Respuesta : enryptacion en sql2000

#11 Maxi

11/04/2006 - 17:51 | Informe spam

Las mejores encriptaciones funcionan asi :-)

Salu2
Maxi [MVP SQL SERVER]
www.sqlgurus.org

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#12 Mauro SB.

11/04/2006 - 19:11 | Informe spam

bueno pero en la del 2005 tenes la posibilidad de usar el certificado para
recuperarla, lo que me sirve si el usuario se la olvida para mandarsela por
mail, sino como hago si es unidireccional?

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#13 Maxi

11/04/2006 - 21:26 | Informe spam

Es un tema largo este como para discutirlo aca, pero el cifrado de datos es
una cosa y la encriptacion es otra. Cuando es unidireccional la seguridad
aumenta y lo que se hace es comparar cadenas encriptadas, esto se usa
generalmente para inicios de sesion en sistemas
Otra cosa es querer proteger un dato y luego poder leer para usarlo de forma
legible, ahi entran en juego por ej los certificados. Un ejemplo de lo
primero seria el algoritmo MD5 o el Hash, estos van hacia un solo lado, en
mis sistemas por lo general uso eso para guardar la informacion de usuarios.

En el ejemplo que te pase es para guardar el numero de trajeta de credito,
el cual seguramente deberas volver para atras y por ej poner en una pantalla
o reporte.

Se entiende?

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www.sqlgurus.org

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#14 Mauro SB.

11/04/2006 - 21:37 | Informe spam

entiendo que es largopara discutirlo eneste thread,asi que volviendo a SQL,
basicamente lo que yo necesito es lo que me ofrece el 2005 ,certificados,
con lo que podria en caso de
que un usario se le olvide su clave enviarsela por mail, descifrada o
desencriptada(no se que termino se aplica)
ahora, se puede hacer una funcion en sql 2000 que haga algo similar ?

saludos
Mauro

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#15 Mauro SB.

11/04/2006 - 21:57 | Informe spam

fijate esta funcion basada en RC4 anda bien en el 2000

strings up to 255 characters in length. Based on Brad Baker's RC4.sql
script, it runs about 100 times faster, fixes a minor bug, and is packaged
as a UDF. It can be modified for SQL7 by putting in a stored procedure. For
SQL Server 6.5, the "set" statements also need to be changed to "select"s.

SET QUOTED_IDENTIFIER ON SET ANSI_NULLS ON
GO

if exists (select * from sysobjects where id object_id(N'[dbo].[fn_string_helper]')
and (OBJECTPROPERTY(id, N'IsTableFunction')
+ OBJECTPROPERTY(id, N'IsInlineFunction')
+ OBJECTPROPERTY(id, N'IsScalarFunction') = 1 ) )
drop function [dbo].[fn_string_helper]
GO
create function dbo.fn_string_helper
(@long_string varchar(255),
@short_string varchar(32) )
RETURNS varchar(255)
with encryption
as
/***************************************************************************
************
* Proc: fn_string_helper
*
* Purpose: Do encryption/ decryption: The name is deliberately vague and
misleading for security
*
* This procedure uses RC4 to encrypt/decrypt the first parameter
* using the second parameter in the encryption key.
*
* Input Parameters:
* @long_string varchar(255) - The string to be encrypted/decrypted.
* @short_string varchar(32) - The string key used to
encrypt/decrypt.
*
* Output Parameters:
* @out_string varchar(255) - The encrypted/decrypted string.
*
* CalledBy:
* n/a
*
* History:
* Date Developer Description
* - --
* 01/22/2002 Brad Baker Created procedure.
* 02/19/2002 Mike Arney Optimized extensively and put in a function.
* 03/06/2002 Mike Arney Use datalength instead of len because datalength
* does an rtrim, which messes up decryption if the last
* encrypted character happens to be 0x20 (space)
*
* Notes:
* 1. RC4 is a stream cipher symmetric key algorithm.
* It was developed in 1987 by Ronald Rivest and kept as a trade secret
by RSA Data Security.
* On September 9, 1994, the RC4 algorithm was anonymously posted on the
Internet on the CyperpunksÆ ôanonymous remailersö list.
*
* 2. RC4 uses a variable length key from 1 to 256 bytes to initialize a
256-byte state table.
* The state table is used for subsequent generation of pseudo-random
bytes and then to generate a pseudo-random stream which is XORed
* with the plaintext to give the ciphertext.
* Each element in the state table is swapped at least once.
*
* 3. The RC4 key is often limited to 40 bits, because of export
restrictions but it is sometimes used as a 128 bit key.
* It has the capability of using keys between 1 and 2048 bits.
* RC4 is used in many commercial software packages such as Lotus Notes
and Oracle Secure SQL.
* It is also part of the Cellular Specification.
*
* 4. Procedure name and parameter names should be meaningless.
* Renaming this procedure RC4 would be very helpful to hackers.
*
* 5. This procedure should always be encrypted.
*
* 6. Since this procedure is used for both encryption and decryption,
* it is important to limit permissions to it.
*
* 7. If using this function to encrypt a column in a table, it is strongly
suggested
* that you use a different of @short_string for each row. Eg:
* select dbo.fn_string_helper(name, convert(varchar, id)) from sysobjects
* If you don't do this, a user who can figure out the encryption for
one row can
* easily figure it out for all rows.
*
****************************************************************************
***********/
begin

