Version 3.1.1
ex_encrypt.c

Shows how to extend WiredTiger with a simple encryption algorithm.

/*-
* Public Domain 2014-2018 MongoDB, Inc.
* Public Domain 2008-2014 WiredTiger, Inc.
*
* This is free and unencumbered software released into the public domain.
*
* Anyone is free to copy, modify, publish, use, compile, sell, or
* distribute this software, either in source code form or as a compiled
* binary, for any purpose, commercial or non-commercial, and by any
* means.
*
* In jurisdictions that recognize copyright laws, the author or authors
* of this software dedicate any and all copyright interest in the
* software to the public domain. We make this dedication for the benefit
* of the public at large and to the detriment of our heirs and
* successors. We intend this dedication to be an overt act of
* relinquishment in perpetuity of all present and future rights to this
* software under copyright law.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*
* ex_encrypt.c
* demonstrates how to use the encryption API.
*/
#include <test_util.h>
#ifdef _WIN32
/*
* Explicitly export this function so it is visible when loading extensions.
*/
__declspec(dllexport)
#endif
int add_my_encryptors(WT_CONNECTION *connection);
static const char *home;
#define SYS_KEYID "system"
#define SYS_PW "system_password"
#define USER1_KEYID "user1"
#define USER2_KEYID "user2"
#define USERBAD_KEYID "userbad"
#define ITEM_MATCHES(config_item, s) \
(strlen(s) == (config_item).len && \
strncmp((config_item).str, s, (config_item).len) == 0)
typedef struct {
WT_ENCRYPTOR encryptor; /* Must come first */
int rot_N; /* rotN value */
uint32_t num_calls; /* Count of calls */
char *keyid; /* Saved keyid */
char *password; /* Saved password */
} MY_CRYPTO;
#define CHKSUM_LEN 4
#define IV_LEN 16
/*
* make_checksum --
* This is where one would call a checksum function on the encrypted
* buffer. Here we just put a constant value in it.
*/
static void
make_checksum(uint8_t *dst)
{
int i;
/*
* Assume array is big enough for the checksum.
*/
for (i = 0; i < CHKSUM_LEN; i++)
dst[i] = 'C';
}
/*
* make_iv --
* This is where one would generate the initialization vector.
* Here we just put a constant value in it.
*/
static void
make_iv(uint8_t *dst)
{
int i;
/*
* Assume array is big enough for the initialization vector.
*/
for (i = 0; i < IV_LEN; i++)
dst[i] = 'I';
}
/*
* Rotate encryption functions.
*/
/*
* do_rotate --
* Perform rot-N on the buffer given.
*/
static void
do_rotate(char *buf, size_t len, int rotn)
{
uint32_t i;
/*
* Now rotate
*/
for (i = 0; i < len; i++)
if (isalpha((unsigned char)buf[i])) {
if (islower((unsigned char)buf[i]))
buf[i] = ((buf[i] - 'a') + rotn) % 26 + 'a';
else
buf[i] = ((buf[i] - 'A') + rotn) % 26 + 'A';
}
}
/*
* rotate_decrypt --
* A simple rotate decryption.
*/
static int
rotate_decrypt(WT_ENCRYPTOR *encryptor, WT_SESSION *session,
uint8_t *src, size_t src_len,
uint8_t *dst, size_t dst_len,
size_t *result_lenp)
{
MY_CRYPTO *my_crypto = (MY_CRYPTO *)encryptor;
size_t mylen;
uint32_t i;
(void)session; /* Unused */
++my_crypto->num_calls;
if (src == NULL)
return (0);
/*
* Make sure it is big enough.
*/
mylen = src_len - (CHKSUM_LEN + IV_LEN);
if (dst_len < mylen) {
fprintf(stderr,
"Rotate: ENOMEM ERROR: dst_len %zu src_len %zu\n",
dst_len, src_len);
return (ENOMEM);
}
/*
* !!! Most implementations would verify any needed
* checksum and initialize the IV here.
*/
/*
* Copy the encrypted data to the destination buffer and then
* decrypt the destination buffer in place.
*/
i = CHKSUM_LEN + IV_LEN;
memcpy(&dst[0], &src[i], mylen);
/*
* Call common rotate function on the text portion of the
* buffer. Send in dst_len as the length of the text.
*/
/*
* !!! Most implementations would need the IV too.
