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gms/LG/sdkfreebsd64.bak/libs/libmcrypt-2.5.7/doc/example.c

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+/* First example: Encrypts stdin to stdout using TWOFISH with 128 bit key and CFB */
+
+#include <mcrypt.h>
+#include <stdio.h>
+#include <stdlib.h>
+/* #include <mhash.h> */
+
+main() {
+
+  MCRYPT td;
+  int i;
+  char *key;
+  char password[20];
+  char block_buffer;
+  char *IV;
+  int keysize=19; /* 128 bits */
+
+  key=calloc(1, keysize);
+  strcpy(password, "A_large_key");
+
+/* Generate the key using the password */
+/*  mhash_keygen( KEYGEN_MCRYPT, MHASH_MD5, key, keysize, NULL, 0, password, strlen(password));
+ */
+  memmove( key, password, strlen(password));
+
+  td = mcrypt_module_open("twofish", NULL, "cfb", NULL);
+  if (td==MCRYPT_FAILED) {
+     return 1;
+  }
+  IV = malloc(mcrypt_enc_get_iv_size(td));
+
+/* Put random data in IV. Note these are not real random data, 
+ * consider using /dev/random or /dev/urandom.
+ */
+
+  /*  srand(time(0)); */
+  for (i=0; i< mcrypt_enc_get_iv_size( td); i++) {
+    IV[i]=rand();
+  }
+
+  i=mcrypt_generic_init( td, key, keysize, IV);
+  if (i<0) {
+     mcrypt_perror(i);
+     return 1;
+  }
+
+  /* Encryption in CFB is performed in bytes */
+  while ( fread (&block_buffer, 1, 1, stdin) == 1 ) {
+      mcrypt_generic (td, &block_buffer, 1);
+
+/* Comment above and uncomment this to decrypt */
+/*    mdecrypt_generic (td, &block_buffer, 1);  */
+
+      fwrite ( &block_buffer, 1, 1, stdout);
+  }
+  mcrypt_generic_deinit(td);
+
+  mcrypt_module_close(td);
+
+  return 0;
+
+}
+
+#if 0
+/* Second Example: encrypts using CBC and SAFER+ with 192 bits key */
+
+#include <mcrypt.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+main() {
+
+  MCRYPT td;
+  int i;
+  char *key; /* created using mcrypt_gen_key */
+  char *block_buffer;
+  char *IV;
+  int blocksize;
+  int keysize = 24; /* 192 bits == 24 bytes */
+
+
+  key = calloc(1, keysize);
+  strcpy(key, "A_large_and_random_key"); 
+
+  td = mcrypt_module_open("saferplus", NULL, "cbc", NULL);
+
+  blocksize = mcrypt_enc_get_block_size(td);
+  block_buffer = malloc(blocksize);
+/* but unfortunately this does not fill all the key so the rest bytes are
+ * padded with zeros. Try to use large keys or convert them with mcrypt_gen_key().
+ */
+
+  IV=malloc(mcrypt_enc_get_iv_size(td));
+
+/* Put random data in IV. Note these are not real random data, 
+ * consider using /dev/random or /dev/urandom.
+ */
+
+/* srand(time(0)); */
+  for (i=0; i < mcrypt_enc_get_iv_size(td); i++) {
+    IV[i]=rand();
+  }
+
+  mcrypt_generic_init ( td key, keysize, IV);
+
+  /* Encryption in CBC is performed in blocks */
+  while ( fread (block_buffer, 1, blocksize, stdin) == blocksize ) {
+      mcrypt_generic (td, block_buffer, blocksize);
+/*      mdecrypt_generic (td, block_buffer, blocksize); */
+      fwrite ( block_buffer, 1, blocksize, stdout);
+  }
+  mcrypt_generic_end (td);
+
+  return 0;
+
+}
+
+#endif