diff --git a/pisi/api.py b/pisi/api.py
index aba70acf..2bc7c511 100644
--- a/pisi/api.py
+++ b/pisi/api.py
@@ -301,7 +301,7 @@ def index(dirs, output = 'pisi-index.xml', skip_sources=False):
         repo_dir = str(repo_dir)
         ctx.ui.info(_('* Building index of PISI files under %s') % repo_dir)
         index.index(repo_dir, skip_sources)
-    index.write(output, sha1sum=True, compress=File.xmill)
+    index.write(output, sha1sum=True, compress=File.xmill, sign=File.detached)
     ctx.ui.info(_('* Index file written'))
 
 def add_repo(name, indexuri):
@@ -321,15 +321,22 @@ def update_repo(repo, force=False):
     ctx.ui.info(_('* Updating repository: %s') % repo)
     index = Index()
     if ctx.repodb.has_repo(repo):
+        repouri = ctx.repodb.get_repo(repo).indexuri.get_uri()
         try:
-            index.read_uri(ctx.repodb.get_repo(repo).indexuri.get_uri(), repo)
-            ctx.txn_proc(lambda txn : index.update_db(repo, txn=txn))
-            ctx.ui.info(_('* Package database updated.'))
+            index.read_uri(repouri, repo)
         except pisi.file.AlreadyHaveException, e:
             ctx.ui.info(_('No updates available for repository %s.' % repo))
             if force:
                 ctx.ui.info(_('Updating database at any rate as requested'))
-                raise Error(_('OPTION NOT IMPLEMENTED YET'))
+                index.read_uri(repouri, repo, force = force)
+            else:
+                return
+        try:
+            index.check_signature(repouri, repo)
+        except pisi.file.NoSignatureFound, e:
+            ctx.ui.warning(e)
+        ctx.txn_proc(lambda txn : index.update_db(repo, txn=txn))
+        ctx.ui.info(_('* Package database updated.'))            
     else:
         raise Error(_('No repository named %s found.') % repo)
 
diff --git a/pisi/cli/__init__.py b/pisi/cli/__init__.py
index dabf83cc..021547d4 100644
--- a/pisi/cli/__init__.py
+++ b/pisi/cli/__init__.py
@@ -73,12 +73,14 @@ class CLI(UI):
         self.output( unicode(msg) + msgend, verbose=verbose)
 
     def warning(self, msg, verbose = False):
+        msg = unicode(msg)
         if ctx.get_option('no_color'):
             self.output(_('Warning: ') + msg + '\n', err=True, verbose=verbose)
         else:
             self.output(colorize(msg + '\n', 'purple'), err=True, verbose=verbose)
 
     def error(self, msg):
+        msg = unicode(msg)
         if ctx.get_option('no_color'):
             self.output(_('Error: ') + msg + '\n', err=True)
         else:
@@ -86,6 +88,7 @@ class CLI(UI):
 
     def action(self, msg, verbose = False):
         #TODO: this seems quite redundant?
+        msg = unicode(msg)
         self.output(colorize(msg + '\n', 'green'))
 
     def choose(self, msg, opts):
@@ -102,6 +105,7 @@ class CLI(UI):
                 pass
         
     def confirm(self, msg):
+        msg = unicode(msg)
         if ctx.config.options and ctx.config.options.yes_all:
             return True
         while True:
@@ -124,6 +128,7 @@ class CLI(UI):
 
     def status(self, msg = None):
         if msg:
+            msg = unicode(msg)
             self.output(colorize(msg + '\n', 'purple'))
             util.xterm_title(msg)
 
diff --git a/pisi/file.py b/pisi/file.py
index 0f600da1..0c67f13f 100644
--- a/pisi/file.py
+++ b/pisi/file.py
@@ -18,7 +18,7 @@ we are just encapsulating a common pattern in our program, nothing big.
 like all pisi classes, it has been programmed in a non-restricting way
 """
 
