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DeriveKey(3)
NAME
  DeriveKey, CSSM_DeriveKey, CSP_DeriveKey - Derive new symmetric key (CDSA)

SYNOPSIS
  # include <cdsa/cssm.h>

       API:
       CSSM_RETURN CSSMAPI CSSM_DeriveKey
       (CSSM_CC_HANDLE CCHandle,
       CSSM_DATA_PTR Param,
       uint32 KeyUsage,
       uint32 KeyAttr,
       const CSSM_DATA *KeyLabel,
       const CSSM_RESOURCE_CONTROL_CONTEXT *CredAndAclEntry,
       CSSM_KEY_PTR DerivedKey)
       SPI:
       CSSM_RETURN CSSMCSPI CSP_DeriveKey
       (CSSM_CSP_HANDLE CSPHandle,
       CSSM_CC_HANDLE CCHandle,
       const CSSM_CONTEXT *Context,
       CSSM_DATA_PTR Param,
       uint32 KeyUsage,
       uint32 KeyAttr,
       const CSSM_DATA *KeyLabel,
       const CSSM_RESOURCE_CONTROL_CONTEXT *CredAndAclEntry,
       CSSM_KEY_PTR DerivedKey)

LIBRARY
  Common Security Services Manager library (libcssm.so)

API PARAMETERS
  CCHandle (input)
	  The handle that describes the context of this cryptographic
	  operation.

  Param (input/output)
	  This parameter varies depending on the derivation algorithm.
	  Password based derivation algorithms use this parameter to return a
	  cipher block chaining initialization vector.	Concatenation
	  algorithms use this parameter to get the second item to
	  concatenate.

  KeyUsage (input)
	  A bit mask indicating all permitted uses for the new derived key.

  KeyAttr (input)
	  A bit mask defining other attribute values for the new derived key.

  KeyLabel (input/optional)
	  Pointer to a byte string that will be used as the label for the
	  derived key.

  CredAndAclEntry (input/optional)
	  A structure containing one or more credentials authorized for
	  creating a key and the prototype ACL entry that will control future
	  use of the newly created key. The credentials and ACL entry
	  prototype can be presented as immediate values or callback
	  functions can be provided for use by the CSP to acquire the
	  credentials and/or the subject of the ACL entry interactively. If
	  the CSP provides public access for creating a key, then the
	  credentials can be NULL. If the CSP defines a default initial ACL
	  entry for the new key, then the ACL entry prototype can be empty.

  DerivedKey (output)
	  A pointer to a CSSM_KEY structure that returns the derived key.

SPI PARAMETERS
  CSPHandle (input)
	  The handle that describes the add-in cryptographic service provider
	  module used to perform up calls to CSSM for the memory functions
	  managed by CSSM.

  Context (input)
	  Pointer to CSSM_CONTEXT structure that describes the attributes
	  with this context.

DESCRIPTION
  This function derives a new symmetric key using the context and/or
  information from the base key in the context. The CSP can require that the
  cryptographic context include access credentials for authentication and
  authorization checks when using a private key or a secret key.

  Authorization policy can restrict the set of callers who can create a new
  resource. In this case, the caller must present a set of access credentials
  for authorization. Upon successfully authenticating the credentials, the
  template that verified the presented samples identifies the ACL entry that
  will be used in the authorization computation. If the caller is authorized,
  the new resource is created.

  The caller must provide an initial ACL entry to be associated with the
  newly created resource. This entry is used to control future access to the
  new resource and (since the subject is deemed to be the "Owner") exercise
  control over its associated ACL. The caller can specify the following items
  for initializing an ACL entry:

  Subject A CSSM_LIST structure, containing the type of the subject and a
	  template value that can be used to verify samples that are
	  presented in credentials when resource access is requested.

  Delegation flag
	  A value indicating whether the Subject can delegate the permissions
	  recorded in the AuthorizationTag. (This item only applies to public
	  key subjects).

  Authorization tag
	  The set of permissions that are granted to the Subject.

  Validity period
	  The start time and the stop time for which the ACL entry is valid.

  ACL entry tag
	  A user-defined string value associated with the ACL entry.

	  The service provider can modify the caller-provided initial ACL
	  entry to conform to any innate resource-access policy that the
	  service provider may be required to enforce. If the initial ACL
	  entry provided by the caller contains values or permissions that
	  are not supported by the service provider, then the service
	  provider can modify the initial ACL appropriately or can fail the
	  request to create the new resource. Service providers list their
	  supported AuthorizationTag values in their Module Directory
	  Services primary record.

	  The CSP can require that the cryptographic context include access
	  credentials for authentication and authorization checks when using
	  a private key or a secret key.

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.	See CDSA_intro(3).

       CSSMERR_CSP_KEY_LABEL_ALREADY_EXISTS

COMMENTS
  The KeyData field of the CSSM_KEY structure is allocated by the CSP. The
  application is required to free this memory using the CSSM_FreeKey() (CSSM
  API), or CSP_FreeKey() (CSP SPI) call, or with the memory functions
  registered for the CSPHandle.

SEE ALSO
  Books

  Intel CDSA Application Developer's Guide (see CDSA_intro(3))

  Reference Pages

  Functions: CSSM_CSP_CreateDeriveKeyContext(3)

Index for Section 3

Alphabetical listing for D

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