diff --git a/branches/ucs-3.1/ucs/management/univention-directory-manager-modules/modules/univention/admin/handlers/users/user.py b/branches/ucs-3.1/ucs/management/univention-directory-manager-modules/modules/univention/admin/handlers/users/user.py
index 5ff0b4f..7eee99b 100644
--- a/branches/ucs-3.1/ucs/management/univention-directory-manager-modules/modules/univention/admin/handlers/users/user.py
+++ b/branches/ucs-3.1/ucs/management/univention-directory-manager-modules/modules/univention/admin/handlers/users/user.py
@@ -1008,77 +1008,28 @@ def sambaWorkstationsUnmap(workstations):
 	return string.split(workstations[0],',')
 
 def logonHoursMap(logontimes):
-	"converts the bitfield 001110010110...100 to the respective string"
-
-	# convert list of bit numbers to bit-string
-	# bitstring = '0' * 168
-	bitstring = ''.join( map( lambda x: x in logontimes and '1' or '0', range( 168 ) ) )
-
-	# for idx in logontimes:
-	# 	bitstring[ idx ] = '1'
-
-	logontimes = bitstring
-
+	"""Converts array of bits set to an hex-string."""
+	octets = [0] * (24 * 7 / 8)
 	# the order of the bits of each byte has to be reversed. The reason for this is that
-	# consecutive bytes mean consecutive 8-hrs-intervals, but the leftmost bit stands for
-	# the last hour in that interval, the 2nd but leftmost bit for the second-but-last
+	# consecutive bytes mean consecutive 8-hrs-intervals, but the MSB stands for
+	# the last hour in that interval, the 2nd leftmost bit for the second-to-last
 	# hour and so on. We want to hide this from anybody using this feature.
-	# See http://ma.ph-freiburg.de/tng/tng-technical/2003-04/msg00015.html for details.
-
-	newtimes = ""
-	for i in range(0,21):
-		bitlist=list(logontimes[(i*8):(i*8)+8])
-		bitlist.reverse()
-		newtimes+="".join(bitlist)
-	logontimes = newtimes
-
-	# create a hexnumber from each 8-bit-segment
-	ret=""
-	for i in range(0,21):
-	        val=0
-	        exp=7
-	        for j in range((i*8), (i*8)+8):
-	                if not (logontimes[j]=="0"):
-	                        val+=2**exp
-	                exp-=1
-		# we now have: 0<=val<=255
-	        hx=hex(val)[2:4]
-	        if len(hx)==1: hx="0"+hx
-	        ret+=hx
-
-	return ret
+	# See <http://ma.ph-freiburg.de/tng/tng-technical/2003-04/msg00015.html> for details.
+	for hour in logontimes:
+		idx, bit = divmod(hour, 8)
+		octets[idx] |= 1 << bit
+	return ''.join(['%02x' % _ for _ in octets])
 
 def logonHoursUnmap(logontimes):
-	"converts the string to a bit array"
-
-	times=logontimes[0][:42]
-	while len(times)<42:
-		times=times
-        ret=""
-        for i in range(0,42,2):
-                val=int(times[i:i+2],16)
-                ret+=intToBinary(val)
-
-	# reverse order of the bits in each byte. See above for details
-	newtime = ""
-	for i in range(0, 21):
-		bitlist=list(ret[(i*8):(i*8)+8])
-		bitlist.reverse()
-		newtime+="".join(bitlist)
-
-	# convert bit-string to list
-	return filter( lambda i: newtime[ i ] == '1', range( 168 ) )
-
-def intToBinary(val):
-        ret=""
-        while val>0:
-                ret=str(val&1)+ret
-                val=val>>1
-        # pad with leading 0s until length is n*8
-        if ret=="": ret="0"
-        while not (len(ret)%8==0):
-                ret="0"+ret
-        return ret
+	"""Converts hex-string to an array of bits set."""
+	times = logontimes[0].ljust(42, '0')[:42]
+	assert len(times) == 24 * 7 / 4
+	octets = [int(times[i : i + 2], 16) for i in range(0, len(times), 2)]
+	assert len(octets) == 24 * 7 / 8
+	return [idx * 8 + bit
+			for (idx, value) in enumerate(octets)
+			for bit in range(8)
+			if value & (1 << bit)]
 
 def GMTOffset():
 	# returns the difference in hours between local time and GMT (is -1 for CET and CEST)