问题
Ok I am trying to write a basic converter of a string to md5 hash code but when I run my program I keep getting an error that say's:
Traceback (most recent call last):
File "C:\Users\Shane\Documents\Amer CISC\lab4.py", line 30, in <module>
assertEqual (computeMD5hash("The quick brown fox jumps over the lazy dog"),("9e107d9d372bb6826bd81d3542a419d6"))
File "C:\Users\Shane\Documents\Amer CISC\lab4.py", line 27, in computeMD5hash
m.update(string)
TypeError: Unicode-objects must be encoded before hashing
My code looks like this:
def computeMD5hash(string):
import hashlib
from hashlib import md5
m = hashlib.md5()
m.update((string))
md5string=m.digest()
return md5string
回答1:
As the error suggests, your string must be unicode and you have to encode it. Looking at the call you make (from your stack trace):
computeMD5hash("The quick brown fox jumps over the lazy dog")
it looks like you must be running Python 3 where strings are unicode objects. To encode to a byte representation which can then be processed by the hashlib, change this
m.update((string))
to this (if utf-8 is an appropriate encoding for you to use - it depends how you will be using this):
m.update(string.encode('utf-8'))
If this is all news to you, you should probably read the excellent Python 3 Unicode HOWTO.
Also, while I'm here, your code has some other issues
- some unecessary bits - no need for the
from hashlib importline or the temporarymd5string. - it's bad form to import modules from within a function, so
import hashlibshould be moved to module scope. - the function is returning the digest() which is raw binary, and from your stack trace it looks like you're expecting the hexdigest() instead which is the same thing represented as a hexadecimal string.
To fix and tidy it all up, try this:
import hashlib
def computeMD5hash(my_string):
m = hashlib.md5()
m.update(my_string.encode('utf-8'))
return m.hexdigest()
回答2:
Rather than trying to hash the string, you should hash an encoded byte sequence. Instead of
>>> import hashlib
>>> hashlib.md5("fred")
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: Unicode-objects must be encoded before hashing
you should encode it, e.g.:
>>> "fred".encode("utf")
b'fred'
>>> hashlib.md5("fred".encode("utf")).hexdigest()
'570a90bfbf8c7eab5dc5d4e26832d5b1'
In Python 2 you could get away without doing this, and it led to no end of unnoticed bugs. Fortunately Python 3 has much saner unicode support, and distinguishes between bytes and strings.
回答3:
Seems you have to encode the string before hashing:
http://www.dreamincode.net/forums/topic/246026-generating-string-hash-issue/
回答4:
#!/usr/bin/env python
# coding=utf-8
import sys, os, stat
import pygtk, gtk
import zbarpygtk
import pycurl
from time import strftime, localtime
import pango
class qrdat:
def __init__(self):
""" VARIABLES DE CONFIGURACION """
# Prefijo para el nombre de los archivos de registros
prefijo = 'Registro'
# Lugar de almacenamiento de archivos de registros
# Por defecto se guarda en la carpeta personal del usuario
directorio = os.getenv('HOME')
# Descomentar la siguiente linea y digitar la ruta de la carpeta
# donde se guardaran los archivos
#directorio = '/home/olpc/Escritorio'
# Modo de reproduccion de sonido:
# 1 : sonido enviado directamente a la tarjeta de sonido
# 2 : sonido de alerta del sistema
self.beep_mode = 1
# No modificar abajo
self.open_file = None
self.video_device = '/dev/video0'
self.fecha = strftime("%Y-%m-%d",localtime())
self.filename = directorio+'/'+prefijo+'-'+self.fecha+'.csv'
if len(sys.argv) > 1:
self.video_device = sys.argv[1]
def decoded(self, zbar, data):
"""funcion invocada cuando un codigo es decodificado por el
control zbar.
"""
datos = data.split(':')
qrdata = datos[1]
# guardar datos
self.save(qrdata)
# sonido de recepcion
self.beep(self.beep_mode)
# mostrar datos
buf = self.results.props.buffer
end = buf.get_end_iter()
buf.insert(end, self.hora()+' - '+qrdata+"\n")
self.results.scroll_to_iter(end, 0)
def show(self):
"""Funcion que crea muestra la ventana principal """
# threads *must* be properly initialized to use zbarpygtk
gtk.gdk.threads_init()
gtk.gdk.threads_enter()
window = gtk.Window()
window.set_title("Control de Asistencia QR")
window.set_border_width(8)
window.connect("destroy", gtk.main_quit)
# zbar
self.zbar = zbarpygtk.Gtk()
self.zbar.connect("decoded-text", self.decoded)
self.video_device = '/dev/video0'
self.zbar.connect("notify::video-enabled", self.video_enabled)
self.zbar.connect("notify::video-opened", self.video_opened)
self.zbar.set_video_device(self.video_device)
# combine combo box and buttons horizontally
hbox = gtk.HBox(spacing=8)
# text box for holding results
self.results = gtk.TextView()
self.results.set_size_request(320, 128)
self.results.props.editable = self.results.props.cursor_visible = False
self.results.modify_font(pango.FontDescription("monospace 12"))
self.results.set_left_margin(4)
# combine inputs, scanner, and results vertically
vbox = gtk.VBox(spacing=8)
vbox.pack_start(hbox, expand=False)
vbox.pack_start(self.zbar)
vbox.pack_start(self.results, expand=False)
window.add(vbox)
window.set_geometry_hints(self.zbar, min_width=320, min_height=240)
window.show_all()
def run(self):
"""Funcion que inicia el funcionamiento de la ventana"""
gtk.main()
gtk.gdk.threads_leave()
def save(self,data):
""" Funcion que guarda el archivo de registro """
f = open(self.filename,'a')
f.write(self.fecha+','+self.hora()+','+data+'\n')
f.close()
def hora(self):
""" Funcion que obtiene la hora local """
return strftime("%H:%M:%S",localtime())
def beep(self, beep_mode):
if os.access('/dev/audio', os.W_OK ) and beep_mode == 1:
""" Genera un sonido enviado a la tarjeta de sonido"""
frequency = 100
amplitude = 200
duration = 2
sample = 8000
half_period = int(sample/frequency/2)
beep = chr(amplitude)*half_period+chr(0)*half_period
beep *= int(duration*frequency)
audio = file('/dev/audio', 'wb')
audio.write(beep)
audio.close()
else:
""" Reproduce sonido del propio sistema """
f=open('/dev/tty','w')
f.write(chr(7))
f.close()
def video_enabled(self, zbar, param):
"""callback invoked when the zbar widget enables or disables
video streaming. updates the status button state to reflect the
current video state
"""
enabled = zbar.get_video_enabled()
def video_opened(self, zbar, param):
"""callback invoked when the zbar widget opens or closes a video
device. also called when a device is closed due to error.
updates the status button state to reflect the current video state
"""
opened = zbar.get_video_opened()
def video_changed(self, widget):
"""callback invoked when a new video device is selected from the
drop-down list. sets the new device for the zbar widget,
which will eventually cause it to be opened and enabled
"""
dev = self.video_list.get_active_text()
if dev[0] == '<':
dev = ''
self.zbar.set_video_device(dev)
if __name__ == "__main__":
qr = qrdat()
qr.show()
qr.run()
来源：https://stackoverflow.com/questions/13259691/convert-string-to-md5