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func_aes.c
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1/*
2 * Asterisk -- An open source telephony toolkit.
3 *
4 * Copyright (C) 2009, Digium, Inc.
5 *
6 * See http://www.asterisk.org for more information about
7 * the Asterisk project. Please do not directly contact
8 * any of the maintainers of this project for assistance;
9 * the project provides a web site, mailing lists and IRC
10 * channels for your use.
11 *
12 * This program is free software, distributed under the terms of
13 * the GNU General Public License Version 2. See the LICENSE file
14 * at the top of the source tree.
15 */
16
17/*! \file
18 *
19 * \brief AES encryption/decryption dialplan functions
20 *
21 * \author David Vossel <dvossel@digium.com>
22 * \ingroup functions
23 */
24
25/*** MODULEINFO
26 <depend>res_crypto</depend>
27 <depend>crypto</depend>
28 <support_level>core</support_level>
29 ***/
30
31#include "asterisk.h"
32
33#include "asterisk/module.h"
34#include "asterisk/pbx.h"
35#include "asterisk/app.h"
36#include "asterisk/crypto.h"
37
38#define AES_BLOCK_SIZE 16
39
40/*** DOCUMENTATION
41 <function name="AES_ENCRYPT" language="en_US">
42 <since>
43 <version>1.6.1.0</version>
44 </since>
45 <synopsis>
46 Encrypt a string with AES given a 16 character key.
47 </synopsis>
48 <syntax>
49 <parameter name="key" required="true">
50 <para>AES Key</para>
51 </parameter>
52 <parameter name="string" required="true">
53 <para>Input string</para>
54 </parameter>
55 </syntax>
56 <description>
57 <para>Returns an AES encrypted string encoded in base64.</para>
58 </description>
59 <see-also>
60 <ref type="function">AES_DECRYPT</ref>
61 <ref type="function">BASE64_ENCODE</ref>
62 <ref type="function">BASE64_DECODE</ref>
63 </see-also>
64 </function>
65 <function name="AES_DECRYPT" language="en_US">
66 <since>
67 <version>1.6.1.0</version>
68 </since>
69 <synopsis>
70 Decrypt a string encoded in base64 with AES given a 16 character key.
71 </synopsis>
72 <syntax>
73 <parameter name="key" required="true">
74 <para>AES Key</para>
75 </parameter>
76 <parameter name="string" required="true">
77 <para>Input string.</para>
78 </parameter>
79 </syntax>
80 <description>
81 <para>Returns the plain text string.</para>
82 </description>
83 <see-also>
84 <ref type="function">AES_ENCRYPT</ref>
85 <ref type="function">BASE64_ENCODE</ref>
86 <ref type="function">BASE64_DECODE</ref>
87 </see-also>
88 </function>
89 ***/
90
91
92static int aes_helper(struct ast_channel *chan, const char *cmd, char *data,
93 char *buf, size_t len)
94{
95 unsigned char curblock[AES_BLOCK_SIZE] = { 0, };
96 char *tmp;
97 char *tmpP;
98 int data_len, encrypt;
99 ast_aes_encrypt_key ecx; /* AES 128 Encryption context */
101
103 AST_APP_ARG(key);
104 AST_APP_ARG(data);
105 );
106
108
109 if (ast_strlen_zero(args.data) || ast_strlen_zero(args.key)) {
110 ast_log(LOG_WARNING, "Syntax: %s(<key>,<data>) - missing argument!\n", cmd);
111 return -1;
112 }
113
114 if (strlen(args.key) != AES_BLOCK_SIZE) { /* key must be of 16 characters in length, 128 bits */
115 ast_log(LOG_WARNING, "Syntax: %s(<key>,<data>) - <key> parameter must be exactly 16 characters!\n", cmd);
116 return -1;
117 }
118
119 ast_aes_set_encrypt_key((unsigned char *) args.key, &ecx); /* encryption: plaintext -> encryptedtext -> base64 */
120 ast_aes_set_decrypt_key((unsigned char *) args.key, &dcx); /* decryption: base64 -> encryptedtext -> plaintext */
121 tmp = ast_calloc(1, len); /* requires a tmp buffer for the base64 decode */
122 if (!tmp) {
123 ast_log(LOG_ERROR, "Unable to allocate memory for data\n");
124 return -1;
125 }
126 tmpP = tmp;
127 encrypt = strcmp("AES_DECRYPT", cmd); /* -1 if encrypting, 0 if decrypting */
128
129 if (encrypt) { /* if decrypting first decode src to base64 */
130 ast_copy_string(tmp, args.data, len);
131 data_len = strlen(tmp);
132 } else {
133 data_len = ast_base64decode((unsigned char *) tmp, args.data, len);
134 }
135
136 if (data_len >= len) { /* make sure to not go over buffer len */
137 ast_log(LOG_WARNING, "Syntax: %s(<keys>,<data>) - <data> exceeds buffer length. Result may be truncated!\n", cmd);
138 data_len = len - 1;
139 }
140
