Andy Reza

Dibandingan dengan MySQL enkrip-dekrip di SQL Server jauh lebih rumit (itu sih pendapat gwe loh). Cukup banyak variasi enkrip-dekrip di MySQL seperti :

• AES_ENCRYPT(str,key_str), AES_DECRYPT(crypt_str,key_str) 
• ENCODE(str,pass_str), DECODE(crypt_str,pass_str)
• DES_DECRYPT(crypt_str[,key_str]), DES_ENCRYPT(str[,{key_num|key_str}]) 
• ENCRYPT(str[,salt]) 
• MD5(str) 
• SHA1(str), SHA(str) 

Setelah browsing beberapa lama akhirnya gwe temuin juga function enkrip-dekrip (pake RC4) di SQL Server. Gwe lupa dapet darimana. Kalian bisa copas function berikut:

--------------------------
CREATE FUNCTION dbo.fnInitRc4
(
 @Pwd VARCHAR(256)
)
RETURNS @Box TABLE (i TINYINT, v TINYINT)
with ENCRYPTION
AS

BEGIN
 DECLARE @Key TABLE (i TINYINT, v TINYINT)

 DECLARE @Index SMALLINT,
  @PwdLen TINYINT

 SELECT @Index = 0,
  @PwdLen = LEN(@Pwd)

 WHILE @Index <= 255
  BEGIN
  INSERT @Key(i,v)
  VALUES (@Index,ASCII(SUBSTRING(@Pwd, @Index % @PwdLen + 1, 1)))

  INSERT @Box(i,v)
  VALUES (@Index,@Index)

  SELECT @Index = @Index + 1
  END


 DECLARE @t TINYINT,
  @b SMALLINT

 SELECT @Index = 0,
  @b = 0

 WHILE @Index <= 255
  BEGIN
  SELECT @b = (@b + b.v + k.v) % 256
  FROM @Box AS b
  INNER JOIN @Key AS k ON k.i = b.i
  WHERE b.i = @Index

  SELECT @t = v
  FROM @Box
  WHERE i = @Index

  UPDATE b1
  SET b1.v = (SELECT b2.v FROM @Box b2 WHERE b2.i = @b)
  FROM @Box b1
  WHERE b1.i = @Index

  UPDATE @Box
  SET v = @t
  WHERE i = @b

  SELECT @Index = @Index + 1
  END

 RETURN
END

---------------------

CREATE FUNCTION dbo.fnRC4
(
 @Pwd VARCHAR(256),
 @Text VARCHAR(8000)
)
RETURNS VARCHAR(8000)
with ENCRYPTION
AS

BEGIN
 DECLARE @Box TABLE (i TINYINT, v TINYINT)

 INSERT @Box(i,v)
 SELECT i,v
 FROM dbo.fnInitRc4(@Pwd)

 DECLARE @Index SMALLINT,
  @i SMALLINT,
  @j SMALLINT,
  @t TINYINT,
  @k SMALLINT,
  @CipherBy TINYINT,
  @Cipher VARCHAR(8000)

 SELECT @Index = 1, @i = 0, @j = 0, @Cipher = ''

 WHILE @Index <= DATALENGTH(@Text)
  BEGIN
  SELECT @i = (@i + 1) % 256

  SELECT @j = (@j + b.v) % 256
  FROM @Box b
  WHERE b.i = @i

  SELECT @t = v
  FROM @Box
  WHERE i = @i

  UPDATE b
  SET b.v = (SELECT w.v FROM @Box w WHERE w.i = @j)
  FROM @Box b
  WHERE b.i = @i

  UPDATE @Box
  SET v = @t
  WHERE i = @j

  SELECT @k = v
  FROM @Box
  WHERE i = @i

  SELECT @k = (@k + v) % 256
  FROM @Box
  WHERE i = @j

  SELECT @k = v
  FROM @Box
  WHERE i = @k

  SELECT @CipherBy = ASCII(SUBSTRING(@Text, @Index, 1)) ^ @k,
  @Cipher = @Cipher + CHAR(@CipherBy)

  SELECT @Index = @Index +1
  END

 RETURN @Cipher
END

------------------------------
kalau kalian punya metode lain bisa di share dunk .... :)

(koral web)