-import os.path
+import os, os.path
 import types
 
 import gettext
@@ -37,14 +37,26 @@ class AlreadyHaveException(pisi.Exception):
         self.url = url 
         self.localfile = localfile
 
+class NoSignatureFound(pisi.Exception):
+    def __init__(self, url):
+        pisi.Exception.__init__(self, "No signature found for %s" % url)
+        self.url = url
+        
 class Error(pisi.Error):
     pass
 
+class InvalidSignature(pisi.Error):
+    def __init__(self, url):
+        pisi.Exception.__init__(self, " invalid for %s" % url)
+        self.url = url
+
 class File:
 
     (read, write) = range(2) # modes
     (xmill, sevenzip) = range(2) # compress enums
 
+    (detached, whatelse) = range(2)
+
     @staticmethod
     def make_uri(uri):
         "handle URI arg"
@@ -70,6 +82,7 @@ class File:
                  sha1sum = False, compress = None, sign = None):
 
         assert type(uri == URI)
+
         if sha1sum:
             sha1filename = File.download(URI(uri.get_uri() + '.sha1sum'), transfer_dir)
             sha1f = file(sha1filename)
@@ -106,8 +119,13 @@ class File:
     def __init__(self, uri, mode, transfer_dir = "/tmp", 
                  sha1sum = False, compress = None, sign = None):
         "it is pointless to open a file without a URI and a mode"
+
+        self.transfer_dir = transfer_dir
         self.sha1sum = sha1sum
         self.compress = compress
+        self.sign = sign
+        
+
         uri = File.make_uri(uri)
         if mode==File.read or mode==File.write:
             self.mode = mode
@@ -137,18 +155,31 @@ class File:
     def close(self, delete_transfer = False):
         "this method must be called at the end of operation"
         self.__file__.close()
-        if self.compress == File.xmill:
-            pisi.util.run_batch('xcmill -9 -f ' + self.localfile)
-            self.localfile = self.localfile[:-4] + '.xmi'
-        elif self.compress == File.sevenzip:
-            raise Error(_("sevenzip compression not supported yet"))
         if self.mode == File.write:
+            if self.compress == File.xmill:
+                pisi.util.run_batch('xcmill -9 -f ' + self.localfile)
+                self.localfile = self.localfile[:-4] + '.xmi'
+            elif self.compress == File.sevenzip:
+                raise Error(_("sevenzip compression not supported yet"))
             if self.sha1sum:
                 sha1 = pisi.util.sha1_file(self.localfile)
                 cs = file(self.localfile + '.sha1sum', 'w')
                 cs.write(sha1)
                 cs.close()
-    
+            if self.sign==File.detached:
+                pisi.util.run_batch('gpg --detach-sig ' + self.localfile)
+                
+    @staticmethod
+    def check_signature(uri, transfer_dir, sign=detached):
+        if sign==File.detached:
+            try:
+                sigfilename = File.download(URI(uri + '.sig'), transfer_dir)
+            except:
+                raise NoSignatureFound(uri)
+            if os.system('gpg --verify ' + sigfilename) != 0:
+                raise InvalidSignature(uri)
+            # everything is all right here
+                
     def flush(self):
         self.__file__.flush()
 
diff --git a/pisi/index.py b/pisi/index.py
index dc920b3f..62f2a848 100644
--- a/pisi/index.py
+++ b/pisi/index.py
@@ -50,10 +50,16 @@ class Index(XmlFile):
     t_Packages = [ [metadata.Package], autoxml.optional, "Package"]
     t_Components = [ [component.Component], autoxml.optional, "Component"]
 
