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#include <stdio.h>
#include <string.h>
#include <errno.h>
#define u8 unsigned char
/**
* Temporary holding place for functions relating to filename
* encryption
*/
/* 64 characters forming a 6-bit target field */
static unsigned char *portable_filename_chars = ("-.0123456789ABCD"
"EFGHIJKLMNOPQRST"
"UVWXYZabcdefghij"
"klmnopqrstuvwxyz");
static unsigned char filename_rev_map[] = {
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 7 */
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 15 */
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 23 */
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 31 */
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 39 */
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* 47 */
0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, /* 55 */
0x0A, 0x0B, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 63 */
0x00, 0x0C, 0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12, /* 71 */
0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, /* 79 */
0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, /* 87 */
0x23, 0x24, 0x25, 0x00, 0x00, 0x00, 0x00, 0x00, /* 95 */
0x00, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, /* 103 */
0x2D, 0x2E, 0x2F, 0x30, 0x31, 0x32, 0x33, 0x34, /* 111 */
0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, /* 119 */
0x3D, 0x3E, 0x3F
};
/**
* ecryptfs_encode_for_filename
* @src_size Size of the source in bytes
*
*/
int ecryptfs_encode_for_filename(unsigned char *dst, size_t *dst_size,
unsigned char *src, size_t src_size)
{
size_t num_blocks;
size_t block_num = 0;
unsigned char last_block[3];
size_t dst_offset = 0;
int rc = 0;
if (src_size == 0) {
rc = -EINVAL;
goto out;
}
num_blocks = (src_size / 3);
if ((src_size % 3) == 0) {
memcpy(last_block, (&src[src_size - 3]), 3);
} else {
num_blocks++;
last_block[2] = 0x00;
switch(src_size % 3) {
case 1:
last_block[0] = src[src_size - 1];
last_block[1] = 0x00;
break;
case 2:
last_block[0] = src[src_size - 2];
last_block[1] = src[src_size - 1];
}
}
(*dst_size) = (num_blocks * 4);
if (!dst)
goto out;
while (block_num < num_blocks) {
unsigned char *src_block;
unsigned char dst_block[4];
if (block_num == (num_blocks - 1))
src_block = last_block;
else
src_block = &src[block_num * 3];
dst_block[0] = ((src_block[0] >> 2) & 0x3f);
dst_block[1] = (((src_block[0] << 4) & 0x30)
| ((src_block[1] >> 4) & 0x0f));
dst_block[2] = (((src_block[1] << 2) & 0x3c)
| ((src_block[2] >> 6) & 0x03));
dst_block[3] = (src_block[2] & 0x3f);
dst[dst_offset++] = portable_filename_chars[dst_block[0]];
dst[dst_offset++] = portable_filename_chars[dst_block[1]];
dst[dst_offset++] = portable_filename_chars[dst_block[2]];
dst[dst_offset++] = portable_filename_chars[dst_block[3]];
block_num++;
}
out:
return rc;
}
int ecryptfs_decode_from_filename(unsigned char *dst, size_t *dst_size,
unsigned char *src, size_t src_size)
{
size_t src_byte_offset = 0;
size_t dst_byte_offset = 0;
u8 current_bit_offset = 0;
int rc = 0;
while (src_byte_offset < src_size) {
src[src_byte_offset] = filename_rev_map[src[src_byte_offset]];
switch (current_bit_offset) {
case 0:
dst[dst_byte_offset] = (src[src_byte_offset] << 2);
current_bit_offset = 6;
break;
case 6:
dst[dst_byte_offset++] |= (src[src_byte_offset] >> 4);
dst[dst_byte_offset] = ((src[src_byte_offset] & 0xF)
<< 4);
current_bit_offset = 4;
break;
case 4:
dst[dst_byte_offset++] |= (src[src_byte_offset] >> 2);
dst[dst_byte_offset] = (src[src_byte_offset] << 6);
current_bit_offset = 2;
break;
case 2:
dst[dst_byte_offset++] |= (src[src_byte_offset]);
dst[dst_byte_offset] = 0;
current_bit_offset = 0;
break;
}
src_byte_offset++;
}
(*dst_size) = dst_byte_offset;
out:
return rc;
}
/* char *str = "This is a test of the eCryptfs packet encoding
* code. If this were an actual chunk of kernel code, your video card
* would spout 6-inch flames and your neighbor's inodes would flash
* your television's BIOS."; */
unsigned char str[43] = { 0x46, 0x29, 0x7f, 0xa0, 0x6f, 0x4b, 0x66, 0xfc,
0xde, 0x02, 0x07, 0xf8, 0x31, 0x61, 0xb2, 0xee,
0x65, 0x9e, 0x68, 0xdf, 0x81, 0x0b, 0x54, 0x70,
0x0c, 0x2c, 0xe6, 0xf4, 0x79, 0xb7, 0xd3, 0xbf,
0xa5, 0x96, 0x11, 0x11, 0xf5, 0xc1, 0x5b, 0x87,
0x16, 0x4e, 0xed };
/*unsigned char encoded[61] = {
0x46, 0x29, 0x7f, 0xa0, 0x6f, 0x4b, 0x66, 0xfc, 0xde, 0x02, 0x07, 0xaf, 0x33, 0xdc, 0xf4, 0xfd,
0xa1, 0x40, 0xf2, 0x77, 0x86, 0xfa, 0x86, 0xbc, 0x48, 0xed, 0x26, 0x75, 0xc2, 0x9a, 0x7d, 0xf7,
0x42, 0x27, 0xfe, 0x55, 0xa7, 0x4e, 0x3b, 0x4a, 0xb3, 0x2a, 0xc7, 0x00, 0x00
}; */
unsigned char *encoded = "";
int main()
{
char enc[1024];
char dec[1024];
size_t enc_size;
size_t dec_size;
int i;
int rc = 0;
ecryptfs_encode_for_filename(NULL, &enc_size, str, 43);
printf("enc_size = [%d]\n", enc_size);
ecryptfs_encode_for_filename(enc, &enc_size, str, 43);
enc[enc_size] = '\0';
printf("Encoded: [%s]\n", enc);
ecryptfs_decode_from_filename(dec, &dec_size, enc, enc_size);
printf("Decoded:\n");
for (i = 0; i < dec_size; i++) {
if ((i % 16) == 0)
printf("\n");
printf("0x%.2x.", (unsigned char)dec[i]);
}
printf("\n");
out:
return rc;
}
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