Oblivion:Security

Security is basically a polite word for lockpicking. Throughout the world you will find lockpicks on creatures (goblins and bandits tend to drop them, for example) and in chests, plus a couple of NPCs sell them to you. These can be used to pick locks on the chests and doors you find everywhere.

In-game Description: Use lockpicks to open locked doors and containers.

Mastery
Mastery Perks
The in-game and manual explanations of the mastery perks are a bit misleading.  The mastery perks for Security actually control how many tumblers will not drop when the pick is broken, rather than how many will drop.  For example, an Apprentice in Security that has picked two tumblers in an Average lock and breaks the pick on the third will only have one of the picked tumblers drop.  If that player was a Journeyman instead, he or she would have no tumblers drop.
A Novice drops all picked tumblers when breaking a pick.
An Apprentice keeps one picked tumbler up when breaking a pick.
A Journeyman keeps two picked tumblers up when breaking a pick.
An Expert keeps three picked tumblers up when breaking a pick.
A Master never drops tumblers when breaking a pick.

Skill Benefits
As your Security skill increases, tumblers move less rapidly, giving you more time to fix the tumbler in place.

Skill Increases
You gain 1.5 experience points each time a tumbler is locked into position, regardless of the lock difficulty.  You gain no experience when you break a lockpick trying to set a tumbler.

You also gain 1.5 experience points each time you use the "Auto-Attempt" button, regardless of whether or not it succeeds.

To gain experience in Security, you should try to pick every lock that you encounter; read the tips below to learn how to become more successful at picking locks.  If you are low on lockpicks, it is possible to purchase more from Shady Sam, from Thieves Guild fences (if you are a member), or from M'raaj-Dar (if you are a member of the Dark Brotherhood).

Tricks to increase your Security skill somewhat more artificially include:
If you join the Fighters Guild or Mages Guild, there are locked display cases in the guild halls that can be unlocked without it being considered a crime.  If you close the display cases, the lock will reset after a few days, so you can later return and get more practice opening the same locks.
You can fix the first 3 or 4 tumblers on a Hard/Very Hard lock and then exit the lockpicking minigame. Pick the lock again and repeat.
You can sneak around town at night and pick open the locked doors to people's houses.  A downside to this is that you can not decline to enter the building after successfully picking the lock and the building's inhabitants won't always be happy to see you.
The Thieves Den contains a Security training chest, once you hire the Security Expert for Dunbarrow Cove.  This chest never actually opens; after you pick all the tumblers, it refreshes the lockpicking minigame.
Nocturnal's Daedric Quest provides you with an unbreakable lockpick, the Skeleton Key.  However, this key also fortifies Security by 40 points, which makes training Security take much longer, and limits you to training your skill up to a natural value of 60.  The Skeleton Key page provides more tips on training Security when using this key.
Obtain the Skeleton Key and create a "Drain Security on Self, 100 points, 3 seconds" spell.  Cast the spell, then get to work on a Very Hard lock and repeatedly click "Auto Attempt".  With an effective Security skill of zero, you have no chance of Auto Attempt succeeding, and the Key will keep you from running out of lockpicks.  As mentioned in the previous note, however, this can only be used to get your skill up to a maximum base value of 60.
You can also use the above method by buying large quantities of lockpicks from Thieves Guild fences, since each of them sell 100 of them and they will eventually respawn. This makes it possible to train values higher than 60.
If you pick the lock to an NPC's house and then leave after they see you, they will lock the door again.
See also:
Increasing Skills: General tips on how to improve your skills semi-naturally
Trainers: Pay for Security lessons
 
Skill Books: Books that provide lessons in Security
Increasing Attributes: Tips on training skills to improve Agility
Free Skill Boosts: There are a couple free Security skill boosts available.
Magic Items: There are multiple generic items which Fortify Security.
Unique Items: A list of unique items, some of which fortify Security. These do not include leveled items such as those received from quests, or artifacts.
:Unique items include:
:*The Ring of the Gray is a reward for completing The Rosethorn Cache. Among other enchantments, the ring fortifies Security by 5 points.
:*The Spectre Ring* is obtainable from Hamlof Red-Tooth at Red Diamond Jewelry. Among other enchantments, the ring fortifies Security skill by 5 points.
:*The Apron of the Master Artisan is a unique shirt that among other things, fortifies Security by 7 points. It can be obtained from Norbert Lelles at Lelles' Quality Merchandise.
   

Dialogue
When your skill reaches 70 or higher, NPCs will start saying: "You've got some nimble fingers.  What have you been getting into?"

Character Creation
The following races provide initial skill bonuses in security:

Argonian: +10 bonus
Khajiit: +5 bonus

The following standard classes include Security as a major skill:
Acrobat; Agent; Assassin; Monk; Pilgrim; Thief; Witchhunter.

Picking Locks

When you find a lock and you have a lockpick,  tap the "use" button and you will activate the lockpicking mini-game.

Note: when picking a lock, be very careful and look at your cursor. If the cursor is red instead of the standard yellow or gold, picking the lock is considered a crime.  If you are seen picking that lock you will get in trouble (i.e., you will be attacked and/or have a bounty put on your head).  You can avoid this by being in sneak mode, as long as the eye on your cursor is translucent instead of solid (indicating that you are not being observed by anyone).

Lockpicking: The Mini-Game

The lockpicking mini-game is pretty simple, but can be confusing when you first see it.   You will see a lock in profile with a lockpick sliding underneath a set of five tumblers, some of which may already be set in the "up" position.  Using your lockpick, you need to get all five tumblers locked into the "up" position.  You move the lockpick using your mouse (on PC) or your thumbstick (on console versions).  Moving the pick from left to right determines which tumbler you are working on.  Pushing the pick upwards pops the tumbler up.  

