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)), the RSA keytype implementation supports the
       following.

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

       "e" (OSSL_PKEY_PARAM_RSA_E) <unsigned integer>
           The RSA "e" value.

       "d" (OSSL_PKEY_PARAM_RSA_D) <unsigned integer>
           The RSA "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.

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);

       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), EVP_KEYMGMT(3), EVP_PKEY(3), provider-keymgmt(7)

COPYRIGHT

       Copyright 2020-2021 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>.