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Add unsafe_memzero/1

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This commit is contained in:
Doug Huff 2015-10-28 21:45:13 +00:00
parent 4d5524db61
commit 9849e7310a
3 changed files with 32 additions and 2 deletions
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16
c_src/enacl_nif.c
View File

@ -81,6 +81,21 @@ ERL_NIF_TERM enif_crypto_verify_32(ErlNifEnv *env, int argc, ERL_NIF_TERM const
}
}
/* This is very unsafe. It will not affect things that have been binary_copy()'ed
Use this for destroying key material from ram but nothing more. Be careful! */
static
ERL_NIF_TERM enif_sodium_memzero(ErlNifEnv *env, int argc, ERL_NIF_TERM const argv[]) {
ErlNifBinary x;
if ((argc != 1) || (!enif_inspect_binary(env, argv[0], &x))) {
return enif_make_badarg(env);
}
sodium_memzero(x.data,x.size);
return enif_make_atom(env, "ok");
}
/* Curve 25519 */
static
ERL_NIF_TERM enif_crypto_curve25519_scalarmult(ErlNifEnv *env, int argc, ERL_NIF_TERM const argv[]) {
@ -1172,6 +1187,7 @@ static ErlNifFunc nif_funcs[] = {
{"crypto_hash", 1, enif_crypto_hash, ERL_NIF_DIRTY_JOB_CPU_BOUND},
{"crypto_verify_16", 2, enif_crypto_verify_16},
{"crypto_verify_32", 2, enif_crypto_verify_32},
{"sodium_memzero", 1, enif_sodium_memzero},
{"crypto_curve25519_scalarmult", 2, enif_crypto_curve25519_scalarmult, ERL_NIF_DIRTY_JOB_CPU_BOUND},

14
src/enacl.erl
View File

@ -92,7 +92,8 @@
-export([
hash/1,
verify_16/2,
verify_32/2
verify_32/2,
unsafe_memzero/1
]).
%% Libsodium specific functions (which are also part of the "undocumented" interface to NaCl
@ -214,6 +215,17 @@ verify_16(_, _) -> error(badarg).
verify_32(X, Y) when is_binary(X), is_binary(Y) -> enacl_nif:crypto_verify_32(X, Y);
verify_32(_, _) -> error(badarg).
%% @doc unsafe_memzero/1 ipmlements guaranteed zero'ing of binary data.
%%
%% <p><bold>WARNING:</bold> Take great care. This way be dragons.</p>
%% <p>This is verify unsafe. If any copies of the binary have been made they are unaffected.
%% This is intended for use with cryptographic keys where they are only shared within
%% a running process without copies. This allows removing, eg, symmetric session keys. </p>
%% @end
-spec unsafe_memzero(binary()) -> atom().
unsafe_memzero(X) when is_binary(X) -> enacl_nif:sodium_memzero(X);
unsafe_memzero(_) -> error(badarg).
%% Public Key Crypto
%% ---------------------
%% @doc box_keypair/0 creates a new Public/Secret keypair.

4
src/enacl_nif.erl
View File

@ -109,7 +109,8 @@
crypto_hash/1,
crypto_hash_b/1,
crypto_verify_16/2,
crypto_verify_32/2
crypto_verify_32/2,
sodium_memzero/1
]).
%% Access to the RNG
@ -220,6 +221,7 @@ crypto_hash(Input) when is_binary(Input) -> erlang:nif_error(nif_not_loaded).
crypto_hash_b(Input) when is_binary(Input) -> erlang:nif_error(nif_not_loaded).
crypto_verify_16(_X, _Y) -> erlang:nif_error(nif_not_loaded).
crypto_verify_32(_X, _Y) -> erlang:nif_error(nif_not_loaded).
sodium_memzero(Input) when is_binary(Input) -> erlang:nif_error(nif_not_loaded).
randombytes(_RequestedSize) -> erlang:nif_error(nif_not_loaded).