CK_RV aes_ctr_sample()

in src/encrypt/aes_ctr.c [26:148]
87 lines of code
14 McCabe index (conditional complexity)

CK_RV aes_ctr_sample(CK_SESSION_HANDLE session) {
    CK_RV rv;
    unsigned char* hex_array = NULL;
    CK_BYTE_PTR decrypted_ciphertext = NULL;

    // Generate a 256 bit AES key.
    CK_OBJECT_HANDLE aes_key = CK_INVALID_HANDLE;
    rv = generate_aes_key(session, 32, &aes_key);
    if (CKR_OK != rv) {
        fprintf(stderr, "AES key generation failed: %lu\n", rv);
        return rv;
    }

    CK_BYTE_PTR plaintext = "plaintext payload to encrypt";
    CK_ULONG plaintext_length = (CK_ULONG) strlen(plaintext);
    CK_ULONG ciphertext_length = 0;

    printf("Plaintext: %s\n", plaintext);
    printf("Plaintext length: %lu\n", plaintext_length);

    // Prepare the mechanism
    // The IV is hardcoded to all 0x01 bytes for this example.
    CK_AES_CTR_PARAMS ctr_params;
    CK_BYTE ctr_bytes[16] = {1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1};
    ctr_params.ulCounterBits = 32;
    memcpy(ctr_params.cb, ctr_bytes, sizeof(ctr_params.cb));
    CK_MECHANISM mech = { CKM_AES_CTR, &ctr_params, sizeof(ctr_params) };

    //**********************************************************************************************
    // Encrypt
    //**********************************************************************************************

    rv = funcs->C_EncryptInit(session, &mech, aes_key);
    if (CKR_OK != rv) {
        fprintf(stderr, "Encryption Init failed: %lu\n", rv);
        return rv;
    }

    // Determine how much memory will be required to hold the ciphertext.
    rv = funcs->C_Encrypt(session, plaintext, plaintext_length, NULL, &ciphertext_length);
    if (CKR_OK != rv) {
        fprintf(stderr, "Encryption failed: %lu\n", rv);
        return rv;
    }    

    // Allocate the required memory.
    CK_BYTE_PTR ciphertext = malloc(ciphertext_length);
    if (NULL == ciphertext) {
        fprintf(stderr, "Could not allocate memory for ciphertext\n");
        rv = CKR_HOST_MEMORY;
        goto done;
    }
    memset(ciphertext, 0, ciphertext_length);


    // Encrypt the data.
    rv = funcs->C_Encrypt(session, plaintext, plaintext_length, ciphertext, &ciphertext_length);
    if (CKR_OK != rv) {
        fprintf(stderr, "Encryption failed: %lu\n", rv);
        goto done;
    }

    // Print just the ciphertext in hex format.
    bytes_to_new_hexstring(ciphertext, ciphertext_length, &hex_array);
    if (!hex_array) {
        fprintf(stderr, "Coud not allocate memory for hex array\n");
        rv = CKR_HOST_MEMORY;
        goto done;
    }
    printf("Ciphertext: %s\n", hex_array);
    printf("Ciphertext length: %lu\n", ciphertext_length);

    //**********************************************************************************************
    // Decrypt
    //**********************************************************************************************

    rv = funcs->C_DecryptInit(session, &mech, aes_key);
    if (CKR_OK != rv) {
        fprintf(stderr, "Decryption Init failed: %lu\n", rv);
        return rv;
    }

    // Determine how much memory is required to hold the decrypted text.
    CK_ULONG decrypted_ciphertext_length = 0;
    rv = funcs->C_Decrypt(session, ciphertext, ciphertext_length, NULL, &decrypted_ciphertext_length);
    if (CKR_OK != rv) {
        fprintf(stderr, "Decryption failed: %lu\n", rv);
        goto done;
    }

    // Allocate memory for decrypted ciphertext.
    decrypted_ciphertext = malloc(decrypted_ciphertext_length + 1); //We want to null terminate the raw chars later
    if (NULL == decrypted_ciphertext) {
        fprintf(stderr, "Coud not allocate memory for decrypted ciphertext\n");
        rv = CKR_HOST_MEMORY;
        goto done;
    }

    // Decrypt the ciphertext.
    rv = funcs->C_Decrypt(session, ciphertext, ciphertext_length, decrypted_ciphertext, &decrypted_ciphertext_length);
    if (CKR_OK != rv) {
        fprintf(stderr, "Decryption failed: %lu\n", rv);
        goto done;
    }
    decrypted_ciphertext[decrypted_ciphertext_length] = 0; // Turn the chars into a C-String via null termination

    printf("Decrypted ciphertext: %s\n", decrypted_ciphertext);
    printf("Decrypted ciphertext length: %lu\n", decrypted_ciphertext_length);

done:
    if (NULL != decrypted_ciphertext) {
        free(decrypted_ciphertext);
    }

    if (NULL != hex_array) {
        free(hex_array);
    }

    if (NULL != ciphertext) {
        free(ciphertext);
    }
    return rv;
}