Move BN and RSA utility functions to new files

1 files changed, 175 insertions, 0 deletions

diff --git a/lib/crypto/c_src/rsa.c b/lib/crypto/c_src/rsa.c
new file mode 100644
index 0000000000..2b71b5adde
--- /dev/null
+++ b/lib/crypto/c_src/rsa.c
@@ -0,0 +1,175 @@
+#include "rsa.h"
+#include "bn.h"
+
+static ERL_NIF_TERM rsa_generate_key(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[]);
+static ERL_NIF_TERM put_rsa_private_key(ErlNifEnv* env, const RSA *rsa);
+static int check_erlang_interrupt(int maj, int min, BN_GENCB *ctxt);
+
+int get_rsa_private_key(ErlNifEnv* env, ERL_NIF_TERM key, RSA *rsa)
+{
+    /* key=[E,N,D]|[E,N,D,P1,P2,E1,E2,C] */
+    ERL_NIF_TERM head, tail;
+    BIGNUM *e, *n, *d;
+    BIGNUM *p, *q;
+    BIGNUM *dmp1, *dmq1, *iqmp;
+
+    if (!enif_get_list_cell(env, key, &head, &tail)
+	|| !get_bn_from_bin(env, head, &e)
+	|| !enif_get_list_cell(env, tail, &head, &tail)
+	|| !get_bn_from_bin(env, head, &n)
+	|| !enif_get_list_cell(env, tail, &head, &tail)
+	|| !get_bn_from_bin(env, head, &d)) {
+	return 0;
+    }
+    (void) RSA_set0_key(rsa, n, e, d);
+    if (enif_is_empty_list(env, tail)) {
+	return 1;
+    }
+    if (!enif_get_list_cell(env, tail, &head, &tail)
+	|| !get_bn_from_bin(env, head, &p)
+	|| !enif_get_list_cell(env, tail, &head, &tail)
+	|| !get_bn_from_bin(env, head, &q)
+	|| !enif_get_list_cell(env, tail, &head, &tail)
+	|| !get_bn_from_bin(env, head, &dmp1)
+	|| !enif_get_list_cell(env, tail, &head, &tail)
+	|| !get_bn_from_bin(env, head, &dmq1)
+	|| !enif_get_list_cell(env, tail, &head, &tail)
+	|| !get_bn_from_bin(env, head, &iqmp)
+	|| !enif_is_empty_list(env, tail)) {
+	return 0;
+    }
+    (void) RSA_set0_factors(rsa, p, q);
+    (void) RSA_set0_crt_params(rsa, dmp1, dmq1, iqmp);
+    return 1;
+}
+
+int get_rsa_public_key(ErlNifEnv* env, ERL_NIF_TERM key, RSA *rsa)
+{
+    /* key=[E,N] */
+    ERL_NIF_TERM head, tail;
+    BIGNUM *e, *n;
+
+    if (!enif_get_list_cell(env, key, &head, &tail)
+	|| !get_bn_from_bin(env, head, &e)
+	|| !enif_get_list_cell(env, tail, &head, &tail)
+	|| !get_bn_from_bin(env, head, &n)
+        || !enif_is_empty_list(env, tail)) {
+	return 0;
+    }
+
+    (void) RSA_set0_key(rsa, n, e, NULL);
+    return 1;
+}
+
+/* Creates a term which can be parsed by get_rsa_private_key(). This is a list of plain integer binaries (not mpints). */
+static ERL_NIF_TERM put_rsa_private_key(ErlNifEnv* env, const RSA *rsa)
+{
+    ERL_NIF_TERM result[8];
+    const BIGNUM *n, *e, *d, *p, *q, *dmp1, *dmq1, *iqmp;
+
+    /* Return at least [E,N,D] */
+    n = NULL; e = NULL; d = NULL;
+    RSA_get0_key(rsa, &n, &e, &d);
+
+    result[0] = bin_from_bn(env, e);  // Exponent E
+    result[1] = bin_from_bn(env, n);  // Modulus N = p*q
+    result[2] = bin_from_bn(env, d);  // Exponent D
+
+    /* Check whether the optional additional parameters are available */
+    p = NULL; q = NULL;
+    RSA_get0_factors(rsa, &p, &q);
+    dmp1 = NULL; dmq1 = NULL; iqmp = NULL;
+    RSA_get0_crt_params(rsa, &dmp1, &dmq1, &iqmp);
+
+    if (p && q && dmp1 && dmq1 && iqmp) {
+	result[3] = bin_from_bn(env, p);     // Factor p
+	result[4] = bin_from_bn(env, q);     // Factor q
+	result[5] = bin_from_bn(env, dmp1);  // D mod (p-1)
+	result[6] = bin_from_bn(env, dmq1);  // D mod (q-1)
+	result[7] = bin_from_bn(env, iqmp);  // (1/q) mod p
+
+	return enif_make_list_from_array(env, result, 8);
+    } else {
+	return enif_make_list_from_array(env, result, 3);
+    }
+}
+
+static int check_erlang_interrupt(int maj, int min, BN_GENCB *ctxt)
+{
+    ErlNifEnv *env = BN_GENCB_get_arg(ctxt);
+
+    if (!enif_is_current_process_alive(env)) {
+	return 0;
+    } else {
+	return 1;
+    }
+}
+
+static ERL_NIF_TERM rsa_generate_key(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
+{/* (ModulusSize, PublicExponent) */
+    int modulus_bits;
+    BIGNUM *pub_exp, *three;
+    RSA *rsa;
+    int success;
+    ERL_NIF_TERM result;
+    BN_GENCB *intr_cb;
+#ifndef HAVE_OPAQUE_BN_GENCB
+    BN_GENCB intr_cb_buf;
+#endif
+
+    if (!enif_get_int(env, argv[0], &modulus_bits) || modulus_bits < 256) {
+	return enif_make_badarg(env);
+    }
+
+    if (!get_bn_from_bin(env, argv[1], &pub_exp)) {
+	return enif_make_badarg(env);
+    }
+
+    /* Make sure the public exponent is large enough (at least 3).
+     * Without this, RSA_generate_key_ex() can run forever. */
+    three = BN_new();
+    BN_set_word(three, 3);
+    success = BN_cmp(pub_exp, three);
+    BN_free(three);
+    if (success < 0) {
+	BN_free(pub_exp);
+	return enif_make_badarg(env);
+    }
+
+    /* For large keys, prime generation can take many seconds. Set up
+     * the callback which we use to test whether the process has been
+     * interrupted. */
+#ifdef HAVE_OPAQUE_BN_GENCB
+    intr_cb = BN_GENCB_new();
+#else
+    intr_cb = &intr_cb_buf;
+#endif
+    BN_GENCB_set(intr_cb, check_erlang_interrupt, env);
+
+    rsa = RSA_new();
+    success = RSA_generate_key_ex(rsa, modulus_bits, pub_exp, intr_cb);
+    BN_free(pub_exp);
+
+#ifdef HAVE_OPAQUE_BN_GENCB
+    BN_GENCB_free(intr_cb);
+#endif
+
+    if (!success) {
+        RSA_free(rsa);
+	return atom_error;
+    }
+
+    result = put_rsa_private_key(env, rsa);
+    RSA_free(rsa);
+
+    return result;
+}
+
+ERL_NIF_TERM rsa_generate_key_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
+{
+    /* RSA key generation can take a long time (>1 sec for a large
+     * modulus), so schedule it as a CPU-bound operation. */
+    return enif_schedule_nif(env, "rsa_generate_key",
+			     ERL_NIF_DIRTY_JOB_CPU_BOUND,
+			     rsa_generate_key, argc, argv);
+}