tor/changes/bridgepassword
Nick Mathewson 9a69c24150 Do not use strcmp() to compare an http authenticator to its expected value
This fixes a side-channel attack on the (fortunately unused!)
BridgePassword option for bridge authorities.  Fix for bug 5543;
bugfix on 0.2.0.14-alpha.
2012-04-01 00:42:04 -04:00

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o Security fixes:
- When using the debuging BridgePassword field, a bridge authority
now compares alleged passwords by hashing them, then comparing
the result to a digest of the expected authenticator. This avoids
a potential side-channel attack in the previous code, which
had foolishly used strcmp(). Fortunately, the BridgePassword field
*is not in use*, but if it had been, the timing
behavior of strcmp() might have allowed an adversary to guess the
BridgePassword value, and enumerate the bridges. Bugfix on
0.2.0.14-alpha. Fixes bug 5543.