The following /. post is one that microsoft is asking to be removed,
based on "you cant speak unless you are rich" paragraph in DMCA:
Microsoft Authorization Data Specification v. 1.0
for Microsoft Windows 2000 Operating Systems
April, 2000
) 2000 Microsoft Corporation.
All rights reserved.
Microsoft Confidential
Please review this Specification copy only if you licensed and downloaded
it from Microsoft
Corporations website; if you did not, please destroy this copy, but you
are welcome to license the
Specification at http://www.microsoft.com/technet/security/kerberos.
If you are an authorized licensee, when you downloaded the following
Specification, you agreed
to the Agreement for Microsoft Authorization Data Specification v. 1.0
for Microsoft Windows 2000
Operating Systems (the "Agreement"). For your future reference, that
Agreement is reproduced at
the end of this document.
Abstract
Microsoft Windows 2000 includes OS specific data in the Kerberos V5
authorization data field that is
used for authorization as described in the Kerberos revisions Internet
Draft [1]. This data is used for
user logon and to create an access token. The access token is used by the
system to enforce
access checking when attempting to reference objects. This document
describes the structure of
the Windows 2000 specific authorization data that is carried in that
field.
Top-Level PAC Structure
The PAC is generated by the KDC under the following conditions:
during an AS request that has been validated with pre-authentication
during a TGS request when the client has no PAC and the target is a
service in the domain or a
ticket granting service (referral ticket).
The PAC itself is included in the IF-RELEVANT (ID 1) portion of the
authorization data in a ticket.
Within the IF-RELEVANT portion, it is encoded as a KERB_AUTH_DATA_PAC
with ID 128.
The PAC is defined as a C data type, with integers encoded in
little-endian order. The PAC itself is
made up of several layers. The outer structure, contained directly in the
authorization data, is as
follows. The top-level structure is the PACTYPE structure:
typedef unsigned long ULONG;
typedef unsigned short USHORT;
typedef unsigned long64 ULONG64;
typedef unsigned char UCHAR;
typedef struct _PACTYPE {
ULONG cBuffers;
ULONG Version;
PAC_INFO_BUFFER Buffers[1];
} PACTYPE;
The fields are defined as follows:
cBuffers - contains the number of entries in the array Buffers
Version - this is version zero
Buffers - contains a conformant array of PAC_INFO_BUFFER structures
The PAC_INFO_BUFFER structure contains information about each piece of
the PAC:
typedef struct _PAC_INFO_BUFFER {
ULONG ulType;
ULONG cbBufferSize;
ULONG64 Offset;
} PAC_INFO_BUFFER;
Type fields are defined as follows:
ulType - contains the type of data contained in this buffer. For Windows
2000, it may be one of the
following, which are explained further below:
#define PAC_LOGON_INFO 1
#define PAC_CREDENTIAL_TYPE 2
#define PAC_SERVER_CHECKSUM 6
#define PAC_PRIVSVR_CHECKSUM 7
#define PAC_CLIENT_INFO_TYPE 10
Offset - contains the offset to the beginning of the data, in bytes, from
the beginning of the
PACTYPE structure. The data offset must by a multiple of 8. If the data
pointed to by this field is
complex, the data is typically NDR encoded. If the data is simple
(indicating it includes no pointer
types or complex structures) it is a little-endian format data structure.
PAC Credential Information
PAC_INFO_BUFFERs of type PAC_LOGON_INFO contain the credential
information for the client of
the Kerberos ticket. The data itself is contained in a
KERB_VALIDATION_INFO structure, which is NDR
encoded. The output of the NDR encoding is placed in the PAC_INFO_BUFFER
structure of type
PAC_LOGON_INFO.
typedef struct _KERB_VALIDATION_INFO {
FILETIME LogonTime;
FILETIME LogoffTime;
FILETIME KickOffTime;
FILETIME PasswordLastSet;
FILETIME PasswordCanChange;
FILETIME PasswordMustChange;
UNICODE_STRING EffectiveName;
UNICODE_STRING FullName;
UNICODE_STRING LogonScript;
UNICODE_STRING ProfilePath;
UNICODE_STRING HomeDirectory;
UNICODE_STRING HomeDirectoryDrive;
USHORT LogonCount;
USHORT BadPasswordCount;
ULONG UserId;
ULONG PrimaryGroupId;
ULONG GroupCount;
[size_is(GroupCount)] PGROUP_MEMBERSHIP GroupIds;
ULONG UserFlags;
ULONG Reserved[4];
UNICODE_STRING LogonServer;
UNICODE_STRING LogonDomainName;
PSID LogonDomainId;
ULONG Reserved1[2];
ULONG UserAccountControl;
ULONG Reserved3[7];
ULONG SidCount;
[size_is(SidCount)] PKERB_SID_AND_ATTRIBUTES ExtraSids;
PSID ResourceGroupDomainSid;
ULONG ResourceGroupCount;
[size_is(ResourceGroupCount)] PGROUP_MEMBERSHIP ResourceGroupIds;
} KERB_VALIDATION_INFO;
The fields are defined as follows:
LogonTime - the time the client last logged on.