DECLARE @out_string varchar(255)
DECLARE
@state smallint,
@key char(1),
@tempSwap binary(1),
@a smallint,
@b smallint,
@N smallint,
@temp binary(1),
@i smallint,
@j smallint,
@k smallint,
@cipherby smallint,
@cipher varchar(255),
@code varchar(64),

@keys_key varchar(256),
@keys_state varbinary(256)

arrays,
division.

SET @code = @short_string + ',./;''p[\`0-=Z<?L:"P{|~!@#%^*(_'

SET @keys_key = @code + @code + @code + @code + @code + @code + @code +
@code + @code
SET @keys_state 0x000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F2021222324
25262728292A2B2C2D2E2F303132333435363738393A3B3C3D3E3F404142434445464748494A
4B4C4D4E4F505152535455565758595A5B5C5D5E5F606162636465666768696A6B6C6D6E6F70
7172737475767778797A7B7C7D7E7F808182838485868788898A8B8C8D8E8F90919293949596
9798999A9B9C9D9E9FA0A1A2A3A4A5A6A7A8A9AAABACADAEAFB0B1B2B3B4B5B6B7B8B9BABBBC
BDBEBFC0C1C2C3C4C5C6C7C8C9CACBCCCDCECFD0D1D2D3D4D5D6D7D8D9DADBDCDDDEDFE0E1E2
E3E4E5E6E7E8E9EAEBECEDEEEFF0F1F2F3F4F5F6F7F8F9FAFBFCFDFEFF

SELECT
@b = 0,
@a = 0
WHILE @a < 256
BEGIN
SELECT @b = (@b + convert(int, substring(@keys_state, @a + 1, 1)) +
ascii(substring(@keys_key, @a + 1, 1)) ) % 256
SELECT @tempSwap = substring(@keys_state, @a + 1, 1)

SET @keys_state = convert(varbinary(256), stuff(@keys_state, @a + 1, 1,
substring(@keys_state, @b + 1, 1) ) )

SET @keys_state = convert(varbinary(256), stuff(@keys_state, @b + 1, 1,
@tempSwap) )

SET @a = @a + 1
END

SELECT
@i = 0,
@j = 0,
@a = 1,
@cipher = '',
@cipherby = 0

message.
encrypting key.
WHILE @a < datalength(@long_string) + 1
BEGIN

SET @j = (@j + convert(smallint, substring(@keys_state, @i + 1, 1))) % 256
SET @temp = substring(@keys_state, @i + 1, 1)
SET @i = (@i + 1) % 256

SET @keys_state = convert(varbinary(256), stuff(@keys_state, @i + 1, 1,
substring(@keys_state, @j + 1, 1)) )

SET @keys_state = convert(varbinary(256), stuff(@keys_state, @i + 1, 1,
@temp ) )

SET @k = convert(smallint,
substring(@keys_state,
1 + ((convert(smallint, substring(@keys_state, @i + 1, 1)) +
convert(smallint, substring(@keys_state, @j + 1, 1)) ) % 256),
1) )

SET @cipherby = Ascii(Substring(@long_string, @a, 1)) ^ @k
SET @cipher = @cipher + Char(@cipherby)
SET @a = @a + 1
END

SET @out_string = @cipher

RETURN @out_string
END
GO
'xxx'), 'xxx')
id)), convert(varchar, id)), dbo.fn_string_helper(name, convert(varchar,
id)) from sysobjects

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