Use HMAC on header and encrypted data, avoid regular digest when encrypting.
This commit is contained in:
Moinak Ghosh
parent
6e9ca97bdf
commit
817e16cce6
1 changed files with 45 additions and 29 deletions
42
main.c
42
main.c
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@ -318,8 +318,7 @@ redo:
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memset(tdat->compressed_chunk + cksum_bytes, 0, mac_bytes);
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hmac_reinit(&tdat->chunk_hmac);
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hmac_update(&tdat->chunk_hmac, (uchar_t *)&tdat->len_cmp_be, sizeof (tdat->len_cmp_be));
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hmac_update(&tdat->chunk_hmac, tdat->compressed_chunk,
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cksum_bytes + mac_bytes + CHUNK_FLAG_SZ);
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hmac_update(&tdat->chunk_hmac, tdat->compressed_chunk, tdat->rbytes);
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if (HDR & CHSIZE_MASK) {
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uchar_t *rseg;
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rseg = tdat->compressed_chunk + tdat->rbytes;
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@ -378,13 +377,13 @@ redo:
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sem_post(&tdat->cmp_done_sem);
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return;
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}
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}
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/*
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* Now that HMAC (if any) was verified, recover the stored message
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* Now that header CRC32 was verified, recover the stored message
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* digest.
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*/
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deserialize_checksum(tdat->checksum, tdat->compressed_chunk, cksum_bytes);
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}
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if ((enable_rabin_scan || enable_fixed_scan) && (HDR & CHUNK_FLAG_DEDUP)) {
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uchar_t *cmpbuf, *ubuf;
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@ -471,6 +470,7 @@ redo:
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tdat->cmp_seg = tdat->uncompressed_chunk;
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}
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if (!encrypt_type) {
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/*
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* Re-compute checksum of original uncompressed chunk.
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* If it does not match we set length of chunk to 0 to indicate
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@ -481,6 +481,7 @@ redo:
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tdat->len_cmp = 0;
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fprintf(stderr, "ERROR: Chunk %d, checksums do not match.\n", tdat->id);
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}
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}
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cont:
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sem_post(&tdat->cmp_done_sem);
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@ -666,6 +667,11 @@ start_decompress(const char *filename, const char *to_filename)
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unsigned short d1;
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unsigned int d2;
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/*
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* In encrypted files we do not have a normal digest. The HMAC
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* is computed over header and encrypted data.
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*/
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cksum_bytes = 0;
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compressed_chunksize += mac_bytes;
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encrypt_type = flags & MASK_CRYPTO_ALG;
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if (Read(compfd, &saltlen, sizeof (saltlen)) < sizeof (saltlen)) {
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@ -758,7 +764,7 @@ start_decompress(const char *filename, const char *to_filename)
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memset(pw, 0, MAX_PW_LEN);
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/*
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* Verify header HMAC.
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* Verify file header HMAC.
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*/
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if (hmac_init(&hdr_mac, cksum, &crypto_ctx) == -1) {
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close(uncompfd); unlink(to_filename);
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@ -1071,6 +1077,7 @@ redo:
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* into uncompressed_chunk so that compress transforms uncompressed_chunk
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* back into cmp_seg. Avoids an extra memcpy().
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*/
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if (!encrypt_type)
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compute_checksum(tdat->checksum, cksum, tdat->cmp_seg, tdat->rbytes);
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rctx = tdat->rctx;
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@ -1085,6 +1092,7 @@ redo:
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/*
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* Compute checksum of original uncompressed chunk.
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*/
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if (!encrypt_type)
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compute_checksum(tdat->checksum, cksum, tdat->uncompressed_chunk, tdat->rbytes);
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}
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@ -1206,6 +1214,7 @@ plain_compress:
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*/
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len_cmp = tdat->len_cmp;
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*((typeof (len_cmp) *)(tdat->cmp_seg)) = htonll(tdat->len_cmp);
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if (!encrypt_type)
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serialize_checksum(tdat->checksum, tdat->cmp_seg + sizeof (tdat->len_cmp), cksum_bytes);
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tdat->len_cmp += CHUNK_FLAG_SZ;
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tdat->len_cmp += sizeof (len_cmp);
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@ -1231,7 +1240,7 @@ plain_compress:
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*(tdat->compressed_chunk) = type;
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/*
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* If encrypting, compute HMAC for chunk header and trailer.
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* If encrypting, compute HMAC for full chunk including header.
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*/
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if (encrypt_type) {
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uchar_t *mac_ptr;
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@ -1242,11 +1251,7 @@ plain_compress:
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mac_ptr = tdat->cmp_seg + sizeof (tdat->len_cmp) + cksum_bytes;
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memset(mac_ptr, 0, mac_bytes);
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hmac_reinit(&tdat->chunk_hmac);
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hmac_update(&tdat->chunk_hmac, tdat->cmp_seg, rbytes);
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if (type & CHSIZE_MASK)
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hmac_update(&tdat->chunk_hmac,
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tdat->cmp_seg + tdat->len_cmp - ORIGINAL_CHUNKSZ,
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ORIGINAL_CHUNKSZ);
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hmac_update(&tdat->chunk_hmac, tdat->cmp_seg, tdat->len_cmp);
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hmac_final(&tdat->chunk_hmac, chash, &hlen);
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serialize_checksum(chash, mac_ptr, hlen);
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} else {
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@ -1257,7 +1262,7 @@ plain_compress:
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unsigned int hlen;
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uint32_t crc;
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/* Clean out mac_bytes to 0 for stable HMAC. */
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/* Clean out mac_bytes to 0 for stable CRC32. */
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mac_ptr = tdat->cmp_seg + sizeof (tdat->len_cmp) + cksum_bytes;
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memset(mac_ptr, 0, mac_bytes);
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crc = lzma_crc32(tdat->cmp_seg, rbytes, 0);
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@ -2185,8 +2190,19 @@ main(int argc, char *argv[])
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if (cksum == 0)
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get_checksum_props(DEFAULT_CKSUM, &cksum, &cksum_bytes, &mac_bytes);
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if (!encrypt_type)
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if (!encrypt_type) {
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/*
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* If not encrypting we compute a header CRC32.
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*/
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mac_bytes = sizeof (uint32_t); // CRC32 in non-crypto mode
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} else {
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/*
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* When encrypting we do not compute a normal digest. The HMAC
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* is computed over header and encrypted data.
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*/
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cksum_bytes = 0;
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}
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/*
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* Start the main routines.
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*/
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