlib.sha256).digest()


def getSignatureKey(key, date_stamp, regionName, serviceName):
	kDate = sign(('AWS4' + key).encode('utf-8'), date_stamp)
	kRegion = sign(kDate, regionName)
	kService = sign(kRegion, serviceName)
	kSigning = sign(kService, 'aws4_request')
	return kSigning


if __name__ == '__main__':
	# Read credentials from the environment
	access_key ='xxx'
	secret_key = 'xxx'

	# Uncomment this line if you use temporary credentials via STS or similar
	#token = os.environ.get('AWS_SESSION_TOKEN')

	if access_key is None or secret_key is None:
		print('No access key is available.')
		sys.exit()

	# This code shows the v4 request signing process as shown in
	# http://docs.aws.amazon.com/general/latest/gr/sigv4-signed-request-examples.html

	host = 'rekognition.us-east-1.amazonaws.com'
	endpoint = 'https://rekognition.us-east-1.amazonaws.com'
	service = 'rekognition'

	# Currently, all Rekognition actions require POST requests
	method = 'POST'

	region = 'us-east-1'

	# This defines the service target and sub-service you want to hit
	# In this case you want to use 'CompareFaces'
	amz_target = 'RekognitionService.CompareFaces'



	# Amazon content type - Rekognition expects 1.1 x-amz-json
	content_type = 'application/x-amz-json-1.1'

	# Create a date for headers and the credential string
	now = datetime.datetime.utcnow()
	amz_date = now.strftime('%Y%m%dT%H%M%SZ')
	date_stamp = now.strftime('%Y%m%d') # Date w/o time, used in credential scope

	# Canonical request information
	canonical_uri = '/'
	canonical_querystring = ''
	canonical_headers = 'content-type:' + content_type + '\n' + 'host:' + host + '\n' + 'x-amz-date:' + amz_date + '\n' + 'x-amz-target:' + amz_target + '\n'

	# list of signed headers
	signed_headers = 'content-type;host;x-amz-date;x-amz-target'

	# Our source image: http://i.imgur.com/OK8aDRq.jpg
	'''with open('img/2019-04-18_030303.jpg', 'rb') as source_image:
		source_bytes = base64.b64encode(source_image.read())

	# Our target image: http://i.imgur.com/Xchqm1r.jpg
	with open('2019-04-17_234321.jpg', 'rb') as target_image:
		target_bytes = base64.b64encode(target_image.read())'''

	# here we build the dictionary for our request data
	# that we will convert to JSON

	p1 = requests.get("https://millercenter.org/sites/default/files/styles/gallery_slider_desktop_2x/public/ig-obama-portrait-800x480.jpg",  stream=True)

	p2 = requests.get("https://news.wttw.com/sites/default/files/field/image/Obama%20cropped_3.jpg",  stream=True)

	#base64.b85encode(image_bytes).decode('utf-8'),
	request_dict = {
		"SimilarityThreshold": 2,
		"SourceImage": {
			#"Bytes": json.dumps(base64.b64encode(p1.content.decode("utf-8"))),
			#"Bytes": base64.b85encode(BytesIO(p1.content).read()).decode('utf-8'),
			#"Bytes": base64.b64encode(BytesIO(p1.content).read()),
			"Bytes": base64.b64encode(p1.raw.read()),
			#"Bytes": source_bytes,
		},
		"TargetImage": {
			#"Bytes": target_bytes,
			#"Bytes": base64.b64encode(BytesIO(p2.content).read()),
			"Bytes": base64.b64encode(p2.raw.read()),
		}
	}
	'''# that we will convert to JSON
	request_dict = {
		'SimilarityThreshold': 75.0,
		'SourceImage': {
			'Bytes': source_bytes
		},
		'TargetImage': {
			'Bytes': target_bytes
		}
	}'''

	# Convert our dict to a JSON string as it will be used as our payload
	request_parameters = json.dumps(request_dict)
	print(request_parameters)

	# Generate a hash of our payload for verification by Rekognition
	payload_hash = hashlib.sha256(request_parameters.encode("utf8")).hexdigest()

	# All of this is
	canonical_request = method + '\n' + canonical_uri + '\n' + canonical_querystring + '\n' + canonical_headers + '\n' + signed_headers + '\n' + payload_hash

	algorithm = 'AWS4-HMAC-SHA256'
	credential_scope = date_stamp + '/' + region + '/' + service + '/' + 'aws4_request'
	string_to_sign = algorithm + '\n' +  amz_date + '\n' +  credential_scope + '\n' +  hashlib.sha256(canonical_request.encode("utf8")).hexdigest()

	signing_key = getSignatureKey(secret_key, date_stamp, region, service)
	signature = hmac.new(signing_key, (string_to_sign).encode('utf-8'), hashlib.sha256).hexdigest()

	authorization_header = algorithm + ' ' + 'Credential=' + access_key + '/' + credential_scope + ', ' +  'SignedHeaders=' + signed_headers + ', ' + 'Signature=' + signature

	headers = { 'Content-Type': content_type,
	            'X-Amz-Date': amz_date,
	            'X-Amz-Target': amz_target,

	            # uncomment this if you uncommented the 'token' line earlier
	            #'X-Amz-Security-Token': token,
	            'Authorization': authorization_header}

	r = requests.post(endpoint, data=request_parameters, headers=headers)

	# Let's format the JSON string returned from the API for better output
	formatted_text = json.dumps(json.loads(r.text), indent=4, sort_keys=True)

	print('Response code: {}\n'.format(r.status_code))
	print('Response body:\n{}'.format(formatted_text))