/*

 * Copyright 2020-2024 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the Apache License 2.0 (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 "internal/deprecated.h"

#include <openssl/rsa.h>

#include <openssl/dsa.h>

#include <openssl/dh.h>

#include <openssl/ec.h>

#include <openssl/evp.h>

#include <openssl/err.h>

#include <openssl/proverr.h>

#include <openssl/core_names.h>

#include <openssl/obj_mac.h>

#include "prov/securitycheck.h"

#define OSSL_FIPS_MIN_SECURITY_STRENGTH_BITS 112

int ossl_rsa_key_op_get_protect(const RSA *rsa, int operation, int *outprotect)

{

    int protect = 0;

    switch (operation) {

    case EVP_PKEY_OP_SIGN:

    case EVP_PKEY_OP_SIGNMSG:

        protect = 1;

        /* fallthrough */

    case EVP_PKEY_OP_VERIFY:

    case EVP_PKEY_OP_VERIFYMSG:

        break;

    case EVP_PKEY_OP_ENCAPSULATE:

    case EVP_PKEY_OP_ENCRYPT:

        protect = 1;

        /* fallthrough */

    case EVP_PKEY_OP_VERIFYRECOVER:

    case EVP_PKEY_OP_DECAPSULATE:

    case EVP_PKEY_OP_DECRYPT:

        if (RSA_test_flags(rsa,

                RSA_FLAG_TYPE_MASK)

            == RSA_FLAG_TYPE_RSASSAPSS) {

            ERR_raise_data(ERR_LIB_PROV,

                PROV_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE,

                "operation: %d", operation);

            return 0;

        }

        break;

    default:

        ERR_raise_data(ERR_LIB_PROV, ERR_R_INTERNAL_ERROR,

            "invalid operation: %d", operation);

        return 0;

    }

    *outprotect = protect;

    return 1;

}

/*

 * FIPS requires a minimum security strength of 112 bits (for encryption or

 * signing), and for legacy purposes 80 bits (for decryption or verifying).

 * Set protect = 1 for encryption or signing operations, or 0 otherwise. See

 * https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-131Ar2.pdf.

 */

int ossl_rsa_check_key_size(const RSA *rsa, int protect)

{

    int sz = RSA_bits(rsa);

    if (protect ? (sz < 2048) : (sz < 1024))

        return 0;

    return 1;

}

/*

 * FIPS requires a minimum security strength of 112 bits for key-derivation key.

 * https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-131Ar2.pdf.

 */

int ossl_kdf_check_key_size(size_t keylen)

{

    return (keylen * 8) >= OSSL_FIPS_MIN_SECURITY_STRENGTH_BITS;

}

int ossl_mac_check_key_size(size_t keylen)

{

    return ossl_kdf_check_key_size(keylen);

}

#ifndef OPENSSL_NO_EC

int ossl_ec_check_curve_allowed(const EC_GROUP *group)

{

    const char *curve_name;

    int nid = EC_GROUP_get_curve_name(group);

    /* Explicit curves are not FIPS approved */

    if (nid == NID_undef)

        return 0;

    /* Only NIST curves are FIPS approved */

    curve_name = EC_curve_nid2nist(nid);

    if (curve_name == NULL)

        return 0;

    return 1;

}

/*

 * In FIPS mode:

 * protect should be 1 for any operations that need 112 bits of security

 * strength (such as signing, and key exchange), or 0 for operations that allow

 * a lower security strength (such as verify).

 *

 * For ECDH key agreement refer to SP800-56A

 * https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-56Ar3.pdf

 * "Appendix D"

 *

 * For ECDSA signatures refer to

 * https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-131Ar2.pdf

 * "Table 2"

 */

int ossl_ec_check_security_strength(const EC_GROUP *group, int protect)

{

    /*

     * For EC the security strength is the (order_bits / 2)

     * e.g. P-224 is 112 bits.

     */

    int strength = EC_GROUP_order_bits(group) / 2;

    /* The min security strength allowed for legacy verification is 80 bits */

    if (strength < 80)

        return 0;

    /*

     * For signing or key agreement only allow curves with at least 112 bits of

     * security strength

     */

    if (protect && strength < OSSL_FIPS_MIN_SECURITY_STRENGTH_BITS)

        return 0;

    return 1;

}

#endif /* OPENSSL_NO_EC */

#ifndef OPENSSL_NO_DSA

/*

 * Check for valid key sizes if fips mode. Refer to

 * https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-131Ar2.pdf

 * "Table 2"

 */

int ossl_dsa_check_key(const DSA *dsa, int sign)

{

    size_t L, N;

    const BIGNUM *p, *q;

    if (dsa == NULL)

        return 0;

    p = DSA_get0_p(dsa);

    q = DSA_get0_q(dsa);

    if (p == NULL || q == NULL)

        return 0;

    L = BN_num_bits(p);

    N = BN_num_bits(q);

    /*

     * For Digital signature verification DSA keys with < 112 bits of

     * security strength, are still allowed for legacy

     * use. The bounds given in SP 800-131Ar2 - Table 2 are

     * (512 <= L < 2048 or 160 <= N < 224).

     *

     * We are a little stricter and insist that both minimums are met.

     * For example a L = 256, N = 160 key *would* be allowed by SP 800-131Ar2

     * but we don't.

     */

    if (!sign) {

        if (L < 512 || N < 160)

            return 0;

        if (L < 2048 || N < 224)

            return 1;

    }

    /* Valid sizes for both sign and verify */

    if (L == 2048 && (N == 224 || N == 256)) /* 112 bits */

        return 1;

    return (L == 3072 && N == 256); /* 128 bits */

}

#endif /* OPENSSL_NO_DSA */

#ifndef OPENSSL_NO_DH

/*

 * For DH key agreement refer to SP800-56A

 * https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-56Ar3.pdf

 * "Section 5.5.1.1FFC Domain Parameter Selection/Generation" and

 * "Appendix D" FFC Safe-prime Groups

 */

int ossl_dh_check_key(const DH *dh)

{

    size_t L, N;

    const BIGNUM *p, *q;

    if (dh == NULL)

        return 0;

    p = DH_get0_p(dh);

    q = DH_get0_q(dh);

    if (p == NULL || q == NULL)

        return 0;

    L = BN_num_bits(p);

    if (L < 2048)

        return 0;

    /* If it is a safe prime group then it is ok */

    if (DH_get_nid(dh))

        return 1;

    /* If not then it must be FFC, which only allows certain sizes. */

    N = BN_num_bits(q);

    return (L == 2048 && (N == 224 || N == 256));

}

#endif /* OPENSSL_NO_DH */