Hello,
> Hi!
>
> I tired to use RSA encryption.
>
>
> unsigned char *rsa_in = "Very secret message Very secret message Very secret
> m";
>
> OpenSSL_add_all_algorithms();
> pad = RSA_PKCS1_PADDING;
> rsa_inlen = strlen(rsa_in);
> printf ("rsa_inlen:%d\n",rsa_inlen);
>
> rsa = RSA_generate_key(512,RSA_F4,NULL,NULL);
> keysize = RSA_size(rsa);
> printf ("Keysize:%d\n",keysize);
> rsa_out = OPENSSL_malloc(keysize);
>
> rsa_outlen = RSA_public_encrypt(rsa_inlen, rsa_in, rsa_out, rsa, pad);
> printf ("rsa_outlen:%d\n",rsa_outlen);
> }//end
>
> output :
> rsa_inlen:53
> Keysize:64
> rsa_outlen:64
>
> is good, but if:
> unsigned char *rsa_in = "Very secret message Very secret message Very
> secret me";
> ......
>
> rsa_inlen:54
> Keysize:64
> rsa_outlen:-1
> why? rsa_inlen is 53: working correctly
> rsa_inlen is 54 or above: segmentation fault.
You generated 512 bit key (64 bytes) so you can encrypt
without padding max 64 bytes.
Because you specified RSA_PKCS1_PADDING padding witch requires
minimum 11 bytes of free space than you can encrypt max 53 bytes
with this type of padding (your data is first padded and than
encrypted).
> how to do RSA encrypt with very long string, or with file???
Usually only session keys, shared keys and this type of data
is encrypted with RSA ... usually :-)
Best regards,
--
Marek Marcola <[EMAIL PROTECTED]>
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