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1.1 Glossary

This document uses the following terms:

access control list (ACL): A list of access control entries (ACEs) that collectively describe the security rules for authorizing access to some resource; for example, an object or set of objects.

Active Directory: A general-purpose network directory service. Active Directory also refers to the Windows implementation of a directory service. Active Directory stores information about a variety of objects in the network. Importantly, user accounts, computer accounts, groups, and all related credential information used by the Windows implementation of Kerberos are stored in Active Directory. Active Directory is either deployed as Active Directory Domain Services (AD DS) or Active Directory Lightweight Directory Services (AD LDS). [MS-ADTS] describes both forms. For more information, see [MS-AUTHSOD] section 1.1.1.5.2, Lightweight Directory Access Protocol (LDAP) versions 2 and 3, Kerberos, and DNS.

Advanced Encryption Standard (AES): A block cipher that supersedes the Data Encryption Standard (DES). AES can be used to protect electronic data. The AES algorithm can be used to encrypt (encipher) and decrypt (decipher) information. Encryption converts data to an unintelligible form called ciphertext; decrypting the ciphertext converts the data back into its original form, called plaintext. AES is used in symmetric-key cryptography, meaning that the same key is used for the encryption and decryption operations. It is also a block cipher, meaning that it operates on fixed-size blocks of plaintext and ciphertext, and requires the size of the plaintext as well as the ciphertext to be an exact multiple of this block size. AES is also known as the Rijndael symmetric encryption algorithm [FIPS197].

binary large object (BLOB): A collection of binary data stored as a single entity in a database.

binding: The string representation of the protocol sequence, NetworkAddress, and optionally the endpoint. Also referred to as "string binding". For more information, see [C706] section "String Bindings".

certificate: A certificate is a collection of attributes (1) and extensions that can be stored persistently. The set of attributes in a certificate can vary depending on the intended usage of the certificate. A certificate securely binds a public key to the entity that holds the corresponding private key. A certificate is commonly used for authentication (2) and secure exchange of information on open networks, such as the Internet, extranets, and intranets. Certificates are digitally signed by the issuing certification authority (CA) and can be issued for a user, a computer, or a service. The most widely accepted format for certificates is defined by the ITU-T X.509 version 3 international standards. For more information about attributes and extensions, see [RFC3280] and [X509] sections 7 and 8.

certificate template: A list of attributes that define a blueprint for creating an X.509 certificate. It is often referred to in non-Microsoft documentation as a "certificate profile". A certificate template is used to define the content and purpose of a digital certificate, including issuance requirements (certificate policies), implemented X.509 extensions such as application policies, key usage, or extended key usage as specified in [X509], and enrollment permissions. Enrollment permissions define the rules by which a certification authority (CA) will issue or deny certificate requests. In Windows environments, certificate templates are stored as objects in the Active Directory and used by Microsoft enterprise CAs.

certification authority (CA): A third party that issues public key certificates. Certificates serve to bind public keys to a user identity. Each user and certification authority (CA) can decide whether to trust another user or CA for a specific purpose, and whether this trust should be transitive. For more information, see [RFC3280].

Data Decryption Field (DDF): The portion of the EFSRPC Metadata that contains information that enables authorized users to decrypt the file.

data recovery agent (DRA): A logical entity corresponding to an asymmetric key pair, which is configured as part of Encrypting File System (EFS) administrative policy by an administrator. Whenever an EFS file is created or modified, it is also automatically configured to give authorized access to all DRAs in effect at that time.

data recovery field (DRF): The portion of the EFSRPC Metadata that contains information that enables authorized DRAs to decrypt the file.

decryption: In cryptography, the process of transforming encrypted information to its original clear text form.

domain: A set of users and computers sharing a common namespace and management infrastructure. At least one computer member of the set must act as a domain controller (DC) and host a member list that identifies all members of the domain, as well as optionally hosting the Active Directory service. The domain controller provides authentication (2) of members, creating a unit of trust for its members. Each domain has an identifier that is shared among its members. For more information, see [MS-AUTHSOD] section 1.1.1.5 and [MS-ADTS].

domain controller (DC): The service, running on a server, that implements Active Directory, or the server hosting this service. The service hosts the data store for objects and interoperates with other DCs to ensure that a local change to an object replicates correctly across all DCs. When Active Directory is operating as Active Directory Domain Services (AD DS), the DC contains full NC replicas of the configuration naming context (config NC), schema naming context (schema NC), and one of the domain NCs in its forest. If the AD DS DC is a global catalog server (GC server), it contains partial NC replicas of the remaining domain NCs in its forest. For more information, see [MS-AUTHSOD] section 1.1.1.5.2 and [MS-ADTS]. When Active Directory is operating as Active Directory Lightweight Directory Services (AD LDS), several AD LDS DCs can run on one server. When Active Directory is operating as AD DS, only one AD DS DC can run on one server. However, several AD LDS DCs can coexist with one AD DS DC on one server. The AD LDS DC contains full NC replicas of the config NC and the schema NC in its forest. The domain controller is the server side of Authentication Protocol Domain Support [MS-APDS].

