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Documentation of class 'CRC32Stream':

Class: CRC32Stream

Inheritance
Description
Class protocol
Instance protocol
- initialization
Private classes
Examples

Inheritance:

   Object
   |
   +--Stream
      |
      +--HashStream
         |
         +--CRCStream
            |
            +--CRC32Stream
               |
               +--CRC32Stream::CRC32Stream_Castagnoli

Package:: stx:libbasic2

Category:: System-Crypt-Hashing

Version:: rev: 1.54 date: 2024/03/13 08:56:25; user: cg; file: CRC32Stream.st directory: libbasic2; module: stx stc-classLibrary: libbasic2

Description:

Only use CRC to protect against communication errors;
DO NOT use CRC for cryptography, authentication, security, etc.
- use secure hashes for those instead.

Standard CRC method as defined by ISO 3309 [ISO-3309] or ITU-T V.42 [ITU-T-V42].
The default CRC polynomial employed is

    x^32+x^26+x^23+x^22+x^16+x^12+x^11+x^10+x^8+x^7+x^5+x^4+x^2+x+1
    (or 16r04C11DB7)

You can also create an instance performing the Castagnoli CRC-32C
(used in iSCSI & SCTP [RFC3720], G.hn payload, SSE4.2):

    self newCrc32c

 the polynomial is: 16r1edc6f41
    = x32 + x28 + x27 + x26 + x25 + x23 + x22 + x20 + x19 + x18 + x14 + x13 + x11 + x10 + x9 + x8 + x6 + 1

Notice that CRC32Stream is also used with PNG images;
therefore, its performance directly affects png image processing (png write speed).

throughput:
    235 Mb/s on MacBook Pro (2.6Ghz I7) 
            (360 Mb/s for big chunks of size 50k)
            (100 Mb/s for small chunks of size 10)
    157 Mb/s on a 2.5Ghz 64X2 Athlon 4800+ (64bit)
    150 Mb/s on 2Ghz Duo
    
 new:
    500 Mb/s for castagnoli on MacBook Pro (2.6Ghz I7) 
            (5Gb/s for big chunks of size 50k)


[instance variables:]

[class variables:]

copyrightCOPYRIGHT (c) 2003 by eXept Software AG
             All Rights Reserved

This software is furnished under a license and may be used
only in accordance with the terms of that license and with the
inclusion of the above copyright notice.   This software may not
be provided or otherwise made available to, or used by, any
other person.  No title to or ownership of the software is
hereby transferred.

Class protocol:

instance creation

generatorPolynomMSB: anInteger

notice, in literature, the generator polynom is usually specified as an MSB number

generatorPolynomMSB: anInteger initValue: initValueArg

notice, in literature, the generator polynom is usually specified as an MSB number

generatorPolynomMSB: anInteger initValue: initValueArg xorOut: xorOut

notice, in literature, the generator polynom is usually specified as an MSB number

new

return an instance of the ITU-T CRC-32

newCCITT

return an instance of the ITU-T CRC-32
x^32+x^26+x^23+x^22+x^16+x^12+x^11+x^10+x^8+x^7+x^5+x^4+x^2+x+1

newCastagnoli

return an instance of the Castagnoli CRC-32 also known as CRC32C
x32 + x28 + x27 + x26 + x25 + x23 + x22 + x20 + x19 + x18 + x14 + x13 + x11 + x10 + x9 + x8 + x6 + 1
(used in iSCSI & SCTP, G.hn payload, SSE4.2)

newCrc32c

return an instance of the Castagnoli CRC-32 (CRC32C)

Usage example(s):

     Castagnoli crc:
       self assert:((self newCrc32c)
                                nextPut:'123456789';
                                hashValue) = 3808858755. '16rE3069283'

     default crc:
       self assert:((self new)
                                nextPut:'123456789';
                                hashValue) = 3421780262. '16rCBF43926'

private

canUseFastCRC

return true, if the underlying CPU hast a fast CRC instruction
to be used for the castagnoli CRC32 computation

Usage example(s):

     self canUseFastCRC

queries

hashSize: return the size of the hashvalue returned by instances of this class (in bytes)

Instance protocol:

initialization

generatorPolynom: anLSBInteger: set the generator polynom for this instance.
set start and xorOut to 16rFFFFFFFF.
Note: you have to set the bit-reversed value, so the LSB must be first
generatorPolynom: anLSBInteger initValue: initValueArg: set the generator polynom for this instance.
set start to initValueArg and xorOut to 16rFFFFFFFF.
Note: you have to set the bit-reversed value, so the LSB must be first

