TLS: add ability to hash SPKI instead of certificate. (#44)
TLS: add ability to hash SPKI instead of certificate. (#44)

SPKI doesn't change when certificate is reissued, so it works better
with short-lived certificates.

This is also the same format as used in HTTP Public Key Pinning.

Signed-off-by: Piotr Sikora <ba6f3a1a6d7e1ecae91b31e93969cc392fbd0fdd@google.com>

lyft/envoy-api,jrajahalme/envoy-api,rshriram/envoy-api,jrajahalme/envoy-api,lyft/envoy-api,jrajahalme/envoy-api,rshriram/envoy-api,lyft/envoy-api,jrajahalme/envoy-api,rshriram/envoy-api