Thu Oct 11 06:48:56 2012

Asterisk developer's documentation


func_aes.c File Reference

AES encryption/decryption dialplan functions. More...

#include "asterisk.h"
#include "asterisk/module.h"
#include "asterisk/pbx.h"
#include "asterisk/app.h"
#include "asterisk/aes.h"

Include dependency graph for func_aes.c:

Go to the source code of this file.

Defines

#define AES_BLOCK_SIZE   16

Functions

static void __reg_module (void)
static void __unreg_module (void)
static int aes_helper (struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
static int load_module (void)
static int unload_module (void)

Variables

static struct ast_module_info __mod_info = { .name = AST_MODULE, .flags = AST_MODFLAG_DEFAULT , .description = "AES dialplan functions" , .key = "This paragraph is copyright (c) 2006 by Digium, Inc. \In order for your module to load, it must return this \key via a function called \"key\". Any code which \includes this paragraph must be licensed under the GNU \General Public License version 2 or later (at your \option). In addition to Digium's general reservations \of rights, Digium expressly reserves the right to \allow other parties to license this paragraph under \different terms. Any use of Digium, Inc. trademarks or \logos (including \"Asterisk\" or \"Digium\") without \express written permission of Digium, Inc. is prohibited.\n" , .buildopt_sum = AST_BUILDOPT_SUM, .load = load_module, .unload = unload_module, }
static struct ast_custom_function aes_decrypt_function
static struct ast_custom_function aes_encrypt_function
static struct ast_module_infoast_module_info = &__mod_info


Detailed Description

AES encryption/decryption dialplan functions.

Author:
David Vossel <dvossel@digium.com>

Definition in file func_aes.c.


Define Documentation

#define AES_BLOCK_SIZE   16

Definition at line 35 of file func_aes.c.

Referenced by aes_helper().


Function Documentation

static void __reg_module ( void   )  [static]

Definition at line 173 of file func_aes.c.

static void __unreg_module ( void   )  [static]

Definition at line 173 of file func_aes.c.

static int aes_helper ( struct ast_channel chan,
const char *  cmd,
char *  data,
char *  buf,
size_t  len 
) [static]

Definition at line 83 of file func_aes.c.

References AES_BLOCK_SIZE, ast_aes_decrypt, ast_aes_decrypt_key, ast_aes_encrypt, ast_aes_encrypt_key, AST_APP_ARG, ast_base64decode(), ast_base64encode(), ast_calloc, ast_copy_string(), AST_DECLARE_APP_ARGS, ast_free, ast_log(), AST_STANDARD_APP_ARGS, ast_strlen_zero(), and LOG_WARNING.

00085 {
00086    unsigned char curblock[AES_BLOCK_SIZE] = { 0, };
00087    char *tmp;
00088    char *tmpP;
00089    int data_len, encrypt;
00090    ast_aes_encrypt_key ecx;                        /*  AES 128 Encryption context */
00091    ast_aes_decrypt_key dcx;
00092 
00093    AST_DECLARE_APP_ARGS(args,
00094       AST_APP_ARG(key);
00095       AST_APP_ARG(data);
00096    );
00097 
00098    AST_STANDARD_APP_ARGS(args, data);
00099 
00100    if (ast_strlen_zero(args.data) || ast_strlen_zero(args.key)) {
00101       ast_log(LOG_WARNING, "Syntax: %s(<key>,<data>) - missing argument!\n", cmd);
00102       return -1;
00103    }
00104 
00105    if (strlen(args.key) != AES_BLOCK_SIZE) {        /* key must be of 16 characters in length, 128 bits */
00106       ast_log(LOG_WARNING, "Syntax: %s(<key>,<data>) - <key> parameter must be exactly 16 characters!\n", cmd);
00107       return -1;
00108    }
00109 
00110    ast_aes_encrypt_key((unsigned char *) args.key, &ecx);   /* encryption:  plaintext -> encryptedtext -> base64 */
00111    ast_aes_decrypt_key((unsigned char *) args.key, &dcx);   /* decryption:  base64 -> encryptedtext -> plaintext */
00112    tmp = ast_calloc(1, len);                     /* requires a tmp buffer for the base64 decode */
00113    tmpP = tmp;
00114    encrypt = strcmp("AES_DECRYPT", cmd);           /* -1 if encrypting, 0 if decrypting */
00115 
00116    if (encrypt) {                                  /* if decrypting first decode src to base64 */
00117       ast_copy_string(tmp, args.data, len);
00118       data_len = strlen(tmp);
00119    } else {
00120       data_len = ast_base64decode((unsigned char *) tmp, args.data, len);
00121    }
00122 
00123    if (data_len >= len) {                        /* make sure to not go over buffer len */
00124       ast_log(LOG_WARNING, "Syntax: %s(<keys>,<data>) - <data> exceeds buffer length.  Result may be truncated!\n", cmd);
00125       data_len = len - 1;
00126    }
00127 
00128    while (data_len > 0) {
00129       memset(curblock, 0, AES_BLOCK_SIZE);
00130       memcpy(curblock, tmpP, (data_len < AES_BLOCK_SIZE) ? data_len : AES_BLOCK_SIZE);
00131       if (encrypt) {
00132          ast_aes_encrypt(curblock, (unsigned char *) tmpP, &ecx);
00133       } else {
00134          ast_aes_decrypt(curblock, (unsigned char *) tmpP, &dcx);
00135       }
00136       tmpP += AES_BLOCK_SIZE;
00137       data_len -= AES_BLOCK_SIZE;
00138    }
00139 
00140    if (encrypt) {                            /* if encrypting encode result to base64 */
00141       ast_base64encode(buf, (unsigned char *) tmp, strlen(tmp), len);
00142    } else {
00143       memcpy(buf, tmp, len);
00144    }
00145    ast_free(tmp);
00146 
00147    return 0;
00148 }

static int load_module ( void   )  [static]

static int unload_module ( void   )  [static]

Definition at line 160 of file func_aes.c.

References ast_custom_function_unregister().


Variable Documentation

struct ast_module_info __mod_info = { .name = AST_MODULE, .flags = AST_MODFLAG_DEFAULT , .description = "AES dialplan functions" , .key = "This paragraph is copyright (c) 2006 by Digium, Inc. \In order for your module to load, it must return this \key via a function called \"key\". Any code which \includes this paragraph must be licensed under the GNU \General Public License version 2 or later (at your \option). In addition to Digium's general reservations \of rights, Digium expressly reserves the right to \allow other parties to license this paragraph under \different terms. Any use of Digium, Inc. trademarks or \logos (including \"Asterisk\" or \"Digium\") without \express written permission of Digium, Inc. is prohibited.\n" , .buildopt_sum = AST_BUILDOPT_SUM, .load = load_module, .unload = unload_module, } [static]

Definition at line 173 of file func_aes.c.

Initial value:

 {
   .name = "AES_DECRYPT",
   .read = aes_helper,
}

Definition at line 155 of file func_aes.c.

Initial value:

 {
   .name = "AES_ENCRYPT",
   .read = aes_helper,
}

Definition at line 150 of file func_aes.c.

Definition at line 173 of file func_aes.c.


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