@@ -14,6 +14,7 @@ import rfc822

 import hmac

 import base64

 import errno

+import urllib

 from logging import debug, info, warning, error

@@ -343,12 +344,73 @@ def replace_nonprintables(string):

 __all__.append("replace_nonprintables")

 def sign_string(string_to_sign):

-    #debug("string_to_sign: %s" % string_to_sign)

+    """Sign a string with the secret key, returning base64 encoded results.

+    By default the configured secret key is used, but may be overridden as

+    an argument.

+

+    Useful for REST authentication. See http://s3.amazonaws.com/doc/s3-developer-guide/RESTAuthentication.html

+    """

     signature = base64.encodestring(hmac.new(Config.Config().secret_key, string_to_sign, sha1).digest()).strip()

-    #debug("signature: %s" % signature)

     return signature

 __all__.append("sign_string")

+def sign_url(url_to_sign, expiry):

+    """Sign a URL in s3://bucket/object form with the given expiry

+    time. The object will be accessible via the signed URL until the

+    AWS key and secret are revoked or the expiry time is reached, even

+    if the object is otherwise private.

+

+    See: http://s3.amazonaws.com/doc/s3-developer-guide/RESTAuthentication.html

+    """

+    return sign_url_base(

+        bucket = url_to_sign.bucket(),

+        object = url_to_sign.object(),

+        expiry = expiry

+    )

+__all__.append("sign_url")

+

+def sign_url_base(**parms):

+    """Shared implementation of sign_url methods. Takes a hash of 'bucket', 'object' and 'expiry' as args."""

+    parms['expiry']=time_to_epoch(parms['expiry'])

+    parms['access_key']=Config.Config().access_key

+    debug("Expiry interpreted as epoch time %s", parms['expiry'])

+    signtext = 'GET\n\n\n%(expiry)d\n/%(bucket)s/%(object)s' % parms

+    debug("Signing plaintext: %r", signtext)

+    parms['sig'] = urllib.quote_plus(sign_string(signtext))

+    debug("Urlencoded signature: %s", parms['sig'])

+    return "http://%(bucket)s.s3.amazonaws.com/%(object)s?AWSAccessKeyId=%(access_key)s&Expires=%(expiry)d&Signature=%(sig)s" % parms

+

+def time_to_epoch(t):

+    """Convert time specified in a variety of forms into UNIX epoch time.

+    Accepts datetime.datetime, int, anything that has a strftime() method, and standard time 9-tuples

+    """

+    if isinstance(t, int):

+        # Already an int

+        return t

+    elif isinstance(t, tuple) or isinstance(t, time.struct_time):

+        # Assume it's a time 9-tuple

+        return int(time.mktime(t))

+    elif hasattr(t, 'timetuple'):

+        # Looks like a datetime object or compatible

+        return int(time.mktime(ex.timetuple()))

+    elif hasattr(t, 'strftime'):

+        # Looks like the object supports standard srftime()

+        return int(t.strftime('%s'))

+    elif isinstance(t, str) or isinstance(t, unicode):

+        # See if it's a string representation of an epoch

+        try:

+            return int(t)

+        except ValueError:

+            # Try to parse it as a timestamp string

+            try:

+                return time.strptime(t)

+            except ValueError as ex:

+                # Will fall through

+                debug("Failed to parse date with strptime: %s", ex)

+                pass

+    raise Exceptions.ParameterError('Unable to convert %r to an epoch time. Pass an epoch time. Try `date -d \'now + 1 year\' +%%s` (shell) or time.mktime (Python).' % t)

+

+

 def check_bucket_name(bucket, dns_strict = True):

     if dns_strict:

         invalid = re.search("([^a-z0-9\.-])", bucket)

@@ -25,6 +25,7 @@ import htmlentitydefs

 import socket

 import shutil

 import tempfile

+import S3.Exceptions

 from copy import copy

 from optparse import OptionParser, Option, OptionValueError, IndentedHelpFormatter

@@ -1224,6 +1225,15 @@ def cmd_sign(args):

     signature = Utils.sign_string(string_to_sign)

     output("Signature: %s" % signature)

+def cmd_signurl(args):

+	expiry = args.pop()

+	url_to_sign = S3Uri(args.pop())

+	if url_to_sign.type != 's3':

+		raise ParameterError("Must be S3Uri. Got: %s" % url_to_sign)

+	debug("url to sign: %r" % url_to_sign)

+	signed_url = Utils.sign_url(url_to_sign, expiry)

+	output(signed_url)

+

 def cmd_fixbucket(args):

     def _unescape(text):

         ##

@@ -1541,6 +1551,7 @@ def get_commands_list():

     {"cmd":"setpolicy", "label":"Set an access policy for a bucket", "param":"s3://BUCKET POLICY_STRING", "func":cmd_setpolicy, "argc":2},

     {"cmd":"accesslog", "label":"Enable/disable bucket access logging", "param":"s3://BUCKET", "func":cmd_accesslog, "argc":1},

     {"cmd":"sign", "label":"Sign arbitrary string using the secret key", "param":"STRING-TO-SIGN", "func":cmd_sign, "argc":1},

+    {"cmd":"signurl", "label":"Sign an S3 URL to provide limited public access with expiry", "param":"s3://BUCKET/OBJECT expiry_epoch", "func":cmd_signurl, "argc":2},

     {"cmd":"fixbucket", "label":"Fix invalid file names in a bucket", "param":"s3://BUCKET[/PREFIX]", "func":cmd_fixbucket, "argc":1},

     ## Website commands

@@ -63,6 +63,23 @@ Enable/disable bucket access logging

 s3cmd \fBsign\fR \fISTRING-TO-SIGN\fR

 Sign arbitrary string using the secret key

 .TP

+s3cmd \fBsignurl\fR \fIs3://BUCKET[/OBJECT]\fR \fIexpiry-in-epoch-seconds\fR

+Sign an S3 URL with the secret key, producing a URL that allows access to

+the named object using the credentials used to sign the URL until the date of

+expiry specified in epoch-seconds has passed. This is most useful for publishing

+time- or distribution-limited URLs to otherwise-private S3 objects.

+.br

+This is a purely offline operation. Your API key and secret are not sent on

+the wire, though your public API key is included in the generated URL. Because

+it's offline, no validation is done to ensure that the bucket and object actually

+exist, or that this API key has permission to access them.

+.br

+The URL generated is http:// but you can simply change to https:// if you want.

+.br

+See

+.B http://s3.amazonaws.com/doc/s3-developer-guide/RESTAuthentication.html

+for more information on signed URLs, and the examples section below.

+.TP

 s3cmd \fBfixbucket\fR \fIs3://BUCKET[/PREFIX]\fR

 Fix invalid file names in a bucket

@@ -427,6 +444,12 @@ about matching file names against exclude and include rules.

 For example to exclude all files with ".jpg" extension except those beginning with a number use:

 .PP

 	\-\-exclude '*.jpg' \-\-rinclude '[0-9].*\.jpg'

+.PP

+To produce a signed HTTP URL that allows access to the normally private s3 object

+s3://mybucket/someobj (which you must have permission to access) to anybody

+with the URL for one week from today, use:

+.PP

+        s3cmd signurl s3://mybucket/someobj `date -d 'today + 1 week' +%s` 

 .SH SEE ALSO

 For the most up to date list of options run 

 .B s3cmd \-\-help