# EVP_KEYMGMT-RSA - EVP_PKEY RSA keytype and algorithm support - man(7ssl) - [phpMan]

[_EVP_PKEY-RSA_(7SSL)](https://www.chedong.com/phpMan.php/man/EVPPKEY-RSA/7SSL/markdown)                             OpenSSL                            [_EVP_PKEY-RSA_(7SSL)](https://www.chedong.com/phpMan.php/man/EVPPKEY-RSA/7SSL/markdown)

## NAME
       EVP_PKEY-RSA, EVP_KEYMGMT-RSA, RSA - EVP_PKEY RSA keytype and algorithm support

## DESCRIPTION
       The **RSA **keytype is implemented in OpenSSL's default and FIPS providers.  That implementation
       supports the basic RSA keys, containing the modulus _n_, the public exponent _e_, the private
       exponent _d_, and a collection of prime factors, exponents and coefficient for CRT
       calculations, of which the first few are known as _p_ and _q_, _dP_ and _dQ_, and _qInv_.

### Common RSA parameters
       In addition to the common parameters that all keytypes should support (see "Common
       parameters" in [**provider-keymgmt**(7)](https://www.chedong.com/phpMan.php/man/provider-keymgmt/7/markdown)), the **RSA **keytype implementation supports the following.

       "n" (**OSSL_PKEY_PARAM_RSA_N**) <unsigned integer>
           The RSA modulus "n" value.

       "e" (**OSSL_PKEY_PARAM_RSA_E**) <unsigned integer>
           The RSA public exponent "e" value.  This value must always be set when creating a raw key
           using  [**EVP_PKEY_fromdata**(3)](https://www.chedong.com/phpMan.php/man/EVPPKEYfromdata/3/markdown).   Note  that  when a decryption operation is performed, that
           this value is used for blinding purposes to prevent timing attacks.

       "d" (**OSSL_PKEY_PARAM_RSA_D**) <unsigned integer>
           The RSA private exponent "d" value.

       "rsa-factor1" (**OSSL_PKEY_PARAM_RSA_FACTOR1**) <unsigned integer>
       "rsa-factor2" (**OSSL_PKEY_PARAM_RSA_FACTOR2**) <unsigned integer>
       "rsa-factor3" (**OSSL_PKEY_PARAM_RSA_FACTOR3**) <unsigned integer>
       "rsa-factor4" (**OSSL_PKEY_PARAM_RSA_FACTOR4**) <unsigned integer>
       "rsa-factor5" (**OSSL_PKEY_PARAM_RSA_FACTOR5**) <unsigned integer>
       "rsa-factor6" (**OSSL_PKEY_PARAM_RSA_FACTOR6**) <unsigned integer>
       "rsa-factor7" (**OSSL_PKEY_PARAM_RSA_FACTOR7**) <unsigned integer>
       "rsa-factor8" (**OSSL_PKEY_PARAM_RSA_FACTOR8**) <unsigned integer>
       "rsa-factor9" (**OSSL_PKEY_PARAM_RSA_FACTOR9**) <unsigned integer>
       "rsa-factor10" (**OSSL_PKEY_PARAM_RSA_FACTOR10**) <unsigned integer>
           RSA prime factors. The factors are known as "p", "q" and "r_i" in RFC8017.  Up  to  eight
           additional "r_i" prime factors are supported.

       "rsa-exponent1" (**OSSL_PKEY_PARAM_RSA_EXPONENT1**) <unsigned integer>
       "rsa-exponent2" (**OSSL_PKEY_PARAM_RSA_EXPONENT2**) <unsigned integer>
       "rsa-exponent3" (**OSSL_PKEY_PARAM_RSA_EXPONENT3**) <unsigned integer>
       "rsa-exponent4" (**OSSL_PKEY_PARAM_RSA_EXPONENT4**) <unsigned integer>
       "rsa-exponent5" (**OSSL_PKEY_PARAM_RSA_EXPONENT5**) <unsigned integer>
       "rsa-exponent6" (**OSSL_PKEY_PARAM_RSA_EXPONENT6**) <unsigned integer>
       "rsa-exponent7" (**OSSL_PKEY_PARAM_RSA_EXPONENT7**) <unsigned integer>
       "rsa-exponent8" (**OSSL_PKEY_PARAM_RSA_EXPONENT8**) <unsigned integer>
       "rsa-exponent9" (**OSSL_PKEY_PARAM_RSA_EXPONENT9**) <unsigned integer>
       "rsa-exponent10" (**OSSL_PKEY_PARAM_RSA_EXPONENT10**) <unsigned integer>
           RSA  CRT (Chinese Remainder Theorem) exponents. The exponents are known as "dP", "dQ" and
           "d_i" in RFC8017.  Up to eight additional "d_i" exponents are supported.

