Encrypt and decrypt a string

CREATE VIEW V_rand

As

Select C=unicode (CAST (Round (rand () *255,0) as tinyint)

Go

Create function F_jmstr

(

@str varchar (8000),

@type bit

)

Returns varchar (8000)

/*

* Parameter Description

*STR: The string to encrypt or the character that has been encrypted

*type: Operation type--0 Encryption--decryption

* Return Value Description

* When the operation type is encrypted (type--0): Returns the encrypted STR, which is the string stored in the database

* When the operation type is decrypted (TYPE--1): Returns the actual string, which is the original string after the encrypted string is decrypted

*/

As

Begin

DECLARE @re varchar (8000)--return value

Declare @c int--encrypted characters

DECLARE @i int

/*

* Encryption method is an original character xor or a random ASCII character

*/

If @type =0--encryption

Begin

Select @c=c, @re = ", @i=len (@str) from V_rand

While @i>0

Select @re =nchar (Unicode (substring (@str, @i,1)) ^@c^@i) [email protected]

, @[email protected]

Set @[email Protected]+nchar (@c)

End

else--decryption

Begin

Select @i=len (@str) -1,@c=unicode (substring (@str, @i+1,1)), @re = "

While @i>0

Select @re =nchar (Unicode (substring (@str, @i,1)) ^@c^@i) [email protected], @[email protected]

End

Return (@re)

End

Go

--Test

DECLARE @tempstr varchar (20)

Set @tempstr = ' 1 2 3aA '

Select ' Original value: ', @tempstr

Select ' Encrypted: ', Dbo.f_jmstr (@tempstr, 0)

Select ' Decrypted: ', Dbo.f_jmstr (dbo.f_jmstr (@tempstr, 0), 1)

--Output results

/*

Original value: 1 2 3aA

After encryption: __0 ' 15 ' 17__°{1

After decryption: 1 2 3aA

*/

Encrypt and decrypt a string