LogoffTime - the time at which the clients logon session should expire.
If the logon session should
not expire, this field should be set to (0x7fffffff,0xffffffff).
KickOffTime - the time at which the server should forcibly logoff the
client. If the client should not be
forced off, this field should be set to (0x7fffffff,0xffffffff). The
ticket end time is a replacement for the
KickOffTime. The service ticket lifetime will never be longer than the
KickOffTime for a user.
PasswordLastSet - the time the clients password was last set. If it was
never set, this field is zero.
PasswordCanChange - the time at which the clients password is allowed to
change. If there is no
restriction on when the client may change its password, this field should
be set to the time of the
logon.
PasswordMustChange - the time at which the clients password expires. If
it doesnt expire, this field
is set to (0x7fffffff,0xffffffff).
EffectiveName - This field contains the clients Windows 2000 UserName,
stored in the Active
Directory in the SamAccountName property. This field is optional. If left
blank the length, maxlength
and buffer are all zero.
FullName - this field contains the friendly name of the client, which is
used only for display purpose
and not security purposes. This field is optional. If left blank the
length, maxlength and buffer are all
zero.
LogonScript - This field contains the path to the clients logon script.
This field is optional. If left blank
the length, maxlength and buffer are all zero.
ProfilePath - This field contains the path to the clients profile. This
field is optional. If left blank the
length, maxlength and buffer are all zero.
HomeDirectory - This field contains the path to the clients home
directory. It may be either a local
path name or a UNC path name. This field is optional. If left blank the
length, maxlength and buffer
are all zero.
HomeDirectoryDrive - This field is only used if the clients home
directory is a UNC path name. In that
case, the share on the remote file server is mapped to the local drive
letter specified by this field.
This field is optional. If left blank the length, maxlength and buffer
are all zero.
LogonCount - This field contains the count of how many times the client
is currently logged on. This
statistic is not accurately maintained by Windows 2000 and should not be
used.
BadPasswordCount - This field contains the number of logon or password
change attempts with
bad passwords, since the last successful attempt.
* UserId - This field contains the relative Id for the client.
PrimaryGroupId - This field contains the relative ID for this clients
primary group.
* GroupCount - This field contains the number of groups, within the
clients domain, to which the
client is a member.
* GroupIds - This field contains an array of the relative Ids and
attributes of the groups in the clients
domain of which the client is a member.
* UserFlags - This field contains information about which fields in this
structure are valid. The two bits
that may be set are indicated below. Having these flags set indicates
that the corresponding fields
in the KERB_VALIDATION_INFO structure are present and valid.
#define LOGON_EXTRA_SIDS 0x0020
#define LOGON_RESOURCE_GROUPS 0x0200
LogonServer - This field contains the NETBIOS name of the KDC which
performed the AS ticket
request.
LogonDomainName - This field contains the NETBIOS name of the clients
domain.
* LogonDomainId - This field contains the SID of the clients domain. This
field is used in conjunction
with the UserId, PrimaryGroupId,and GroupIds fields to create the user
and group SIDs for the client.
UserAccountControl - This fields contains a bitfield of information about
the clients account. Valid
values are:
#define USER_ACCOUNT_DISABLED (0x00000001)
#define USER_HOME_DIRECTORY_REQUIRED (0x00000002)
#define USER_PASSWORD_NOT_REQUIRED (0x00000004)
#define USER_TEMP_DUPLICATE_ACCOUNT (0x00000008)
#define USER_NORMAL_ACCOUNT (0x00000010)
#define USER_MNS_LOGON_ACCOUNT (0x00000020)
#define USER_INTERDOMAIN_TRUST_ACCOUNT (0x00000040)
#define USER_WORKSTATION_TRUST_ACCOUNT (0x00000080)
#define USER_SERVER_TRUST_ACCOUNT (0x00000100)
#define USER_DONT_EXPIRE_PASSWORD (0x00000200)
#define USER_ACCOUNT_AUTO_LOCKED (0x00000400)
#define USER_ENCRYPTED_TEXT_PASSWORD_ALLOWED (0x00000800)
#define USER_SMARTCARD_REQUIRED (0x00001000)
#define USER_TRUSTED_FOR_DELEGATION (0x00002000)
#define USER_NOT_DELEGATED (0x00004000)
#define USER_USE_DES_KEY_ONLY (0x00008000)
#define USER_DONT_REQUIRE_PREAUTH (0x00010000)
* SidCount - This field contains the number of SIDs present in the
ExtraSids field. This field is only valid
if the LOGON_EXTRA_SIDS flag has been set in the UserFlags field.
