lrzip/doc/magic.header.txt

lrzip-0.6x file format
March 2011
Con Kolivas

Byte	Content
0-23	Magic
---
24+	Rzip Chunk Data (RCD)
RCD+	Data blocks
--- repeat
(end-MD5_DIGEST_SIZE)->(end) md5 hash

Magic data:
0->3	LRZI
4	LRZIP Major Version Number
5	LRZIP Minor Version Number
6->14	Source File Size or 0 if unknown, or salt in encrypted file
16->20	LZMA Properties Encoded (lc,lp,pb,fb, and dictionary size)
21	1 = md5sum hash is stored at the end of the archive
22	1 = data is encrypted with sha512/aes128
23	Unused

Encrypted salt (bytes 6->14 in magic if encrypted):
0->1	Encoded number of loops to hash password
2->7	Random data
(RCD0 is set to 8 bytes always on encrypted files)

Rzip Chunk Data:
0	Data offsets byte width (meaning length is < (2 * 8)^RCD0)
1	Flag that there is no chunk beyond this
(RCD0 bytes)	Chunk decompressed size (not stored in encrypted file)
XX	Stream 0 header data
XX	Stream 1 header data

Stream Header Data: 
Byte:
0	Compressed data type
(RCD0 bytes)	Compressed data length
(RCD0 bytes)	Uncompressed data length
(RCD0 bytes)	Next block head

Data blocks:
0->(end-2) data
(end-1)->end crc data


lrzip-0.5x file format
March 2011
Con Kolivas

Byte	Content
0->23	Magic
--
24->74	Rzip chunk data
75+	Data blocks
-- repeat
(end-MD5_DIGEST_SIZE)->(end) md5 hash

Magic data:
0->3	LRZI
4	LRZIP Major Version Number
5	LRZIP Minor Version Number
6->14	Source File Size
16->20	LZMA Properties Encoded (lc,lp,pb,fb, and dictionary size)
21	Flag that md5sum hash is stored at the end of the archive
22-23	not used

Rzip chunk data:
0	Data offsets byte width
1-25	Stream 0 header data
26-50	Stream 1 header data

Stream Header Data:
Byte:
0	Compressed data type
1-8	Compressed data length
9-16	Uncompressed data length
17-24	Next block head

Data blocks:
0->(end-2) data
(end-1)->end crc data


lrzip-0.40+ file header format
November 2009
Con Kolivas

Byte	Content
0-3	LRZI
4	LRZIP Major Version Number
5	LRZIP Minor Version Number
6-14	Source File Size
16-20	LZMA Properties Encoded (lc,lp,pb,fb, and dictionary size)
21-24	not used
24-48	Stream 1 header data
49-74	Stream 2 header data

Block Data:
Byte:
0	Compressed data type
1-8	Compressed data length
9-16	Uncompressed data length
17-24	Next block head
25+	Data

End:
0-1	crc data


lrzip-0.24+ file header format
January 2009
Peter Hyman, pete@peterhyman.com

Byte	Content
0-3	LRZI
4	LRZIP Major Version Number
5	LRZIP Minor Version Number
6-9	Source File Size (no HAVE_LARGE_FILES)
6-14	Source File Size
16-20	LZMA Properties Encoded (lc,lp,pb,fb, and dictionary size)
21-23	not used
24-36	Stream 1 header data
37-50	Stream 2 header data
51	Compressed data type