SCH_CREDENTIALS structure (schannel.h)

The SCH_CREDENTIALS structure contains initialization information for an Schannel credential.

Syntax

typedef struct _SCH_CREDENTIALS {
  DWORD           dwVersion;
  DWORD           dwCredFormat;
  DWORD           cCreds;
  PCCERT_CONTEXT  *paCred;
  HCERTSTORE      hRootStore;
  DWORD           cMappers;
  _HMAPPER        **aphMappers;
  struct          _HMAPPER;
  DWORD           dwSessionLifespan;
  DWORD           dwFlags;
  DWORD           cTlsParameters;
  PTLS_PARAMETERS pTlsParameters;
} SCH_CREDENTIALS, *PSCH_CREDENTIALS;

Members

dwVersion

Set to SCH_CREDENTIALS_VERSION.

dwCredFormat

Kernel-mode Schannel supports the following values.

Windows Server 2008, Windows Vista, Windows Server 2003, Windows XP and Windows XP/2000:  This flag is not supported and must be zero.

Value Meaning
SCH_CRED_FORMAT_CERT_HASH
0x00000001
The paCred member of the SCH_CREDENTIALS structure passed in must be a pointer to a byte array of length 20 that contains the certificate thumbprint. The certificate is assumed to be in the "MY" store of the local computer.
SCH_CRED_FORMAT_CERT_HASH_STORE
0x00000002
The paCred member of the SCH_CREDENTIALS structure points to a SCHANNEL_CERT_HASH_STORE structure.

cCreds

The number of structures in the paCred array.

paCred

An array of pointers to CERT_CONTEXT structures. Each pointer specifies a certificate that contains a private key to be used in authenticating the application.

Client applications often pass in an empty list and either depend on Schannel to find an appropriate certificate or create a certificate later if needed.

hRootStore

Optional. Valid for server applications only. Handle to a certificate store that contains self-signed root certificates for certification authorities (CAs) trusted by the application. This member is used only by server-side applications that require client authentication.

cMappers

Reserved.

aphMappers

Reserved.

_HMAPPER

dwSessionLifespan

The number of milliseconds that Schannel keeps the session in its session cache. After this time has passed, any new connections between the client and the server require a new Schannel session. Set the value of this member to zero to use the default value of 36000000 milliseconds (ten hours).

dwFlags

Contains bit flags that control the behavior of Schannel. This member can be zero or a combination of the following values.

Value Meaning
SCH_CRED_AUTO_CRED_VALIDATION
0x00000020
Client only.

This flag is the opposite of SCH_CRED_MANUAL_CRED_VALIDATION and is part of the default behavior of Schannel.

SCH_CRED_CACHE_ONLY_URL_RETRIEVAL_ON_CREATE
0x00020000
Instruct Schannel to pass the CERT_CHAIN_CACHE_ONLY_URL_RETRIEVAL flag to the CertGetCertificateChain function when validating the specified credentials during a call to AcquireCredentialsHandle (Schannel).

Windows Server 2003 and Windows XP/2000:  This flag is not supported.

SCH_DISABLE_RECONNECTS
0x00000080
Server only.

If this flag is set, then full handshakes performed with this credential will not allow reconnects. A cache entry is created, so the session can be made resumable later by using the ApplyControlToken function.

SCH_CRED_IGNORE_NO_REVOCATION_CHECK
0x00000800
When checking for revoked certificates, ignore CRYPT_E_NO_REVOCATION_CHECK errors. For additional restrictions, see Remarks.
SCH_CRED_IGNORE_REVOCATION_OFFLINE
0x00001000
When checking for revoked certificates, ignore CRYPT_E_REVOCATION_OFFLINE errors. For additional restrictions, see Remarks.
SCH_CRED_MANUAL_CRED_VALIDATION
0x00000008
Client only.

Prevent Schannel from validating the received server certificate chain.

SCH_CRED_NO_DEFAULT_CREDS
0x00000010
Client only.

Prevent Schannel from attempting to automatically supply a certificate chain for client authentication.

SCH_CRED_NO_SERVERNAME_CHECK
0x00000004
Client only.

Prevent Schannel from comparing the supplied target name with the subject names in server certificates.

SCH_CRED_NO_SYSTEM_MAPPER
0x00000002
Server only.

Prevent Schannel from using the built-in system certificate mapping functions to map client certificates to a user account.

SCH_CRED_REVOCATION_CHECK_CHAIN
0x00000200
When validating a certificate chain, check all certificates for revocation. For additional restrictions, see Remarks.
SCH_CRED_REVOCATION_CHECK_CHAIN_EXCLUDE_ROOT
0x00000400
When validating a certificate chain, do not check the root for revocation. For additional restrictions, see Remarks.
SCH_CRED_REVOCATION_CHECK_END_CERT
0x00000100
When validating a certificate chain, check only the last certificate for revocation. For additional restrictions, see Remarks.
SCH_CRED_USE_DEFAULT_CREDS
0x00000040
Client only.

Schannel attempts to automatically supply a certificate chain for client authentication. This value is the opposite of SCH_CRED_NO_DEFAULT_CREDS.

SCH_SEND_AUX_RECORD
0x00200000
Instruct Schannel to split data to be encrypted into two separate records to counter weakness present in the SSL/TLS procotol when used with symmetric cipher suite using cipher block chaining mode. For more information, see "Vulnerability in SSL/TLS Could Allow Information Disclosure" in the Help and Support Knowledge Base at http://support.microsoft.com/kb/2643584.

Windows Server 2008 R2, Windows 7, Windows Server 2008, Windows Vista, Windows Server 2003, Windows XP and Windows XP/2000:  This flag is not supported.

SCH_SEND_ROOT_CERT
0x00040000
Schannel sends the root certificate as part of the certificate message.
Note  The root certificate sent over the network by the Schannel client or server is not to be trusted. It should be validated against a trusted hash of the root certificate.
 
SCH_USE_STRONG_CRYPTO
0x00400000
Instructs Schannel to disable known weak cryptographic algorithms, cipher suites, and SSL/TLS protocol versions that may be otherwise enabled for better interoperability.
SCH_USE_PRESHAREDKEY_ONLY
0x00800000
Instructs Schannel to select only PSK cipher suites and disable all other cipher suites.

cTlsParameters

The count of entries in the pTlsParameters array.

It is an error to specify more than SCH_CRED_MAX_SUPPORTED_PARAMETERS.

pTlsParameters

Array of pointers to the TLS_PARAMETERS structures that indicate TLS parameter restrictions, if any. If no restrictions are specified, the system defaults are used. It is recommended that applications rely on the system defaults.

It is an error to include more than one TLS_PARAMETERS structure with cAlpnIds == 0 and rgstrAlpnIds == NULL.

Remarks

To use the SCH_CREDENTIALS structure, define SCHANNEL_USE_BLACKLISTS along with UNICODE_STRING and PUNICODE_STRING. Alternatively, include Ntdef.h, SubAuth.h or Winternl.h.

Requirements

   
Minimum supported client Windows 10 1809 [desktop apps only]
Minimum supported server Windows Server 1809 [desktop apps only]
Header schannel.h

See also

CRYPTO_SETTINGS

TLS_PARAMETERS