Chapter 7 Public-Key Operations 277
Performing Elliptic Curve Operations
Step 6: Destroy
You must free all allocated memory and destroy all objects when they are no longer
needed so that all sensitive information is zeroized and freed:
Generating a Public-Key Acceleration Table
This special-purpose acceleration table can be used to speed up ECDSA verification.
Again, the cost in time to generate the table and space to store it must be weighed
against the speedup in verification that it will provide. This table is most useful if
ECDSA verification will be performed repeatedly with the same public key. The
function
BuildPubKeyAccelTable, used in the sample code and defined in the file
ecparam.c, demonstrates the steps in creating the public-key acceleration table.
Step 1: Create
Create the algorithm object that will be used in building the public-key acceleration
table. Declare a variable to be
B_ALGORITHM_OBJ. As defined in the function prototype
in Chapter 4 of the Reference Manual, its address is the argument for
B_CreateAlgorithmObject:
Step 2: Set
Retrieve the public-key information and place it in the algorithm object used to build
the acceleration table for that public key.
Step 2a: Retrieve the public key information
Because B_GetKeyInfo returns a pointer to memory that belongs to Crypto-C, you
must make a copy of this information. See “Retrieving an Elliptic Curve Key” on
page 271 for the definitions of
AllocAndCopyECPubKeyInfo
and
FreeECPubKeyInfo
.
T_memset(accelTableItem.data, 0, accelTableItem.len);
T_free(accelTableItem.data);
B_DestroyAlgorithmObject(&buildTable);
B_ALGORITHM_OBJ buildTable = (B_ALGORITHM_OBJ)NULL_PTR;
if ((status = B_CreateAlgorithmObject(&buildTable)) != 0)
break;
