with t as
 (select 'Иванов И.И.' as str
    from dual
  union all
  select 'Петров П.П.' as str
    from dual
    union all
   select 'Smith J.' as str
    from dual ),
crypt as (    
select (chr(ascii(substr(str,level,1))/level+2)) sym, str
  from t
connect by level <= length(str)
       and prior str = str
       and prior dbms_random.value is not null)
select listagg(sym,'') within group (order by str) as crypto_str, str from crypt group by str 

with t as
 (select 'Иванов И.И.' as str, dbms_random.value as pk_rowid
    from dual
  union all
  select 'Петров П.П.' as str, dbms_random.value as pk_rowid
    from dual
  union all
  select 'Smith J.' as str, dbms_random.value as pk_rowid
    from dual
    union all
  select 'Петров П.П.' as str, dbms_random.value as pk_rowid
    from dual),
t_s as
 (select level order_s, substr(str, level, 1) sym, str, pk_rowid 
    from t
  connect by level <= length(str)
         and prior str = str
         and prior pk_rowid = pk_rowid
         and prior dbms_random.value is not null),
C_key as
 (select chr(level) as o_s, chr((level + 10) / (dbms_random.value + 1)) c_s
    from dual
  connect by level <= 
69536)
select listagg(k.c_s, '') within group(order by t_s.str, pk_rowid, t_s.order_s) as crypto_str,
       t_s.str
  from t_s, C_key k
 where t_s.sym = k.o_s
 group by pk_rowid, t_s.str