RSA_METH_NEW(3ossl)

📦
version 15.1 · 3 versions
, in freebsd 15.1

💖 NAME 💖

okay so bestie, this is RSA_METH_NEW(3ossl) from OpenSSL — the page for the whole RSA method-building squad 💅. These are the routines to build up RSA methods, and here’s the full friend group, no one left out:

  • app data besties: RSA_meth_get0_app_data, RSA_meth_set0_app_data
  • lifecycle crew: RSA_meth_new, RSA_meth_free, RSA_meth_dup
  • name tag squad: RSA_meth_get0_name, RSA_meth_set1_name
  • flags girlies: RSA_meth_get_flags, RSA_meth_set_flags
  • public encrypt duo: RSA_meth_get_pub_enc, RSA_meth_set_pub_enc
  • public decrypt duo: RSA_meth_get_pub_dec, RSA_meth_set_pub_dec
  • private encrypt duo: RSA_meth_get_priv_enc, RSA_meth_set_priv_enc
  • private decrypt duo: RSA_meth_get_priv_dec, RSA_meth_set_priv_dec
  • mod exp duo: RSA_meth_get_mod_exp, RSA_meth_set_mod_exp
  • bn mod exp duo: RSA_meth_get_bn_mod_exp, RSA_meth_set_bn_mod_exp
  • init duo: RSA_meth_get_init, RSA_meth_set_init
  • finish duo: RSA_meth_get_finish, RSA_meth_set_finish
  • sign duo: RSA_meth_get_sign, RSA_meth_set_sign
  • verify duo: RSA_meth_get_verify, RSA_meth_set_verify
  • keygen duo: RSA_meth_get_keygen, RSA_meth_set_keygen
  • multi-prime keygen duo: RSA_meth_get_multi_prime_keygen, RSA_meth_set_multi_prime_keygen

✨ SYNOPSIS ✨

#include <openssl/rsa.h>

heads up bestie 🚨 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):

RSA_METHOD *RSA_meth_new(const char *name, int flags);
void RSA_meth_free(RSA_METHOD *meth);

RSA_METHOD *RSA_meth_dup(const RSA_METHOD *meth);

const char *RSA_meth_get0_name(const RSA_METHOD *meth);
int RSA_meth_set1_name(RSA_METHOD *meth, const char *name);

int RSA_meth_get_flags(const RSA_METHOD *meth);
int RSA_meth_set_flags(RSA_METHOD *meth, int flags);

void *RSA_meth_get0_app_data(const RSA_METHOD *meth);
int RSA_meth_set0_app_data(RSA_METHOD *meth, void *app_data);

int (*RSA_meth_get_pub_enc(const RSA_METHOD *meth))(int flen, const unsigned char *from,
                                                    unsigned char *to, RSA *rsa, int padding);
int RSA_meth_set_pub_enc(RSA_METHOD *rsa,
                         int (*pub_enc)(int flen, const unsigned char *from,
                                        unsigned char *to, RSA *rsa,
                                        int padding));

int (*RSA_meth_get_pub_dec(const RSA_METHOD *meth))
    (int flen, const unsigned char *from,
     unsigned char *to, RSA *rsa, int padding);
int RSA_meth_set_pub_dec(RSA_METHOD *rsa,
                         int (*pub_dec)(int flen, const unsigned char *from,
                                        unsigned char *to, RSA *rsa,
                                        int padding));

int (*RSA_meth_get_priv_enc(const RSA_METHOD *meth))(int flen, const unsigned char *from,
                                                     unsigned char *to, RSA *rsa,
                                                     int padding);
int RSA_meth_set_priv_enc(RSA_METHOD *rsa,
                          int (*priv_enc)(int flen, const unsigned char *from,
                                          unsigned char *to, RSA *rsa, int padding));

int (*RSA_meth_get_priv_dec(const RSA_METHOD *meth))(int flen, const unsigned char *from,
                                                     unsigned char *to, RSA *rsa,
                                                     int padding);
int RSA_meth_set_priv_dec(RSA_METHOD *rsa,
                          int (*priv_dec)(int flen, const unsigned char *from,
                                          unsigned char *to, RSA *rsa, int padding));

/* Can be null */
int (*RSA_meth_get_mod_exp(const RSA_METHOD *meth))(BIGNUM *r0, const BIGNUM *i,
                                                    RSA *rsa, BN_CTX *ctx);
int RSA_meth_set_mod_exp(RSA_METHOD *rsa,
                         int (*mod_exp)(BIGNUM *r0, const BIGNUM *i, RSA *rsa,
                                        BN_CTX *ctx));

