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Diffstat (limited to 'ANONYMITY_NETWORKS.md')
| -rw-r--r-- | ANONYMITY_NETWORKS.md | 52 |
1 files changed, 33 insertions, 19 deletions
diff --git a/ANONYMITY_NETWORKS.md b/ANONYMITY_NETWORKS.md index feb8528da..6eede44aa 100644 --- a/ANONYMITY_NETWORKS.md +++ b/ANONYMITY_NETWORKS.md @@ -160,25 +160,6 @@ the system clock is noticeably off (and therefore more fingerprintable), linking the public IPv4/IPv6 connections with the anonymity networks will be more difficult. -### Bandwidth Usage - -An ISP can passively monitor `monerod` connections from a node and observe when -a transaction is sent over a Tor/I2P connection via timing analysis + size of -data sent during that timeframe. I2P should provide better protection against -this attack - its connections are not circuit based. However, if a node is -only using I2P for broadcasting Monero transactions, the total aggregate of -I2P data would also leak information. - -#### Mitigation - -There is no current mitigation for the user right now. This attack is fairly -sophisticated, and likely requires support from the internet host of a Monero -user. - -In the near future, "whitening" the amount of data sent over anonymity network -connections will be performed. An attempt will be made to make a transaction -broadcast indistinguishable from a peer timed sync command. - ### Intermittent Monero Syncing If a user only runs `monerod` to send a transaction then quit, this can also @@ -208,3 +189,36 @@ is a tradeoff in potential isses. Also, anyone attempting this strategy really wants to uncover a user, it seems unlikely that this would be performed against every Tor/I2P user. +### I2P/Tor Stream Used Twice + +If a single I2P/Tor stream is used 2+ times for transmitting a transaction, the +operator of the hidden service can conclude that both transactions came from the +same source. If the subsequent transactions spend a change output from the +earlier transactions, this will also reveal the "real" spend in the ring +signature. This issue was (primarily) raised by @secparam on Twitter. + +#### Mitigation + +`monerod` currently selects two outgoing connections every 5 minutes for +transmitting transactions over I2P/Tor. Using outgoing connections prevents an +adversary from making many incoming connections to obtain information (this +technique was taken from Dandelion). Outgoing connections also do not have a +persistent public key identity - the creation of a new circuit will generate +a new public key identity. The lock time on a change address is ~20 minutes, so +`monerod` will have rotated its selected outgoing connections several times in +most cases. However, the number of outgoing connections is typically a small +fixed number, so there is a decent probability of re-use with the same public +key identity. + +@secparam (twitter) recommended changing circuits (Tor) as an additional +precaution. This is likely not a good idea - forcibly requesting Tor to change +circuits is observable by the ISP. Instead, `monerod` should likely disconnect +from peers ocassionally. Tor will rotate circuits every ~10 minutes, so +establishing new connections will use a new public key identity and make it +more difficult for the hidden service to link information. This process will +have to be done carefully because closing/reconnecting connections can also +leak information to hidden services if done improperly. + +At the current time, if users need to frequently make transactions, I2P/Tor +will improve privacy from ISPs and other common adversaries, but still have +some metadata leakages to unknown hidden service operators. |