1 files changed, 107 insertions, 0 deletions
diff --git a/src/lib/crypto/bn.cpp b/src/lib/crypto/bn.cpp
new file mode 100644
index 0000000..d5ae6b4
--- /dev/null
+++ b/src/lib/crypto/bn.cpp
@@ -0,0 +1,107 @@
+/*
+ * Copyright (c) 2017-2021 Ribose Inc.
+ * Copyright (c) 2012 Alistair Crooks <agc@NetBSD.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "bn.h"
+#include <botan/ffi.h>
+#include <stdlib.h>
+#include <assert.h>
+#include "utils.h"
+
+/* essentiually, these are just wrappers around the botan functions */
+/* usually the order of args changes */
+/* the bignum_t API tends to have more const poisoning */
+/* these wrappers also check the arguments passed for sanity */
+
+/* store in unsigned [big endian] format */
+int
+bn_bn2bin(const bignum_t *a, unsigned char *b)
+{
+    if (!a || !b) {
+        return -1;
+    }
+    return botan_mp_to_bin(a->mp, b);
+}
+
+bignum_t *
+mpi2bn(const pgp_mpi_t *val)
+{
+    assert(val);
+    if (!val) {
+        RNP_LOG("NULL val.");
+        return NULL;
+    }
+    bignum_t *res = bn_new();
+    if (!res) {
+        return NULL;
+    }
+    if (botan_mp_from_bin(res->mp, val->mpi, val->len)) {
+        bn_free(res);
+        res = NULL;
+    }
+    return res;
+}
+
+bool
+bn2mpi(const bignum_t *bn, pgp_mpi_t *val)
+{
+    val->len = bn_num_bytes(*bn);
+    if (val->len > PGP_MPINT_SIZE) {
+        RNP_LOG("Too large MPI.");
+        val->len = 0;
+        return false;
+    }
+    return bn_bn2bin(bn, val->mpi) == 0;
+}
+
+bignum_t *
+bn_new(void)
+{
+    bignum_t *a = (bignum_t *) calloc(1, sizeof(*a));
+    if (!a) {
+        return NULL;
+    }
+    botan_mp_init(&a->mp);
+    return a;
+}
+
+void
+bn_free(bignum_t *a)
+{
+    if (a) {
+        botan_mp_destroy(a->mp);
+        free(a);
+    }
+}
+
+size_t
+bn_num_bytes(const bignum_t &a)
+{
+    size_t bytes = 0;
+    if (botan_mp_num_bits(a.mp, &bytes)) {
+        RNP_LOG("botan_mp_num_bits failed.");
+    }
+    return BITS_TO_BYTES(bytes);
+}