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/*
Unix SMB/CIFS implementation.
code to encrypt/decrypt data using the user session key
Copyright (C) Andrew Tridgell 2004
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "includes.h"
/*
encrypt or decrypt a blob of data using the user session key
as used in lsa_SetSecret
before calling, the out blob must be initialised to be the same size
as the in blob
*/
void sess_crypt_blob(DATA_BLOB *out, const DATA_BLOB *in, const DATA_BLOB *session_key,
BOOL forward)
{
int i, k;
for (i=0,k=0;
i<in->length;
i += 8, k += 7) {
uint8_t bin[8], bout[8], key[7];
memset(bin, 0, 8);
memcpy(bin, &in->data[i], MIN(8, in->length-i));
if (k + 7 > session_key->length) {
k = (session_key->length - k);
}
memcpy(key, &session_key->data[k], 7);
des_crypt56(bout, bin, key, forward?1:0);
memcpy(&out->data[i], bout, MIN(8, in->length-i));
}
}
/*
a convenient wrapper around sess_crypt_blob() for strings, using the LSA convention
note that we round the length to a multiple of 8. This seems to be needed for
compatibility with windows
caller should free using data_blob_free()
*/
DATA_BLOB sess_encrypt_string(const char *str, const DATA_BLOB *session_key)
{
DATA_BLOB ret, src;
int slen = strlen(str);
int dlen = (slen+7) & ~7;
src = data_blob(NULL, 8+dlen);
if (!src.data) {
return data_blob(NULL, 0);
}
ret = data_blob(NULL, 8+dlen);
if (!ret.data) {
data_blob_free(&src);
return data_blob(NULL, 0);
}
SIVAL(src.data, 0, slen);
SIVAL(src.data, 4, 1);
memset(src.data+8, 0, dlen);
memcpy(src.data+8, str, slen);
sess_crypt_blob(&ret, &src, session_key, True);
data_blob_free(&src);
return ret;
}
/*
a convenient wrapper around sess_crypt_blob() for strings, using the LSA convention
caller should free the returned string
*/
char *sess_decrypt_string(DATA_BLOB *blob, const DATA_BLOB *session_key)
{
DATA_BLOB out;
int slen;
char *ret;
if (blob->length < 8) {
return NULL;
}
out = data_blob(NULL, blob->length);
if (!out.data) {
return NULL;
}
sess_crypt_blob(&out, blob, session_key, False);
slen = IVAL(out.data, 0);
if (slen > blob->length - 8) {
DEBUG(0,("Invalid crypt length %d\n", slen));
return NULL;
}
if (IVAL(out.data, 4) != 1) {
DEBUG(0,("Unexpected revision number %d in session crypted string\n",
IVAL(out.data, 4)));
return NULL;
}
ret = strndup(out.data+8, slen);
data_blob_free(&out);
return ret;
}
/*
a convenient wrapper around sess_crypt_blob() for DATA_BLOBs, using the LSA convention
note that we round the length to a multiple of 8. This seems to be needed for
compatibility with windows
caller should free using data_blob_free()
*/
DATA_BLOB sess_encrypt_blob(TALLOC_CTX *mem_ctx, DATA_BLOB *blob_in, const DATA_BLOB *session_key)
{
DATA_BLOB ret, src;
int dlen = (blob_in->length+7) & ~7;
src = data_blob_talloc(mem_ctx, NULL, 8+dlen);
if (!src.data) {
return data_blob(NULL, 0);
}
ret = data_blob(NULL, 8+dlen);
if (!ret.data) {
data_blob_free(&src);
return data_blob(NULL, 0);
}
SIVAL(src.data, 0, blob_in->length);
SIVAL(src.data, 4, 1);
memset(src.data+8, 0, dlen);
memcpy(src.data+8, blob_in->data, blob_in->length);
sess_crypt_blob(&ret, &src, session_key, True);
data_blob_free(&src);
return ret;
}
/*
a convenient wrapper around sess_crypt_blob() for strings, using the LSA convention
caller should free the returned string
*/
DATA_BLOB sess_decrypt_blob(TALLOC_CTX *mem_ctx, DATA_BLOB *blob, const DATA_BLOB *session_key)
{
DATA_BLOB out;
int slen;
DATA_BLOB ret;
if (blob->length < 8) {
return data_blob(NULL, 0);
}
out = data_blob_talloc(mem_ctx, NULL, blob->length);
if (!out.data) {
return data_blob(NULL, 0);
}
sess_crypt_blob(&out, blob, session_key, False);
slen = IVAL(out.data, 0);
if (slen > blob->length - 8) {
DEBUG(0,("Invalid crypt length %d\n", slen));
return data_blob(NULL, 0);
}
if (IVAL(out.data, 4) != 1) {
DEBUG(0,("Unexpected revision number %d in session crypted string\n",
IVAL(out.data, 4)));
return data_blob(NULL, 0);
}
ret = data_blob_talloc(mem_ctx, out.data+8, slen);
data_blob_free(&out);
return ret;
}
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