blockchaincom_decrypt.py

import hashlib, json, os, sys

# requires packages requests and pycryptodome
# run with
#     python blockchaincom_decrypt.py [GUID] password

import requests
from Crypto.Cipher import AES

guid = sys.argv[1]
password = sys.argv[2]

cachename = guid + ".json"
if not os.path.isfile(cachename):
    res = requests.get("https://blockchain.info/wallet/%s?api_code=1770d5d9-bcea-4d28-ad21-6cbd5be018a8&format=json" % guid)
    res.raise_for_status()
    open(cachename, "wb").write(res.content)
    
content = open(cachename, "rb").read()
j = json.loads(content)

j = json.loads(j["payload"])
if j["version"] != 3:
    raise Exception("Unsupported version %d" % j["version"])
    
pbkdf2_iterations = j["pbkdf2_iterations"]
payload = j["payload"].decode("base64")

key = hashlib.pbkdf2_hmac("sha1", password, payload[0:16], iterations=pbkdf2_iterations, dklen=256 / 8)

res = AES.new(key, AES.MODE_CBC, payload[0:16]).decrypt(payload[16:])
pad = ord(res[-1])
res = res[:-pad]

j = json.loads(res)

print json.dumps(j, indent=4)