From aa4d426b4d3527d7e166df1a05058c9a4a0f6683 Mon Sep 17 00:00:00 2001
From: Wojtek Kosior <wk@koszkonutek-tmp.pl.eu.org>
Date: Fri, 30 Apr 2021 00:33:56 +0200
Subject: initial/final commit

---
 openssl-1.1.0h/fuzz/bignum.c | 94 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 94 insertions(+)
 create mode 100644 openssl-1.1.0h/fuzz/bignum.c

(limited to 'openssl-1.1.0h/fuzz/bignum.c')

diff --git a/openssl-1.1.0h/fuzz/bignum.c b/openssl-1.1.0h/fuzz/bignum.c
new file mode 100644
index 0000000..43e134b
--- /dev/null
+++ b/openssl-1.1.0h/fuzz/bignum.c
@@ -0,0 +1,94 @@
+/*
+ * Copyright 2016 The OpenSSL Project Authors. All Rights Reserved.
+ *
+ * Licensed under the OpenSSL licenses, (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * https://www.openssl.org/source/license.html
+ * or in the file LICENSE in the source distribution.
+ */
+
+/*
+ * Confirm that a^b mod c agrees when calculated cleverly vs naively, for
+ * random a, b and c.
+ */
+
+#include <stdio.h>
+#include <openssl/bn.h>
+#include "fuzzer.h"
+
+int FuzzerInitialize(int *argc, char ***argv) {
+    return 1;
+}
+
+int FuzzerTestOneInput(const uint8_t *buf, size_t len) {
+    static BN_CTX *ctx;
+    static BIGNUM *b1;
+    static BIGNUM *b2;
+    static BIGNUM *b3;
+    static BIGNUM *b4;
+    static BIGNUM *b5;
+    int success = 0;
+    size_t l1 = 0, l2 = 0, l3 = 0;
+    int s1 = 0, s2 = 0, s3 = 0;
+
+    if (ctx == NULL) {
+        b1 = BN_new();
+        b2 = BN_new();
+        b3 = BN_new();
+        b4 = BN_new();
+        b5 = BN_new();
+        ctx = BN_CTX_new();
+    }
+    /* Divide the input into three parts, using the values of the first two
+     * bytes to choose lengths, which generate b1, b2 and b3. Use three bits
+     * of the third byte to choose signs for the three numbers.
+     */
+    if (len > 2) {
+        len -= 3;
+        l1 = (buf[0] * len) / 255;
+        ++buf;
+        l2 = (buf[0] * (len - l1)) / 255;
+        ++buf;
+        l3 = len - l1 - l2;
+
+        s1 = buf[0] & 1;
+        s2 = buf[0] & 2;
+        s3 = buf[0] & 4;
+        ++buf;
+    }
+    OPENSSL_assert(BN_bin2bn(buf, l1, b1) == b1);
+    BN_set_negative(b1, s1);
+    OPENSSL_assert(BN_bin2bn(buf + l1, l2, b2) == b2);
+    BN_set_negative(b2, s2);
+    OPENSSL_assert(BN_bin2bn(buf + l1 + l2, l3, b3) == b3);
+    BN_set_negative(b3, s3);
+
+    /* mod 0 is undefined */
+    if (BN_is_zero(b3)) {
+        success = 1;
+        goto done;
+    }
+
+    OPENSSL_assert(BN_mod_exp(b4, b1, b2, b3, ctx));
+    OPENSSL_assert(BN_mod_exp_simple(b5, b1, b2, b3, ctx));
+
+    success = BN_cmp(b4, b5) == 0;
+    if (!success) {
+        BN_print_fp(stdout, b1);
+        putchar('\n');
+        BN_print_fp(stdout, b2);
+        putchar('\n');
+        BN_print_fp(stdout, b3);
+        putchar('\n');
+        BN_print_fp(stdout, b4);
+        putchar('\n');
+        BN_print_fp(stdout, b5);
+        putchar('\n');
+    }
+
+ done:
+    OPENSSL_assert(success);
+
+    return 0;
+}
-- 
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