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| author | Hans Nilsson <hans@erlang.org> | 2020-01-08 12:56:56 +0100 |
|---|---|---|
| committer | Hans Nilsson <hans@erlang.org> | 2020-01-08 15:39:04 +0100 |
| commit | 850d016a2de739bf58dc588c13fe378debf758e1 (patch) | |
| tree | dbfff0ef75d67d5a3cd347de5cd4a69485ba7402 | |
| parent | edc678d5add2c741bc6d63f9f434e43e9bb12dae (diff) | |
| download | erlang-850d016a2de739bf58dc588c13fe378debf758e1.tar.gz | |
crypto: Add an equal-time comparision function. (NIF candidate)
| -rw-r--r-- | lib/crypto/src/crypto.erl | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/lib/crypto/src/crypto.erl b/lib/crypto/src/crypto.erl index 0d85b94b57..60f257f49f 100644 --- a/lib/crypto/src/crypto.erl +++ b/lib/crypto/src/crypto.erl @@ -24,6 +24,7 @@ -export([start/0, stop/0, info_lib/0, info_fips/0, supports/0, enable_fips_mode/1, version/0, bytes_to_integer/1]). +-export([equal_const_time/2]). -export([hash/2, hash_init/1, hash_update/2, hash_final/1]). -export([sign/4, sign/5, verify/5, verify/6]). -export([generate_key/2, generate_key/3, compute_key/4]). @@ -130,6 +131,41 @@ info_lib() -> ?nif_stub. info_fips() -> ?nif_stub. +%%%================================================================ +%%% +%%% Compare in constant time +%%% +%%%================================================================ + +%%% Candidate for a NIF + +equal_const_time(X1, X2) -> + equal_const_time(X1, X2, true). + + +equal_const_time(<<B1,R1/binary>>, <<B2,R2/binary>>, Truth) -> + equal_const_time(R1, R2, Truth and (B1 == B2)); +equal_const_time(<<_,R1/binary>>, <<>>, Truth) -> + equal_const_time(R1, <<>>, Truth and false); +equal_const_time(<<>>, <<>>, Truth) -> + Truth; + +equal_const_time([H1|T1], [H2|T2], Truth) -> + equal_const_time(T1, T2, Truth and (H1 == H2)); +equal_const_time([_|T1], [], Truth) -> + equal_const_time(T1, [], Truth and false); +equal_const_time([], [], Truth) -> + Truth; + +equal_const_time(_, _, _) -> + false. + +%%%================================================================ +%%% +%%% Hashing +%%% +%%%================================================================ + -spec enable_fips_mode(boolean()) -> boolean(). enable_fips_mode(_) -> ?nif_stub. |