New base64dec example program, based on code contributed by Jeronimo Pellegrini.

examples/Makefile.in

@@ -17,12 +17,12 @@ RSA_TARGETS = rsa-keygen$(EXEEXT) rsa-sign$(EXEEXT) \
 	      rsa-verify$(EXEEXT) rsa-encrypt$(EXEEXT) rsa-decrypt$(EXEEXT)
 
 TARGETS = nettle-benchmark$(EXEEXT) eratosthenes$(EXEEXT) \
-	  base64enc$(EXEEXT) @IF_HOGWEED@ $(RSA_TARGETS) next-prime$(EXEEXT) random-prime$(EXEEXT)
+	  base64enc$(EXEEXT) base64dec$(EXEEXT) @IF_HOGWEED@ $(RSA_TARGETS) next-prime$(EXEEXT) random-prime$(EXEEXT)
 SOURCES = nettle-benchmark.c eratosthenes.c next-prime.c random-prime.c \
 	nettle-openssl.c \
 	io.c read_rsa_key.c \
 	rsa-encrypt.c rsa-decrypt.c rsa-keygen.c rsa-sign.c rsa-verify.c \
-	base64enc.c
+	base64enc.c base64dec.c
 
 
 GETOPT_OBJS = ../getopt.$(OBJEXT) ../getopt1.$(OBJEXT)
@@ -74,6 +74,10 @@ base64enc$(EXEEXT): base64enc.$(OBJEXT) io.$(OBJEXT)
 	$(LINK) base64enc.$(OBJEXT) io.$(OBJEXT) \
 	-lnettle $(LIBS) -o base64enc$(EXEEXT)
 
+base64dec$(EXEEXT): base64dec.$(OBJEXT) io.$(OBJEXT)
+	$(LINK) base64dec.$(OBJEXT) io.$(OBJEXT) \
+	-lnettle $(LIBS) -o base64dec$(EXEEXT)
+
 eratosthenes$(EXEEXT): eratosthenes.$(OBJEXT) $(GETOPT_OBJS)
 	$(LINK) eratosthenes.$(OBJEXT) $(GETOPT_OBJS) -o eratosthenes$(EXEEXT)
 

examples/base64dec.c

+/* base64dec -- an decoder for base64
+ *
+ * Copyright (C) 2006, 2012 Jeronimo Pellegrini, Niels Möller
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2.1 of the License, or (at your
+ * option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
+ * License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with the nettle library; see the file COPYING.LIB.  If not, write to
+ * the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+ * MA 02111-1307, USA.
+ */
+
+#if HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include <errno.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+#include <nettle/base64.h>
+
+#include "io.h"
+
+#define CHUNK_SIZE 16392
+
+/* The maximum number of bytes generated for each chunk: */
+#define DECODED_SIZE BASE64_DECODE_LENGTH(CHUNK_SIZE)
+
+
+/*
+ * Reads base-64 encoded from stdin, writes decoded to stdout.
+ */
+int
+main(int argc UNUSED, char **argv UNUSED)
+{
+  /* "buffer" will hold the bytes from disk: */
+  uint8_t * buffer = xalloc (CHUNK_SIZE);
+
+  /* "result" will hold bytes before output: */
+  uint8_t * result = xalloc (DECODED_SIZE);
+
+  /* We need a Base64 context for decoding: */
+  struct base64_decode_ctx b64_ctx;
+
+  /* Init the context: */
+  base64_decode_init(&b64_ctx);
+
+#ifdef WIN32
+  _setmode(1, O_BINARY);
+#endif
+
+  for (;;)
+    {
+      int nbytes; /* Number of bytes read frmo disk at each iteration */
+      unsigned decoded_bytes; /* Bytes actually generated at each iteration */
+
+      nbytes = fread(buffer, 1, CHUNK_SIZE, stdin);
+
+      if (nbytes < CHUNK_SIZE && ferror(stdin))
+	{
+	  werror ("Error reading file: %s\n", strerror(errno));
+	  return EXIT_FAILURE;
+	}
+
+      decoded_bytes = BASE64_DECODE_LENGTH(nbytes);
+
+      /* Decodes one chunk: */
+      if (!base64_decode_update(&b64_ctx, &decoded_bytes, result, nbytes, buffer))
+	{
+	  werror ("Error decoding input (not base64?)\n");
+	  return EXIT_FAILURE;
+	}
+
+      if (!write_string (stdout, decoded_bytes, result))
+	{
+	  werror ("Error writing file: %s\n", strerror(errno));
+	  return EXIT_FAILURE;
+	}
+
+      if (nbytes < CHUNK_SIZE)
+	{
+	  /* Check if decoding finalized OK: */
+	  if (!base64_decode_final(&b64_ctx))
+	    {
+	      werror ("Decoding did not finish properly.\n");
+	      return EXIT_FAILURE;
+	    }
+	  break;
+	}
+    }
+
+  if (fflush (stdout) != 0)
+    {
+      werror ("Error writing file: %s\n", strerror(errno));
+      return EXIT_FAILURE;
+    }
+
+  free (buffer);
+  free (result);
+
+  return EXIT_SUCCESS;
+}