Re: Why custom RSA engine is not calling default RSA method?

[Dmitry Belyavsky <beldmit@xxxxxxxxx>]

Dear Shariful,

Yes. You have to provide all the RSA_METHO functions your app is going to use.

On Tue, Sep 28, 2021 at 5:46 PM Shariful Alam <dipto181@xxxxxxxxx> wrote:

Dear Dmitry,

Thank you for your response. 

Here is the stack trace 

I was trying using gdb to debug the error. I get to until RSA_public_encrypt(), then if I step in, I get the segmentation fault,

==================================================================================================

bt
#0  0x0000000000000000 in ?? ()
#1  0x00007ffff77dbfc0 in RSA_public_encrypt (flen=72, from=0x6d8860 "Hi. This is a test message. Hope to see some performace gain with this.\nme", to=0x6d8a70 "x\353;\367\377\177", rsa=0x6d8540, padding=1) at crypto/rsa/rsa_crpt.c:30
#2  0x00000000004479a7 in rsautl_main (argc=0, argv=0x7fffffffde10) at apps/rsautl.c:248
#3  0x00000000004379fa in do_cmd (prog=0x6d5930, argc=11, argv=0x7fffffffde10) at apps/openssl.c:564
#4  0x0000000000436e4d in main (argc=11, argv=0x7fffffffde10) at apps/openssl.c:183

==================================================================================================

To my understanding, instead of pointing to the default encryption function, it is pointing to  0x0000000000000000, thus causing the segmentation fault. 

 

Thanks,
Shariful

On Tue, Sep 28, 2021 at 1:40 AM Dmitry Belyavsky <beldmit@xxxxxxxxx> wrote:

Dear Shariful,

Could you please also provide a stack trace of your segfault?

On Tue, Sep 28, 2021 at 1:06 AM Shariful Alam <dipto181@xxxxxxxxx> wrote:

Hello,

I have the following simple RSA engine code from e_dasync.c.  Following code compiles and works. Until now, I was under the impression that if I do not supply an alternative method in function bind_dasync(), the engine will use the default method. However, it doesn't seem to be the case. If I comment out line 37 and try to perform an encryption operation with the following command, 

"openssl rsautl -encrypt -inkey public.pem -pubin -in msg.txt -out msg.enc -engine rsa-engine-new" 

I get segmentation errors.

Can anyone please tell me why this is happening?

==============================================================================

1. /* Engine Id and Name */
2. static const char *engine_rsa_id = "rsa-engine-new";
3. static const char *engine_rsa_name = "RSA engine for testing";
4. 
   
5. // data encryption function
6. static int eng_rsa_pub_enc(int flen, const unsigned char *from,
7.                           unsigned char *to, RSA *rsa, int padding) {
8.     printf("Encryption\n");
9.     return 0;
10. }
11. 
    
12. // signature verify
13. static int eng_rsa_pub_dec(int flen, const unsigned char *from, unsigned char *to, RSA *rsa, int padding){
14.     printf("Signature verify:\n");
15.     return 0;
16. }
17. 
    
18. // signature
19. static int eng_rsa_priv_enc(int flen, const unsigned char *from, unsigned char *to, RSA *rsa, int padding){
20.     printf("Signature:\n");
21.     return 0;
22. }
23. 
    
24. // data decryption
25. static int eng_rsa_priv_dec(int flen, const unsigned char *from, unsigned char *to, RSA *rsa, int padding){
26.     printf("Decryption\n");
27.     return 0;
28. }
29. 
    
30. 
    
31. static RSA_METHOD *test_rsa_method = NULL;
32. 
    
33. 
    
34. static int bind_dasync(ENGINE *e){
35.     /* Setup RSA_METHOD */
36.     if ((test_rsa_method = RSA_meth_new("Test RSA method", 0)) == NULL
37.        // || RSA_meth_set_pub_enc(test_rsa_method, eng_rsa_pub_enc) == 0
38.         || RSA_meth_set_pub_dec(test_rsa_method, eng_rsa_pub_dec) == 0
39.         || RSA_meth_set_priv_enc(test_rsa_method, eng_rsa_priv_enc) == 0
40.         || RSA_meth_set_priv_dec(test_rsa_method, eng_rsa_priv_dec) == 0
41.             ) {
42. 
    
43.         return 0;
44.     }
45. 
    
46.     /* Ensure the dasync error handling is set up */
47. 
    
48.     if (!ENGINE_set_id(e, engine_rsa_id)
49.         || !ENGINE_set_name(e, engine_rsa_name)
50.         || !ENGINE_set_RSA(e, test_rsa_method)
51.             ) {
52.         return 0;
53.     }
54.     return 1;
55. }
56. 
    
57. static int bind_helper(ENGINE *e, const char *id){
58.     if (!bind_dasync(e)){
59.         printf("2_Error: Inside Bind helper\n");
60.         return 0;
61.     }
62.     return 1;
63. }
64. 
    
65. IMPLEMENT_DYNAMIC_BIND_FN(bind_helper)
66. IMPLEMENT_DYNAMIC_CHECK_FN()

==============================================================================

Regards,

Shariful Alam

--

SY, Dmitry Belyavsky

--

SY, Dmitry Belyavsky