[or-cvs] r12007: Apply changes to rend-spec.txt from Karsten's proposal-114 w (in tor/trunk: . doc/spec)
nickm at seul.org
nickm at seul.org
Wed Oct 17 21:47:28 UTC 2007
Author: nickm
Date: 2007-10-17 17:47:28 -0400 (Wed, 17 Oct 2007)
New Revision: 12007
Modified:
tor/trunk/
tor/trunk/doc/spec/rend-spec.txt
Log:
r15891 at catbus: nickm | 2007-10-17 17:46:40 -0400
Apply changes to rend-spec.txt from Karsten's proposal-114 work. Points that need to be clarified are marked with a [XXXX].
Property changes on: tor/trunk
___________________________________________________________________
svk:merge ticket from /tor/trunk [r15891] on 8246c3cf-6607-4228-993b-4d95d33730f1
Modified: tor/trunk/doc/spec/rend-spec.txt
===================================================================
--- tor/trunk/doc/spec/rend-spec.txt 2007-10-17 21:26:29 UTC (rev 12006)
+++ tor/trunk/doc/spec/rend-spec.txt 2007-10-17 21:47:28 UTC (rev 12007)
@@ -146,6 +146,168 @@
to do that if he previously advertised some introduction points,
and now he doesn't have any. -RD]
+ The format of a "V2" descriptor, that will probably used at some time in
+ the future, is as follows:
+
+ "rendezvous-service-descriptor" descriptor-id NL
+
+ [At start, exactly once]
+
+ Indicates the beginning of the descriptor. "descriptor-id" is a
+ temporary identifier of 160 bits formatted as 32 base32 chars that
+ can only be calculated by the hidden service and its clients,
+ i.e. by everyone who is aware of a "secret-cookie". (Further,
+ everyone can verify that this "descriptor-id" belongs to the rest
+ of the descriptor, even without knowing "secret-cookie", as
+ described below.) The "descriptor-id" is calculated by performing
+ the following operation:
+
+ descriptor-id =
+ H(permanent-id | H(time-period | secret-cookie | replica))
+
+ "permanent-id" is the permanent identifier of the hidden service,
+ consisting of 80 bits. It can be calculated by computing the hash value
+ of the public hidden service key and truncating after the first 80 bits:
+
+ permanent-id = H(public-key)[:10]
+
+ "h(time-period, cookie, replica)" is the secret id part that is
+ necessary to verify that the hidden service is the true originator
+ of this descriptor. It can only be created by the hidden service
+ and its clients, but the "signature" below can only be created by
+ the service.
+
+ "cookie" is a secret password of 120 bits that is shared between the
+ hidden service provider and its clients.
+ [XXXX Why 120? -NM]
+
+ "replica" denotes the number of the non-consecutive replica.
+ [XXXX What does this mean? -NM]
+
+ The "time-period" changes periodically depending on the global time and
+ as a function of "permanent-id". The current value for "time-period" can
+ be calculated using the following formula:
+
+ time-period = (current-time + permanent-id-byte * 86400 / 256)
+ / 86400
+
+ "current-time" contains the current system time in seconds since
+ 1970-01-01 00:00, e.g. 1188241957. "permanent-id-byte" is the first
+ (unsigned) byte of the permanent identifier (which is in network
+ order), e.g. 143. Adding the product of "permanent-id-byte" and
+ 86400 (seconds per day), divided by 256, prevents "time-period" from
+ changing for all descriptors at the same time of the day. The result
+ of the overall operation is a (network-ordered) 32-bit integer, e.g.
+ 13753 or 0x000035B9 with the example values given above.
+
+ "version" version-number NL
+
+ [Exactly once]
+
+ The version number of this descriptor's format. In this case: 2.
+
+ "permanent-key" NL a public key in PEM format
+
+ [Exactly once]
+
+ The public key of the hidden service which is required to verify the
+ "descriptor-id" and the "signature".
+
+ "secret-id-part" secret-id-part NL
+
+ [Exactly once]
+
+ The result of the following operation as explained above, formatted as
+ 32 base32 chars. Using this secret id part, everyone can verify that
+ the signed descriptor belongs to "descriptor-id".
+
+ secret-id-part = H(time-period | cookie | replica)
+
+ "publication-time" YYYY-MM-DD HH:MM:SS NL
+
+ [Exactly once]
+
+ A timestamp when this descriptor has been created.
+
+ "protocol-versions" version-string NL
+
+ [Exactly once]
+
+ A bitmask of allowed rendezvous protocols.
+ [XXXX what do the numbers this mean? And why a bitmask??? -NM]
+
+ "introduction-points" NL encrypted-string
+
+ [At most once]
+
+ A list of introduction points that is encrypted with AES in CTR mode
+ with a random initialization vector of 128 bits that is written to
+ the beginning of the encrypted string, and the secret key "cookie",
+ that is 120 bits long and padded with zeros to be 128 bits long.
+ [XXXX again, why 120 bits?? -NM]
+
+ The encrypted-string is encoded in base64, and surrounded with
+ "-----BEGIN AES ENCRYPTED MESSAGE-----" and
+ "-----END AES ENCRYPTED MESSAGE-----".
+
+ The unencrypted string may begin with:
+
+ ["authentication" auth-type NL auth-data ... reserved]
+
+ [At start, any number]
+
+ Subsequently, an arbitrary number of introduction point entries may
+ follow, each containing the following data:
+
+ "introduction-point" identifier NL
+
+ [At start, exactly once]
+
+ The identifier of this introduction point.
+ [XXXX What's the identifier? -NM]
+
+ "ip-address" ip-address NL
+
+ [Exactly once]
+
+ The IP address of this introduction point.
+
+ "onion-port" port NL
+
+ [Exactly once]
+
+ The TCP port on which the introduction point is listening for
+ incoming onion requests.
+
+ "onion-key" NL a public key in PEM format
+
+ [Exactly once]
+
+ The public key that can be used to encrypt messages to this
+ introduction point.
+
+ "service-key" NL a public key in PEM format
+
+ [Exactly once]
+
+ The public key that can be used to encrypt messages to the hidden
+ service.
+
+ ["authentication" auth-type NL auth-data ... reserved]
+
+ [Any number]
+ [XXXX this is valid at the start *and* at the end? -NM]
+
+
+ (This ends the fields in the encrypted portion of the descriptor.)
+
+ "signature" NL signature-string
+
+ [At end, exactly once]
+
+ A signature of all fields above with the private key of the hidden
+ service.
+
1.2.1. Other descriptor formats we don't use.
The V1 descriptor format was understood and accepted from
@@ -459,4 +621,3 @@
2. Authentication and authorization.
Foo.
-
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