MakeSignature function (sspi.h)

Article
10/13/2021

The MakeSignature function generates a cryptographic checksum of the message, and also includes sequencing information to prevent message loss or insertion. MakeSignature allows the application to choose between several cryptographic algorithms, if supported by the chosen mechanism. The MakeSignature function uses the security context referenced by the context handle.

This function is not supported by the Schannel security support provider (SSP).

Syntax

KSECDDDECLSPEC SECURITY_STATUS SEC_ENTRY MakeSignature(
  [in]      PCtxtHandle    phContext,
  [in]      unsigned long  fQOP,
  [in, out] PSecBufferDesc pMessage,
  [in]      unsigned long  MessageSeqNo
);

Parameters

[in] phContext

A handle to the security context to use to sign the message.

[in] fQOP

Package-specific flags that indicate the quality of protection. A security package can use this parameter to enable the selection of cryptographic algorithms.

When using the Digest SSP, this parameter must be set to zero.

[in, out] pMessage

A pointer to a SecBufferDesc structure. On input, the structure references one or more SecBuffer structures that contain the message to be signed. The function does not process buffers with the SECBUFFER_READONLY_WITH_CHECKSUM attribute.

The SecBufferDesc structure also references a SecBuffer structure of type SECBUFFER_TOKEN that receives the signature.

When the Digest SSP is used as an HTTP authentication protocol, the buffers should be configured as follows.

Buffer #/buffer type	Meaning
0 SECBUFFER_TOKEN	Empty.
1 SECBUFFER_PKG_PARAMS	Method.
2 SECBUFFER_PKG_PARAMS	URL.
3 SECBUFFER_PKG_PARAMS	HEntity. For more information, see Input Buffers for the Digest Challenge Response.
4 SECBUFFER_PADDING	Empty. Receives the signature.

When the Digest SSP is used as an SASL mechanism, the buffers should be configured as follows.

Buffer #/buffer type	Meaning
0 SECBUFFER_TOKEN	Empty. Receives the signature. This buffer must be large enough to hold the largest possible signature. Determine the size required by calling the QueryContextAttributes (General) function and specifying SECPKG_ATTR_SIZES. Check the returned SecPkgContext_Sizes structure member cbMaxSignature.
1 SECBUFFER_DATA	Message to be signed.
2 SECBUFFER_PADDING	Empty.

[in] MessageSeqNo

The sequence number that the transport application assigned to the message. If the transport application does not maintain sequence numbers, this parameter is zero.

When using the Digest SSP, this parameter must be set to zero. The Digest SSP manages sequence numbering internally.

Return value

If the function succeeds, the function returns SEC_E_OK.

If the function fails, it returns one of the following error codes.

Return code	Description
SEC_I_RENEGOTIATE	The remote party requires a new handshake sequence or the application has just initiated a shutdown. Return to the negotiation loop and call AcceptSecurityContext (General) or InitializeSecurityContext (General) again. An empty input buffer is passed in the first call.
SEC_E_INVALID_HANDLE	The context handle specified by phContext is not valid.
SEC_E_INVALID_TOKEN	pMessage did not contain a valid SECBUFFER_TOKEN buffer or contained too few buffers.
SEC_E_OUT_OF_SEQUENCE	The nonce count is out of sequence.
SEC_E_NO_AUTHENTICATING_AUTHORITY	The security context (phContext) must be revalidated.
STATUS_INVALID_PARAMETER	The nonce count is not numeric.
SEC_E_QOP_NOT_SUPPORTED	The quality of protection negotiated between the client and server did not include integrity checking.

Remarks

The MakeSignature function generates a signature that is based on the message and the session key for the context.

The VerifySignature function verifies the messages signed by the MakeSignature function.

If the transport application created the security context to support sequence detection and the caller provides a sequence number, the function includes this information in the signature. This protects against reply, insertion, and suppression of messages. The security package incorporates the sequence number passed down from the transport application.

Requirements

Requirement	Value
Minimum supported client	Windows XP [desktop apps only]
Minimum supported server	Windows Server 2003 [desktop apps only]
Target Platform	Windows
Header	sspi.h (include Security.h)
Library	Secur32.lib
DLL	Secur32.dll