EFSRPC Metadata: The additional data stored with an encrypted file to enable authorized users to access the data in the file. The format of this metadata is implementation-dependent. The EFSRPC Metadata general requirements are specified in detail in section 2.2.2 and the Windows format is specified in associated endnotes in Appendix B of this specification.

EFSRPC Raw Data Format: The data format used by the EFSRPC raw methods to marshal the contents and metadata of an encrypted file into a single-bit stream. It is specified in section 2.2.3.

Encrypting File System (EFS): The name for the encryption capability of the NTFS file system. When a file is encrypted using EFS, a symmetric key known as the file encryption key (FEK) is generated and the contents of the file are encrypted with the FEK. For each user or data recovery agent (DRA) that is authorized to access the file, a copy of the FEK is encrypted with that user's or DRA's public key and is stored in the file's metadata. For more information about EFS, see [MSFT-EFS].

encryption: In cryptography, the process of obscuring information to make it unreadable without special knowledge.

endpoint: A network-specific address of a remote procedure call (RPC) server process for remote procedure calls. The actual name and type of the endpoint depends on the RPC protocol sequence that is being used. For example, for RPC over TCP (RPC Protocol Sequence ncacn_ip_tcp), an endpoint might be TCP port 1025. For RPC over Server Message Block (RPC Protocol Sequence ncacn_np), an endpoint might be the name of a named pipe. For more information, see [C706].

file: A unit of data in the file system. An encrypted file consists of encrypted data along with the metadata required for a user to decrypt the file. The file and its metadata are protected using public key cryptography such that an authorized user's private key is required to decrypt the file.

File Encryption Key (FEK): The symmetric key that is used to encrypt the data in an EFS-protected file. The FEK is further encrypted and stored in the file metadata such that only authorized users can access it.

file system: A system that enables applications to store and retrieve files on storage devices. Files are placed in a hierarchical structure. The file system specifies naming conventions for files and the format for specifying the path to a file in the tree structure. Each file system consists of one or more drivers and DLLs that define the data formats and features of the file system. File systems can exist on the following storage devices: diskettes, hard disks, jukeboxes, removable optical disks, and tape backup units.

flags: A set of values used to configure or report options or settings.

folder: A container for files and other folders. A folder may be encrypted. The semantics of encrypting a folder are implementation-dependent. In the Windows implementation, encrypting a folder does not directly cause any data to be encrypted. Encrypting a folder in Windows has the following consequences of EFSRPC Metadata is created and stored with the folder and an NTFS attribute is set on the folder to signify that it is encrypted. NTFS checks this attribute when any new files or folders are created in the folder. NTFS will automatically encrypt any files or folders created within a folder that has this attribute set.

fully qualified domain name (FQDN): An unambiguous domain name (2) that gives an absolute location in the Domain Name System's (DNS) hierarchy tree, as defined in [RFC1035] section 3.1 and [RFC2181] section 11.

globally unique identifier (GUID): A term used interchangeably with universally unique identifier (UUID) in Microsoft protocol technical documents (TDs). Interchanging the usage of these terms does not imply or require a specific algorithm or mechanism to generate the value. Specifically, the use of this term does not imply or require that the algorithms described in [RFC4122] or [C706] must be used for generating the GUID. See also universally unique identifier (UUID).

Kerberos constrained delegation: A form of authentication delegation in which Kerberos can be used to impersonate users that send requests for certain services, as opposed to all services.

key: In cryptography, a generic term used to refer to cryptographic data that is used to initialize a cryptographic algorithm. Keys are also sometimes referred to as keying material.

Lightweight Directory Access Protocol (LDAP): The primary access protocol for Active Directory. Lightweight Directory Access Protocol (LDAP) is an industry-standard protocol, established by the Internet Engineering Task Force (IETF), which allows users to query and update information in a directory service (DS), as described in [MS-ADTS]. The Lightweight Directory Access Protocol can be either version 2 [RFC1777] or version 3 [RFC3377].

named pipe: A named, one-way, or duplex pipe for communication between a pipe server and one or more pipe clients.

New Technology File System (NTFS): The native file system of Windows 2000 operating system, Windows XP operating system, Windows Vista operating system, Windows 7 operating system, and Windows 8 operating system. Within this document, this term is occasionally used to refer to the operating system subsystem that implements NTFS support. For more information, see [MSFT-NTFS].

NT file system (NTFS): A proprietary Microsoft file system. For more information, see [MSFT-NTFS].

opnum: An operation number or numeric identifier that is used to identify a specific remote procedure call (RPC) method or a method in an interface. For more information, see [C706] section 12.5.2.12 or [MS-RPCE].

plaintext: In cryptography, ordinary readable text before it is encrypted into ciphertext, or after it has been decrypted.

private key: One of a pair of keys used in public-key cryptography. The private key is kept secret and is used to decrypt data that has been encrypted with the corresponding public key. For an introduction to this concept, see [CRYPTO] section 1.8 and [IEEE1363] section 3.1.

public key: One of a pair of keys used in public-key cryptography. The public key is distributed freely and published as part of a digital certificate. For an introduction to this concept, see [CRYPTO] section 1.8 and [IEEE1363] section 3.1.

remote procedure call (RPC): A context-dependent term commonly overloaded with three meanings. Note that much of the industry literature concerning RPC technologies uses this term interchangeably for any of the three meanings. Following are the three definitions: (*) The runtime environment providing remote procedure call facilities. The preferred usage for this meaning is "RPC runtime". (*) The pattern of request and response message exchange between two parties (typically, a client and a server). The preferred usage for this meaning is "RPC exchange". (*) A single message from an exchange as defined in the previous definition. The preferred usage for this term is "RPC message". For more information about RPC, see [C706].

