Re: error: redefinition of ‘struct rsa_meth_st’

[Matt Caswell]

You can look at the dummy async engine which wraps the standard RSA 
functions inside an engine (as well as various other crypto primitives). 
You can see it here:

https://github.com/openssl/openssl/blob/OpenSSL_1_1_1-stable/engines/e_dasync.c

Matt

On 12/04/2021 17:32, Shariful Alam wrote:
> Dr. Pauli,
> Goodmorning. Thank you for replying. I found the documentation a bit 
> difficult for me to understand. I was wondering if you can direct me to 
> a sample skeleton code for creating a custom RSA engine.
> 
> Regards,
> Shariful Alam
> 
> On Sun, Apr 11, 2021 at 6:00 PM Dr Paul Dale <pauli at openssl.org 
> <mailto:pauli at openssl.org>> wrote:
> 
>     You shouldn't be accessing the internal of a private structure. That
>     structure was made private for a reason and duplicating it in your
>     engine will break when we change the structure's contents.
> 
>     Your engine should be using the EVP_PKEY_meth_set_* function to do
>     what you want (for 1.1.1).  For 3.0, you should be writing a
>     provider instead.
> 
> 
>     Pauli
> 
>     On 12/4/21 5:04 am, Shariful Alam wrote:
>>     Hello,
>>     Hope you guys are doing well. I'm trying to develop an RSA engine.
>>     My engine was somewhat working until I try to integrate my engine
>>     with an apache httpd server. After installing the httpd from the
>>     source code, it turns out that, I can't compile my engine anymore.
>>     I get the following error while I try to compile (it was compiling
>>     before and I did not make any changes to my engine code).
>>
>>     ==============================
>>
>>     *$gcc -fPIC -c r_engine.c*
>>     *r_engine.c:29:8: error: redefinition of ‘struct rsa_meth_st’
>>      struct rsa_meth_st {
>>             ^
>>     In file included from /usr/include/openssl/crypto.h:131:0,
>>                      from r_engine.c:7:
>>     /usr/include/openssl/ossl_typ.h:147:16: note: originally defined here
>>      typedef struct rsa_meth_st RSA_METHOD;*
>>
>>     =============================
>>
>>     and my *struct rsa_meth_st *looks like the following,
>>
>>     ================================================================================
>>
>>     *struct rsa_meth_st {
>>
>>         const char *name;
>>         int (*rsa_pub_enc) (int flen, const unsigned char *from,
>>     unsigned char *to, RSA *rsa, int padding);
>>         int (*rsa_pub_dec) (int flen, const unsigned char *from,
>>     unsigned char *to, RSA *rsa, int padding);
>>         int (*rsa_priv_enc) (int flen, const unsigned char *from,
>>     unsigned char *to, RSA *rsa, int padding);
>>         int (*rsa_priv_dec) (int flen, const unsigned char *from,
>>     unsigned char *to, RSA *rsa, int padding);
>>
>>         int (*rsa_mod_exp) (BIGNUM *r0, const BIGNUM *I, RSA *rsa,
>>     BN_CTX *ctx);
>>
>>         int (*bn_mod_exp) (BIGNUM *r, const BIGNUM *a, const BIGNUM
>>     *p, const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx);
>>
>>         int (*init) (RSA *rsa);
>>
>>         int (*finish) (RSA *rsa);
>>
>>         int flags;
>>
>>         char *app_data;
>>
>>         int (*rsa_sign) (int type, const unsigned char *m, unsigned
>>     int m_length, unsigned char *sigret, unsigned int *siglen, const
>>     RSA *rsa);
>>
>>         int (*rsa_verify) (int dtype, const unsigned char *m, unsigned
>>     int m_length, const unsigned char *sigbuf, unsigned int siglen,
>>     const RSA *rsa);
>>
>>         int (*rsa_keygen) (RSA *rsa, int bits, BIGNUM *e, BN_GENCB *cb);
>>
>>     };
>>     *
>>
>>     =================================================================================
>>
>>     My sample skeleton code is here https://pastebin.com/uNXYknEA
>>     <https://pastebin.com/uNXYknEA>
>>
>>     Can anyone please tell me what I'm I doing wrong?
>>
>>     Regards,
>>     Shariful Alam
>