Added an hmac_multi_digest function in order to take the HMAC of a string concantanted with itself variable amount of times.
Added an hmac_multi_digest function in order to take the HMAC of a string concantanted with itself variable amount of times.

lavabit/magma,lavabit/magma,lavabit/magma,lavabit/magma,lavabit/magma,lavabit/magma,lavabit/magma,lavabit/magma