       "rsa-coefficient1" (**OSSL_PKEY_PARAM_RSA_COEFFICIENT1**) <unsigned integer>
       "rsa-coefficient2" (**OSSL_PKEY_PARAM_RSA_COEFFICIENT2**) <unsigned integer>
       "rsa-coefficient3" (**OSSL_PKEY_PARAM_RSA_COEFFICIENT3**) <unsigned integer>
       "rsa-coefficient4" (**OSSL_PKEY_PARAM_RSA_COEFFICIENT4**) <unsigned integer>
       "rsa-coefficient5" (**OSSL_PKEY_PARAM_RSA_COEFFICIENT5**) <unsigned integer>
       "rsa-coefficient6" (**OSSL_PKEY_PARAM_RSA_COEFFICIENT6**) <unsigned integer>
       "rsa-coefficient7" (**OSSL_PKEY_PARAM_RSA_COEFFICIENT7**) <unsigned integer>
       "rsa-coefficient8" (**OSSL_PKEY_PARAM_RSA_COEFFICIENT8**) <unsigned integer>
       "rsa-coefficient9" (**OSSL_PKEY_PARAM_RSA_COEFFICIENT9**) <unsigned integer>
           RSA CRT (Chinese Remainder Theorem) coefficients. The coefficients are  known  as  "qInv"
           and "t_i".  Up to eight additional "t_i" exponents are supported.

### RSA key generation parameters
       When generating RSA keys, the following key generation parameters may be used.

       "bits" (**OSSL_PKEY_PARAM_RSA_BITS**) <unsigned integer>
           The value should be the cryptographic length for the **RSA **cryptosystem, in bits.

       "primes" (**OSSL_PKEY_PARAM_RSA_PRIMES**) <unsigned integer>
           The  value  should  be the number of primes for the generated **RSA **key.  The default is 2.
           It isn't permitted to specify a larger number  of  primes  than  10.   Additionally,  the
           number  of  primes  is  limited  by  the length of the key being generated so the maximum
           number could be less.  Some providers may only support a value of 2.

       "e" (**OSSL_PKEY_PARAM_RSA_E**) <unsigned integer>
           The RSA "e" value. The value may be any odd number greater than or equal  to  65537.  The
           default  value  is  65537.   For legacy reasons a value of 3 is currently accepted but is
           deprecated.

### RSA key generation parameters for FIPS module testing
       When generating RSA keys, the following additional key generation parameters may be used  for
       algorithm  testing  purposes  only.  Do  not  use these to generate RSA keys for a production
       environment.

       "xp" (**OSSL_PKEY_PARAM_RSA_TEST_XP**) <unsigned integer>
       "xq" (**OSSL_PKEY_PARAM_RSA_TEST_XQ**) <unsigned integer>
           These 2 fields are normally randomly generated and are used to generate "p" and "q".

       "xp1" (**OSSL_PKEY_PARAM_RSA_TEST_XP1**) <unsigned integer>
       "xp2" (**OSSL_PKEY_PARAM_RSA_TEST_XP2**) <unsigned integer>
       "xq1" (**OSSL_PKEY_PARAM_RSA_TEST_XQ1**) <unsigned integer>
       "xq2" (**OSSL_PKEY_PARAM_RSA_TEST_XQ2**) <unsigned integer>
           These 4 fields are normally randomly generated. The prime factors "p1",  "p2",  "q1"  and
           "q2" are determined from these values.

### RSA key parameters for FIPS module testing
       The  following  intermediate values can be retrieved only if the values specified in "RSA key
       generation parameters for FIPS module testing" are set.  These should not be  accessed  in  a
       production environment.

       "p1" (**OSSL_PKEY_PARAM_RSA_TEST_P1**) <unsigned integer>
       "p2" (**OSSL_PKEY_PARAM_RSA_TEST_P2**) <unsigned integer>
       "q1" (**OSSL_PKEY_PARAM_RSA_TEST_Q1**) <unsigned integer>
       "q2" (**OSSL_PKEY_PARAM_RSA_TEST_Q2**) <unsigned integer>
           The auxiliary probable primes.