Rivest-Shamir-Adleman (RSA): A system for public key cryptography. RSA is specified in [PKCS1] and [RFC3447].

RPC protocol sequence: A character string that represents a valid combination of a remote procedure call (RPC) protocol, a network layer protocol, and a transport layer protocol, as described in [C706] and [MS-RPCE].

RPC transport: The underlying network services used by the remote procedure call (RPC) runtime for communications between network nodes. For more information, see [C706] section 2.

security context: An abstract data structure that contains authorization information for a particular security principal in the form of a Token/Authorization Context (see [MS-DTYP] section 2.5.2). A server uses the authorization information in a security context to check access to requested resources. A security context also contains a key identifier that associates mutually established cryptographic keys, along with other information needed to perform secure communication with another security principal.

security identifier (SID): An identifier for security principals in Windows that is used to identify an account or a group. Conceptually, the SID is composed of an account authority portion (typically a domain) and a smaller integer representing an identity relative to the account authority, termed the relative identifier (RID). The SID format is specified in [MS-DTYP] section 2.4.2; a string representation of SIDs is specified in [MS-DTYP] section 2.4.2 and [MS-AZOD] section 1.1.1.2.

security provider: A pluggable security module that is specified by the protocol layer above the remote procedure call (RPC) layer, and will cause the RPC layer to use this module to secure messages in a communication session with the server. The security provider is sometimes referred to as an authentication service. For more information, see [C706] and [MS-RPCE].

Security Support Provider Interface (SSPI): A Windows-specific API implementation that provides the means for connected applications to call one of several security providers to establish authenticated connections and to exchange data securely over those connections. This is the Windows equivalent of Generic Security Services (GSS)-API, and the two families of APIs are on-the-wire compatible.

server: A computer on which the remote procedure call (RPC) server is executing.

Server Message Block (SMB): A protocol that is used to request file and print services from server systems over a network. The SMB protocol extends the CIFS protocol with additional security, file, and disk management support. For more information, see [CIFS] and [MS-SMB].

sparse file: A file containing large sections of data composed only of zeros, which is marked as such in the NTFS. The file system saves disk space by only allocating as many ranges on disk as are required to completely reconstruct the non-zero data. When an attempt is made to read in the nonallocated portions of the file (also known as holes), the file system automatically returns zeros to the caller.

stream: A sequence of bytes written to a file on the NTFS file system. Every file stored on a volume that uses the NTFS file system contains at least one stream, which is normally used to store the primary contents of the file. Additional streams within the file can be used to store file attributes, application parameters, or other information specific to that file. Every file has a default data stream, which is unnamed by default. That data stream, and any other data stream associated with a file, can optionally be named.

UncPath: The location of a file in a network of computers, as specified in Universal Naming Convention (UNC) syntax.

Unicode: A character encoding standard developed by the Unicode Consortium that represents almost all of the written languages of the world. The Unicode standard [UNICODE5.0.0/2007] provides three forms (UTF-8, UTF-16, and UTF-32) and seven schemes (UTF-8, UTF-16, UTF-16 BE, UTF-16 LE, UTF-32, UTF-32 LE, and UTF-32 BE).

universally unique identifier (UUID): A 128-bit value. UUIDs can be used for multiple purposes, from tagging objects with an extremely short lifetime, to reliably identifying very persistent objects in cross-process communication such as client and server interfaces, manager entry-point vectors, and RPC objects. UUIDs are highly likely to be unique. UUIDs are also known as globally unique identifiers (GUIDs) and these terms are used interchangeably in the Microsoft protocol technical documents (TDs). Interchanging the usage of these terms does not imply or require a specific algorithm or mechanism to generate the UUID. Specifically, the use of this term does not imply or require that the algorithms described in [RFC4122] or [C706] must be used for generating the UUID.

valid data length (VDL): In NTFS, there are two important concepts of file length: the end-of-file (EOF) marker and the valid data length (VDL). The EOF indicates the actual length of the file. The VDL identifies the length of valid data on disk. Any reads between VDL and EOF automatically return zeros.

well-known endpoint: A preassigned, network-specific, stable address for a particular client/server instance. For more information, see [C706].

X.509: An ITU-T standard for public key infrastructure subsequently adapted by the IETF, as specified in [RFC3280].

MAY, SHOULD, MUST, SHOULD NOT, MUST NOT: These terms (in all caps) are used as defined in [RFC2119]. All statements of optional behavior use either MAY, SHOULD, or SHOULD NOT.

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