Bring back the X9.31 padding helpers

Nothing should be using this anymore, except that salt decided to use
it in its home-cooked protocol, which already had its share of issues.
Hopefully the efforts to switch salt to something more reasonable and
standardized like mTLS will succeed sooner rather than later.

tested as part of a larger patch by robert
ok jsing

diff --git a/lib/libcrypto/rsa/rsa_x931.c b/lib/libcrypto/rsa/rsa_x931.c
new file mode 100644 (file)
index 0000000..52f3f80
--- /dev/null
+++ b/lib/libcrypto/rsa/rsa_x931.c
@@ -0,0 +1,164 @@
+/* $OpenBSD: rsa_x931.c,v 1.12 2023/05/05 12:19:37 tb Exp $ */
+/* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
+ * project 2005.
+ */
+/* ====================================================================
+ * Copyright (c) 2005 The OpenSSL Project.  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.
+ *
+ * 3. All advertising materials mentioning features or use of this
+ *    software must display the following acknowledgment:
+ *    "This product includes software developed by the OpenSSL Project
+ *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
+ *
+ * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
+ *    endorse or promote products derived from this software without
+ *    prior written permission. For written permission, please contact
+ *    licensing@OpenSSL.org.
+ *
+ * 5. Products derived from this software may not be called "OpenSSL"
+ *    nor may "OpenSSL" appear in their names without prior written
+ *    permission of the OpenSSL Project.
+ *
+ * 6. Redistributions of any form whatsoever must retain the following
+ *    acknowledgment:
+ *    "This product includes software developed by the OpenSSL Project
+ *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
+ * EXPRESSED 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 OpenSSL PROJECT OR
+ * ITS CONTRIBUTORS 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.
+ * ====================================================================
+ *
+ * This product includes cryptographic software written by Eric Young
+ * (eay@cryptsoft.com).  This product includes software written by Tim
+ * Hudson (tjh@cryptsoft.com).
+ *
+ */
+
+#include <stdio.h>
+#include <string.h>
+
+#include <openssl/bn.h>
+#include <openssl/err.h>
+#include <openssl/objects.h>
+#include <openssl/rsa.h>
+
+int
+RSA_padding_add_X931(unsigned char *to, int tlen, const unsigned char *from,
+    int flen)
+{
+       int j;
+       unsigned char *p;
+
+       /*
+        * Absolute minimum amount of padding is 1 header nibble, 1 padding
+        * nibble and 2 trailer bytes: but 1 hash if is already in 'from'.
+        */
+       j = tlen - flen - 2;
+
+       if (j < 0) {
+               RSAerror(RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
+               return -1;
+       }
+
+       p = (unsigned char *)to;
+
+       /* If no padding start and end nibbles are in one byte */
+       if (j == 0)
+               *p++ = 0x6A;
+       else {
+               *p++ = 0x6B;
+               if (j > 1) {
+                       memset(p, 0xBB, j - 1);
+                       p += j - 1;
+               }
+               *p++ = 0xBA;
+       }
+       memcpy(p, from, flen);
+       p += flen;
+       *p = 0xCC;
+       return 1;
+}
+
+int
+RSA_padding_check_X931(unsigned char *to, int tlen, const unsigned char *from,
+    int flen, int num)
+{
+       int i = 0, j;
+       const unsigned char *p = from;
+
+       if (num != flen || (*p != 0x6A && *p != 0x6B)) {
+               RSAerror(RSA_R_INVALID_HEADER);
+               return -1;
+       }
+
+       if (*p++ == 0x6B) {
+               j = flen - 3;
+               for (i = 0; i < j; i++) {
+                       unsigned char c = *p++;
+                       if (c == 0xBA)
+                               break;
+                       if (c != 0xBB) {
+                               RSAerror(RSA_R_INVALID_PADDING);
+                               return -1;
+                       }
+               }
+
+               if (i == 0) {
+                       RSAerror(RSA_R_INVALID_PADDING);
+                       return -1;
+               }
+
+               j -= i;
+       } else
+               j = flen - 2;
+
+       if (j < 0 || p[j] != 0xCC) {
+               RSAerror(RSA_R_INVALID_TRAILER);
+               return -1;
+       }
+
+       memcpy(to, p, j);
+
+       return j;
+}
+
+/* Translate between X931 hash ids and NIDs */
+
+int
+RSA_X931_hash_id(int nid)
+{
+       switch (nid) {
+       case NID_sha1:
+               return 0x33;
+       case NID_sha256:
+               return 0x34;
+       case NID_sha384:
+               return 0x36;
+       case NID_sha512:
+               return 0x35;
+       }
+
+       return -1;
+}