### RSA key validation
       For  RSA  keys,  [**EVP_PKEY_param_check**(3)](https://www.chedong.com/phpMan.php/man/EVPPKEYparamcheck/3/markdown)  and  [**EVP_PKEY_param_check_quick**(3)](https://www.chedong.com/phpMan.php/man/EVPPKEYparamcheckquick/3/markdown)  both  return  1
       unconditionally.

       For RSA keys, [**EVP_PKEY_public_check**(3)](https://www.chedong.com/phpMan.php/man/EVPPKEYpubliccheck/3/markdown) conforms to the SP800-56Br1 _public_ _key_ _check_ when  the
       OpenSSL  FIPS  provider  is  used.  The  OpenSSL  default provider performs similar tests but
       relaxes the keysize restrictions for backwards compatibility.

       For RSA keys, [**EVP_PKEY_public_check_quick**(3)](https://www.chedong.com/phpMan.php/man/EVPPKEYpubliccheckquick/3/markdown) is the same as [**EVP_PKEY_public_check**(3)](https://www.chedong.com/phpMan.php/man/EVPPKEYpubliccheck/3/markdown).

       For RSA keys, [**EVP_PKEY_private_check**(3)](https://www.chedong.com/phpMan.php/man/EVPPKEYprivatecheck/3/markdown) conforms to the SP800-56Br1 _private_ _key_ _test_.

       For RSA keys, [**EVP_PKEY_pairwise_check**(3)](https://www.chedong.com/phpMan.php/man/EVPPKEYpairwisecheck/3/markdown) conforms to the SP800-56Br1 _KeyPair_ _Validation_ _check_
       for the OpenSSL FIPS provider. The OpenSSL default provider allows testing of the validity of
       multi-primes.

## CONFORMING TO
       FIPS186-4
           Section B.3.6  Generation of Probable Primes with Conditions Based on Auxiliary  Probable
           Primes

       RFC 8017, excluding RSA-PSS and RSA-OAEP

## EXAMPLES
       An **EVP_PKEY **context can be obtained by calling:

           EVP_PKEY_CTX *pctx =
               EVP_PKEY_CTX_new_from_name(NULL, "RSA", NULL);

       An **RSA **key can be generated simply like this:

           pkey = [EVP_RSA_gen(4096)](https://www.chedong.com/phpMan.php/man/EVPRSAgen/4096/markdown);

       or like this:

           EVP_PKEY *pkey = NULL;
           EVP_PKEY_CTX *pctx =
               EVP_PKEY_CTX_new_from_name(NULL, "RSA", NULL);

           EVP_PKEY_keygen_init(pctx);
           EVP_PKEY_generate(pctx, &pkey);
           EVP_PKEY_CTX_free(pctx);

       An **RSA **key can be generated with key generation parameters:

           unsigned int primes = 3;
           unsigned int bits = 4096;
           OSSL_PARAM params[3];
           EVP_PKEY *pkey = NULL;
           EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_from_name(NULL, "RSA", NULL);

           EVP_PKEY_keygen_init(pctx);

           params[0] = OSSL_PARAM_construct_uint("bits", &bits);
           params[1] = OSSL_PARAM_construct_uint("primes", &primes);
           params[2] = OSSL_PARAM_construct_end();
           EVP_PKEY_CTX_set_params(pctx, params);

           EVP_PKEY_generate(pctx, &pkey);
           EVP_PKEY_print_private(bio_out, pkey, 0, NULL);
           EVP_PKEY_CTX_free(pctx);

## SEE ALSO
       [**EVP_RSA_gen**(3)](https://www.chedong.com/phpMan.php/man/EVPRSAgen/3/markdown), [**EVP_KEYMGMT**(3)](https://www.chedong.com/phpMan.php/man/EVPKEYMGMT/3/markdown), [**EVP_PKEY**(3)](https://www.chedong.com/phpMan.php/man/EVPPKEY/3/markdown), [**provider-keymgmt**(7)](https://www.chedong.com/phpMan.php/man/provider-keymgmt/7/markdown)

## COPYRIGHT
       Copyright 2020-2023 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>>.

3.0.13                                       2026-07-29                           [_EVP_PKEY-RSA_(7SSL)](https://www.chedong.com/phpMan.php/man/EVPPKEY-RSA/7SSL/markdown)