/*

 * Copyright 2005-2018 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the OpenSSL license (the "License").  You may not use

 * this file except in compliance with the License.  You can obtain a copy

 * in the file LICENSE in the source distribution or at

 * https://www.openssl.org/source/license.html

 */

#include <stdio.h>

#include "internal/cryptlib.h"

#include <openssl/bn.h>

#include <openssl/rsa.h>

#include <openssl/evp.h>

#include <openssl/rand.h>

#include <openssl/sha.h>

#include "rsa_local.h"

static const unsigned char zeroes[] = { 0, 0, 0, 0, 0, 0, 0, 0 };

#if defined(_MSC_VER) && defined(_ARM_)

# pragma optimize("g", off)

#endif

int RSA_verify_PKCS1_PSS(RSA *rsa, const unsigned char *mHash,

                         const EVP_MD *Hash, const unsigned char *EM,

                         int sLen)

{

    return RSA_verify_PKCS1_PSS_mgf1(rsa, mHash, Hash, NULL, EM, sLen);

}

int RSA_verify_PKCS1_PSS_mgf1(RSA *rsa, const unsigned char *mHash,

                              const EVP_MD *Hash, const EVP_MD *mgf1Hash,

                              const unsigned char *EM, int sLen)

{

    int i;

    int ret = 0;

    int hLen, maskedDBLen, MSBits, emLen;

    const unsigned char *H;

    unsigned char *DB = NULL;

    EVP_MD_CTX *ctx = EVP_MD_CTX_new();

    unsigned char H_[EVP_MAX_MD_SIZE];

    if (ctx == NULL)

        goto err;

    if (mgf1Hash == NULL)

        mgf1Hash = Hash;

    hLen = EVP_MD_size(Hash);

    if (hLen < 0)

        goto err;

    /*-

     * Negative sLen has special meanings:

     *      -1      sLen == hLen

     *      -2      salt length is autorecovered from signature

     *      -3      salt length is maximized

     *      -N      reserved

     */

    if (sLen == RSA_PSS_SALTLEN_DIGEST) {

        sLen = hLen;

    } else if (sLen < RSA_PSS_SALTLEN_MAX) {

        RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, RSA_R_SLEN_CHECK_FAILED);

        goto err;

    }

    MSBits = (BN_num_bits(rsa->n) - 1) & 0x7;

    emLen = RSA_size(rsa);

    if (EM[0] & (0xFF << MSBits)) {

        RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, RSA_R_FIRST_OCTET_INVALID);

        goto err;

    }

    if (MSBits == 0) {

        EM++;

        emLen--;

    }

    if (emLen < hLen + 2) {

        RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, RSA_R_DATA_TOO_LARGE);

        goto err;

    }

    if (sLen == RSA_PSS_SALTLEN_MAX) {

        sLen = emLen - hLen - 2;

    } else if (sLen > emLen - hLen - 2) { /* sLen can be small negative */

        RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, RSA_R_DATA_TOO_LARGE);

        goto err;

    }

    if (EM[emLen - 1] != 0xbc) {

        RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, RSA_R_LAST_OCTET_INVALID);

        goto err;

    }

    maskedDBLen = emLen - hLen - 1;

    H = EM + maskedDBLen;

    DB = OPENSSL_malloc(maskedDBLen);

    if (DB == NULL) {

        RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, ERR_R_MALLOC_FAILURE);

        goto err;

    }

    if (PKCS1_MGF1(DB, maskedDBLen, H, hLen, mgf1Hash) < 0)

        goto err;

    for (i = 0; i < maskedDBLen; i++)

        DB[i] ^= EM[i];

    if (MSBits)

        DB[0] &= 0xFF >> (8 - MSBits);

    for (i = 0; DB[i] == 0 && i < (maskedDBLen - 1); i++) ;

    if (DB[i++] != 0x1) {

        RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, RSA_R_SLEN_RECOVERY_FAILED);

        goto err;

    }

    if (sLen != RSA_PSS_SALTLEN_AUTO && (maskedDBLen - i) != sLen) {

        RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, RSA_R_SLEN_CHECK_FAILED);

        goto err;

    }

    if (!EVP_DigestInit_ex(ctx, Hash, NULL)

        || !EVP_DigestUpdate(ctx, zeroes, sizeof(zeroes))

        || !EVP_DigestUpdate(ctx, mHash, hLen))

        goto err;

    if (maskedDBLen - i) {

        if (!EVP_DigestUpdate(ctx, DB + i, maskedDBLen - i))

            goto err;

