Avoid timing side channels in signature validation #28
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Use a blinded HMAC comparison to verify signatures, which avoids timing side-channel's through use of ===. See https://paragonie.com/blog/2015/11/preventing-timing-attacks-on-string-comparison-with-double-hmac-strategy for more details
This PR introduces a dependency on
paragonie/random_compat
, which adds a polyfill forrandom_bytes
from PHP7. It doesn't affect PHP7+ installs, but is the recommended way to scramble for random data on older systems.Happy to submit some backports if required.