crypto: Added optional length to paramlist in generate_key

2 files changed, 25 insertions, 9 deletions

diff --git a/lib/crypto/c_src/crypto.c b/lib/crypto/c_src/crypto.c
index c100fc8ee2..ffa51bcfae 100644
--- a/lib/crypto/c_src/crypto.c
+++ b/lib/crypto/c_src/crypto.c
@@ -61,7 +61,6 @@
 #include <openssl/evp.h>
 #include <openssl/hmac.h>
 
-
 /* Helper macro to construct a OPENSSL_VERSION_NUMBER.
  * See openssl/opensslv.h
  */
@@ -326,7 +325,7 @@ static ErlNifFunc nif_funcs[] = {
     {"rsa_private_crypt", 4, rsa_private_crypt},
     {"dh_generate_parameters_nif", 2, dh_generate_parameters_nif},
     {"dh_check", 1, dh_check},
-    {"dh_generate_key_nif", 3, dh_generate_key_nif},
+    {"dh_generate_key_nif", 4, dh_generate_key_nif},
     {"dh_compute_key_nif", 3, dh_compute_key_nif},
     {"srp_value_B_nif", 5, srp_value_B_nif},
     {"srp_user_secret_nif", 7, srp_user_secret_nif},
@@ -2727,12 +2726,13 @@ static ERL_NIF_TERM dh_check(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[]
 }   
 
 static ERL_NIF_TERM dh_generate_key_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
-{/* (PrivKey, DHParams=[P,G], Mpint) */
+{/* (PrivKey|undefined, DHParams=[P,G], Mpint, Len|0) */
     DH* dh_params;
     int pub_len, prv_len;
     unsigned char *pub_ptr, *prv_ptr;
     ERL_NIF_TERM ret, ret_pub, ret_prv, head, tail;
     int mpint; /* 0 or 4 */
+    unsigned long len = 0;
 
     dh_params = DH_new();
 
@@ -2743,11 +2743,21 @@ static ERL_NIF_TERM dh_generate_key_nif(ErlNifEnv* env, int argc, const ERL_NIF_
 	|| !enif_get_list_cell(env, tail, &head, &tail)
 	|| !get_bn_from_bin(env, head, &dh_params->g)
 	|| !enif_is_empty_list(env, tail)
-	|| !enif_get_int(env, argv[2], &mpint) || (mpint & ~4)) {
+	|| !enif_get_int(env, argv[2], &mpint) || (mpint & ~4)
+	|| !enif_get_ulong(env, argv[3], &len)  ) {
 	DH_free(dh_params);
 	return enif_make_badarg(env);
     }
 
+    if (len) {
+        if (len < BN_num_bits(dh_params->p))
+            dh_params->length = len;
+        else {
+            DH_free(dh_params);
+            return enif_make_badarg(env);
+        }
+    }
+
     if (DH_generate_key(dh_params)) {
 	pub_len = BN_num_bytes(dh_params->pub_key);
 	prv_len = BN_num_bytes(dh_params->priv_key);    
diff --git a/lib/crypto/src/crypto.erl b/lib/crypto/src/crypto.erl
index a87b480f60..deeb763145 100644
--- a/lib/crypto/src/crypto.erl
+++ b/lib/crypto/src/crypto.erl
@@ -547,9 +547,15 @@ exor(Bin1, Bin2) ->
 generate_key(Type, Params) ->
     generate_key(Type, Params, undefined).
 
-generate_key(dh, DHParameters, PrivateKey) ->
+generate_key(dh, DHParameters0, PrivateKey) ->
+    {DHParameters, Len} =
+        case DHParameters0 of
+            [P,G,L] -> {[P,G], L};
+            [P,G] -> {[P,G], 0}
+        end,
     dh_generate_key_nif(ensure_int_as_bin(PrivateKey),
-			map_ensure_int_as_bin(DHParameters), 0);
+			map_ensure_int_as_bin(DHParameters),
+                        0, Len);
 
 generate_key(srp, {host, [Verifier, Generator, Prime, Version]}, PrivArg)
   when is_binary(Verifier), is_binary(Generator), is_binary(Prime), is_atom(Version) ->
@@ -1201,11 +1207,11 @@ dh_check([_Prime,_Gen]) -> ?nif_stub.
 			     {binary(),binary()}.
 
 dh_generate_key(DHParameters) ->
-    dh_generate_key_nif(undefined, map_mpint_to_bin(DHParameters), 4).
+    dh_generate_key_nif(undefined, map_mpint_to_bin(DHParameters), 4, 0).
 dh_generate_key(PrivateKey, DHParameters) ->
-    dh_generate_key_nif(mpint_to_bin(PrivateKey), map_mpint_to_bin(DHParameters), 4).
+    dh_generate_key_nif(mpint_to_bin(PrivateKey), map_mpint_to_bin(DHParameters), 4, 0).
 
-dh_generate_key_nif(_PrivateKey, _DHParameters, _Mpint) -> ?nif_stub.
+dh_generate_key_nif(_PrivateKey, _DHParameters, _Mpint, _Length) -> ?nif_stub.
 
 %% DHParameters = [P (Prime)= mpint(), G(Generator) = mpint()]
 %% MyPrivKey, OthersPublicKey = mpint()