HQC harness

Test encapsulation

Attention

Testing encapsulation requires a reference implementation to decapsulate the ciphertexts, as encapsulation is a non-deterministic operation. We are working on integrating one so this function is only for testing the encapsulation/decapsulation invariant for now.

The naming convention for the encapsulation function is:

CC_HQC_<paramset>_encaps

Where paramset is one of: 128, 192, 256.

The harness function must have the following signature:

int HQC_encaps(
uint8_t *ct,
size_t ct_size,
uint8_t *ss,
size_t ss_size,
const uint8_t *pk,
size_t pk_size,
)

Encapsulates with HQC.

Parameters:

  • ct – [Out] An allocated buffer to return the resulting ciphertext.

  • ct_size – [In] The size in bytes of ct.

  • ss – [Out] An allocated buffer to return the resulting shared secret.

  • ss_size – [In] The size in bytes of ss.

  • pk – [In] The public key to encapsulate to.

  • pk_size – [In] The size in bytes of pk.

Returns:

A status value.

Return values:

  • 1 – OK.

  • 0 – An error occurred.

Test decapsulation

The naming convention for the decapsulation function is:

CC_HQC_<paramset>_decaps

Where paramset is one of: 128, 192, 256.

The harness function must have the following signature:

int HQC_decaps(
uint8_t *ss,
size_t ss_size,
const uint8_t *sk,
size_t sk_size,
const uint8_t *ct,
size_t ct_size,
)

Decapsulates a shared secret with HQC.

Parameters:

  • ss – [Out] An allocated buffer to return the resulting shared secret.

  • ss_size – [In] The size in bytes of ss.

  • sk – [In] The secret key to use for decapsulation.

  • sk_size – [In] The size in bytes of sk.

  • ct – [In] The ciphertext.

  • ct_size – [In] The size in bytes of ct.

Returns:

A status value.

Return values:

  • 1 – OK.

  • 0 – An error occurred.

Test encapsulation/decapsulation invariant

Encapsulating to a public key then decapsulating with the corresponding secret key should always yield the same share secret. To test this invariant, create the following function and a harness for both encapsulation and decapsulation, as detailed above.

CC_HQC_<paramset>_invariant

Where paramset is one of: 128, 192, 256.

The function is a stub to indicate crypto-condor to test the invariant, no operations are actually performed with it.

void HQC_invariant(void)

For example:

int CC_HQC_128_encaps(...) {
    ...
}

int CC_HQC_128_decaps(...) {
    ...
}

void CC_HQC_128_invariant() {};