add aesgcm demo

yeah I know, it's GNU specific, therefore it's also only added to the
GNU makefiles

.gitignore

@@ -22,6 +22,8 @@ doc/crypt.pdf
 doc/refman.pdf
 
 # *nix/windows test executables
+aesgcm
+aesgcm.exe
 constants
 constants.exe
 ltcrypt

demos/aesgcm.c

@@ -0,0 +1,146 @@
+/* LibTomCrypt, modular cryptographic library -- Tom St Denis
+ *
+ * LibTomCrypt is a library that provides various cryptographic
+ * algorithms in a highly modular and flexible manner.
+ *
+ * The library is free for all purposes without any express
+ * guarantee it works.
+ */
+
+/**
+  @file aesgcm.c
+  AES128-GCM demo - file en-&decryption, Steffen Jaeckel
+  Uses the format: |ciphertext|tag-16-bytes|
+*/
+
+#define _GNU_SOURCE
+
+#include <tomcrypt.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <dirent.h>
+#include <string.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#include "gcm-file/gcm_filehandle.c"
+#include "gcm-file/gcm_file.c"
+
+
+static off_t fsize(const char *filename)
+{
+   struct stat st;
+
+   if (stat(filename, &st) == 0) return st.st_size;
+
+   return -1;
+}
+
+static int mv(const char *old_name, const char *new_name)
+{
+   int fd;
+   if (rename(old_name, new_name) == -1) return -1;
+   fd = open(new_name, 0);
+   if (fd == -1) return -1;
+   if (fsync(fd) != 0) goto OUT;
+   syncfs(fd);
+OUT:
+   close(fd);
+   return 0;
+}
+
+/* https://stackoverflow.com/a/23898449 */
+static void scan_hex(const char* str, uint8_t* bytes, size_t blen)
+{
+   uint8_t  pos;
+   uint8_t  idx0;
+   uint8_t  idx1;
+
+   const uint8_t hashmap[] =
+   {
+     0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, /* 01234567 */
+     0x08, 0x09, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 89:;<=>? */
+     0x00, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x00, /* @ABCDEFG */
+     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* HIJKLMNO */
+     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* PQRSTUVW */
+     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* XYZ[\]^_ */
+     0x00, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x00, /* `abcdefg */
+   };
+
+   for (pos = 0; ((pos < (blen*2)) && (pos < strlen(str))); pos += 2)
+   {
+      idx0 = (uint8_t)(str[pos+0] & 0x1F) ^ 0x10;
+      idx1 = (uint8_t)(str[pos+1] & 0x1F) ^ 0x10;
+      bytes[pos/2] = (uint8_t)(hashmap[idx0] << 4) | hashmap[idx1];
+   }
+}
+
+static void die(int ret)
+{
+   fprintf(stderr, "Usage: aesgcm <-e|-d> <infile> <outfile> <96 char hex-string 'IV | key'>\n");
+   exit(ret);
+}
+
+int main(int argc, char **argv)
+{
+   int ret = 0, err, arg, direction, res, tmp;
+   size_t keylen;
+   uint8_t keybuf[48] = {0};
+   char *out = NULL;
+   const char *mode, *in_file, *out_file, *key_string;
+
+   if (argc < 5) die(__LINE__);
+
+   arg = 1;
+   mode = argv[arg++];
+   in_file = argv[arg++];
+   out_file = argv[arg++];
+   key_string = argv[arg++];
+
+   if(strcmp(mode, "-d") == 0) direction = GCM_DECRYPT;
+   else if(strcmp(mode, "-e") == 0) direction = GCM_ENCRYPT;
+   else die(__LINE__);
+
+   if (fsize(in_file) <= 0) die(__LINE__);
+
+   keylen = strlen(key_string);
+   if (keylen != 96) die(__LINE__);
+
+   scan_hex(key_string, keybuf, sizeof(keybuf));
+
+   register_all_ciphers();
+
+   if(asprintf(&out, "%s-XXXXXX", out_file) < 0) die(__LINE__);
+   if((tmp = mkstemp(out)) == -1) {
+      ret = __LINE__;
+      goto cleanup;
+   }
+   close(tmp);
+   if((err = gcm_file(find_cipher("aes"), &keybuf[16], 32, keybuf, 16, NULL, 0, in_file, out, 16, direction, &res)) != CRYPT_OK) {
+      fprintf(stderr, "boooh %s\n", error_to_string(err));
+      ret = __LINE__;
+      goto cleanup;
+   }
+
+   if(res != 1) {
+      ret = __LINE__;
+   }
+   else
+   {
+      if (mv(out, out_file) != 0) ret = __LINE__;
+   }
+
+cleanup:
+   if(ret != 0) unlink(out);
+   free(out);
+
+
+   return ret;
+}
+
+/* ref:         $Format:%D$ */
+/* git commit:  $Format:%H$ */
+/* commit time: $Format:%ai$ */

makefile_include.mk

@@ -147,9 +147,10 @@ USEABLE_DEMOS  = ltcrypt sizes constants
 TEST_DEMOS     = small tv_gen
 
 # Demos that are in one config broken
-#  openssl-enc - can't be build with LTC_EASY
+#  aesgcm      - can't be built with LTC_EASY
+#  openssl-enc - can't be built with LTC_EASY
 #  timing      - not really broken, but older gcc builds spit warnings
-BROKEN_DEMOS   = openssl-enc timing
+BROKEN_DEMOS   = aesgcm openssl-enc timing
 
 # Combine demos in groups
 UNBROKEN_DEMOS = $(TEST_DEMOS) $(USEABLE_DEMOS) $(USEFUL_DEMOS)