--- description: Contains definitions of security terms that begin with the letter L. ROBOTS: NOINDEX, NOFOLLOW ms.assetid: 65dd9a04-fc7c-4179-95ff-dac7dad4668f title: L (Security Glossary) ms.topic: glossary ms.date: 05/31/2018 --- # L (Security Glossary) [A](a-gly.md) [B](b-gly.md) [C](c-gly.md) [D](d-gly.md) [E](e-gly.md) F [G](g-gly.md) [H](h-gly.md) [I](i-gly.md) J [K](k-gly.md) L [M](m-gly.md) [N](n-gly.md) [O](o-gly.md) [P](p-gly.md) Q [R](r-gly.md) [S](s-gly.md) [T](t-gly.md) [U](u-gly.md) [V](v-gly.md) [W](w-gly.md) [X](x-gly.md) Y Z
**LDAP**
See *Lightweight Directory Access Protocol*
**Lightweight Directory Access Protocol**
A more easily implemented subset of the X.500 DAP standard for directory services.
**little-endian**
A memory or data format in which the least significant byte is stored at the lower address or arrives first. See also [*big-endian*](b-gly.md).
**locally unique identifier**
(LUID) A 64-bit value that is guaranteed to be unique on the operating system that generated it until the system is restarted.
**local registration authority**
(LRA) An intermediary between a publisher and a [*certification authority*](c-gly.md) (CA). The LRA can, for example, verify a publisher's credentials before sending them to the CA.
**Local Security Authority**
(LSA) A protected subsystem that authenticates and logs users onto the local system. LSA also maintains information about all aspects of local security on a system, collectively known as the Local Security Policy of the system.
**logical store**
See [*virtual store*](v-gly.md).
**logon data**
Information presented to the system by a [*security principal*](s-gly.md) for authentication.
**logon identifier**
An LUID that identifies a *logon session*. A logon ID is valid until the user logs off. A logon ID is unique while the computer is running; no other logon session will have the same logon ID. However, the set of possible logon IDs is reset when the computer starts up. To retrieve the logon ID from an [*access token*](a-gly.md), call the **GetTokenInformation** function for TokenStatistics; the logon ID is in the **AuthenticationId** member.
**logon session**
A logon session begins whenever a user logs on to a computer. All processes in a logon session have the same primary [*access token*](a-gly.md). The access token contains information about the security context of the logon session, including the user's SID, the *logon identifier*, and the *logon SID*.
**logon SID**
A [*security identifier*](s-gly.md) (SID) that identifies a *logon session*. You can use the logon SID in a [*DACL*](d-gly.md) to control access during a logon session. A logon SID is valid until the user logs off. A logon SID is unique while the computer is running; no other logon session will have the same logon SID. However, the set of possible logon SIDs is reset when the computer starts up. To retrieve the logon SID from an [*access token*](a-gly.md), call the **GetTokenInformation** function for TokenGroups.
**low-level message functions**
Message management functions that operate at a higher level than the base cryptographic functions. These functions provide functionality for encoding data for transmission and for decoding data that has been received. Low-level message functions provide more flexibility than simplified message functions, but require more function calls. See also [*simplified message functions*](s-gly.md).
**LSA**
See *Local Security Authority*.
**LUID**
See *locally unique identifier*.