-    def read_uri(self, filename, repo = None):
+    # read index for a given repo, force means download even if remote not updated
+    def read_uri(self, filename, repo = None, force = False):
         """Read PSPEC file"""
         tmpdir = os.path.join(ctx.config.index_dir(), repo)
-        self.read(filename, tmpDir=tmpdir, sha1sum=True, compress=File.xmill)
+        self.read(filename, tmpDir=tmpdir, sha1sum=not force, 
+                  compress=File.xmill, sign=File.detached)
+                  
+    def check_signature(self, filename, repo):
+        tmpdir = os.path.join(ctx.config.index_dir(), repo)
+        File.check_signature(filename, tmpdir)
 
     def index(self, repo_uri, skip_sources=False):
         self.repo_dir = repo_uri
diff --git a/pisi/pxml/autoxml.py b/pisi/pxml/autoxml.py
index 08f9a40a..9a603e63 100644
--- a/pisi/pxml/autoxml.py
+++ b/pisi/pxml/autoxml.py
@@ -429,9 +429,9 @@ class autoxml(oo.autosuper, oo.autoprop):
             
         if xmlfile_support:
             def read(self, uri, keepDoc = False, tmpDir = '/tmp',
-                     sha1sum = False, compress = None):
+                     sha1sum = False, compress = None, sign = None):
                 "read XML file and decode it into a python object"
-                self.readxml(uri, tmpDir, sha1sum=sha1sum, compress=compress)
+                self.readxml(uri, tmpDir, sha1sum=sha1sum, compress=compress, sign=sign)
                 errs = []
                 self.decode(self.rootNode(), errs)
                 if hasattr(self, 'read_hook'):
@@ -449,7 +449,7 @@ class autoxml(oo.autosuper, oo.autoprop):
                     raise Error(*errs)
                     
             def write(self, uri, keepDoc = False, tmpDir = '/tmp',
-                      sha1sum = False, compress = None):
+                      sha1sum = False, compress = None, sign = None):
                 "encode the contents of the python object into an XML file"
                 errs = self.errors()
                 if errs:
@@ -463,7 +463,7 @@ class autoxml(oo.autosuper, oo.autoprop):
                 if errs:
                     errs.append(_("autoxml.write: File encoding '%s' has errors") % uri)
                     raise Error(*errs)
-                self.writexml(uri, tmpDir, sha1sum=sha1sum, compress=compress)
+                self.writexml(uri, tmpDir, sha1sum=sha1sum, compress=compress, sign=sign)
                 if not keepDoc:
                     self.unlink() # get rid of the tree
             
diff --git a/pisi/pxml/xmlfilecdom.py b/pisi/pxml/xmlfilecdom.py
index bbf78256..eceabd85 100644
--- a/pisi/pxml/xmlfilecdom.py
+++ b/pisi/pxml/xmlfilecdom.py
@@ -67,9 +67,9 @@ class XmlFile(object):
         """returns root document element"""
         return self.doc.documentElement
 
-    def readxml(self, uri, tmpDir='/tmp', sha1sum=False, compress=None):
+    def readxml(self, uri, tmpDir='/tmp', sha1sum=False, compress=None, sign=None):
         uri = File.make_uri(uri)
-        localpath = File.download(uri, tmpDir,sha1sum=sha1sum,compress=compress)
+        localpath = File.download(uri, tmpDir,sha1sum=sha1sum,compress=compress,sign=sign)
         try:
             self.doc = NoExtDtdReader.parseUri(Ft.Lib.Uri.OsPathToUri(localpath))
             return self.doc.documentElement
@@ -78,8 +78,8 @@ class XmlFile(object):
         except exceptions.ValueError, e:
             raise Error(_("File '%s' not found") % localpath )
 
-    def writexml(self, uri, tmpDir = '/tmp', sha1sum=False, compress=None):
-        f = File(uri, File.write, sha1sum=sha1sum, compress=compress)
+    def writexml(self, uri, tmpDir = '/tmp', sha1sum=False, compress=None, sign=None):
+        f = File(uri, File.write, sha1sum=sha1sum, compress=compress, sign=sign)
         PrettyPrint(self.rootNode(), stream = f)
         f.close()