    }

    if (!EVP_DigestFinal_ex(ctx, H_, NULL))

        goto err;

    if (memcmp(H_, H, hLen)) {

        RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, RSA_R_BAD_SIGNATURE);

        ret = 0;

    } else {

        ret = 1;

    }

 err:

    OPENSSL_free(DB);

    EVP_MD_CTX_free(ctx);

    return ret;

}

int RSA_padding_add_PKCS1_PSS(RSA *rsa, unsigned char *EM,

                              const unsigned char *mHash,

                              const EVP_MD *Hash, int sLen)

{

    return RSA_padding_add_PKCS1_PSS_mgf1(rsa, EM, mHash, Hash, NULL, sLen);

}

int RSA_padding_add_PKCS1_PSS_mgf1(RSA *rsa, unsigned char *EM,

                                   const unsigned char *mHash,

                                   const EVP_MD *Hash, const EVP_MD *mgf1Hash,

                                   int sLen)

{

    int i;

    int ret = 0;

    int hLen, maskedDBLen, MSBits, emLen;

    unsigned char *H, *salt = NULL, *p;

    EVP_MD_CTX *ctx = NULL;

    if (mgf1Hash == NULL)

        mgf1Hash = Hash;

    hLen = EVP_MD_size(Hash);

    if (hLen < 0)

        goto err;

    /*-

     * Negative sLen has special meanings:

     *      -1      sLen == hLen

     *      -2      salt length is maximized

     *      -3      same as above (on signing)

     *      -N      reserved

     */

    if (sLen == RSA_PSS_SALTLEN_DIGEST) {

        sLen = hLen;

    } else if (sLen == RSA_PSS_SALTLEN_MAX_SIGN) {

        sLen = RSA_PSS_SALTLEN_MAX;

    } else if (sLen < RSA_PSS_SALTLEN_MAX) {

        RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_PSS_MGF1, RSA_R_SLEN_CHECK_FAILED);

        goto err;

    }

    MSBits = (BN_num_bits(rsa->n) - 1) & 0x7;

    emLen = RSA_size(rsa);

    if (MSBits == 0) {

        *EM++ = 0;

        emLen--;

    }

    if (emLen < hLen + 2) {

        RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_PSS_MGF1,

               RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);

        goto err;

    }

    if (sLen == RSA_PSS_SALTLEN_MAX) {

        sLen = emLen - hLen - 2;

    } else if (sLen > emLen - hLen - 2) {

        RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_PSS_MGF1,

               RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);

        goto err;

    }

    if (sLen > 0) {

        salt = OPENSSL_malloc(sLen);

        if (salt == NULL) {

            RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_PSS_MGF1,

                   ERR_R_MALLOC_FAILURE);

            goto err;

        }

        if (RAND_bytes(salt, sLen) <= 0)

            goto err;

    }

    maskedDBLen = emLen - hLen - 1;

    H = EM + maskedDBLen;

    ctx = EVP_MD_CTX_new();

    if (ctx == NULL)

        goto err;

    if (!EVP_DigestInit_ex(ctx, Hash, NULL)

        || !EVP_DigestUpdate(ctx, zeroes, sizeof(zeroes))

        || !EVP_DigestUpdate(ctx, mHash, hLen))

        goto err;

    if (sLen && !EVP_DigestUpdate(ctx, salt, sLen))

        goto err;

    if (!EVP_DigestFinal_ex(ctx, H, NULL))

        goto err;

    /* Generate dbMask in place then perform XOR on it */

    if (PKCS1_MGF1(EM, maskedDBLen, H, hLen, mgf1Hash))

        goto err;

    p = EM;

    /*

     * Initial PS XORs with all zeroes which is a NOP so just update pointer.

     * Note from a test above this value is guaranteed to be non-negative.

     */

    p += emLen - sLen - hLen - 2;

    *p++ ^= 0x1;

    if (sLen > 0) {

        for (i = 0; i < sLen; i++)

            *p++ ^= salt[i];

    }

    if (MSBits)

        EM[0] &= 0xFF >> (8 - MSBits);

    /* H is already in place so just set final 0xbc */

    EM[emLen - 1] = 0xbc;

    ret = 1;

 err:

    EVP_MD_CTX_free(ctx);

    OPENSSL_clear_free(salt, (size_t)sLen); /* salt != NULL implies sLen > 0 */

    return ret;

}

#if defined(_MSC_VER)

# pragma optimize("",on)

#endif