Provided by: openssl_3.0.5-2ubuntu1_amd64 
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.
RSA key validation
For RSA keys, EVP_PKEY_param_check(3) and EVP_PKEY_param_check_quick(3) both return 1
unconditionally.
For RSA keys, EVP_PKEY_public_check(3) conforms to the SP800-56Br1 public key check when
the OpenSSL FIPS provider is used. The OpenSSL default provider performs similiar tests
but relaxes the keysize restrictions for backwards compatibility.
For RSA keys, EVP_PKEY_public_check_quick(3) is the same as EVP_PKEY_public_check(3).
For RSA keys, EVP_PKEY_private_check(3) conforms to the SP800-56Br1 private key test.
For RSA keys, EVP_PKEY_pairwise_check(3) 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);
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 2020-2022 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>.