RSA_size, RSA_bits, RSA_security_bits - get RSA modulus size or security bits

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       Licensed under the Apache License 2.0 (the "License").  You may not use this file except in compliance
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       <https://www.openssl.org/source/license.html>.

3.5.0                                              2025-06-04                                     RSA_SIZE(3SSL)

RSA_bits() returns the number of significant bits.

       rsa and rsa->n must not be NULL.

       The remaining functions described on this page are deprecated.  Applications should instead use
       EVP_PKEY_get_size(3), EVP_PKEY_get_bits(3) and EVP_PKEY_get_security_bits(3).

       RSA_size() returns the RSA modulus size in bytes. It can be used to determine how much memory must be
       allocated for an RSA encrypted value.

       RSA_security_bits() returns the number of security bits of the given rsa key. See BN_security_bits(3).

       The RSA_size() and RSA_security_bits() functions were deprecated in OpenSSL 3.0.

       The RSA_bits() function was added in OpenSSL 1.1.0.

       RSA_size, RSA_bits, RSA_security_bits - get RSA modulus size or security bits

RSA_bits() returns the number of bits in the key.

       RSA_size() returns the size of modulus in bytes.

       RSA_security_bits() returns the number of security bits.

BN_num_bits(3)

        #include <openssl/rsa.h>

        int RSA_bits(const RSA *rsa);

       The following functions have been deprecated since OpenSSL 3.0, and can be hidden entirely by defining
       OPENSSL_API_COMPAT with a suitable version value, see openssl_user_macros(7):

        int RSA_size(const RSA *rsa);

        int RSA_security_bits(const RSA *rsa);