.. _Code_Sample:

===============================
Setting Up pQCee SPP toolkit
===============================

To use SPP toolkit Windows target, you can do the following:

1) Have Microsoft Visual Studio 2017 installed

2) Open a "x64 Native Tools Command Prompt"

3) Copy all files into a directory
    - sha256.h
    - sha256.c 
    - pqspp.h 
    - main.c
    - pqspp_sdk.dll.lib

4) Compile the code using "cl main.c sha256.c pqspp_sdk.dll.lib". It will result in main.exe created.

5) Execute main.exe, and expect to see the following output:

    Generated a secret key and a public key (DER encoded of length 91)!

    Signed a message; got a pq_proof of size 210982 bytes

    Successfully verified the signature and the preimage proof!



========================
pQCee main.c Code Sample
========================

.. code-block:: c

    // This is pQCee's main.c code sample
    #include "pqspp.h"
    #include "sha256.h"

    #include <stdio.h>
    #include <stdlib.h>

    int main() {

    uint8_t *sk = NULL;
    uint8_t *pk = NULL;
    int pk_len = -1;

    // call PQSPP_keygen to generate a secret key, public key and the length of each key
    int ret = PQSPP_keygen(&sk, &pk, &pk_len);
    if (ret != PQSPP_OK) {
        printf("Error in keygen: %d\n", ret);
        return -1;
    }
    printf(
        "Generated a secret key and a public key (DER encoded of length %d)!\n",
        pk_len);

    // your message digest
    uint8_t message[4] = {0x01, 0x02, 0x03, 0x04};

    // hash the message digest 
    unsigned char hash[32];
    SHA256_CTX ctx;

    sha256_init(&ctx);
    sha256_update(&ctx,message,sizeof(message));
    sha256_final(&ctx,hash);

    uint8_t *ec_sig = NULL;
    int ec_sig_len = -1;
    uint8_t *pip = NULL;
    int pip_len = -1;

    // call PQSPP_sign_digest to sign the hashed message 
    ret =
        PQSPP_sign_digest(sk, hash,sizeof(hash), &ec_sig, &ec_sig_len, &pip, &pip_len);
    if (ret != PQSPP_OK) {
        printf("Error in sign: %d\n", ret);
        PQSPP_free_memory(sk);
        PQSPP_free_memory(pk);
        return -2;
    }
    printf("Signed a message; got a pq_proof of size %d bytes\n", pip_len);

    // call PQSPP_verify_digest to verify the hashed message against its signature
    ret = PQSPP_verify_digest(pk, pk_len, hash, sizeof(hash), ec_sig, ec_sig_len, pip,
        pip_len);
    if (ret != PQSPP_OK) {
        printf("Error in verify: %d\n", ret);
        PQSPP_free_memory(sk);
        PQSPP_free_memory(pk);
        PQSPP_free_memory(ec_sig);
        PQSPP_free_memory(pip);
        return -3;
    }

    printf("Successfully verified the signature and the preimage proof!\n");

    // call PQSPP_free_memory to free memories used during the signing process 
    PQSPP_free_memory(sk);
    PQSPP_free_memory(pk);
    PQSPP_free_memory(ec_sig);
    PQSPP_free_memory(pip);

    return 0;
    }