diff -up scrub-2.6.1/configure.ac.libgcrypt scrub-2.6.1/configure.ac

--- scrub-2.6.1/configure.ac.libgcrypt	2014-08-26 14:15:12.000000000 -0400

+++ scrub-2.6.1/configure.ac	2021-02-22 13:42:48.489217200 -0500

@@ -70,6 +70,25 @@ AC_CHECK_FUNCS( \

 X_AC_CHECK_PTHREADS

 ##

+# gcrypt library

+##

+have_libgcrypt=no

+AC_ARG_WITH(libgcrypt, AS_HELP_STRING([--without-libgcrypt], [build without libgcrypt;

+                                         fallback to custom AES implementation]))

+AS_IF([test "x$with_libgcrypt" != "xno"],

+  [AM_PATH_LIBGCRYPT([1.5.0],

+    [AC_DEFINE([HAVE_LIBGCRYPT], [1], [libgcrypt API available])

+      gcrypt_CFLAGS="$LIBGCRYPT_CFLAGS"

+      gcrypt_LIBS="$LIBGCRYPT_LIBS"

+      have_libgcrypt=yes

+    ]

+  )]

+)

+AM_CONDITIONAL([LIBGCRYPT], [test "$have_libgcrypt" = "yes"])

+AC_SUBST([gcrypt_CFLAGS])

+AC_SUBST([gcrypt_LIBS])

+

+##

 # Arrange for large file support

 ## 

 AC_SYS_LARGEFILE

diff -up scrub-2.6.1/src/genrand.c.libgcrypt scrub-2.6.1/src/genrand.c

--- scrub-2.6.1/src/genrand.c.libgcrypt	2014-08-20 17:33:43.000000000 -0400

+++ scrub-2.6.1/src/genrand.c	2021-02-22 13:42:48.490217204 -0500

@@ -37,21 +37,27 @@

 #include <assert.h>

 #include <libgen.h>

-#include "aes.h"

 #include "util.h"

 #include "genrand.h"

 #include "hwrand.h"

-#define PATH_URANDOM    "/dev/urandom"

-

-#define PAYLOAD_SZ  16

-#define KEY_SZ      16

+#ifdef HAVE_LIBGCRYPT

+#include <gcrypt.h>

+#else

+#include "aes.h"

+#endif /* HAVE_LIBGCRYPT. */

 extern char *prog;

 static bool no_hwrand = false;

 static hwrand_t gen_hwrand;

+#ifndef HAVE_LIBGCRYPT

+#define PATH_URANDOM    "/dev/urandom"

+

+#define PAYLOAD_SZ  16

+#define KEY_SZ      16

+

 static aes_context  ctx;

 static unsigned char ctr[PAYLOAD_SZ];

@@ -140,17 +146,26 @@ churnrand(void)

 error:

     return -1;

 }

+#endif /* HAVE_LIBGCRYPT. */

 /* Initialize the module.

  */

 int

 initrand(void)

 {

+#ifndef HAVE_LIBGCRYPT

     struct timeval tv;

+#else

+    if (!gcry_check_version(GCRYPT_VERSION)) {

+        goto error;

+    }

+    gcry_control(GCRYCTL_INITIALIZATION_FINISHED, 0);

+#endif /* HAVE_LIBGCRYPT */

     if (!no_hwrand)

         gen_hwrand = init_hwrand();

+#ifndef HAVE_LIBGCRYPT

     /* Always initialize the software random number generator as backup */

     if (gettimeofday(&tv, NULL) < 0)

@@ -163,6 +178,7 @@ initrand(void)

 #endif

     if (churnrand() < 0)

         goto error;

+#endif /* HAVE_LIBGCRYPT. */

     return 0;

 error:

     return -1;

@@ -173,9 +189,11 @@ error:

 void 

 genrand(unsigned char *buf, int buflen)

 {

+#ifndef HAVE_LIBGCRYPT

     int i;

     unsigned char out[PAYLOAD_SZ];

     int cpylen = PAYLOAD_SZ;

+#endif /* HAVE_LIBGCRYPT. */

     if (gen_hwrand) {

         bool hwok = gen_hwrand(buf, buflen);

@@ -183,6 +201,7 @@ genrand(unsigned char *buf, int buflen)

             return;

     }

+#ifndef HAVE_LIBGCRYPT

     for (i = 0; i < buflen; i += cpylen) {

         aes_encrypt(&ctx, ctr, out);

         incr128(ctr);

@@ -191,6 +210,9 @@ genrand(unsigned char *buf, int buflen)

         memcpy(&buf[i], out, cpylen);

     }

     assert(i == buflen);

+#else

+    gcry_randomize(buf, buflen, GCRY_STRONG_RANDOM);

