Small improvements to rsa-encrypt and rsa-decrypt example programs.

diff --git a/ChangeLog b/ChangeLog
index c9e27101a95b486416c02c9dd0bec7c528d299d5..06167790d059806c9cdb2b6702ff5c08fe7201f8 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,12 @@
 2012-04-14  Niels Möller  <nisse@lysator.liu.se>
 
+       * examples/rsa-encrypt.c (process_file): Reorganized fread loop.
+       (usage): New function.
+       (main): Implemented --help option.
+
+       * examples/rsa-decrypt.c (process_file): Improved error message
+       for too short input file.
+
        * aes-set-decrypt-key.c (gf2_log, gf2_exp): Deleted tables.
        (mult, inv_mix_column): Deleted functions.
        (mtable): New table.

diff --git a/examples/rsa-decrypt.c b/examples/rsa-decrypt.c
index 7a92a71cc30a3970222357a5a4901badbb1a0521..fbd6d73631454367abbf8f55d43faf92279c2804 100644 (file)
--- a/examples/rsa-decrypt.c
+++ b/examples/rsa-decrypt.c
@@ -123,9 +123,12 @@ process_file(struct rsa_session *ctx,
   unsigned padding;
 
   size = fread(buffer, 1, BUF_FINAL, in);
-  if (size < BUF_FINAL || ferror(in))
+  if (size < BUF_FINAL)
     {
-      werror("Reading input failed: %s\n", strerror(errno));
+      if (ferror(in))
+       werror("Reading input failed: %s\n", strerror(errno));
+      else
+       werror("Unexpected EOF on input.\n");
       return 0;
     }
 
@@ -133,7 +136,7 @@ process_file(struct rsa_session *ctx,
     {
       size = fread(buffer + BUF_FINAL, 1, BUF_SIZE, in);
 
-      if (ferror(in))
+      if (size < BUF_SIZE && ferror(in))
        {
          werror("Reading input failed: %s\n", strerror(errno));
          return 0;

diff --git a/examples/rsa-encrypt.c b/examples/rsa-encrypt.c
index c8cf48062e15f1c7fbcfde58c2a1c85c43f2164c..14f253e9e7eaaa72aec80824357acea4362c640f 100644 (file)
--- a/examples/rsa-encrypt.c
+++ b/examples/rsa-encrypt.c
@@ -26,6 +26,7 @@
 # include "config.h"
 #endif
 
+#include <assert.h>
 #include <ctype.h>
 #include <errno.h>
 #include <stdlib.h>
@@ -93,35 +94,54 @@ write_bignum(FILE *f, mpz_t x)
   return res;
 }
 
+#define BLOCK_SIZE (AES_BLOCK_SIZE * 100)
+
 static int
 process_file(struct rsa_session *ctx,
             FILE *in, FILE *out)
 {
-  uint8_t buffer[AES_BLOCK_SIZE * 100];
-  unsigned leftover;
-  unsigned padding;
-
-  padding = leftover = 0;
+  uint8_t buffer[BLOCK_SIZE + SHA1_DIGEST_SIZE];
 
   for (;;)
     {
-      size_t size = fread(buffer, 1, sizeof(buffer), in);
-      if (ferror(in))
-       {
-         werror("Reading input failed: %s\n", strerror(errno));
-         return 0;
-       }
-
+      size_t size = fread(buffer, 1, BLOCK_SIZE, in);
       hmac_sha1_update(&ctx->hmac, size, buffer);
-      if (size < sizeof(buffer))
+
+      if (size < BLOCK_SIZE)
        {
-         /* Setting padding != ends the loop */
+         unsigned leftover;
+         unsigned padding;
+
+         if (ferror(in))
+           {
+             werror("Reading input failed: %s\n", strerror(errno));
+             return 0;
+           }
+         
          leftover = size % AES_BLOCK_SIZE;
          padding = AES_BLOCK_SIZE - leftover;
-         size -= leftover;
 
-         if (!size)
-           break;
+         assert (size + padding <= BLOCK_SIZE);
+         
+         if (padding > 1)
+           yarrow256_random(&ctx->yarrow, padding - 1, buffer + size);
+
+         size += padding;
+
+         buffer[size - 1] = padding;
+         CBC_ENCRYPT(&ctx->aes, aes_encrypt, size, buffer, buffer);
+
+         assert (size + SHA1_DIGEST_SIZE <= sizeof(buffer));
+
+         hmac_sha1_digest(&ctx->hmac, SHA1_DIGEST_SIZE, buffer + size);
+         size += SHA1_DIGEST_SIZE;
+
+         if (!write_string(out, size, buffer))
+           {
+             werror("Writing output failed: %s\n", strerror(errno));
+             return 0;
+           }
+         return 1;
        }
 
       CBC_ENCRYPT(&ctx->aes, aes_encrypt, size, buffer, buffer);
@@ -130,29 +150,16 @@ process_file(struct rsa_session *ctx,
          werror("Writing output failed: %s\n", strerror(errno));
          return 0;
        }
-
-      if (padding)
-       {
-         if (leftover)
-           memcpy(buffer, buffer + size, leftover);
-
-         break;
-       }
-    }
-  if (padding > 1)
-    yarrow256_random(&ctx->yarrow, padding - 1, buffer + leftover);
-
-  buffer[AES_BLOCK_SIZE - 1] = padding;
-  CBC_ENCRYPT(&ctx->aes, aes_encrypt, AES_BLOCK_SIZE, buffer, buffer);
-  hmac_sha1_digest(&ctx->hmac, SHA1_DIGEST_SIZE, buffer + AES_BLOCK_SIZE);
-
-  if (!write_string(out, AES_BLOCK_SIZE + SHA1_DIGEST_SIZE, buffer))
-    {
-      werror("Writing output failed: %s\n", strerror(errno));
-      return 0;
     }
+}
 
-  return 1;
+static void
+usage (FILE *out)
+{
+  fprintf (out, "Usage: rsa-encrypt [OPTIONS] PUBLIC-KEY < cleartext\n"
+          "Options:\n"
+          "   -r, --random=FILE   seed file for randomness generator\n"
+          "       --help          display this help\n");  
 }
 
 int
@@ -167,8 +174,17 @@ main(int argc, char **argv)
   int c;
   const char *random_name = NULL;
 
-  /* FIXME: --help option. */
-  while ( (c = getopt(argc, argv, "o:r:")) != -1)
+  enum { OPT_HELP = 300 };
+  
+  static const struct option options[] =
+    {
+      /* Name, args, flag, val */
+      { "help", no_argument, NULL, OPT_HELP },
+      { "random", required_argument, NULL, 'r' },
+      { NULL, 0, NULL, 0}
+    };
+  
+  while ( (c = getopt_long(argc, argv, "o:r:", options, NULL)) != -1)
     switch (c)
       {
       case 'r':
@@ -178,6 +194,9 @@ main(int argc, char **argv)
       case '?':
        return EXIT_FAILURE;
 
+      case OPT_HELP:
+       usage(stdout);
+       return EXIT_SUCCESS;
       default:
        abort();
       }
@@ -187,7 +206,7 @@ main(int argc, char **argv)
 
   if (argc != 1)
     {
-      werror("Usage: rsa-encrypt [-r random-file] PUBLIC-KEY < cleartext\n");
+      usage (stderr);
       return EXIT_FAILURE;
     }