CODEWITHSUNDEEP
pythongoogle-app-engine
Chad
Chad

Reputation: 2455

Python UnicodeEncodeError using PyCrypto on App Engine

I'm trying to pass an encrypted query string to another URL.

The following code gives me this error:

UnicodeEncodeError: 'ascii' codec can't encode character u'\u04b7' in position 7: ordinal not in range(128)

The encryption module is PyCrypto

Running Python 2.5.2 on App Engine

PAGE A

    import Crypto
    from Crypto.Cipher import ARC4

    obj=ARC4.new('stackoverflow')
    msg = 'This is my secret msg'
    encrypted = obj.encrypt(msg);

    self.redirect('/pageb?' + urllib.urlencode({'q': encrypted}))

PAGE B

    import Crypto
    from Crypto.Cipher import ARC4

    encrypted = self.request.get('q')
    obj=ARC4.new('stackoverflow')
    decrypted = obj.decrypt(encrypted)

    get_data = cgi.parse_qs(decrypted)

    self.response.out.write(decrypted)
    self.response.out.write(pprint.pprint(get_data))

Traceback

Traceback (most recent call last):
  File "C:\Program Files\Google\google_appengine\google\appengine\ext\webapp\_webapp25.py", line 701, in __call__
    handler.get(*groups)
  File "C:\Program Files\Google\google_appengine\demos\guestbook\guestbook.py", line 47, in get
    decrypted = obj.decrypt(encrypted)
UnicodeEncodeError: 'ascii' codec can't encode character u'\u04b7' in position 7: ordinal not in range(128)

Upvotes: 2

Views: 2475

Answers (2)

Alvin K.
Alvin K.

Reputation: 4379

General guidelines: add base64 encoding/decoding step in your encrypted stuff.

import base64

base64_encrypted_message = base64.b64encode(encrypted_message)
// send your message via POST as GET can be seen on system logs

encrypted_message = base64.b64decode(base64_encrypted_message)
// decrypt your message

For the other error, try reading up on unicode & utf-8 encoding of non-ascii characters. You need this step before passing it to your de/encrypt function.

Upvotes: 6

John Machin
John Machin

Reputation: 83032

All that can be deduced from the information available is that something is expecting a bytestring but you have fed it a unicode object containing the Unicode character U+04B7 CYRILLIC SMALL LETTER CHE WITH DESCENDER ... this is of course not encodable in ASCII (the default encoding), hence the error message.

Best possible answer so far: Don't do that.

Update 1: You still haven't asked a question. Nonetheless:

So "something" is some crypto gadget's decrypt method. That surely needs a str object. What does print repr(encrypted) tell you? If it looks like random rubbish (as encrypted stuff should), then somehow it has been converted from a str object to a unicode object. You need to back-track to see how this is happening. If encrypted looks like meaningful text, then your encryption process is broken.

Step 1: Start with some known plaintext, encrypt it, and decrypt it again in a simple script outside the GAE apparatus. Use print repr() at each stage so that you have reasonable expectations for the next step.

Step 2: Repeat step 1 using GAE, inspecting the type and contents of each piece of data.

Update 2 It appears that you have a urlencode in page A, but no corresponding urldecode in page B; is this (part of) the problem?

Upvotes: 1

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