141 while (data_len > 0) {
142 memset(curblock, 0, AES_BLOCK_SIZE);
143 memcpy(curblock, tmpP, (data_len < AES_BLOCK_SIZE) ? data_len : AES_BLOCK_SIZE);
144 if (encrypt) {
145 ast_aes_encrypt(curblock, (unsigned char *) tmpP, &ecx);
146 } else {
147 ast_aes_decrypt(curblock, (unsigned char *) tmpP, &dcx);
148 }
149 tmpP += AES_BLOCK_SIZE;
150 data_len -= AES_BLOCK_SIZE;
151 }
152
153 if (encrypt) { /* if encrypting encode result to base64 */
154 ast_base64encode(buf, (unsigned char *) tmp, tmpP - tmp, len);
155 } else {
156 memcpy(buf, tmp, len);
157 }
158 ast_free(tmp);
159
160 return 0;
161}
162
164 .name = "AES_ENCRYPT",
165 .read = aes_helper,
166};
167
169 .name = "AES_DECRYPT",
170 .read = aes_helper,
171};
172
173static int unload_module(void)
174{
177}
178
179static int load_module(void)
180{
184}
185
186AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_DEFAULT, "AES dialplan functions",
187 .support_level = AST_MODULE_SUPPORT_CORE,
188 .load = load_module,
189 .unload = unload_module,
190 .requires = "res_crypto",
Asterisk main include file. File version handling, generic pbx functions.
#define ast_free(a)
Definition: astmm.h:180
#define ast_calloc(num, len)
A wrapper for calloc()
Definition: astmm.h:202
#define ast_log
Definition: astobj2.c:42
Provide cryptographic signature routines.
int ast_aes_set_encrypt_key(const unsigned char *key, ast_aes_encrypt_key *ctx)
Set an encryption key.
Definition: res_crypto.c:700
int ast_aes_set_decrypt_key(const unsigned char *key, ast_aes_decrypt_key *ctx)
Set a decryption key.
Definition: res_crypto.c:709
int ast_aes_encrypt(const unsigned char *in, unsigned char *out, const ast_aes_encrypt_key *key)
AES encrypt data.
Definition: res_crypto.c:749
int ast_aes_decrypt(const unsigned char *in, unsigned char *out, const ast_aes_decrypt_key *key)
AES decrypt data.
Definition: res_crypto.c:790
char buf[BUFSIZE]
Definition: eagi_proxy.c:66
static int aes_helper(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
Definition: func_aes.c:92
static struct ast_custom_function aes_decrypt_function
Definition: func_aes.c:168
static struct ast_custom_function aes_encrypt_function
Definition: func_aes.c:163
static int load_module(void)
Definition: func_aes.c:179
static int unload_module(void)
Definition: func_aes.c:173
#define AES_BLOCK_SIZE
Definition: func_aes.c:38
static int len(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t buflen)
Application convenience functions, designed to give consistent look and feel to Asterisk apps.
#define AST_APP_ARG(name)
Define an application argument.
#define AST_DECLARE_APP_ARGS(name, arglist)
Declare a structure to hold an application's arguments.
#define AST_STANDARD_APP_ARGS(args, parse)
Performs the 'standard' argument separation process for an application.
#define LOG_ERROR
#define LOG_WARNING
Asterisk module definitions.
@ AST_MODFLAG_DEFAULT
Definition: module.h:329
#define AST_MODULE_INFO(keystr, flags_to_set, desc, fields...)
Definition: module.h:557
@ AST_MODULE_SUPPORT_CORE
Definition: module.h:121
#define ASTERISK_GPL_KEY
The text the key() function should return.
Definition: module.h:46
@ AST_MODULE_LOAD_SUCCESS
Definition: module.h:70
@ AST_MODULE_LOAD_DECLINE
Module has failed to load, may be in an inconsistent state.
Definition: module.h:78
Core PBX routines and definitions.
#define ast_custom_function_register(acf)
Register a custom function.
Definition: pbx.h:1559
int ast_custom_function_unregister(struct ast_custom_function *acf)
Unregister a custom function.
static force_inline int attribute_pure ast_strlen_zero(const char *s)
Definition: strings.h:65
void ast_copy_string(char *dst, const char *src, size_t size)
Size-limited null-terminating string copy.
Definition: strings.h:425
Definition: crypto.h:39
Main Channel structure associated with a channel.
Data structure associated with a custom dialplan function.
Definition: pbx.h:118
const char * name
Definition: pbx.h:119
const char * args
int ast_base64decode(unsigned char *dst, const char *src, int max)
Decode data from base64.
Definition: utils.c:296
int ast_base64encode(char *dst, const unsigned char *src, int srclen, int max)
Encode data in base64.
Definition: utils.c:406