Class: SHA1Stream

• Inheritance
• Description
• Related information
• Class protocol
  • initialization
  • queries
  • testing
• Instance protocol
  • initialization
  • positioning
  • queries
  • writing
• Examples

Inheritance:

   Object
   |
   +--Stream
      |
      +--HashStream
         |
         +--SHA1Stream

Package:

stx:libbasic

Category:

System-Crypt-Hashing

Version:

rev: 1.19 date: 2010/04/13 14:36:36

user: cg

file: SHA1Stream.st directory: libbasic

module: stx stc-classLibrary: libbasic

Author:

Stefan Vogel

Description:

Generate a SHA-1 hash value as defined in
NIST, FIPS PUB 180-1: Secure Hash Standard, April 1995.
This may be used as checksum
or for generating cryptographic signatures.

performance: roughly
       47400 Kb/s on a 2Ghz Duo
        9580 Kb/s on a 400Mhz PIII
        3970 Kb/s on a 300Mhz Sparc



[class variables:]
    HashSize        size of returned hash value
    ContextSize     (implementation) size of hash context

[instance variables:]
    hashContext     (implementation)
                    internal buffer for computation of the hash value

Related information:

    MD5Stream

Class protocol:

 initialize

 blockSize

return the block size used internally by the compression function

 hashSize

return the size of the hashvalue returned by instances of this class

 testVector

Test Vectors (from FIPS PUB 180-1)

Instance protocol:

 initialize

 reset

reset the stream in order to compute a new hash value

 hashValue

Get the value hashed so far.
The context is kept, so that more objects may be hashed after
retrieving a hash value

 nextPut: anObject

update our hash value for anObject.
anObject may be a String, a Character, a Smallinteger or an Array of primitive
types like ByteArray.

 nextPutBytes: count from: anObject startingAt: start

update the hash value with count bytes from an object starting at index start.
The object must have non-pointer indexed instvars
(i.e. be a ByteArray, String, Float- or DoubleArray),
or an externalBytes object (with known size)

Examples:

|hashStream|

hashStream := SHA1Stream new.
hashStream nextPut:'abc'.
hashStream hashValue printOn:Transcript base:16. Transcript cr.
hashStream nextPut:'dbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq'.
hashStream hashValue printOn:Transcript base:16. Transcript cr.

|hashValue|

hahValue := SHA1Stream hashValueOf:'abc'.
hashValue printOn:Transcript base:16. Transcript cr.

|hashStream|

hashStream := SHA1Stream new.
hashStream nextPut:'abc' asByteArray.
hashStream hashValue printOn:Transcript base:16. Transcript cr.
hashStream nextPut:'dbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq' asByteArray.
hashStream hashValue printOn:Transcript base:16. Transcript cr.

|hashStream|

hashStream := SHA1Stream new.
1000000 timesRepeat:[ hashStream nextPut:$a ].
hashStream hashValue printOn:Transcript base:16. Transcript cr.

|hashStream|

hashStream := SHA1Stream new.
hashStream nextPut:'a'.
hashStream hashValue printOn:Transcript base:16. Transcript cr.

|hashStream|

hashStream := SHA1Stream new.
hashStream nextPut:$a.
hashStream hashValue printOn:Transcript base:16. Transcript cr.

|hashStream n t|

hashStream := SHA1Stream new.
n := 1000000.
t := Time millisecondsToRun:[
        n timesRepeat:[
            hashStream nextPutAll:'12345678901234567890123456789012345678901234567890'.
        ].
     ].
t := (t / 1000) asFloat.
Transcript show:t; show:' seconds for '; show:(50*n/1024) asFloat; showCR:' Kb'.
Transcript show:(n*50/1024 / t); showCR:' Kb/s'