*/
do_rotate((char *)dst, mylen, 26 - my_crypto->rot_N);
*result_lenp = mylen;
return (0);
}
/*
* rotate_encrypt --
* A simple rotate encryption.
*/
static int
rotate_encrypt(WT_ENCRYPTOR *encryptor, WT_SESSION *session,
uint8_t *src, size_t src_len,
uint8_t *dst, size_t dst_len,
size_t *result_lenp)
{
MY_CRYPTO *my_crypto = (MY_CRYPTO *)encryptor;
uint32_t i;
(void)session; /* Unused */
++my_crypto->num_calls;
if (src == NULL)
return (0);
if (dst_len < src_len + CHKSUM_LEN + IV_LEN)
return (ENOMEM);
i = CHKSUM_LEN + IV_LEN;
/*
* Skip over space reserved for checksum and initialization
* vector. Copy text into destination buffer then encrypt
* in place.
*/
memcpy(&dst[i], &src[0], src_len);
/*
* Call common rotate function on the text portion of the
* destination buffer. Send in src_len as the length of
* the text.
*/
do_rotate((char *)dst + i, src_len, my_crypto->rot_N);
/*
* Checksum the encrypted buffer and add the IV.
*/
i = 0;
make_checksum(&dst[i]);
i += CHKSUM_LEN;
make_iv(&dst[i]);
*result_lenp = dst_len;
return (0);
}
/*
* rotate_sizing --
* A sizing example that returns the header size needed.
*/
static int
rotate_sizing(WT_ENCRYPTOR *encryptor, WT_SESSION *session,
size_t *expansion_constantp)
{
MY_CRYPTO *my_crypto = (MY_CRYPTO *)encryptor;
(void)session; /* Unused parameters */
++my_crypto->num_calls; /* Call count */
*expansion_constantp = CHKSUM_LEN + IV_LEN;
return (0);
}
/*
* rotate_customize --
* The customize function creates a customized encryptor
*/
static int
rotate_customize(WT_ENCRYPTOR *encryptor, WT_SESSION *session,
WT_CONFIG_ARG *encrypt_config, WT_ENCRYPTOR **customp)
{
MY_CRYPTO *my_crypto;
WT_CONFIG_ITEM keyid, secret;
int ret;
const MY_CRYPTO *orig_crypto;
extapi = session->connection->get_extension_api(session->connection);
orig_crypto = (const MY_CRYPTO *)encryptor;
if ((my_crypto = calloc(1, sizeof(MY_CRYPTO))) == NULL) {
ret = errno;
goto err;
}
*my_crypto = *orig_crypto;
my_crypto->keyid = my_crypto->password = NULL;
/*
* Stash the keyid and the (optional) secret key from the configuration
* string.
*/
error_check(extapi->config_get(
extapi, session, encrypt_config, "keyid", &keyid));
if (keyid.len != 0) {
if ((my_crypto->keyid = malloc(keyid.len + 1)) == NULL) {
ret = errno;
goto err;
}
strncpy(my_crypto->keyid, keyid.str, keyid.len + 1);
my_crypto->keyid[keyid.len] = '\0';
}
ret = extapi->config_get(
extapi, session, encrypt_config, "secretkey", &secret);
if (ret == 0 && secret.len != 0) {
if ((my_crypto->password = malloc(secret.len + 1)) == NULL) {
ret = errno;
goto err;
}
strncpy(my_crypto->password, secret.str, secret.len + 1);
my_crypto->password[secret.len] = '\0';
}
/*
* Presumably we'd have some sophisticated key management
* here that maps the id onto a secret key.
*/
if (ITEM_MATCHES(keyid, "system")) {
if (my_crypto->password == NULL ||
strcmp(my_crypto->password, SYS_PW) != 0) {
ret = EPERM;
goto err;
}
my_crypto->rot_N = 13;
} else if (ITEM_MATCHES(keyid, USER1_KEYID))
my_crypto->rot_N = 4;
else if (ITEM_MATCHES(keyid, USER2_KEYID))
my_crypto->rot_N = 19;
else {
ret = EINVAL;
goto err;
}
++my_crypto->num_calls; /* Call count */
*customp = (WT_ENCRYPTOR *)my_crypto;
return (0);
err: free(my_crypto->keyid);
free(my_crypto->password);
free(my_crypto);
return (ret);
}
/*
* rotate_terminate --
* WiredTiger rotate encryption termination.