Private classes:

    CRC32Stream_Castagnoli

Examples:

expect 60C1D0A0

  self information:(CRC32Stream hashValueOf:'resume') hexPrintString

expect 16r60C1D0A0

  self information:(CRC32Stream new
                          nextPut:$r;
                          nextPut:$e;
                          nextPut:$s;
                          nextPut:$u;
                          nextPut:$m;
                          nextPut:$e;
                          hashValue) hexPrintString

expect 16r70E46888:

  self information:(CRC32Stream hashValueOf:#[1 2 3 4 5 6 7]) hexPrintString

expect 16r8CD04C73:

  self information:((CRC32Stream hashValueOf:#[16rFF 16rFF 16rFF 16rFF 16rFF 16rFF 16rFF 16rFF 16rFF 16rFF
           16rFF 16rFF 16rFF 16rFF 16rFF 16rFF 16rFF 16rFF 16rFF 16rFF
           16rFF 16rFF 16rFF 16rFF 16rFF 16rFF 16rFF 16rFF 16rFF 16rFF
           16rFF 16rFF 16rFF 16rFF 16rFF 16rFF 16rFF 16rFF 16rFF 16rFF]) hexPrintString)

timing throughput: 230Mb/s (on MacBook Pro 2012 / 2.6Ghz I7)

  |hashStream n t|

  hashStream := CRC32Stream new.
  n := 2000000.
  t := Time millisecondsToRun:[
          n timesRepeat:[
              hashStream nextPutAll:'12345678901234567890123456789012345678901234567890'.
          ].
       ].
  t := (t / 1000) asFloat.
  Transcript show:'crc32:'; showCR: hashStream hashValue hexPrintString.
  Transcript show:t; show:' seconds for '; show:(50*n/1024/1024) asFloat; showCR:' Mb'.
  Transcript show:(n*50/1024/1024 / t); showCR:' Mb/s'

500Mb/s (on MacBook Pro 2012 / 2.6Ghz I7)

  |hashStream s n t l|

  hashStream := CRC32Stream newCastagnoli.
  n := 2000000.
  s := '12345678901234567890123456789012345678901234567890'.
  l := s size.
  t := Time millisecondsToRun:[
          n timesRepeat:[
              hashStream nextPutAll:'12345678901234567890123456789012345678901234567890'.
          ].
       ].
  t := (t / 1000) asFloat.
  Transcript show:'crc32:'; showCR: hashStream hashValue hexPrintString.
  Transcript show:t; show:' seconds for '; show:(l*n/1024/1024) asFloat; showCR:' Mb'.
  Transcript show:(n*l/1024/1024 / t); showCR:' Mb/s'

the real speed is shown with longer inputs...

  |hashStream n t l s|

  hashStream := CRC32Stream newCastagnoli.
  n := 20000.
  s := '1234567890' ,* 10000.
  l := s size.
  t := Time millisecondsToRun:[
          n timesRepeat:[
              hashStream nextPutAll:s
          ].
       ].
  t := (t / 1000) asFloat.
  Transcript show:'crc32:'; showCR: hashStream hashValue hexPrintString.
  Transcript show:t; show:' seconds for '; show:(l*n/1024/1024) asFloat; showCR:' Mb'.
  Transcript show:(n*l/1024/1024 / t); showCR:' Mb/s'

test vectors from https://tools.ietf.org/html/rfc3720#page-217: expect 0

  self information:(CRC32Stream newCrc32c hashValueOf:'') hexPrintString

expect C1D04330

  self information:(CRC32Stream newCrc32c hashValueOf:'a') hexPrintString

expect E3069283

  self information:(CRC32Stream newCrc32c hashValueOf:'123456789') hexPrintString

expect 8A9136AA

  self information:(CRC32Stream newCrc32c hashValueOf:(ByteArray new:32 withAll:0)) hexPrintString

expect 62a8ab43

  self information:(CRC32Stream newCrc32c hashValueOf:(ByteArray new:32 withAll:16rFF)) hexPrintString

expect 46dd794e

  self information:(CRC32Stream newCrc32c hashValueOf:(0 to:31) asByteArray) hexPrintString

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