* ExtraSids - This field contains a list of SIDs for groups to which the
user is a member. This field is only
valid if the LOGON_EXTRA_SIDS flag has been set in the UserFlags field.
* ResouceGroupCount - This field contains the number of resource groups
in the ResourceGroupIds
field. This field is only valid if the LOGON RESOURCE_GROUPS flag has
been set in the UserFlags
field._
* ResourceGroupDomainSid - This field contains the SID of the resource
domain. This field is used in
conjunction with the ResourceGroupIds field to create the group SIDs for
the client.
* ResourceGroupIds - This field contains an array of the relative Ids and
attributes of the groups in
the resource domain of which the resource is a member.
Fields marked with a '*' are used in the NT token.
When used in the KERB_VALIDATION_INFO, this is NDR encoded. The FILETIME
type is defined as
follows:
typedef unsigned int DWORD;
typedef struct _FILETIME {
DWORD dwLowDateTime;
DWORD dwHighDateTime;
} FILETIME;
Times are encoded as the number of 100 nanosecond increments since
January 1, 1601, in UTC
time.
When used in the KERB_VALIDATION_INFO, this is NDR encoded. The
UNICODE_STRING structure is
defined as:
typedef struct _UNICODE_STRING
USHORT Length;
USHORT MaximumLength;
[size_is(MaximumLength / 2), length_is((Length) / 2) ] USHORT * Buffer;
} UNICODE_STRING;
The Length field contains the number of bytes in the string, not
including the null terminator, and the
MaximumLength field contains the total number of bytes in the buffer
containing the string.
The GROUP_MEMBERSHIP structure contains the relative ID of a group and
the corresponding
attributes for the group.
typedef struct _GROUP_MEMBERSHIP {
ULONG RelativeId;
ULONG Attributes;
} *PGROUP_MEMBERSHIP;
The group attributes must be:
#define SE_GROUP_MANDATORY (0x00000001L)
#define SE_GROUP_ENABLED_BY_DEFAULT (0x00000002L)
#define SE_GROUP_ENABLED (0x00000004L)
The SID structure is defined as follows:
typedef struct _SID_IDENTIFIER_AUTHORITY {
UCHAR Value[6];
} SID_IDENTIFIER_AUTHORITY, *PSID_IDENTIFIER_AUTHORITY;
The constant value for the NT Authority is:
#define SECURITY_NT_AUTHORITY {0,0,0,0,0,5}
typedef struct _SID {
UCHAR Revision;
UCHAR SubAuthorityCount;
SID_IDENTIFIER_AUTHORITY IdentifierAuthority;
[size_is(SubAuthorityCount)] ULONG SubAuthority[*];
} SID, *PSID;
The SubAuthorityCount field contains the number of elements in the actual
SubAuthority
conformant array. The maximum number of subauthorities allowed is 15.
The KERB_SID_AND_ATTRIBUTES structure contains entire group SIDs and
their corresponding
attributes:
typedef struct _KERB_SID_AND_ATTRIBUTES {
PSID Sid;
ULONG Attributes;
} KERB_SID_AND_ATTRIBUTES, *PKERB_SID_AND_ATTRIBUTES;
The attributes are the same as the group attributes defined above.
Client Information
The client information is included in the PAC to allow a server to verify
that the PAC in a ticket is
applicable to the client of the ticket, which prevents splicing of PACs
between tickets. The
PAC_CLIENT_INFO structure is included in a PAC_INFO_BUFFER of type
PAC_CLIENT_INFO_TYPE.
typedef struct _PAC_CLIENT_INFO {
FILETIME ClientId;
USHORT NameLength;
WCHAR Name[1];
} PAC_CLIENT_INFO, *PPAC_CLIENT_INFO;
The fields are defined as follows:
ClientId - This field contains a conversion of the AuthTime field of the
ticket into a FILETIME structure.
NameLength - This field contains the length, in bytes, of the Name field.
Name - This field contains the client name from the ticket, converted to
Unicode and encoded
using "/" to separate parts of the client principal name with an "@"
separating the client principal
name from the realm name. The string is not null terminated.
Supplemental Credentials
The KDC may return supplemental credentials in the PAC as well.
Supplemental credentials are
data associated with a security package that is private to that package.
They can be used to
return an appropriate user key that is specific to that package for the
purposes of authentication.
Supplemental creds are only used in conjunction with PKINIT[2].
Supplemental credentials are
always encrypted using the client key. The PAC_CREDENTIAL_DATA structure
is NDR encoded and
then encrypted with the key used to encrypt the KDCs reply to the client.
The
PAC_CREDENTIAL_INFO structure is included in PAC_INFO_BUFFER of type
PAC_CREDENTIAL_TYPE.
