Class: HashStream

• Inheritance
• Description
• Related information
• Class protocol
  • compatibility - squeak
  • instance creation
  • queries
  • self tests
  • utilities
• Instance protocol
  • accessing
  • not implemented
  • operations
  • queries
  • testing
  • writing

Inheritance:

   Object
   |
   +--Stream
      |
      +--HashStream
         |
         +--CRC32Stream
         |
         +--MD5Stream
         |
         +--SHA1Stream

Package:

stx:libbasic

Category:

System-Crypt-Hashing

Version:

rev: 1.13 date: 2010/03/04 14:34:21

user: cg

file: HashStream.st directory: libbasic

module: stx stc-classLibrary: libbasic

Author:

Stefan Vogel

Description:

Abstract class. Subclasses generate hash values used as checksums
or for generating cryptographic signatures.

Related information:

    SHA1Stream
    MD5Stream

Class protocol:

 hashMessage: aStringOrByteArrayOrStream

SQUEAK compatibility
- but this is a bad choice - squeak uses #digestMessage: at the instance side

 new

have to re-allow new - it was disabled in Stream

 random

create a random number generator using myself

 canStream

simple hash functions (squeak-ported) cannot stream.
Use hashFunction: there

 test

test against testVector

 testVector

define a testvector to test the implementation

** This method raises an error - it must be redefined in concrete classes **

 digestMessage: aStringOrByteArrayOrStream

 hashValueOf: aStringOrByteArrayOrStream

 hashValueOfFile: aFilename

Instance protocol:

 contents

return the entire contents of the stream
- this is our hashValue.

 next

 digestMessage: bytes

answer the digest of bytes

 hmac

answer a hmac stream with myself

 reset

initialize to a clean state

** This method raises an error - it must be redefined in concrete classes **

 blockSize

the class knows about the basic block size

 hashSize

the class knows about the basic hash size

 hashValue

retunr the value of the computeted hash

** This method raises an error - it must be redefined in concrete classes **

 isReadable

return true, if reading is supported by the recevier.
Always return false here

 isWritable

return true, if writing is supported by the recevier.
Always return true here

 atEnd

return true if the end of the stream has been reached;
this is never reached

 nextPut: anObject

add the hash of anObject to the computed hash so far.
anObject can be a Character, SmallInteger, or Character-, Byte-
Integer-Array

** This method raises an error - it must be redefined in concrete classes **

 nextPutAll: aCollection

Hash streams handle Strings and ByteArrays in nextPut:

 nextPutBytes: count from: anObject startingAt: start

write count bytes from an object starting at index start.
Return the number of bytes written.
The object must have non-pointer indexed instvars
(i.e. be a ByteArray, String, Float- or DoubleArray).
Use with care - non object oriented i/o.
This is provided for compatibility with externalStream;
to support binary storage.

Redefined, because HashStream encodes integers as 4 bytes.
You should implement this method in subclasses