Cryptography for Intel® Integrated Performance Primitives Developer Reference

Developer Reference

Contents

GFpInit

Initializes the context of a prime finite field GF(q).

Syntax

IppStatus ippsGFpInit(const IppsBigNumState*
pPrime
, int
primeBitSize
, const IppsGFpMethod*
method
, IppsGFpState*
pGF
);
Include Files
ippcp.h
Parameters
pPrime
Pointer to the Big Number context storing the GF(
q
) modulus.
primeBitSize
Size, in bytes, of the odd prime number
p
 (modulus of GF(
q
)).
method
Pointer to the implementation of a basic arithmetic (methods) over the prime finite field GF(
q
).
If your application uses one of predefined values of the modulus
q
, the use of the
GFpMethod
 function corresponding to that value is preferable. In other cases, use
ippsGfpMethod_pArb()
.
pGF
Pointer to the context of the GF(
q
) field being initialized.
Description
The function initializes the
pGF
 context parameter with the values of the input parameters
pPrime
,
primeBitSize
, and
method
. The three parameters have to be compatible with each other.
The
method
 parameter must be an output from one of the
GFpMethod
 functions with predefined modulus
q
, and the parameters
primeBitSize
 and
method
 must be compatible with each other.
If
pPrime
 is not
NULL
, and
method
 is an output from one of the
GFpMethod
 functions with predefined modulus
q
, then the pair
pPrime
 and
primeBitSize
 should define the same prime
q
 as defined in
method
.
If both
pPrime
 and
method
 are not
NULL
, then
ippsGFpInit()
 provides the required initialization if the parameters are compatible with each other.
The initialized context is used in the functions that create contexts of elements of the GF(
p
) field, which, in turn, are used to perform operations with the field elements.
This function does not check if
pPrime
 actually refers to a prime value.
Return Values
ippStsNoErr
Indicates no error. Any other value indicates an error or warning.
ippStsNullPtrErr
Indicates an error condition in the following cases:
  • pGF
     is
    NULL
    .
  • Both
    pPrime
     and
    method
     are
    NULL
    .
ippStsSizeErr
Indicates an error condition if
primeBitSize
 is less than 2 or greater than 1024.
ippStsContextMatchErr
Indicates an error condition if the
pPrime
 context parameter is not
NULL
 and does not match the operation.
ippStsBadArgErr
Indicates an error condition in the following cases:
  • The modulus
    q
     defined in
    pPrime
     is less than 3.
  • bitsize(
    q
    ) !=
    primeBitSize
    .
  • q
     is even.
  • method
     is not
    NULL
     and not an output of
    GFpMethod
    .
  • method
     is an output from one of the
    GFpMethod
     functions with predefined modulus
    q
    , but:
    • The bit size of
      q
       of
      method
       is different from the bit size of the value stored in the context pointed to by
      pPrime
      .
    • q
       of
      method
       is different from the value stored in the context pointed to by
      pPrime
      .

Product and Performance Information

1

Performance varies by use, configuration and other factors. Learn more at www.Intel.com/PerformanceIndex.