+#endif /* HAVE_LIBGCRYPT. */

 }

 /*

diff -up scrub-2.6.1/src/genrand.h.libgcrypt scrub-2.6.1/src/genrand.h

--- scrub-2.6.1/src/genrand.h.libgcrypt	2014-08-20 17:33:43.000000000 -0400

+++ scrub-2.6.1/src/genrand.h	2021-02-22 13:42:48.490217204 -0500

@@ -1,8 +1,14 @@

+#include "config.h"

+

 void disable_hwrand(void);

 int initrand(void);

-int churnrand(void);

 void genrand(unsigned char *buf, int buflen);

+#ifndef HAVE_LIBGCRYPT

+int churnrand(void);

+#endif /* HAVE_LIBGCRYPT. */

+

+

 /*

  * vi:tabstop=4 shiftwidth=4 expandtab

  */

diff -up scrub-2.6.1/src/Makefile.am.libgcrypt scrub-2.6.1/src/Makefile.am

--- scrub-2.6.1/src/Makefile.am.libgcrypt	2014-08-20 17:33:43.000000000 -0400

+++ scrub-2.6.1/src/Makefile.am	2021-02-22 13:43:47.008492696 -0500

@@ -1,8 +1,6 @@

 bin_PROGRAMS = scrub

 scrub_SOURCES = \

-	aes.c \

-	aes.h \

 	filldentry.c \

 	filldentry.h \

 	fillfile.c \

@@ -24,3 +22,9 @@ scrub_SOURCES = \

 	util.h

 scrub_LDADD = $(LIBPTHREAD)

+

+if LIBGCRYPT

+scrub_LDADD += $(gcrypt_LIBS)

+else

+scrub_SOURCES += aes.c aes.h

+endif

diff -up scrub-2.6.1/src/scrub.c.libgcrypt scrub-2.6.1/src/scrub.c

--- scrub-2.6.1/src/scrub.c.libgcrypt	2021-02-22 13:42:48.488217195 -0500

+++ scrub-2.6.1/src/scrub.c	2021-02-22 13:42:48.490217204 -0500

@@ -459,11 +459,13 @@ scrub(char *path, off_t size, const sequ

             case PAT_RANDOM:

                 printf("%s: %-8s", prog, "random");

                 progress_create(&p, pcol);

+#ifndef HAVE_LIBGCRYPT

                 if (churnrand() < 0) {

                     fprintf(stderr, "%s: churnrand: %s\n", prog,

                              strerror(errno));

                     exit(1);

                 }

+#endif /* HAVE_LIBGCRYPT. */

                 written = fillfile(path, size, buf, bufsize, 

                                    (progress_t)progress_update, p, 

                                    (refill_t)genrand, sparse, enospc);

diff -up scrub-2.6.1/test/Makefile.am.libgcrypt scrub-2.6.1/test/Makefile.am

--- scrub-2.6.1/test/Makefile.am.libgcrypt	2014-08-26 14:11:14.000000000 -0400

+++ scrub-2.6.1/test/Makefile.am	2021-02-22 13:44:59.301833042 -0500

@@ -1,8 +1,8 @@

-check_PROGRAMS = pad trand aestest tprogress tgetsize tsig tsize pat

+check_PROGRAMS = pad trand tprogress tgetsize tsig tsize pat

 TESTS_ENVIRONMENT = env 

 TESTS_ENVIRONMENT += "PATH_SCRUB=$(top_builddir)/src/scrub"

-TESTS = t00 t01 t02 t03 t04 t05 t06 t07 t08 t09 t10 t11 t12 t13 t14 t15 t16 \

+TESTS = t01 t02 t03 t04 t05 t06 t07 t08 t09 t10 t11 t12 t13 t14 t15 t16 \

 	t17 t18 t19 t20 t21 t22

 CLEANFILES = *.out *.diff testfile

@@ -13,17 +13,24 @@ common_sources = \

 	$(top_srcdir)/src/getsize.c \

 	$(top_srcdir)/src/genrand.c \

 	$(top_srcdir)/src/hwrand.c \

-	$(top_srcdir)/src/aes.c \

 	$(top_srcdir)/src/util.c \

 	$(top_srcdir)/src/progress.c \

 	$(top_srcdir)/src/sig.c

 pad_SOURCES = pad.c $(common_sources)

 trand_SOURCES = trand.c $(common_sources)

-aestest_SOURCES = aestest.c $(common_sources)

 tprogress_SOURCES = tprogress.c $(common_sources)

 tgetsize_SOURCES = tgetsize.c $(common_sources)

 tsig_SOURCES = tsig.c $(common_sources)

 pat_SOURCES = pat.c $(common_sources)

+if LIBGCRYPT

+AM_LDFLAGS = $(gcrypt_LIBS)

+else

+check_PROGRAMS += aestest

+TESTS += t00

+common_sources += $(top_srcdir)/src/aes.c

+aestest_SOURCES = aestest.c $(common_sources)

+endif

+

 EXTRA_DIST = $(TESTS) $(TESTS:%=%.exp)