Watch the tumbler carefully as it pops up. It goes at two distinct speeds - very fast (almost immediately) and noticeably slower, about the speed the lockpick moves. How often it goes fast or slow is dependent on your character's Security skill and the lock difficulty. Seemingly short delays between pushing the tumbler produce more "slow tumbles" than pressing it repeatedly too.

If the tumbler goes up quickly, just let it fall. You can push the tumbler as many times as you want, and the lockpick won't be affected until you press "A" or "X" (console versions) or the mouse button (PC). You can't latch it while it is rising.

If the tumbler pops up at a similar rate to the lockpick popping up, click the left mouse (PC), "A" (Xbox 360), or "X" (PS3) button after the the top of the tumbler passed the upper cross shaft but before the tumbler starts falling ( , but not too late).  If you time it right, the tumbler will stay at the top of the chamber, and you can move onto the next tumbler.  If you don't, the lockpick will break, the tumbler will fall and depending on your skill and the difficulty of the lock, other already-set tumblers may fall. As long as you click the mouse while the tumbler is all the way up (and not a pixel lower) the tumbler will stay up. Depending on the speed the tumbler happens to be traveling at, you may have as little as a tenth of a second, or as much as a whole second to click.

The right timing is easier to achieve for some by using your ears rather than your eyes. When the tumbler reaches the top of its chamber, you hear a distinct double click, sharper than usual when it is ready to be fixed. As soon as you hear that, press the button, et voila, the tumbler is up. 
Another good way to do this is when you have pushed the tumbler up immediately click start (on Xbox and PS3). If the tumbler is mid level (not in top position) then click start and immediately press the lock button. If the tumbler is already at the top then un-pause and try again.

While this can be frustrating, the other side of the coin is that once you get good enough at lock picking it is possible to pick any lock in the game (except those that require a key), even with low-skill characters.  Keep your cool and take your time.

Messages
The following table provides the messages that are displayed when your Security skill levels up.



Notes

There is an exploit to pick locks without wasting lockpicks. It only works on doors that cause loading screens. Save your game right in front of the door before attempting this. Auto-attempt to pick the lock until you hear that it has been picked. Quickly, before you load into the next room, press start . It will sound like the door is opening, but it won't. Go back to the last save you made in front of the door. When it loads, you will be in the desired room. 
When entering the second room, there is an error that causes the room to give off light as if you were outside, sometimes causing the screen to get very bright, or very dark at night. Plasma and DLP TVs are particularly affected.

While breaking into a house, if you are spotted upon exiting the house the locks will be reset by the owner.

Time does not pass during the lockpicking minigame, so if nearby NPCs can't see you when you begin, they won't detect you.  Just wait for the eye-symbol to indicate that you're successfully sneaking, and you're safe to pick the lock.

Locks can also be opened magically.  A high Alteration skill is necessary to open harder locks, and Very Hard Locks can only be opened if you create a custom spell.  Locks opened via Alteration spells provide experience toward Alteration, not Security.  Open spells cannot be cast underwater: lockpicks are the only way to open underwater locks. One major advantage to open spells is that no bounty is incurred casting them, no matter if the door/container unlocked is owned or if there are any NPCs and/or guards in the area.

There is somewhat of a pattern to how the tumblers drop.  The quickest tumbler drop is always followed by a significantly slower tumbler movement.  If you learn to recognize the quickest tumbler drop, then you can immediately use your pick to set the tumbler at the start of the next pick attempt.  This trick works even for low skill characters picking Very Hard locks.  The difficult part is recognizing the quickest tumbler drop: on the right one, the tumbler doesn't even pause at the top of its motion and falls more quickly than usual.  Spend some time watching the tumblers rise and fall to become familiar with the patterns for the current lock difficulty.

The tumblers make different sounds depending upon their speed. If the two clicks are quick and slightly higher pitched, then the tumbler is moving fast; if they are slow and slightly lower pitched, then the tumbler is moving slow.  Distinguishing the difference between the sounds can help in recognizing the tumbler's speed.

  If you have a fast system and video card and get higher FPS in interiors than your monitor's refresh rate (typically 60 or 75 Hz/FPS), you can make lockpicking easier by going into Options in the Oblivion launcher and ensure that "V.Sync" is checked, which caps the FPS at your monitor's refresh rate. The display FPS affects the speed of the tumblers, so lockpicking becomes correspondingly more difficult at very high FPS. For example, if your monitor refreshes at 75 Hz, with V. Sync off if you get 150 FPS while picking a lock the tumblers will move twice as fast.

If you have access to the Arcane University or Frostcrag Spire, then you can craft a cheap spell that dramatically boosts your Security and Agility. If you get locked into jail at a low level, this spell will make that one lockpick count. Make the spell last 1-2 seconds, and you can easily cast it with Novice or Apprentice Restoration skill.

Once your combined Fame and Infamy reaches 40, you can visit the Sithian Heaven Stone to receive the greater power Sithian Web.  One of several benefits of this power is that it fortifies Security by 20 points once a day for 120 seconds.

Lockpicks are zero-weight items, so they can be reverse-pickpocketed onto NPCs. If a particular NPC attempts to access a locked door to which they have no key (Gelephor at Bravil's Skooma Den; Farwil Indarys at Riverview), they will successfully open that door if they possess a lockpick.

When a lock is picked, the gears that move the locking mechanism will slightly cock back, but then spin clockwise as if locking it.