/* ed25519_verify.c
 *
 * Copyright (C) 2006-2020 wolfSSL Inc.
 *
 * This file is part of wolfSSL. (formerly known as CyaSSL)
 *
 * wolfSSL is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * wolfSSL is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
 */

/* Example to demonstrate Ed25519 Verify */
/* 
./configure --enable-ed25519 && make && sudo make install
gcc -lwolfssl -o ed25519_verify ed25519_verify.c
*/

#ifndef WOLFSSL_USER_SETTINGS
    #include <wolfssl/options.h>
#endif
#include <wolfssl/wolfcrypt/settings.h>
#include <wolfssl/wolfcrypt/sha256.h>
#include <wolfssl/wolfcrypt/ed25519.h>
#include <wolfssl/wolfcrypt/integer.h>
#include <wolfssl/wolfcrypt/error-crypt.h>
#include <wolfssl/wolfcrypt/logging.h>

#include <stdint.h>
#include <stdio.h>

#if defined(HAVE_ED25519) && defined(HAVE_ED25519_VERIFY)

/* Test Vectors */
static const uint8_t kMsg[] = {
    0x69, 0xbc, 0x9f, 0xce, 0x68, 0x17, 0xc2, 0x10,
    0xea, 0xfc, 0x10, 0x65, 0x67, 0x52, 0xed, 0x78,
    0x6e, 0xb8, 0x83, 0x9c, 0x9a, 0xb4, 0x56, 0x0d,
    0xc1, 0x0d, 0x1f, 0x78, 0x6e, 0x75, 0xd7, 0xbe,
    0x92, 0x6b, 0x12, 0xf6, 0x76, 0x60, 0x8e, 0xb1,
    0xf4, 0x19, 0x0c, 0x81, 0xe7, 0x54, 0x5e, 0xbc,
    0xe0, 0xae, 0xc2, 0x7d, 0x1b, 0xc4, 0x6e, 0xec,
    0xb1, 0x99, 0x6c, 0xbf, 0x0e, 0x38, 0xa8, 0x01,
    0xa6, 0x9a, 0x48, 0x12, 0xe4, 0xc9, 0x3b, 0xf0,
    0x63, 0x46, 0x15, 0xb4, 0x61, 0xa8, 0x1a, 0x60,
    0x71, 0x87, 0x98, 0xd7, 0x6f, 0x98, 0x7b, 0x2d,
    0xb9, 0x19, 0x1b, 0x21, 0x9c, 0x70, 0x58, 0xe8,
    0x0d, 0x0f, 0xe9, 0x2d, 0x9a, 0x9a, 0xf1, 0x55,
    0xa0, 0x4c, 0xd3, 0x07, 0xbd, 0x97, 0x48, 0xec,
    0x88, 0x0a, 0xaf, 0xb3, 0x80, 0x78, 0xa4, 0x59,
    0x43, 0x57, 0xd3, 0xa7, 0x01, 0x66, 0x0e, 0xfc
};
static const uint8_t kPubKey[] = {
    /* y */
    0x37, 0x3e, 0xd5, 0x8d, 0x22, 0x1a, 0x05, 0x81,
    0xbf, 0x24, 0x6e, 0xdc, 0x5a, 0x42, 0x08, 0x83,
    0xff, 0xac, 0xfb, 0x28, 0xd0, 0x83, 0xb8, 0x2d,
    0x1c, 0xb7, 0x04, 0xaf, 0xa8, 0x41, 0x79, 0x23
};
static const uint8_t kSigRS[] = {
    /* R */
    0x4A, 0xD1, 0xF1, 0x9D, 0x1A, 0xDE, 0x2D, 0xF9,
    0x7F, 0x0B, 0x43, 0xF5, 0x95, 0x95, 0x02, 0x5E,
    0xDA, 0x4C, 0xE9, 0x60, 0x2A, 0xCA, 0x65, 0x91,
    0x25, 0x0F, 0xDF, 0x72, 0x9F, 0x76, 0xA1, 0xE8,
    /* S */
    0x91, 0x76, 0x06, 0x40, 0xB5, 0xCF, 0xBC, 0x5A,
    0x55, 0x86, 0x0C, 0x19, 0xA8, 0xE8, 0xB0, 0xF2,
    0xAA, 0xE2, 0x7A, 0xFB, 0x94, 0xD9, 0x81, 0xFB,
    0xD3, 0x04, 0xB0, 0x6D, 0x69, 0x24, 0xA4, 0x0F 
};


/* perform verify of signature and message using public key */
/* key is public y */
/* sig is r + s */
int crypto_ed25519_verify(const uint8_t *key, uint32_t keySz,
    const uint8_t *sig, uint32_t sigSz)
{
    int ret, verify_res = 0;
    ed25519_key ed25519;

    /* validate arguments */
    if (key == NULL || sig == NULL) {
        return BAD_FUNC_ARG;
    }

    /* Setup the Ed25519 key */
    ret = wc_ed25519_init(&ed25519);
    if (ret < 0) {
        return ret;
    }

    /* Import public key x/y */
    ret = wc_ed25519_import_public(
        (byte*)key, keySz,      /* public "y" Coordinate */
        &ed25519                /* key context */
    );

    /* Verify Ed25519 Signature */
    if (ret == 0) {
        ret = wc_ed25519_verify_msg(
            sig, sigSz,         /* r/s encoded */
            kMsg, sizeof(kMsg), /* message */
            &verify_res,        /* verification result 1=success */
            &ed25519            /* key context */
        );
    }
    
    /* check verify result */
    if (ret == 0 && verify_res == 0) {
        ret = SIG_VERIFY_E;
    }

    wc_ed25519_free(&ed25519);

    return ret;
}

int main()
{
    int ret;
    
#ifdef DEBUG_WOLFSSL
    wolfSSL_Debugging_ON();
#endif

    printf("Running Verify Test Vector\n");

    ret = crypto_ed25519_verify(
        kPubKey, sizeof(kPubKey), /* public key point x/y */
        kSigRS, sizeof(kSigRS)    /* signature r/s */
    );

    if (ret == 0) {
        printf("Success\n");
    }
    else {
        printf("Failure %d: %s\n", ret, wc_GetErrorString(ret));
        ret = 1;
    }

    return ret;
}

#else

int main()
{
    printf("wolfSSL requires Ed25519\n");
    return 1;
}

#endif /* HAVE_ED25519 && HAVE_ED25519_VERIFY */