Changeset 10808

Timestamp:

02/15/08 00:46:13 (2 years ago)

Author:

dave

Message:

removing 64-bit key limitation and going to 160-bit since this matches the length of a sha-1 digest.

Files:

• dotorg/trunk_fixed/html/beps/bep_0008.rst (modified) (4 diffs)

dotorg/trunk_fixed/html/beps/bep_0008.rst

@@ -86 +86 @@
 be of arbitrary length and is sent in plaintext.
 
-If the tracker sends no initialization vector then the first 64-bits
-of the infohash are used as the RC4 key.  If the tracker provides an
+If the tracker sends no initialization vector then the infohash is
+used as the RC4 key (160 bit key).  If the tracker provides an
 initialization vector then the RC4 key is generated by appending the
-vector to the infohash and then hashing with SHA-1.  The first 64 bits
-of the resulting hash are then used as the RC4 key.  The string from
-which the RC4 key is derived whether it be the infohash or the SHA-1 of
-the initialization vector appended to the infohash is called the
+vector to the infohash and then hashing with SHA-1.  The resulting
+hash is then used as the RC4 key.  The string from which the RC4 key
+is derived whether it be the infohash or the SHA-1 of the
+initialization vector appended to the infohash is called the
 *intermediate string*.
 
@@ -101 +101 @@
 ::
  
-   intermediate = sha1( 'aaf4c61ddcc5e8a2dabedef3b482cd9aea9434dabcd' )
-   key = intermediate[0:64]
-
-where [i:j] denotes the ith through *jth* bit including the *ith* but
-excluding the *jth*.  The resulting key in hex is ``f36e9cae87cf33e0``.
-
-A 64-bit key is used to avoid U.S. export restrictions. 
+   key = sha1( 'aaf4c61ddcc5e8a2dabedef3b482cd9aea9434dabcd' )
+
+where [i:j] denotes the *ith* through *jth* bit including the *ith*
+but excluding the *jth*.  The resulting key in hex is
+``f36e9cae87cf33e07645ef5ca745a8a83469f31e``.
 
 It is RECOMMENDED that the tracker use the initialization vector, and
@@ -258 +256 @@
 return the desired number of peers then it MAY include peers that are
 not assumed to support MSE.  If a peer closes a connection in response
-to an encrypted header then the initiating peer SHOULD try other peers
-in the peer list returning to the peer that closed the connection only
-when all other peers known or not yet known to support MSE have been
-tried and have failed to provide "adequate performance."  We
+to an encrypted header then the initiating peer SHOULD assume that the
+peer does not support MSE.  The initiating peer however SHOULD ONLY
+initiate unencrypted connections when all peers have been tried and
+those that support MSE fail to provide "adequate performance."  We
 intentionally omit any definition of "adequate performance."
 
@@ -428 +426 @@
     global iv, x, n, n_xor_y, obfuscated_tracker_peer_list
     iv = rand(20)
-    rc4.key = sha(infohash + iv).digest()[0:8]
+    rc4.key = sha(infohash + iv).digest()
     rc4(768)                         # discard first 768
     x = rc4(4)