/* Can be null */
int (*RSA_meth_get_bn_mod_exp(const RSA_METHOD *meth))(BIGNUM *r, const BIGNUM *a,
                                                       const BIGNUM *p, const BIGNUM *m,
                                                       BN_CTX *ctx, BN_MONT_CTX *m_ctx);
int RSA_meth_set_bn_mod_exp(RSA_METHOD *rsa,
                            int (*bn_mod_exp)(BIGNUM *r, const BIGNUM *a,
                                              const BIGNUM *p, const BIGNUM *m,
                                              BN_CTX *ctx, BN_MONT_CTX *m_ctx));

/* called at new */
int (*RSA_meth_get_init(const RSA_METHOD *meth) (RSA *rsa);
int RSA_meth_set_init(RSA_METHOD *rsa, int (*init (RSA *rsa));

/* called at free */
int (*RSA_meth_get_finish(const RSA_METHOD *meth))(RSA *rsa);
int RSA_meth_set_finish(RSA_METHOD *rsa, int (*finish)(RSA *rsa));

int (*RSA_meth_get_sign(const RSA_METHOD *meth))(int type, const unsigned char *m,
                                                 unsigned int m_length,
                                                 unsigned char *sigret,
                                                 unsigned int *siglen, const RSA *rsa);
int RSA_meth_set_sign(RSA_METHOD *rsa,
                      int (*sign)(int type, const unsigned char *m,
                                  unsigned int m_length, unsigned char *sigret,
                                  unsigned int *siglen, const RSA *rsa));

int (*RSA_meth_get_verify(const RSA_METHOD *meth))(int dtype, const unsigned char *m,
                                                   unsigned int m_length,
                                                   const unsigned char *sigbuf,
                                                   unsigned int siglen, const RSA *rsa);
int RSA_meth_set_verify(RSA_METHOD *rsa,
                        int (*verify)(int dtype, const unsigned char *m,
                                      unsigned int m_length,
                                      const unsigned char *sigbuf,
                                      unsigned int siglen, const RSA *rsa));

int (*RSA_meth_get_keygen(const RSA_METHOD *meth))(RSA *rsa, int bits, BIGNUM *e,
                                                   BN_GENCB *cb);
int RSA_meth_set_keygen(RSA_METHOD *rsa,
                        int (*keygen)(RSA *rsa, int bits, BIGNUM *e,
                                      BN_GENCB *cb));

int (*RSA_meth_get_multi_prime_keygen(const RSA_METHOD *meth))(RSA *rsa, int bits,
                                                               int primes, BIGNUM *e,
                                                               BN_GENCB *cb);

int RSA_meth_set_multi_prime_keygen(RSA_METHOD *meth,
                                    int (*keygen) (RSA *rsa, int bits,
                                                   int primes, BIGNUM *e,
                                                   BN_GENCB *cb));

💅 DESCRIPTION 💅

⚠️ Okay bestie, listen up first: all of the functions described on this page are deprecated. Not "kinda old," not "use with caution" — deprecated. Applications should instead use the OSSL_PROVIDER APIs. If you're starting something new here, babes, you're building on a haunted foundation. 🏚️✨

The RSA_METHOD type is a structure used for the provision of custom RSA implementations. Think of it as the backstage pass 🎟️ — it hands OpenSSL a whole set of functions that it then uses to pull off the various RSA capabilities. It's giving "build-your-own-RSA-engine" energy, and honestly? Iconic for its time. 🔥

🌸 The constructor / destructor crew 🌸

  • RSA_meth_new() — creates a fresh new RSA_METHOD structure. You feed it a unique name and a set of flags. The name should be a NULL terminated string, which will be duplicated and stored inside the RSA_METHOD object — so heads up: it is the caller's responsibility to free the original string. 💀 The flags get used during the construction of a new RSA object based on this RSA_METHOD, and any new RSA object will have those flags set by default. Set it once, carried forever, no cap.
  • RSA_meth_dup() — makes a duplicate copy of the RSA_METHOD object you pass as a parameter. Super useful for creating a new RSA_METHOD based on an existing one, but with some differences. Copy-paste but make it fashion. 🎀
  • RSA_meth_free() — destroys an RSA_METHOD structure and frees up any memory associated with it. And if the argument is NULL? Nothing is done. Sweet, no drama, no crash. 🫶

🦋 Name & flags 🦋

  • RSA_meth_get0_name() — returns a pointer to the name of this RSA_METHOD. Heads up though: this is a pointer to the internal name string, so should not be freed by the caller. Don't touch, don't free, just look. 👀
  • RSA_meth_set1_name() — sets the name of the RSA_METHOD to name. The string is duplicated and the copy is stored in the RSA_METHOD structure, so the caller remains responsible for freeing the memory associated with name.
  • RSA_meth_get_flags() — returns the current value of the flags associated with this RSA_METHOD. ✨
  • RSA_meth_set_flags() — provides the ability to set those flags.

