DLPGetDP

Retrieves a particular domain parameter of the DL-based cryptosystem over GF(p).

Syntax

IppStatus ippsDLPGetDP(const IppsBigNumState* pDP, IppsDLPKeyTag tag, IppsDLPState* pCtx);

Parameters

pDP	Pointer to the output Big Number context.
tag	Tag specifying the domain parameter to be retrieved.
pCtx	Pointer to the cryptosystem context.

Description

This function is declared in the ippcp.h file. The function retrieves value of a particular domain parameter of the DL-based cryptosystem from the IppsDLPState context and stores the value in the Big Number context *pDP. The domain parameter to be retrieved is determined by tag as follows:

If tag == IppDLPkeyP, the function retrieves value of the characteristic p, the size of the prime finite field GF(p).
If tag == IppDLPkeyR, the function retrieves value of the characteristic r, the prime divisor of (p-1) and the order of g.
If tag == IppDLPkeyG, the function retrieves value of the characteristic g, the element of GF(p) generating a multiplicative subgroup of order r.

Return Values

ippStsNoErr	Indicates no error. Any other value indicates an error or warning.
ippStsNullPtrErr	Indicates an error condition if any of the specified pointers is NULL.
ippStsContextMatchErr	Indicates an error condition if the context parameter does not match the operation.
ippStsIncompleteContextErr	Indicates an error condition if the cryptosystem context has not been properly set up.
ippStsOutOfRangeErr	Indicates an error condition if the Big Number specified by pDP is too small for the DL parameter.
ippStsBadArgErr	Indicates an error condition if the domain parameter specified by the tag does not match the IppsDLPState context.