peazip  7.7.0
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peazip Documentation

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readme
The basic routines in this archive can be compiled with most current Pascal
(TP 5/5.5/6, BP 7, VP 2.1, FPC 1.0/2.0/2.2) and Delphi versions (tested with
V1 up to V7/9/10).

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Last changes:

  * Renamed and expanded KDF unit with key derivations functions kdf1, kdf2,
    kdf3, mgf1, pbkdf1, pbkdf2
  * improved and fixed crcmodel unit (now included in DLL)
  * New crcm_cat unit with predefined parameter records for more than 30 CRC
    algorithms


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Since Feb. 2006 there is a new Hash/HMAC architecture: Hash descriptor records
allow a simple and uniform HMAC implementation for all hash algorithms; the
key derivation functions can use all supported hash algorithms. A separate
short introduction (intro.txt) gives some more information about the Hash/HMAC
units and procedures.

Since May 2008 the cryptographic hash and HMAC routines support messages with
arbitrary bit lengths.

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The basic routines were slightly improved in the previous versions, but
optimizing seems to be black magic. The cycles/times are heavily dependent on
CPU, cache, compiler, code position, etc. For example: if the SHA256 loop is
unrolled, the calculation slows down for about 40% on one machine (1.8GHz P4,
D6, Win98), but is about 15% faster on another (AMD 2600+, D5, Win98). In the
archive sha256unroll.zip you can find some snippets related to SHA256 loop
unrolling.

With the test program T_SpeedA and the high resolution timer from hrtimer you
can measure the CPU cycles per byte (Cyc/B) and the processing rate in MB/s
(note that the CPU frequency is determined dynamically). Here are the values
for Delphi/FPC on Win98 with Pentium 4 / 1.8 GHz using a blocksize of 50000
bytes (Std: standard routines with BASM, PP: Pure Pascal with inline for D10
and FPC2.2 -O3):

       +-----------+--------+--------+--------+-------+--------+--------+
       |           | D3/Std | D3/Std | D6/Std | D6/PP | D10/PP | FPC/PP |
       |      Name |   MB/s |  Cyc/B |  Cyc/B | Cyc/B |  Cyc/B |  Cyc/B |
       +-----------+--------+--------+--------+-------+--------+--------+
       |     CRC16 | 206.37 |    8.7 |    8.8 |  34.4 |   27.6 |   45.6 |
       |     CRC24 | 185.48 |    9.7 |    9.7 |  31.0 |   27.5 |   43.0 |
       |     CRC32 | 287.27 |    6.2 |    6.4 |  18.7 |   19.7 |   22.8 |
       |    FCRC32 | 406.65 |    4.4 |    4.5 |  20.0 |   18.7 |   18.9 |
       |   Adler32 | 400.05 |    4.5 |    5.1 |   4.7 |    3.8 |    8.4 |
       |     CRC64 |  95.33 |   18.8 |   18.7 |  96.4 |   98.2 |   64.8 |
       |   eDonkey | 212.36 |    8.4 |    8.4 |   8.4 |    8.6 |   21.6 |
       |       MD4 | 214.93 |    8.3 |    8.4 |   8.4 |    8.4 |   20.1 |
       |       MD5 | 155.54 |   11.5 |   11.6 |  11.6 |   11.7 |   31.7 |
       |    RMD160 |  55.00 |   32.6 |   33.1 |  33.1 |   32.0 |   92.9 |
       |      SHA1 |  51.04 |   35.1 |   36.7 |  40.0 |   36.3 |   45.2 |
       |    SHA224 |  30.35 |   59.1 |   58.9 |  72.3 |   53.1 |   55.2 |
       |    SHA256 |  30.79 |   58.2 |   58.1 |  72.1 |   52.1 |   54.7 |
       |    SHA384 |  10.06 |  178.3 |  213.7 | 214.3 |  213.3 |  205.8 |
       |    SHA512 |  10.06 |  178.3 |  213.1 | 213.6 |  214.3 |  201.0 |
       | Whirlpool |  17.60 |  101.9 |  132.3 | 132.4 |  102.8 |  101.0 |
       +-----------+--------+--------+--------+-------+--------+--------+

MD4, eDonkey/eMule: For files/messages with a multiple of 9728000 bytes the
eDonkey and eMule hashes are different; the ed2k unit always calculates both
digests. The demo programs and the FAR plugin display both values if they are
different.

Int64 support for SHA384/512:  Unfortunately there are conflicting processor
specific results: on a P4 / 1.8GHz the speed decreases to 83% of the longint
speed (Cyc/B increase from 174 to 209). For a Celeron 500MHz the speed
increases more than 30%, the Cyc/B decrease from 146 (longint) to 111 (Int64).
In the source Int64 is default for D4+ and FPC (conditional define UseInt64 in
SHA512.PAS)

BASM16 table alignment: Because some BASM16 implementations use 32 bit access
to 32 bit tables, these tables should be dword aligned for optimal speed. But
the 16 bit compilers support byte or word alignment only! Therefore the
defines from the align.inc include file allow to generate dummy words, which
align the tables to 32 bit boundaries. This feature is implemented for CRC24
... CRC64; if more than one of these units are used, it may be necessary to
iterate the alignment procedure.

Rocksoft^tm Model CRC Algorithm: The crcmodel unit is a Pascal implementation of
Ross William's parameterized model CRC algorithm described in A Painless Guide
to CRC Error Detection Algorithms. Most of the usual CRC algorithms with
polynomials up to degree 32 can be modeled by this unit. The crcm_cat unit has
predefined parameter records for more than 30 CRC algorithms, most of them
adapted from Greg Cook's Catalogue of Parameterised CRC Algorithms, more
references are listed in the unit header.

W.Ehrhardt, July 16, 2008