File libgcrypt-rsa-no-blinding.patch of Package libgcrypt.14858

--- libgcrypt-1.8.2.orig/cipher/rsa.c	2020-03-26 07:23:17.392861551 +0100
+++ libgcrypt-1.8.2.orig/cipher/rsa.c	2020-03-26 15:43:29.556282072 +0100
@@ -91,10 +91,16 @@ static const char sample_secret_key[] =
 "       79C974A6FA69E4D52FE796650623DE70622862713932AA2FD9F2EC856EAEAA77"
 "       88B4EA6084DC81C902F014829B18EA8B2666EC41586818E0589E18876065F97E"
 "       8D22CE2DA53A05951EC132DCEF41E70A9C35F4ACC268FFAC2ADF54FA1DA110B919#)"
+"))";
+/* We need to get rid of the u value, in order to end in
+ * secret_core_std when called from secret. It's not used anyway. */
+
+/*
 "   (u #67CF0FD7635205DD80FA814EE9E9C267C17376BF3209FB5D1BC42890D2822A04"
 "       479DAF4D5B6ED69D0F8D1AF94164D07F8CD52ECEFE880641FA0F41DDAB1785E4"
 "       A37A32F997A516480B4CD4F6482B9466A1765093ED95023CA32D5EDC1E34CEE9"
 "       AF595BC51FE43C4BF810FA225AF697FB473B83815966188A4312C048B885E3F7#)))";
+*/
 
 /* A sample 2048 bit RSA key used for the selftests (public only).  */
 static const char sample_public_key[] =
@@ -1252,8 +1258,8 @@ rsa_check_secret_key (gcry_sexp_t keypar
   RSA_secret_key sk = {NULL, NULL, NULL, NULL, NULL, NULL};
 
   /* To check the key we need the optional parameters. */
-  rc = sexp_extract_param (keyparms, NULL, "nedpqu",
-                           &sk.n, &sk.e, &sk.d, &sk.p, &sk.q, &sk.u,
+  rc = sexp_extract_param (keyparms, NULL, "npq",
+                           &sk.n, &sk.p, &sk.q,
                            NULL);
   if (rc)
     goto leave;
@@ -1263,11 +1269,8 @@ rsa_check_secret_key (gcry_sexp_t keypar
 
  leave:
   _gcry_mpi_release (sk.n);
-  _gcry_mpi_release (sk.e);
-  _gcry_mpi_release (sk.d);
   _gcry_mpi_release (sk.p);
   _gcry_mpi_release (sk.q);
-  _gcry_mpi_release (sk.u);
   if (DBG_CIPHER)
     log_debug ("rsa_testkey    => %s\n", gpg_strerror (rc));
   return rc;
@@ -1710,11 +1713,11 @@ static const char *
 selftest_sign_2048 (gcry_sexp_t pkey, gcry_sexp_t skey)
 {
   static const char sample_data[] =
-    "(data (flags pkcs1)"
+    "(data (flags pkcs1 no-blinding)"
     " (hash sha256 #11223344556677889900aabbccddeeff"
     /**/           "102030405060708090a0b0c0d0f01121#))";
   static const char sample_data_bad[] =
-    "(data (flags pkcs1)"
+    "(data (flags pkcs1 no-blinding)"
     " (hash sha256 #11223344556677889900aabbccddeeff"
     /**/           "802030405060708090a0b0c0d0f01121#))";
 
@@ -1857,7 +1860,7 @@ selftest_encr_2048 (gcry_sexp_t pkey, gc
   gcry_mpi_t ref_mpi = NULL;
 
   /* Put the plaintext into an S-expression.  */
-  err = sexp_build (&plain, NULL, "(data (flags raw) (value %s))", plaintext);
+  err = sexp_build (&plain, NULL, "(data (flags raw no-blinding) (value %s))", plaintext);
   if (err)
     {
       errtxt = "converting data failed";
@@ -1897,6 +1900,26 @@ selftest_encr_2048 (gcry_sexp_t pkey, gc
       goto leave;
     }
 
+  /* This sexp trickery is to prevent the use of blinding.
+   * The flag doesn't get inherited by encr, so we have to
+   * derive a new sexp from the ciphertext */
+  char buf[1024];
+  memset(buf, 0, sizeof(buf));
+  err = _gcry_mpi_print (GCRYMPI_FMT_STD, buf, sizeof buf, NULL, ciphertext);
+  if (err)
+    {
+      errtxt = "Dumping ciphertext mpi to buffer failed";
+      goto leave;
+    }
+
+  sexp_release (encr);
+  err = sexp_build (&encr, NULL, "(enc-val (flags no-blinding) (rsa (a %s)))", buf);
+  if (err)
+    {
+      errtxt = "Adding no-blinding flag to ciphertext failed";
+      goto leave;
+    }
+
   /* Decrypt.  */
   err = _gcry_pk_decrypt (&decr, encr, skey);
   if (err)