Commit 3bded9cd authored by Andy Polyakov's avatar Andy Polyakov
Browse files

rsa/rsa_gen.c: harmonize keygen's ability with RSA_security_bits. 



Reviewed-by: default avatarRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4791)
parent 0122add6

crypto/rsa/rsa_chk.c

+7 −4
Original line number Diff line number Diff line
@@ -30,11 +30,14 @@ int RSA_check_key_ex(const RSA *key, BN_GENCB *cb) 
    }



    /* multi-prime? */

    if (key->version == RSA_ASN1_VERSION_MULTI

        && (ex_primes = sk_RSA_PRIME_INFO_num(key->prime_infos)) <= 0) {

    if (key->version == RSA_ASN1_VERSION_MULTI) {

        ex_primes = sk_RSA_PRIME_INFO_num(key->prime_infos);

        if (ex_primes <= 0

                || (ex_primes + 2) > rsa_multip_cap(BN_num_bits(key->n))) {

            RSAerr(RSA_F_RSA_CHECK_KEY_EX, RSA_R_INVALID_MULTI_PRIME_KEY);

            return 0;

        }

    }



    i = BN_new();

    j = BN_new();

crypto/rsa/rsa_gen.c

+2 −26
Original line number Diff line number Diff line
@@ -72,16 +72,6 @@ static int rsa_builtin_keygen(RSA *rsa, int bits, int primes, BIGNUM *e_value, 
    BN_CTX *ctx = NULL;

    BN_ULONG bitst = 0;



    /*

     * From Github pull request #4241:

     *

     * We are in disagreement on how to handle security trade-off, in other

     * words:

     *

     * mechanical-check-for-maximum-of-16-prime-factors vs.

     * limiting-number-depending-on-length-less-factors-for-shorter-keys.

     */



    /*

     * When generating ridiculously small keys, we can get stuck

     * continually regenerating the same prime values.
@@ -92,8 +82,8 @@ static int rsa_builtin_keygen(RSA *rsa, int bits, int primes, BIGNUM *e_value, 
        goto err;

    }



    if (primes < RSA_DEFAULT_PRIME_NUM

        || primes > RSA_MAX_PRIME_NUM || bits <= primes) {

    if (primes < RSA_DEFAULT_PRIME_NUM || primes > rsa_multip_cap(bits)) {

        ok = 0;             /* we set our own err */

        RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, RSA_R_KEY_PRIME_NUM_INVALID);

        goto err;

    }
@@ -112,20 +102,6 @@ static int rsa_builtin_keygen(RSA *rsa, int bits, int primes, BIGNUM *e_value, 
    quo = bits / primes;

    rmd = bits % primes;



    if (primes > RSA_DEFAULT_PRIME_NUM && quo < RSA_MIN_PRIME_SIZE) {

        /*

         * this means primes are too many for the key bits.

         *

         * This only affects multi-prime keys. For normal RSA,

         * it's limited above (bits >= 16, hence each prime >= 8).

         *

         * This is done in this way because the original normal

         * RSA's behavior should not alter at least in OpenSSL 1.1.1.

         */

        RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, RSA_R_KEY_PRIME_NUM_INVALID);

        goto err;

    }



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

        bitsr[i] = (i < rmd) ? quo + 1 : quo;

doc/man3/RSA_generate_key.pod

+8 −2
Original line number Diff line number Diff line
@@ -35,6 +35,13 @@ modulus will be B<primes>, and the public exponent will be B<e>. Key sizes 
with B<num> E<lt> 1024 should be considered insecure. The exponent is an odd

number, typically 3, 17 or 65537.



In order to maintain adequate security level, the maximum number of permitted

B<primes> depends on modulus bit length:



   <1024 | >=1024 | >=4096 | >=8192

   ------+--------+--------+-------

     2   |   3    |   4    |   5



A callback function may be used to provide feedback about the

progress of the key generation. If B<cb> is not B<NULL>, it

will be called as follows using the BN_GENCB_call() function
@@ -81,8 +88,7 @@ B<BN_GENCB_call(cb, 2, x)> is used with two different meanings. 


=head1 SEE ALSO



L<ERR_get_error(3)>, L<RAND_bytes(3)>,

L<RSA_generate_key_ex(3)>, L<BN_generate_prime(3)>

L<ERR_get_error(3)>, L<RAND_bytes(3)>, L<BN_generate_prime(3)>



=head1 HISTORY

test/recipes/15-test_mp_rsa.t

+6 −21
Original line number Diff line number Diff line
@@ -17,7 +17,7 @@ use OpenSSL::Test::Utils; 


setup("test_mp_rsa");



plan tests => 61;

plan tests => 31;



ok(run(test(["rsa_mp_test"])), "running rsa multi prime test");
@@ -29,30 +29,15 @@ my @test_param = ( 
        primes => '3',

        bits => '2048',

    },

    # 4 primes, 2048-bit

    # 4 primes, 4096-bit

    {

        primes => '4',

        bits => '2048',

    },

    # 8 primes, 2048-bit

    {

        primes => '8',

        bits => '2048',

    },

    # 15 primes, 2048-bit

    {

        primes => '15',

        bits => '2048',

    },

    # 8 primes, 15360-bit (3 & 4 primes for 15360 bit is too long to gen a key)

    {

        primes => '8',

        bits => '15360',

        bits => '4096',

    },

    # 15 primes, 15360-bit

    # 5 primes, 8192-bit

    {

        primes => '15',

        bits => '15360',

        primes => '5',

        bits => '8192',

    },

);

test/rsa_mp_test.c

+124 −264

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