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"The Tor design doesn't try to protect against an attacker who can see or measure both traffic going into the Tor network and also traffic coming out of the Tor

by Create 14y ago

"The Tor design doesn't try to protect against an attacker who can see or measure both traffic going into the Tor network and also traffic coming out of the Tor network. That's because if you can see both flows, some simple statistics let you decide whether they match up." We now know, that entire nations' & worldwide traffic is being intercepted and logged. One would probably see I2P as an overkill without knowing the downfalls of its predecessor. Tor was once a wonderful multi-proxy used for hiding IP addresses and bouncing off servers all over the world. At one time, it was even trusted by most governments for strong anonymity. All of that seemed to change after an article was posted in 2600 Hacker Quarterly. One author exposed how becoming an exit node for Tor allowed all the traffic on the Tor network to pass right through your machine. Becoming an exit node was the same as performing a Man-In-The-Middle attack. All one had to do was open up a packet sniffer and see all the traffic going through encrypted. Tor is still used by people trying to protect their privacy. But at the same time it has become a playground for hackers and governments monitoring what they consider suspicious. I2P has secured this problem while adding more functionality. Proper German engineering: http://www.i2p2.de/index.html http://www.i2p2.de/index.html

derrida 14y ago
> One author exposed how becoming an exit node for Tor allowed all the traffic on the Tor network to pass right through your machine. Becoming an exit node was the same as performing a Man-In-The-Middle attack. This is de-contextualised scaremongering. What the poster is referring to is that when you leave the Tor network, the connection is as it would have been before. This is by design. So if you were not using TLS, then your traffic could be read, as is the case with ALL http etc. Simple. Use SSL/TLS/SSH/ etc Do a trace route to google. All those intermediate parties are capable of the same thing. But if you use TLS the attack is useless. Tor provides one property, Anonymity, and it does this incredibly well. Anonymity and Privacy are related by distinct properties. Obviously if you send traffic to a site and sign off with your name, Tor can't help you be anonymous there. Tor cannot prevent misuse & ignorance. As for this 'MITM' attack, Tor's design is such that you do not have to trust the exit nodes for it to work. As for the comparison with I2P, I don't know much about it, but I support any FOSS project that aims to provide new types of anonymity. As I understand it the problem with I2p at the moment is that there is 1 exit node facing the regular net. It's not entirely clear how I2P evades what you consider 'the problem with Tor' when connecting with the regular net. EDIT: Yep, did a bit of research and i2p is subject to the same sort of "attack" you describe "Like Tor, I2P does not magically encrypt the Internet. You are vulnerable to snooping by the outproxy operators." http://www.i2p2.de/faq.html#outproxy http://www.i2p2.de/faq.html#outproxy
- deleted 14y ago
  [deleted]
- graue 14y ago
  Great explanation, just want to add that when you use Tor hidden services to communicate (i.e. no exit node involved or needed), everything is end-to-end encrypted and the MITM attack scenario doesn't apply. Hidden services are also not vulnerable to: > "The Tor design doesn't try to protect against an attacker who can see or measure both traffic going into the Tor network and also traffic coming out of the Tor network. That's because if you can see both flows, some simple statistics let you decide whether they match up." because all traffic is within the Tor network.
- Create 14y ago
  The host part is the transport layer-dependent permanent hidden service ID. For Tor, which is the primary transport layer supported by cables communication, it is a 16-character Base32 representation of a half of Tor's hidden service RSA-1024 public key fingerprint (an 80-bit part of SHA-1 cryptographic hash), with an .onion domain suffix. For I2P, it is a 52-character Base32 encoding of eepSite's ElGamal-2048 public key SHA-256 fingerprint, with a .b32.i2p suffix. In this way, message security (inability of the attacker to reveal the message contents) is independent of the transport layer security (inability of the attacker to reveal the contents of network traffc and the location of correspondents). This is important because, at present, Tor appears to disallow “too much” security by design: - RSA-1024 is universally used as a public key cipher (identity, onion, connection, and private keys, and likely for SSLv3 connections as well; although long-term directory authority identity keys are RSA-3072). This RSA key size is likely inadequate against a resourceful adversary such as the NSA/CSS. RSA-1024 provides only ~80 bits of security (see NIST SP 800-57 Part 1, §5.6.1). - AES-128 is used as a stream cipher, although this key size is not allowed for highly sensitive data protection in the government of USA (see CNSS Policy №15 FS №1). - SHA-1 80-MSB are used as the hidden service ID, offering at most 80 bits of security against hidden service impersonation. The security might be weaker than even that, since an MSB section of a cryptographic hash does not automatically inherit the second-preimage attack resistance properties of the original hash. http://dee.su/cables-security http://dee.su/cables-security