*/
static int
rotate_terminate(WT_ENCRYPTOR *encryptor, WT_SESSION *session)
{
MY_CRYPTO *my_crypto = (MY_CRYPTO *)encryptor;
(void)session; /* Unused parameters */
++my_crypto->num_calls; /* Call count */
/* Free the allocated memory. */
free(my_crypto->password);
my_crypto->password = NULL;
free(my_crypto->keyid);
my_crypto->keyid = NULL;
free(encryptor);
return (0);
}
/*
* add_my_encryptors --
* A simple example of adding encryption callbacks.
*/
int
add_my_encryptors(WT_CONNECTION *connection)
{
MY_CRYPTO *m;
/*
* Initialize our top level encryptor.
*/
if ((m = calloc(1, sizeof(MY_CRYPTO))) == NULL)
return (errno);
wt = (WT_ENCRYPTOR *)&m->encryptor;
wt->encrypt = rotate_encrypt;
wt->decrypt = rotate_decrypt;
wt->sizing = rotate_sizing;
wt->customize = rotate_customize;
wt->terminate = rotate_terminate;
m->num_calls = 0;
error_check(connection->add_encryptor(
connection, "rotn", (WT_ENCRYPTOR *)m, NULL));
return (0);
}
/*
* simple_walk_log --
* A simple walk of the write-ahead log.
* We wrote text messages into the log. Print them.
* This verifies we're decrypting properly.
*/
static void
simple_walk_log(WT_SESSION *session)
{
WT_CURSOR *cursor;
WT_ITEM logrec_key, logrec_value;
uint64_t txnid;
uint32_t fileid, log_file, log_offset, opcount, optype, rectype;
int found, ret;
error_check(session->open_cursor(session, "log:", NULL, NULL, &cursor));
found = 0;
while ((ret = cursor->next(cursor)) == 0) {
error_check(cursor->get_key(
cursor, &log_file, &log_offset, &opcount));
error_check(cursor->get_value(cursor, &txnid,
&rectype, &optype, &fileid, &logrec_key, &logrec_value));
if (rectype == WT_LOGREC_MESSAGE) {
found = 1;
printf("Application Log Record: %s\n",
(char *)logrec_value.data);
}
}
scan_end_check(ret == WT_NOTFOUND);
error_check(cursor->close(cursor));
if (found == 0) {
fprintf(stderr, "Did not find log messages.\n");
exit(EXIT_FAILURE);
}
}
#define MAX_KEYS 20
#define EXTENSION_NAME "local=(entry=add_my_encryptors)"
#define WT_OPEN_CONFIG_COMMON \
"create,cache_size=100MB,extensions=[" EXTENSION_NAME "],"\
"log=(archive=false,enabled=true)," \
#define WT_OPEN_CONFIG_GOOD \
WT_OPEN_CONFIG_COMMON \
"encryption=(name=rotn,keyid=" SYS_KEYID ",secretkey=" SYS_PW ")"
#define COMP_A "AAAAAAAAAAAAAAAAAA"
#define COMP_B "BBBBBBBBBBBBBBBBBB"
#define COMP_C "CCCCCCCCCCCCCCCCCC"
int
main(int argc, char *argv[])
{
WT_CURSOR *c1, *c2, *nc;
WT_SESSION *session;
int i, ret;
char keybuf[32], valbuf[32];
char *key1, *key2, *key3, *val1, *val2, *val3;
home = example_setup(argc, argv);
error_check(wiredtiger_open(home, NULL, WT_OPEN_CONFIG_GOOD, &conn));
error_check(conn->open_session(conn, NULL, NULL, &session));
/*
* Write a log record that is larger than the base 128 bytes and
* also should compress well.
*/
error_check(session->log_printf(session,
COMP_A COMP_B COMP_C COMP_A COMP_B COMP_C
COMP_A COMP_B COMP_C COMP_A COMP_B COMP_C
"The quick brown fox jumps over the lazy dog "));
simple_walk_log(session);
/*
* Create and open some encrypted and not encrypted tables.
* Also use column store and compression for some tables.
