DecryptDataUpdate

NAME

CSSM_DecryptDataUpdate, CSP_DecryptDataUpdate — Continue the staged decryption process (CDSA)

SYNOPSIS

# include <cssm.h>

API:
CSSM_RETURN CSSMAPI CSSM_DecryptDataUpdate
(CSSM_CC_HANDLE CCHandle,
const CSSM_DATA *CipherBufs,
uint32 CipherBufCount,
CSSM_DATA_PTR ClearBufs,
uint32 ClearBufCount,
uint32 *bytesDecrypted)
SPI:
CSSM_RETURN CSSMCSPI CSP_DecryptDataUpdate
(CSSM_CSP_HANDLE CSPHandle,
CSSM_CC_HANDLE CCHandle,
const CSSM_DATA *CipherBufs,
uint32 CipherBufCount,
CSSM_DATA_PTR ClearBufs,
uint32 ClearBufCount,
uint32 *bytesDecrypted)

LIBRARY

Common Security Services Manager library (cdsa$incssm300_shr.exe)

API PARAMETERS

`CCHandle` (`input`)		The handle that describes the context of this cryptographic operation used to link to the CSP-managed information.
`CipherBufs` (`input`)
		A pointer to a vector of CSSM_DATA structures that contain the data to be operated on.
`CipherBufCount` (`input`)
		The number of `CipherBufs`.
`ClearBufs` (`output`)
		A pointer to a vector of CSSM_DATA structures that contain the decrypted data resulting from the decryption operation.
`ClearBufCount` (`input`)
		The number of `ClearBufs`.
`bytesDecrypted` (`output`)
		A pointer to `uint32` for the size of the decrypted data in bytes.

SPI PARAMETER

`CSPHandle` (`input`)
		The handle that describes the add-in Cryptographic Service Provider module used to perform calls to CSSM for the memory functions managed by CSSM.

DESCRIPTION

This function continues the staged decryption process over all data in the set of input buffers. There can be algorithm-specific and token-specific rules restricting the lengths of data in CSSM_DecryptUpdate() calls, but multiple input buffers are supported. The minimum number of buffers required to contain the resulting plain text is produced as output. Excess output buffer space is not remembered across staged decryption calls. Each staged call begins filling one or more new output buffers. The CSSM_QuerySize() (CSSM API), or CSP_QuerySize() (CSP SPI), function can be used to estimate the output buffer size required for each update call.

NOTES FOR API

The output is returned to the caller either by filling the caller-specified buffer or by using the application's declared memory allocation functions to allocate buffer space. To specify a specific, preallocated output buffer, the caller must provide an array of one or more CSSM_DATA structures, each containing a Length field value greater than zero and a non-NULL data pointer field value. To specify automatic output buffer allocation by the CSP, the caller must provide an array of one or more CSSM_DATA structures, each containing a Length field value equal to zero and a NULL data pointer field value. The application is always responsible for deallocating the memory when it is no longer needed. In-place decryption can be done by supplying the same input and output buffers.

NOTES FOR SPI

The output is returned to the caller as specified in Buffer Management for Cryptographic Services.

RETURN VALUE

A CSSM_RETURN value indicating success or specifying a particular error condition. The value CSSM_OK indicates success. All other values represent an error condition.

ERRORS

Errors are described in the CDSA Technical Standard.

None specific to this call.

DecryptDataUpdate

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