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Use HMAC on header and encrypted data, avoid regular digest when encrypting.

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This commit is contained in:
Moinak Ghosh 2012-11-23 22:27:14 +05:30
parent 6e9ca97bdf
commit 817e16cce6
1 changed files with 45 additions and 29 deletions
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74
main.c
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@ -318,8 +318,7 @@ redo:
memset(tdat->compressed_chunk + cksum_bytes, 0, mac_bytes);
hmac_reinit(&tdat->chunk_hmac);
hmac_update(&tdat->chunk_hmac, (uchar_t *)&tdat->len_cmp_be, sizeof (tdat->len_cmp_be));
hmac_update(&tdat->chunk_hmac, tdat->compressed_chunk,
cksum_bytes + mac_bytes + CHUNK_FLAG_SZ);
hmac_update(&tdat->chunk_hmac, tdat->compressed_chunk, tdat->rbytes);
if (HDR & CHSIZE_MASK) {
uchar_t *rseg;
rseg = tdat->compressed_chunk + tdat->rbytes;
@ -378,13 +377,13 @@ redo:
sem_post(&tdat->cmp_done_sem);
return;
}
}
/*
* Now that HMAC (if any) was verified, recover the stored message
* digest.
*/
deserialize_checksum(tdat->checksum, tdat->compressed_chunk, cksum_bytes);
/*
* Now that header CRC32 was verified, recover the stored message
* digest.
*/
deserialize_checksum(tdat->checksum, tdat->compressed_chunk, cksum_bytes);
}
if ((enable_rabin_scan || enable_fixed_scan) && (HDR & CHUNK_FLAG_DEDUP)) {
uchar_t *cmpbuf, *ubuf;
@ -471,15 +470,17 @@ redo:
tdat->cmp_seg = tdat->uncompressed_chunk;
}
/*
* Re-compute checksum of original uncompressed chunk.
* If it does not match we set length of chunk to 0 to indicate
* exit to the writer thread.
*/
compute_checksum(checksum, cksum, tdat->uncompressed_chunk, _chunksize);
if (memcmp(checksum, tdat->checksum, cksum_bytes) != 0) {
tdat->len_cmp = 0;
fprintf(stderr, "ERROR: Chunk %d, checksums do not match.\n", tdat->id);
if (!encrypt_type) {
/*
* Re-compute checksum of original uncompressed chunk.
* If it does not match we set length of chunk to 0 to indicate
* exit to the writer thread.
*/
compute_checksum(checksum, cksum, tdat->uncompressed_chunk, _chunksize);
if (memcmp(checksum, tdat->checksum, cksum_bytes) != 0) {
tdat->len_cmp = 0;
fprintf(stderr, "ERROR: Chunk %d, checksums do not match.\n", tdat->id);
}
}
cont:
@ -666,6 +667,11 @@ start_decompress(const char *filename, const char *to_filename)
unsigned short d1;
unsigned int d2;
/*
* In encrypted files we do not have a normal digest. The HMAC
* is computed over header and encrypted data.
*/
cksum_bytes = 0;
compressed_chunksize += mac_bytes;
encrypt_type = flags & MASK_CRYPTO_ALG;
if (Read(compfd, &saltlen, sizeof (saltlen)) < sizeof (saltlen)) {
@ -758,7 +764,7 @@ start_decompress(const char *filename, const char *to_filename)
memset(pw, 0, MAX_PW_LEN);
/*
* Verify header HMAC.
* Verify file header HMAC.
*/
if (hmac_init(&hdr_mac, cksum, &crypto_ctx) == -1) {
close(uncompfd); unlink(to_filename);
@ -1071,7 +1077,8 @@ redo:
* into uncompressed_chunk so that compress transforms uncompressed_chunk
* back into cmp_seg. Avoids an extra memcpy().
*/
compute_checksum(tdat->checksum, cksum, tdat->cmp_seg, tdat->rbytes);
if (!encrypt_type)
compute_checksum(tdat->checksum, cksum, tdat->cmp_seg, tdat->rbytes);
rctx = tdat->rctx;
reset_dedupe_context(tdat->rctx);
@ -1085,7 +1092,8 @@ redo:
/*
* Compute checksum of original uncompressed chunk.
*/
compute_checksum(tdat->checksum, cksum, tdat->uncompressed_chunk, tdat->rbytes);
if (!encrypt_type)
compute_checksum(tdat->checksum, cksum, tdat->uncompressed_chunk, tdat->rbytes);
}
/*
@ -1206,7 +1214,8 @@ plain_compress:
*/
len_cmp = tdat->len_cmp;
*((typeof (len_cmp) *)(tdat->cmp_seg)) = htonll(tdat->len_cmp);
serialize_checksum(tdat->checksum, tdat->cmp_seg + sizeof (tdat->len_cmp), cksum_bytes);
if (!encrypt_type)
serialize_checksum(tdat->checksum, tdat->cmp_seg + sizeof (tdat->len_cmp), cksum_bytes);
tdat->len_cmp += CHUNK_FLAG_SZ;
tdat->len_cmp += sizeof (len_cmp);
tdat->len_cmp += (cksum_bytes + mac_bytes);
@ -1231,7 +1240,7 @@ plain_compress:
*(tdat->compressed_chunk) = type;
/*
* If encrypting, compute HMAC for chunk header and trailer.
* If encrypting, compute HMAC for full chunk including header.
*/
if (encrypt_type) {
uchar_t *mac_ptr;
@ -1242,11 +1251,7 @@ plain_compress:
mac_ptr = tdat->cmp_seg + sizeof (tdat->len_cmp) + cksum_bytes;
memset(mac_ptr, 0, mac_bytes);
hmac_reinit(&tdat->chunk_hmac);
hmac_update(&tdat->chunk_hmac, tdat->cmp_seg, rbytes);
if (type & CHSIZE_MASK)
hmac_update(&tdat->chunk_hmac,
tdat->cmp_seg + tdat->len_cmp - ORIGINAL_CHUNKSZ,
ORIGINAL_CHUNKSZ);
hmac_update(&tdat->chunk_hmac, tdat->cmp_seg, tdat->len_cmp);
hmac_final(&tdat->chunk_hmac, chash, &hlen);
serialize_checksum(chash, mac_ptr, hlen);
} else {
@ -1257,7 +1262,7 @@ plain_compress:
unsigned int hlen;
uint32_t crc;
/* Clean out mac_bytes to 0 for stable HMAC. */
/* Clean out mac_bytes to 0 for stable CRC32. */
mac_ptr = tdat->cmp_seg + sizeof (tdat->len_cmp) + cksum_bytes;
memset(mac_ptr, 0, mac_bytes);
crc = lzma_crc32(tdat->cmp_seg, rbytes, 0);
@ -2185,8 +2190,19 @@ main(int argc, char *argv[])
if (cksum == 0)
get_checksum_props(DEFAULT_CKSUM, &cksum, &cksum_bytes, &mac_bytes);
if (!encrypt_type)
if (!encrypt_type) {
/*
* If not encrypting we compute a header CRC32.
*/
mac_bytes = sizeof (uint32_t); // CRC32 in non-crypto mode
} else {
/*
* When encrypting we do not compute a normal digest. The HMAC
* is computed over header and encrypted data.
*/
cksum_bytes = 0;
}
/*
* Start the main routines.
*/