// This file was extracted from the TCG Published

// Trusted Platform Module Library

// Part 3: Commands

// Family "2.0"

// Level 00 Revision 01.16

// October 30, 2014

#include "InternalRoutines.h"

#include "ECDH_KeyGen_fp.h"

#ifdef TPM_ALG_ECC

//

//

//     Error Returns                     Meaning

//

//     TPM_RC_ATTRIBUTES                 If the key is restricted or the key is not a decryption key

//     TPM_RC_KEY                        keyHandle does not reference a non-restricted decryption ECC key

//

TPM_RC

TPM2_ECDH_KeyGen(

   ECDH_KeyGen_In        *in,                 // IN: input parameter list

   ECDH_KeyGen_Out       *out                 // OUT: output parameter list

   )

{

   OBJECT                    *eccKey;

   TPM2B_ECC_PARAMETER        sensitive;

   TPM_RC                     result;

// Input Validation

   eccKey = ObjectGet(in->keyHandle);

   // Input key must be a non-restricted, decrypt ECC key

   if(   eccKey->publicArea.type != TPM_ALG_ECC)

       return TPM_RC_KEY + RC_ECDH_KeyGen_keyHandle;

   if(     eccKey->publicArea.objectAttributes.restricted == SET

      ||   eccKey->publicArea.objectAttributes.decrypt != SET

     )

       return TPM_RC_ATTRIBUTES + RC_ECDH_KeyGen_keyHandle;

// Command Output

   do

   {

       // Create ephemeral ECC key

       CryptNewEccKey(eccKey->publicArea.parameters.eccDetail.curveID,

                      &out->pubPoint.t.point, &sensitive);

       out->pubPoint.t.size = TPMS_ECC_POINT_Marshal(&out->pubPoint.t.point,

                              NULL, NULL);

       // Compute Z

       result = CryptEccPointMultiply(&out->zPoint.t.point,

                                  eccKey->publicArea.parameters.eccDetail.curveID,

                                  &sensitive, &eccKey->publicArea.unique.ecc);

       // The point in the key is not on the curve. Indicate that the key is bad.

       if(result == TPM_RC_ECC_POINT)

           return TPM_RC_KEY + RC_ECDH_KeyGen_keyHandle;

       // The other possible error is TPM_RC_NO_RESULT indicating that the

       // multiplication resulted in the point at infinity, so get a new

       // random key and start over (hardly ever happens).

   }

   while(result == TPM_RC_NO_RESULT);

   if(result == TPM_RC_SUCCESS)

       // Marshal the values to generate the point.

       out->zPoint.t.size = TPMS_ECC_POINT_Marshal(&out->zPoint.t.point,

                                                   NULL, NULL);

   return result;

}

#endif