libs/crypto/libpqnist/examples/run_encap_decap.c

/*
   Encapsulate a secret and use the secret to encrypt a message
   Decapsulate the secret and use the secret to decrypt the encrypted message
*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <amcl/utils.h>
#include <amcl/randapi.h>
#include <amcl/bls_BLS381.h>
#include <oqs/oqs.h>
#include <pqnist/pqnist.h>

#define NTHREADS 8
#define MAXSIZE 256

#define G2LEN 4*BFS_BLS381

int main()
{
    int i,rc;

    // Seed value for CSPRNG
    char seed[PQNIST_SEED_LENGTH];
    octet SEED = {sizeof(seed),sizeof(seed),seed};

    // Seed value for key generation
    char seedkeys[NTHREADS][PQNIST_SEED_LENGTH];

    csprng RNG;

    // Initialization vector
    char iv[PQNIST_AES_IV_LENGTH];
    octet IV= {sizeof(iv),sizeof(iv),iv};

    // Message to be sent to Bob
    char p[NTHREADS][MAXSIZE];
    octet P[NTHREADS];

    // AES CBC ciphertext
    char c[NTHREADS][MAXSIZE];
    octet C[NTHREADS];

    // non random seed value
    for (i=0; i<PQNIST_SEED_LENGTH; i++) SEED.val[i]=i+1;
    printf("SEED: ");
    OCT_output(&SEED);
    printf("\n");

    // initialise random number generator
    CREATE_CSPRNG(&RNG,&SEED);

    // Initialise key generation seed
    for(i=0; i<NTHREADS; i++)
    {
        for(int j=0; j<PQNIST_SEED_LENGTH; j++)
        {
            seedkeys[i][j] = i;
        }
    }

    // Bob's SIKE keys
    uint8_t SIKEpk[NTHREADS][OQS_KEM_sike_p751_length_public_key];
    uint8_t SIKEsk[NTHREADS][OQS_KEM_sike_p751_length_secret_key];

    // Alice's BLS keys (not used)
    char BLSpk[NTHREADS][G2LEN];
    char BLSsk[NTHREADS][BGS_BLS381];

    #pragma omp parallel for
    for(i=0; i<NTHREADS; i++)
    {
        rc = pqnist_keys(seedkeys[i], SIKEpk[i], SIKEsk[i], BLSpk[i], BLSsk[i]);
        if (rc)
        {
            fprintf(stderr, "ERROR pqnist_keys rc: %d\n", rc);
            exit(EXIT_FAILURE);
        }

        int j = OQS_KEM_sike_p751_length_public_key;
        printf("Bob SIKE pklen %d pk: ", j);
        amcl_print_hex(SIKEpk[i], j);
        j = OQS_KEM_sike_p751_length_secret_key;
        printf("Bob SIKE sklen %d sk: ", j);
        amcl_print_hex(SIKEsk[i], j);

    }

    // Alice

    for(i=0; i<NTHREADS; i++)
    {
        bzero(p[i],sizeof(p[i]));
        P[i].max = MAXSIZE;
        P[i].len = sprintf(p[i], "Hello Bob! This is a message from Alice %d", i);
        P[i].val = p[i];
        // Pad message
        int l = 16 - (P[i].len % 16);
        if (l < 16)
        {
            OCT_jbyte(&P[i],0,l);
        }
    }

    // Random initialization value
    generateRandom(&RNG,&IV);
    printf("Alice IV: ");
    OCT_output(&IV);

    // Copy plaintext
    for(i=0; i<NTHREADS; i++)
    {
        C[i].val = c[i];
        C[i].max = MAXSIZE;
        OCT_copy(&C[i],&P[i]);
        printf("Alice Plaintext: ");
        OCT_output_string(&C[i]);
        printf("\n");
    }

    // SIKE encapsulated key
    uint8_t ek[NTHREADS][OQS_KEM_sike_p751_length_ciphertext];

    #pragma omp parallel for
    for(i=0; i<NTHREADS; i++)
    {

        // Generate an AES which is ecapsulated using SIKE. Use this key to
        // AES encrypt the K parameter.
        rc = pqnist_encapsulate_encrypt(C[i].val, C[i].len, IV.val, SIKEpk[i], ek[i]);
        if(rc)
        {
            fprintf(stderr, "ERROR pqnist_encapsulate_encrypt rc: %d\n", rc);
            exit(EXIT_FAILURE);
        }

        printf("Alice ciphertext: ");
        OCT_output(&C[i]);

        printf("Alice ek %lu ek: ", sizeof(ek[i]));
        amcl_print_hex(ek[i], sizeof(ek[i]));
        printf("\n");

    }

    // Bob

    #pragma omp parallel for
    for(i=0; i<NTHREADS; i++)
    {
        // Obtain encapsulated AES key and decrypt C
        rc = pqnist_decapsulate_decrypt(C[i].val, C[i].len, IV.val, SIKEsk[i], ek[i]);
        if(rc)
        {
            fprintf(stderr, "ERROR pqnist_decapsulate_decrypt rc: %d\n", rc);
            exit(EXIT_FAILURE);
        }

        printf("Bob Plaintext: ");
        OCT_output(&C[i]);

        printf("Bob Plaintext: ");
        OCT_output_string(&C[i]);
        printf("\n");

        // Compare sent and recieved message (returns 0 for failure)
        rc = OCT_comp(&P[i],&C[i]);
        if(!rc)
        {
            fprintf(stderr, "ERROR OCT_comp rc: %d\n", rc);
            exit(EXIT_FAILURE);
        }
    }

    // clear memory

    OCT_clear(&IV);
    for(i=0; i<NTHREADS; i++)
    {
        OQS_MEM_cleanse(SIKEsk[i], OQS_KEM_sike_p751_length_secret_key);
        OQS_MEM_cleanse(BLSsk[i], OQS_SIG_picnic_L5_FS_length_secret_key);
        OCT_clear(&P[i]);
        OCT_clear(&C[i]);
    }

    KILL_CSPRNG(&RNG);

    exit(EXIT_SUCCESS);
}