🧚 Your personal little data pouch 🧚

  • RSA_meth_get0_app_data() and RSA_meth_set0_app_data() — provide the ability to associate implementation specific data with the RSA_METHOD. Cute! But — it is the application's responsibility to free this data before the RSA_METHOD is freed via a call to RSA_meth_free(). Clean up after yourself, bestie. 🙈

✨ The function-pointer glow-ups ✨

🖊️ Signing

  • RSA_meth_get_sign() and RSA_meth_set_sign() — get and set the function used for creating an RSA signature respectively. This function will be called in response to the application calling RSA_sign(). The parameters for the function have the same meaning as for RSA_sign().

✅ Verifying

  • RSA_meth_get_verify() and RSA_meth_set_verify() — get and set the function used for verifying an RSA signature respectively. This function will be called in response to the application calling RSA_verify(). The parameters for the function have the same meaning as for RSA_verify().

🧮 CRT math hours

  • RSA_meth_get_mod_exp() and RSA_meth_set_mod_exp() — get and set the function used for CRT computations.
  • RSA_meth_get_bn_mod_exp() and RSA_meth_set_bn_mod_exp() — get and set the function used for CRT computations, specifically this value right here:
 r = a ^ p mod m

Both the mod_exp() and bn_mod_exp() functions are called by the default OpenSSL method during encryption, decryption, signing and verification. So yeah, they're kind of a big deal in the pipeline. 💅

🌱 Lifecycle: birth & death

  • RSA_meth_get_init() and RSA_meth_set_init() — get and set the function used for creating a new RSA instance respectively. This function will be called in response to the application calling RSA_new() (if the current default RSA_METHOD is this one) or RSA_new_method(). Both RSA_new() and RSA_new_method() will allocate the memory for the new RSA object, and a pointer to this newly allocated structure will be passed as a parameter to the function. This function may be NULL.
  • RSA_meth_get_finish() and RSA_meth_set_finish() — get and set the function used for destroying an instance of an RSA object respectively. This function will be called in response to the application calling RSA_free(). A pointer to the RSA to be destroyed is passed as a parameter. The destroy function should be used for RSA implementation specific clean up — but the memory for the RSA itself should not be freed by this function. 🚨 Read that twice. This function may be NULL.

🔑 Key generation

  • RSA_meth_get_keygen() and RSA_meth_set_keygen() — get and set the function used for generating a new RSA key pair respectively. This function will be called in response to the application calling RSA_generate_key_ex(). The parameter for the function has the same meaning as for RSA_generate_key_ex().
  • RSA_meth_get_multi_prime_keygen() and RSA_meth_set_multi_prime_keygen() — get and set the function used for generating a new multi-prime RSA key pair respectively. This function will be called in response to the application calling RSA_generate_multi_prime_key(). The parameter for the function has the same meaning as for RSA_generate_multi_prime_key(). More primes, more fun. 🔥

🔐 Encrypt / decrypt squad

RSA_meth_get_pub_enc(), RSA_meth_set_pub_enc(), RSA_meth_get_pub_dec(), RSA_meth_set_pub_dec(), RSA_meth_get_priv_enc(), RSA_meth_set_priv_enc(), RSA_meth_get_priv_dec(), RSA_meth_set_priv_dec() — get and set the functions used for public and private key encryption and decryption. These functions will be called in response to the application calling RSA_public_encrypt(), RSA_private_decrypt(), RSA_private_encrypt() and RSA_public_decrypt() and take the same parameters as those. Four directions, all the vibes. 🌈

🎀 RETURN VALUES 🎀

  • RSA_meth_new() and RSA_meth_dup() return the newly allocated RSA_METHOD object or NULL on failure. 😭
  • RSA_meth_get0_name() and RSA_meth_get_flags() return the name and flags associated with the RSA_METHOD respectively.
  • All other RSA_meth_get_*() functions return the appropriate function pointer that has been set in the RSA_METHOD, or NULL if no such pointer has yet been set.
  • RSA_meth_set1_name and all RSA_meth_set_*() functions return 1 on success or 0 on failure. Slay = 1, oops = 0. 💅

🦋 SEE ALSO 🦋

RSA_new(3), RSA_generate_key_ex(3), RSA_sign(3), RSA_set_method(3), RSA_size(3), RSA_get0_key(3), RSA_generate_multi_prime_key(3)

Go read those too, iykyk. 📚

⭐ HISTORY ⭐

  • All of these functions were deprecated in OpenSSL 3.0. Yeah. All of them. 🫠
  • RSA_meth_get_multi_prime_keygen() and RSA_meth_set_multi_prime_keygen() were added in OpenSSL 1.1.1.
  • Other functions described here were added in OpenSSL 1.1.0.

Copyright 2016-2024 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>.

And that's the whole page, bestie! 🫶 This lil masterpiece is from version 3.5.6, dated 2026-04-07, and it lives at RSA_METH_NEW(3ossl) — go forth and maybe use the OSSL_PROVIDER APIs instead, mwah 💋✨

📦 where this page comes from