Constant-time evaluation of non-bcrypt passwords #5247
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Signed-off-by: Neil Twigg <neil@nats.io>
| // turning a string into []byte normally. | ||
| spass := stringToBytes(serverPassword) | ||
| cpass := stringToBytes(clientPassword) | ||
| if subtle.ConstantTimeCompare(spass, cpass) == 0 { |
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So this will slow down reconnect yes?
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Should be marginal, standard string comparison will give up on the first mismatching character, whereas ConstantTimeCompare iterates over all characters before returning (unless they're different lengths, in which case it gives up immediately).
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Should be about no difference in time for valid credentials. Should only make invalid credential rejection slower.
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This ensures that comparison of non-bcrypted passwords is done in constant time, whereas otherwise timing information may be apparent on a network with next to no jitter.
Reported-by: Trail of Bits https://www.trailofbits.com
Signed-off-by: Neil Twigg neil@nats.io