Scramble/Obfuscate email values in SQL Server - sql-server

Question

I would like to improve the following function to randomize the letters in an email column.
So far I have the following function but the output is not what I expected:
CREATE VIEW dbo.vwRandom
AS
SELECT RAND() as RandomValue;
GO
CREATE FUNCTION dbo.Character_Scramble
(
#OrigVal varchar(MAX)
)
RETURNS varchar(MAX)
WITH ENCRYPTION
AS
BEGIN
-- Variables used
DECLARE #NewVal VARCHAR(MAX);
DECLARE #OrigLen INT;
DECLARE #CurrLen INT;
DECLARE #LoopCt INT;
DECLARE #Rand INT;
-- Set variable default values
SET #NewVal = '';
SET #OrigLen = DATALENGTH(#OrigVal);
SET #CurrLen = #OrigLen;
SET #LoopCt = 1;
-- Loop through the characters passed
WHILE #LoopCt <= #OrigLen
BEGIN
-- Current length of possible characters
SET #CurrLen = DATALENGTH(CHARINDEX('#', #OrigVal));
-- Random position of character to use
SELECT
#Rand = Convert(int,(((1) - #CurrLen) *
RandomValue + #CurrLen))
FROM
dbo.vwRandom;
-- Assembles the value to be returned
SET #NewVal =
SUBSTRING(#OrigVal,#Rand,1) + #NewVal;
-- Removes the character from available options
SET #OrigVal =
Replace(#OrigVal,SUBSTRING(#Origval,#Rand,1),'');
-- Advance the loop="color:black">
SET #LoopCt = #LoopCt + 1;
END
-- Returns new value
Return LOWER(#NewVal);
END
GO
The output returned by the function is:
SELECT dbo.Character_Scramble('waltero.lukase#gmail.com')
-- output: vmgoli.#cuares
The output I want would be to respect the length of the word and the position of the symbols (., #, _, etc.).
SELECT dbo.Character_Scramble('waltero.lukase#gmail.com')
-- pkderso.modefk#poajf.lpd
Any help would help me enormously.
Thank you!

Answer 1

Maybe not exactly what you are doing, but the solution randomize the sequence of the alphabet set a-z and then use translate() to translate from normal sequence (a to z) to the randomize sequence
Due to string_agg() constraint, it cannot have two order by in the same scope, 2 separate CTE is used to generate the #normal and #scramble
declare #original varchar(100) = 'waltero.lukase#gmail.com';
declare #normal varchar(26),
#scramble varchar(26);
with chars as
(
select *
from
(
values ('a'), ('b'), ('c'), ('d'), ('e'), ('f'), ('g'), ('h'), ('i'), ('j'),
('k'), ('l'), ('m'), ('n'), ('o'), ('p'), ('q'), ('r'), ('s'), ('t'),
('u'), ('v'), ('w'), ('x'), ('y'), ('z')
) a (a)
),
normal as
(
-- normal ordering : a to z
select normal = string_agg(a, '') within group (order by a)
from chars
),
scramble as
(
-- randomize ordering
select scramble = string_agg(a, '') within group (order by newid())
from chars
)
select #normal = normal,
#scramble = scramble
from normal cross join scramble
select original = #original,
scrambled = translate(#original, #normal, #scramble);
UPDATE:
to apply this to your table, just add the FROM to the end of the query and change #original to your table name
with chars as
. . .
select original = email,
scrambled = translate(email, #normal, #scramble)
from yourtable
db<>fiddle demo