在11.1之前的版本,很多人可能都知道，可以通过alter user identified by values password 来还原oracle 数据库历史密码,但是在11g中出现几个问题:

1. dba_users中无password记录(值为空)，这个问题可以通过直接查询user$.password依然有记录

SQL> select password from dba_users where username='SYS';

PASSWORD

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

SQL> select password from user$ WHERE name='SYS';

PASSWORD

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

8A8F025737A9097A

2.在11.1开始user$中的SPARE4有值,从而使得数据库密码区分大小写，参考blog:关于ORACLE 11G密码大小写敏感猜想(USER$.SPARE4)

SQL> select SPARE4 from user$ WHERE name='SYS';

SPARE4

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

S:C7C81BBE7760B5BBB3973F0971AA36C737BF6DCC4A34FE925CE70B0739BD

现在就存在疑问,在11G版本中,如何来还原Oracle数据库用户历史密码呢？,这里通过试验的方式证明,alter user identified by values后面值可以是user$.password 也可以是user$.SPARE4，只是两者在密码大小写上有区别,具体试验如下：

创建测试用户xifenfei

[oracle@localhost ~]$ ss

SQL*Plus: Release 11.2.0.4.0 Production on Fri Apr 10 16:00:03 2015

Copyright (c) 1982, 2013, Oracle. All rights reserved.

Connected to:

Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production

With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> select * from v$version;

BANNER

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

Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production

PL/SQL Release 11.2.0.4.0 - Production

CORE 11.2.0.4.0 Production

TNS for Linux: Version 11.2.0.4.0 - Production

NLSRTL Version 11.2.0.4.0 - Production

SQL> select sysdate "www.xifenfei.com" from dual;

www.xifen

---------

10-APR-15

SQL> create user xifenfei identified by oracle;

User created.

SQL> grant create session to xifenfei;

Grant succeeded.

SQL> conn xifenfei/oracle

Connected.

SQL> conn xifenfei/ORACLE

ERROR:

ORA-01017: invalid username/password; logon denied

Warning: You are no longer connected to ORACLE.

SQL> conn / as sysdba

Connected.

SQL> show parameter sec_case_sensitive_logon ;

NAME TYPE VALUE

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

sec_case_sensitive_logon boolean TRUE

这里由于sec_case_sensitive_logon参数默认为true,因此密码区分大小写

修改数据库密码

SQL> select spare4,password from user$ where name='XIFENFEI';

SPARE4

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

PASSWORD

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

S:6E34E993900317BBFD6289E4AE619D634AA6AD804C765A3DEE1CCABCC50D

1BA871FA3B1C3F45

SQL> alter user xifenfei identified by xifenfei;

User altered.

SQL> select spare4,password from user$ where name='XIFENFEI';

SPARE4

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

PASSWORD

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

S:A75A184EA2767488E698C443E97CB2473B46A9C80C2C61833BA867CB8B17

1682CAA2339F770F

SQL> conn xifenfei/xifenfei

Connected.

SQL> conn xifenfei/XIFENFEI

ERROR:

ORA-01017: invalid username/password; logon denied

Warning: You are no longer connected to ORACLE.

SQL> conn xifenfei/oracle

ERROR:

ORA-01017: invalid username/password; logon denied

这里把xifenfei用户的密码从oracle修改为xifenfei

尝试values user$.password恢复以前密码

SQL> conn / as sysdba

Connected.

SQL> alter user xifenfei identified by values '1BA871FA3B1C3F45';

User altered.

SQL> select spare4,password from user$ where name='XIFENFEI';

SPARE4

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

PASSWORD

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

1BA871FA3B1C3F45

SQL> conn xifenfei/oracle

Connected.

SQL> conn xifenfei/ORACLE

Connected.

SQL> conn xifenfei/xifenfei

ERROR:

ORA-01017: invalid username/password; logon denied

Warning: You are no longer connected to ORACLE.

通过该方式还原上次密码后，发现user$.SPARE4为空,也就使得Oracle不再区分密码大小写.

尝试values user$.spare4恢复以前密码

SQL> conn / as sysdba

Connected.

SQL> alter user xifenfei identified by xifenfei;

User altered.

SQL> select spare4,password from user$ where name='XIFENFEI';

SPARE4

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

PASSWORD

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

S:48A11864AD633E904126C20E8C374A4AA45D87BB005D35AD2B10766E8E11

1682CAA2339F770F

SQL> conn xifenfei/xifenfei

Connected.

SQL> conn xifenfei/oracle

ERROR:

ORA-01017: invalid username/password; logon denied

Warning: You are no longer connected to ORACLE.

SQL> conn xifenfei/XIFENFEI

ERROR:

ORA-01017: invalid username/password; logon denied

SQL> alter user xifenfei identified by values '6E34E993900317BBFD6289E4AE619D634AA6AD804C765A3DEE1CCABCC50D';

SP2-0640: Not connected

SQL> conn / as sysdba

Connected.

SQL> alter user xifenfei identified by values '6E34E993900317BBFD6289E4AE619D634AA6AD804C765A3DEE1CCABCC50D';

alter user xifenfei identified by values '6E34E993900317BBFD6289E4AE619D634AA6AD804C765A3DEE1CCABCC50D'

*

ERROR at line 1:

ORA-00600: internal error code, arguments: [kzsviver:2], [], [], [], [], [],

[], [], [], [], [], []

--少写了S:,直接报ORA-600错误，怀疑S:是spare4列的某种标识

SQL>

SQL>

SQL>

SQL> alter user xifenfei identified by values 'S:6E34E993900317BBFD6289E4AE619D634AA6AD804C765A3DEE1CCABCC50D';

User altered.

SQL> select spare4,password from user$ where name='XIFENFEI';

SPARE4

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

PASSWORD

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

S:6E34E993900317BBFD6289E4AE619D634AA6AD804C765A3DEE1CCABCC50D

SQL> conn xifenfei/oracle

Connected.

SQL> conn xifenfei/ORACLE

ERROR:

ORA-01017: invalid username/password; logon denied

Warning: You are no longer connected to ORACLE.

SQL> conn xifenfei/xifenfei

ERROR:

ORA-01017: invalid username/password; logon denied

这里发现通过values user$.spare4恢复以前密码后,user$.password列为空,但是密码依旧区分大小写。这里可以看出来，user$.password项以后可能取消掉,为了兼容性,因此Oracle在后续版本中依旧保留.

关于oracle 11G中恢复以前密码操作总结

1. 通过values user$.password恢复以前密码后,不区分大小写

2. 通过values user$.spare4恢复以前密码后,区分大小写

3. 目前两种方式都可以实现11g恢复以前密码，但是推荐使用user$.spare4值修改