by Create 14y ago

derrida 14y ago

> One author exposed how becoming an exit node for Tor allowed all the traffic on the Tor network to pass right through your machine. Becoming an exit node was the same as performing a Man-In-The-Middle attack. This is de-contextualised scaremongering. What the poster is referring to is that when you leave the Tor network, the connection is as it would have been before. This is by design. So if you were not using TLS, then your traffic could be read, as is the case with ALL http etc. Simple. Use SSL/TLS/SSH/ etc Do a trace route to google. All those intermediate parties are capable of the same thing. But if you use TLS the attack is useless. Tor provides one property, Anonymity, and it does this incredibly well. Anonymity and Privacy are related by distinct properties. Obviously if you send traffic to a site and sign off with your name, Tor can't help you be anonymous there. Tor cannot prevent misuse & ignorance. As for this 'MITM' attack, Tor's design is such that you do not have to trust the exit nodes for it to work. As for the comparison with I2P, I don't know much about it, but I support any FOSS project that aims to provide new types of anonymity. As I understand it the problem with I2p at the moment is that there is 1 exit node facing the regular net. It's not entirely clear how I2P evades what you consider 'the problem with Tor' when connecting with the regular net. EDIT: Yep, did a bit of research and i2p is subject to the same sort of "attack" you describe "Like Tor, I2P does not magically encrypt the Internet. You are vulnerable to snooping by the outproxy operators." http://www.i2p2.de/faq.html#outproxy http://www.i2p2.de/faq.html#outproxy

deleted 14y ago
[deleted]
graue 14y ago
Great explanation, just want to add that when you use Tor hidden services to communicate (i.e. no exit node involved or needed), everything is end-to-end encrypted and the MITM attack scenario doesn't apply. Hidden services are also not vulnerable to: > "The Tor design doesn't try to protect against an attacker who can see or measure both traffic going into the Tor network and also traffic coming out of the Tor network. That's because if you can see both flows, some simple statistics let you decide whether they match up." because all traffic is within the Tor network.
Create 14y ago
The host part is the transport layer-dependent permanent hidden service ID. For Tor, which is the primary transport layer supported by cables communication, it is a 16-character Base32 representation of a half of Tor's hidden service RSA-1024 public key fingerprint (an 80-bit part of SHA-1 cryptographic hash), with an .onion domain suffix. For I2P, it is a 52-character Base32 encoding of eepSite's ElGamal-2048 public key SHA-256 fingerprint, with a .b32.i2p suffix. In this way, message security (inability of the attacker to reveal the message contents) is independent of the transport layer security (inability of the attacker to reveal the contents of network traffc and the location of correspondents). This is important because, at present, Tor appears to disallow “too much” security by design: - RSA-1024 is universally used as a public key cipher (identity, onion, connection, and private keys, and likely for SSLv3 connections as well; although long-term directory authority identity keys are RSA-3072). This RSA key size is likely inadequate against a resourceful adversary such as the NSA/CSS. RSA-1024 provides only ~80 bits of security (see NIST SP 800-57 Part 1, §5.6.1). - AES-128 is used as a stream cipher, although this key size is not allowed for highly sensitive data protection in the government of USA (see CNSS Policy №15 FS №1). - SHA-1 80-MSB are used as the hidden service ID, offering at most 80 bits of security against hidden service impersonation. The security might be weaker than even that, since an MSB section of a cryptographic hash does not automatically inherit the second-preimage attack resistance properties of the original hash. http://dee.su/cables-security http://dee.su/cables-security