ica_ecdh_derive_secret

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Purpose

Calculates the Diffie-Hellman shared secret (z value) of a first given private ICA_EC_KEY data structure (with given D value) and a second given public ICA_EC_KEY data structure (with given X and Y values).

Format


int ica_ecdh_derive_secret(ica_adapter_handle_t adapter_handle,
  const ICA_EC_KEY   *privkey_A, 
  const ICA_EC_KEY   *pubkey_B,
  unsigned char      *z, 
  unsigned int       z_length);

Required hardware support

  • At least, a Crypto Express4S CCA coprocessor is required (CEX4C or later).
  • MSA9 (IBM z15® or later) for ECDH and ECDSA support via CPACF for these elliptic curves: p256, p384, p521.

Parameters

ica_adapter_handle_t adapter_handle
Pointer to a previously opened device handle.
const ICA_EC_KEY *privkey_A
A pointer to a private ICA_EC_KEY object, initialized via ica_ec_key_init or ica_ec_key_generate.
const ICA_EC_KEY *pubkey_B
A pointer to a public ICA_EC_KEY object, initialized via ica_ec_key_init or ica_ec_key_generate.
unsigned char *z
Pointer to a writable buffer where the shared secret (z) is returned.
unsigned int z_length
The length in bytes of the z buffer. This length must be greater or equal to privlen, as returned when creating the ICA_EC_KEY objects. Both keys are supposed to be based on the same elliptic curve, so both keys have the same length of D, and the same (X,Y).

Return codes

0
Success
EINVAL
If at least one invalid parameter is given.
EFAULT
If an internal processing error occurred.
EPERM
If the EC curve is not supported in this environment.

For return codes indicating exceptions, see Return codes.