*/
error_check(session->create(session, "table:crypto1",
"encryption=(name=rotn,keyid=" USER1_KEYID"),"
"columns=(key0,value0),"
"key_format=S,value_format=S"));
error_check(session->create(session, "index:crypto1:byvalue",
"encryption=(name=rotn,keyid=" USER1_KEYID"),"
"columns=(value0,key0)"));
error_check(session->create(session, "table:crypto2",
"encryption=(name=rotn,keyid=" USER2_KEYID"),"
"key_format=S,value_format=S"));
error_check(session->create(session, "table:nocrypto",
"key_format=S,value_format=S"));
/*
* Send in an unknown keyid. WiredTiger will try to add in the
* new keyid, but the customize function above will return an
* error since it is unrecognized.
*/
ret = session->create(session, "table:cryptobad",
"encryption=(name=rotn,keyid=" USERBAD_KEYID"),"
"key_format=S,value_format=S");
if (ret == 0) {
fprintf(stderr, "Did not detect bad/unknown keyid error\n");
exit(EXIT_FAILURE);
}
error_check(session->open_cursor(
session, "table:crypto1", NULL, NULL, &c1));
error_check(session->open_cursor(
session, "table:crypto2", NULL, NULL, &c2));
error_check(session->open_cursor(
session, "table:nocrypto", NULL, NULL, &nc));
/*
* Insert a set of keys and values. Insert the same data into
* all tables so that we can verify they're all the same after
* we decrypt on read.
*/
for (i = 0; i < MAX_KEYS; i++) {
(void)snprintf(keybuf, sizeof(keybuf), "key%d", i);
c1->set_key(c1, keybuf);
c2->set_key(c2, keybuf);
nc->set_key(nc, keybuf);
(void)snprintf(valbuf, sizeof(valbuf), "value%d", i);
c1->set_value(c1, valbuf);
c2->set_value(c2, valbuf);
nc->set_value(nc, valbuf);
error_check(c1->insert(c1));
error_check(c2->insert(c2));
error_check(nc->insert(nc));
if (i % 5 == 0)
error_check(session->log_printf(
session, "Wrote %d records", i));
}
error_check(session->log_printf(
session, "Done. Wrote %d total records", i));
while (c1->next(c1) == 0) {
error_check(c1->get_key(c1, &key1));
error_check(c1->get_value(c1, &val1));
printf("Read key %s; value %s\n", key1, val1);
}
simple_walk_log(session);
printf("CLOSE\n");
error_check(conn->close(conn, NULL));
/*
* We want to close and reopen so that we recreate the cache
* by reading the data from disk, forcing decryption.
*/
printf("REOPEN and VERIFY encrypted data\n");
error_check(wiredtiger_open(home, NULL, WT_OPEN_CONFIG_GOOD, &conn));
error_check(conn->open_session(conn, NULL, NULL, &session));
/*
* Verify we can read the encrypted log after restart.
*/
simple_walk_log(session);
error_check(session->open_cursor(
session, "table:crypto1", NULL, NULL, &c1));
error_check(session->open_cursor(
session, "table:crypto2", NULL, NULL, &c2));
error_check(session->open_cursor(
session, "table:nocrypto", NULL, NULL, &nc));
/*
* Read the same data from each cursor. All should be identical.
*/
while (c1->next(c1) == 0) {
error_check(c2->next(c2));
error_check(nc->next(nc));
error_check(c1->get_key(c1, &key1));
error_check(c1->get_value(c1, &val1));
error_check(c2->get_key(c2, &key2));
error_check(c2->get_value(c2, &val2));
error_check(nc->get_key(nc, &key3));
error_check(nc->get_value(nc, &val3));
if (strcmp(key1, key2) != 0)
fprintf(stderr, "Key1 %s and Key2 %s do not match\n",
key1, key2);
if (strcmp(key1, key3) != 0)
fprintf(stderr, "Key1 %s and Key3 %s do not match\n",
key1, key3);
if (strcmp(key2, key3) != 0)
fprintf(stderr, "Key2 %s and Key3 %s do not match\n",
key2, key3);
if (strcmp(val1, val2) != 0)
fprintf(stderr, "Val1 %s and Val2 %s do not match\n",
val1, val2);
if (strcmp(val1, val3) != 0)
fprintf(stderr, "Val1 %s and Val3 %s do not match\n",
val1, val3);
if (strcmp(val2, val3) != 0)
fprintf(stderr, "Val2 %s and Val3 %s do not match\n",
val2, val3);
printf("Verified key %s; value %s\n", key1, val1);
}
error_check(conn->close(conn, NULL));
return (EXIT_SUCCESS);
}