Support generation of strong random numbers

1 files changed, 34 insertions, 0 deletions

diff --git a/lib/crypto/c_src/crypto.c b/lib/crypto/c_src/crypto.c
index b2f31870b9..0e17279e62 100644
--- a/lib/crypto/c_src/crypto.c
+++ b/lib/crypto/c_src/crypto.c
@@ -429,6 +429,7 @@ static ERL_NIF_TERM aes_ige_crypt_nif(ErlNifEnv* env, int argc, const ERL_NIF_TE
 static ERL_NIF_TERM aes_ctr_stream_init(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[]);
 static ERL_NIF_TERM aes_ctr_stream_encrypt(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[]);
 static ERL_NIF_TERM strong_rand_bytes_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[]);
+static ERL_NIF_TERM strong_rand_uniform_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[]);
 static ERL_NIF_TERM rand_uniform_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[]);
 static ERL_NIF_TERM mod_exp_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[]);
 static ERL_NIF_TERM dss_verify_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[]);
@@ -501,6 +502,7 @@ static ErlNifFunc nif_funcs[] = {
     {"aes_ctr_stream_encrypt", 2, aes_ctr_stream_encrypt},
     {"aes_ctr_stream_decrypt", 2, aes_ctr_stream_encrypt},
     {"strong_rand_bytes_nif", 1, strong_rand_bytes_nif},
+    {"strong_rand_uniform_nif", 2, strong_rand_uniform_nif},
     {"rand_uniform_nif", 2, rand_uniform_nif},
     {"mod_exp_nif", 4, mod_exp_nif},
     {"dss_verify_nif", 4, dss_verify_nif},
@@ -2331,6 +2333,38 @@ static ERL_NIF_TERM bin_from_bn(ErlNifEnv* env, const BIGNUM *bn)
     return term;
 }
 
+static ERL_NIF_TERM strong_rand_uniform_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
+{/* (Lo,Hi) */
+    BIGNUM *bn_from = NULL, *bn_to, *bn_rand;
+    unsigned char* data;
+    unsigned dlen;
+    ERL_NIF_TERM ret;
+
+    if (!get_bn_from_mpint(env, argv[0], &bn_from)
+	|| !get_bn_from_mpint(env, argv[1], &bn_rand)) {
+	if (bn_from) BN_free(bn_from);
+	return enif_make_badarg(env);
+    }
+
+    bn_to = BN_new();
+    BN_sub(bn_to, bn_rand, bn_from);
+    if (BN_rand_range(bn_rand, bn_to) != 1) {
+        ret = atom_false;
+    }
+    else {
+        BN_add(bn_rand, bn_rand, bn_from);
+        dlen = BN_num_bytes(bn_rand);
+        data = enif_make_new_binary(env, dlen+4, &ret);
+        put_int32(data, dlen);
+        BN_bn2bin(bn_rand, data+4);
+        ERL_VALGRIND_MAKE_MEM_DEFINED(data+4, dlen);
+    }
+    BN_free(bn_rand);
+    BN_free(bn_from);
+    BN_free(bn_to);
+    return ret;
+}
+
 static ERL_NIF_TERM rand_uniform_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
 {/* (Lo,Hi) */
     BIGNUM *bn_from = NULL, *bn_to, *bn_rand;