Hi Andreas,
Well I would wrap C routines for either MD5 or SHA1, which I have been
intending to complete Real-Soon-Now for sometime.
Only four C calls are needed:
sha1.initialize
sha1.process (address: POINTER; count: INTEGER)
sha1.finalize
signature := sha1.result_as_string
or something like that ...
I will send you a couple of Eiffel files that will need adapting; they were
last used with SmartEiffel and the result_as_string routine will need to be
adapted to Gobo's string and character routines.
See md5deep.sourceforge.net
If you get it working, I would be obliged if you would return the working
classes ...
Howard
#############################################################
indexing
description: "Hashing Algorithms"
deferred class FILE_HASH
feature
init is
-- Initialise prior to processing a byte sequence
deferred
end
process(area: POINTER; count: INTEGER) is
-- Process a contiguous sequence of bytes
deferred
end
finalise is
-- Post processing of remaining steps
deferred
end
end
#############################################################
indexing
description: "SHA1 Secure Hash Algorithm"
class HASH_STREAM_SHA1
inherit
FILE_HASH -- Note name to be changed
create
make
feature -- Attributes
sha1_context: POINTER
result_buffer: ARRAY [ INTEGER_8 ]
feature -- Routines
make is
local
b: ARRAY [ INTEGER_8 ]
do
create b.make (1, sha1_context_size_temp)
sha1_context := b.to_external
create result_buffer.make(1, 20)
end
init is
do
sha1_init (sha1_context)
end
process (data: POINTER; count: INTEGER) is
do
sha1_process (sha1_context, data, count)
end
finalise is
do
sha1_finalise (result_buffer.to_external, sha1_context)
end
result_as_string: STRING is
local
i: INTEGER
do
create Result.make (40)
from
i := 1
until
i > 20
loop
-- Result.append ((result_buffer @ i).to_hex_string)
(result_buffer @ i).to_hexadecimal_in(Result)
i := i + 1
end
end
feature {NONE} -- TEMP
sha1_context_size_temp: INTEGER is
do
Result := (5 + 2) * 8
Result := Result + 64
end
feature {NONE} -- External routines, SHA1 implementation
sha1_context_size: INTEGER is
-- Size of the C struct containing the SHA1 Context
external "C use %"md5deep.h%""
alias "sizeof(SHA1_CTX)"
end
sha1_init (p: POINTER) is
-- Call initialisation routine for the Context
external "C"
alias "SHA1Init"
end
sha1_process (p_ctx: POINTER; p_data: POINTER; n: INTEGER) is
external "C"
alias "SHA1Update"
end
sha1_finalise (p_result: POINTER; p_ctx: POINTER) is
external "C"
alias "SHA1Final"
end
invariant
sha1_context /= default_pointer
end
################################################################
On Friday 14 Mar 2008, Andreas Leitner wrote:
> Hi all,
>
> we need to calculate the checksum of a stream of characters. Basically
> we would like to a quick way to check if two streams of characters are
> he same. False positives are not a big deal, since we can always fall
> back and compare the streams character for character (as long as it does
> not happen too often).
>
> Does anybody know if such an algorithm is already implemented somewhere
> in Eiffel that we could use?
>
> I only found Franck's library
> (
http://eiffelzone.com/esd/crc/index.html), but it is written against
> TowerEiffel using BIT, both of which are no longer supported.
>
> many thanks in advance,
> Andreas
>
>
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Howard Thomson
--
"Only two things are infinite, the universe and human stupidity,
and I'm not sure about the former." -- Albert Einstein
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