I just tried this, and it works as expected. Thanks for this useful piece
of code Niphlod.
Just a bunch of 'gotchas', which I thought might help someone else trying
this code:
- I had existing data in the table, which was in plain text format. When
I introduced this code I encountered errors like "..Incorrect padding...".
Went ahead and commented out the filter* assignments, exported the plain
text data. Un-commented the filter* assignments, and imported the data.
- My data has long / integer / numeric fields, and I noticed errors in
the pad() method. Works well for non-numeric fields - primarily string
fields.
- Also removed NULL/None values from the dataset.
On Wednesday, June 26, 2013 12:12:29 AM UTC+5:30, Niphlod wrote:
>
> sorry, cut&paste error.
>
>
>
> import gluon.contrib.aes as AES
> import threading
> import os
> import base64
>
> def fast_urandom16(urandom=[], locker=threading.RLock()):
> """
> this is 4x faster than calling os.urandom(16) and prevents
> the "too many files open" issue with concurrent access to os.urandom()
> """
> try:
> return urandom.pop()
> except IndexError:
> try:
> locker.acquire()
> ur = os.urandom(16 * 1024)
> urandom += [ur[i:i + 16] for i in xrange(16, 1024 * 16, 16)]
> return ur[0:16]
> finally:
> locker.release()
>
> def pad(s, n=32, padchar=' '):
> return s + (32 - len(s) % 32) * padchar
>
> def AES_new(key, IV=None):
> """ Returns an AES cipher object and random IV if None specified """
> if IV is None:
> IV = fast_urandom16()
>
> return AES.new(key, AES.MODE_CBC, IV), IV
>
> def w2p_encrypt(data):
> key = 'asdsaddasdasdas'
> key = pad(key[:32])
> cipher, IV = AES_new(key)
> encrypted_data = IV + cipher.encrypt(pad(data))
> return base64.urlsafe_b64encode(encrypted_data)
>
> def w2p_decrypt(data):
> key = 'asdsaddasdasdas'
> key = pad(key[:32])
> data = base64.urlsafe_b64decode(data)
> IV, data = data[:16], data[16:]
> cipher, _ = AES_new(key, IV=IV)
> data = cipher.decrypt(data)
> data = data.rstrip(' ')
> return data
>
> db.define_table('t_test',
> Field('f_field')
> )
>
> db.t_test.f_field.filter_in = lambda value : w2p_encrypt(value)
> db.t_test.f_field.filter_out = lambda value : w2p_decrypt(value)
>
>
>
--
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