Supplemental credentials for a single package are NDR encoded as follows:
typedef struct _SECPKG_SUPPLEMENTAL_CRED {
UNICODE_STRING PackageName;
ULONG CredentialSize;
[size_is(CredentialSize)]PUCHAR Credentials;
} SECPKG_SUPPLEMENTAL_CRED, *PSECPKG_SUPPLEMENTAL_CRED;
The fields in this structure are defined as follows:
PackageName - This field contains the name of the package for which
credentials are presented.
CredentialSize - This field contains the length, in bytes, of the
presented credentials.
Credentials - This field contains a pointer to the credential data.
The set of all supplemental credentials is NDR encoded in a
PAC_CREDENTIAL_DATA structure:
typedef struct _PAC_CREDENTIAL_DATA {
ULONG CredentialCount;
[size_is(CredentialCount)] SECPKG_SUPPLEMENTAL_CRED Credentials[*];
} PAC_CREDENTIAL_DATA, *PPAC_CREDENTIAL_DATA;
The fields are defined as follows:
CredentialCount - This field contains the number of credential present in
the Credentials array.
Credentials - This field contains an array of the presented supplemental
credentials.
The PAC_CREDENTIAL_DATA structure is NDR encoded and then encrypted with
the key used to
encrypt the KDC reply. The resulting buffer is returned in the following
structure:
typedef struct _PAC_CREDENTIAL_INFO {
ULONG Version;
ULONG EncryptionType;
UCHAR Data[1];
} PAC_CREDENTIAL_INFO, *PPAC_CREDENTIAL_INFO;
The fields are defined as follows:
Version - This field contains the version field of the key used to
encrypt the data, or zero if the field is
not present.
EncryptType - This field contains the encryption type used to encrypt the
data. The encryption type
uses the same values as the defined encryptions types for Kerberos [1].
Data - This field contains an array of bytes containing the encrypted
supplemental credential data.
Signatures
The PAC contains two digital signatures: one using the key of the server,
and one using the key of
the KDC. The signatures are present for two reasons. First, the signature
with the servers key is
present to prevent a client from generating their own PAC and sending it
to the KDC as encrypted
authorization data to be included in tickets. Second, the signature with
the KDCs key is present to
prevent an untrusted service from forging a ticket to itself with an
invalid PAC. The two signatures
are sent in PAC_INFO_BUFFERs of type PAC_SERVER_CHECKSUM and
PAC_KDC_CHECKSUM
respectively.
The signatures are contained in the following structure:
typedef struct _PAC_SIGNATURE_DATA {
ULONG SignatureType;
UCHAR Signature[1];
} PAC_SIGNATURE_DATA, *PPAC_SIGNATURE_DATA;
The fields are defined as follows:
SignatureType - This field contains the type of checksum used to create a
signature. The checksum
must be a keyed checksum.
Signature - This field consists of an array of bytes containing the
checksum data. The length of bytes
may be determined by the wrapping PAC_INFO_BUFFER structure.
For the servers checksum, the key used to generate the signature should
be the same key used to
encrypt the ticket. Thus, if the enc_tkt_in_skey option is used, the
session key from the servers TGT
should be used. The Key used to encrypt ticket-granting tickets is used
to generate the KDCs
checksum.
The checksums are computed as follows:
1. The complete PAC is built, including space for both checksums
2. The data portion of both checksums is zeroed.
3. The entire PAC structure is checksummed with the servers key, and the
result is stored in the
servers checksum structure.
4. The servers checksum is then checksummed with the KDC's key.
5. The checksum with the KDC key is stored in the KDC's checksum
structure.
PAC Request Pre-Auth Data
Normally, the PAC is included in every pre-authenticated ticket received
from an AS request.
However, a client may also explicitly request either to include or to not
include the PAC. This is done
by sending the PAC-REQUEST preauth data.
KERB-PA-PAC-REQUEST ::= SEQUENCE {
include-pac[0] BOOLEAN -- if TRUE, and no PAC present,
-- include PAC.
---If FALSE, and PAC
-- present, remove PAC
}
The fields are defined as follows:
include-pac - This field indicates whether a PAC should be included or
not. If the value is TRUE, a
PAC will be included independent of other preauth data. If the value is
FALSE, then no PAC will be
included, even if other preauth data is present.
The preauth ID is:
#define KRB5_PADATA_PAC_REQUEST 128
References
1 Neuman, C., Kohl, J., Ts'o, T., "The Kerberos Network Authentication
Service (V5)", draft-ietf-cat-kerberos-
revisions-05.txt, March 10, 2000
2 Tung, B., Hur, M., Medvinsky, A., Medvinsky, S., Wray, J., Trostle, J.,
" Public Key Cryptography for
Initial Authentication in Kerberos",
draft-ietf-cat-kerberos-pk-init-11.txt, March 15, 2000
) 2000 Microsoft Corporation. All rights reserved. Microsoft Confidential.
