Use fixed-size packets (Trac #1623)

[str4d]

Messages should be divided and/or packed to fixed size packets, so that the variable size of cannot leak information.

from forum: "I am also concerned that it may be possible to correlate packets of unusual size and unmask the sender and or receiver."

http://forum.i2p/viewtopic.php?t=11906

and have some form of forward error correction.

Quoting an anonymous guest on forum.i2p:

My thoughts were to add at least one extra packet for messages which would produce 1 to 4 packets, then progressively more FEC packets.

e.g.
original packets; fec packets; total packets; # of packets needed for recovery
        1             1             2                        1/2
        2             1             3                        2/3
        3             1             4                        3/4
        4             1             5                        4/5
        5             2             7                        5/7
        6             2             8                        6/8
etc
       10             2            12                       10/12
       11             3            14                       11/14
etc

1. all packets should be of same size
2. FEC should be there
3. if possible, eliminate the (visual for storage node) distinction between email packets and index packets. This already gives too much information about the structure. Even if that means downloading a few more packets and trying to decrypt them.

Migrated from https://trac.i2p2.de/ticket/1623

{
    "status": "assigned", 
    "changetime": "2017-01-15T13:56:37", 
    "description": "\nMessages should be divided and/or packed to fixed size packets, so that the variable size of cannot leak information.\n\nfrom forum: \"I am also concerned that it may be possible to correlate packets of unusual size and unmask the sender and or receiver.\"\n\nhttp://forum.i2p/viewtopic.php?t=11906\n\n\nand have some form of forward error correction.\n\nQuoting an anonymous guest on forum.i2p:\n{{{\nMy thoughts were to add at least one extra packet for messages which would produce 1 to 4 packets, then progressively more FEC packets.\n\ne.g.\noriginal packets; fec packets; total packets; # of packets needed for recovery\n        1             1             2                        1/2\n        2             1             3                        2/3\n        3             1             4                        3/4\n        4             1             5                        4/5\n        5             2             7                        5/7\n        6             2             8                        6/8\netc\n       10             2            12                       10/12\n       11             3            14                       11/14\netc\n}}}\n\n1) all packets should be of same size\n2) FEC should be there\n3) if possible, eliminate the (visual for storage node) distinction between email packets and index packets. This already gives too much information about the structure. Even if that means downloading a few more packets and trying to decrypt them.\n\n", 
    "reporter": "user", 
    "cc": "", 
    "resolution": "", 
    "_ts": "1484488597502095", 
    "component": "apps/plugins", 
    "summary": "I2P-Bote: single-size packets", 
    "priority": "minor", 
    "keywords": "I2P-Bote", 
    "version": "0.9.20", 
    "parents": "", 
    "time": "2015-07-29T08:17:36", 
    "milestone": "undecided", 
    "owner": "str4d", 
    "type": "enhancement"
}

[str4d]

Trac update at 20170115T13:56:37:

• zzz changed owner from "" to "str4d"
• zzz changed status from "new" to "assigned"