Citation from the letter of Ludovic FLAMENT
<[EMAIL PROTECTED]>:
> Angel Martinez Gonzalez wrote:
>
> >Hello:
> >
> >I wrote a BIGNUM into a file using the function:
> >
> > int BN_print_fp(FILE *fp, const BIGNUM *a);
> >
> >But, How I can read this bignum from this file?. I don?t
> know a openssl
> >function to read a bignum from a file.
> >
> >
> Hello, you can read Bignum from file with this
> method,
>
> #include <stdio.h>
> #include <stdlib.h>
> #include <openssl/bn.h>
>
> int main()
> {
> BIGNUM *b;
> FILE *f;
> char buff[128]; /* must depend of Bignum size
> */
>
> b = BN_new();
> if (b == NULL)
> return 0;
>
> BN_add_word(b, 123456789);
>
> f = fopen("bignum", "w");
> if (f == NULL)
> return 0;
>
> BN_print_fp(f, b);
>
> BN_free(b);
> fclose(f);
>
> /* start reading */
> f = fopen("bignum", "r");
> if (f == NULL)
> return 0;
>
> if (fread(buff, sizeof(char), sizeof(buff), f) <=
> 0)
> {
> fclose(f);
> return 0;
> }
> fclose(f);
>
> if (!BN_hex2bn(&b, buff))
> return 0;
>
> printf("BN read from file : ");
> BN_print_fp(stdout, b);
> printf("\n");
>
> BN_add_word(b, 1);
>
> printf("BN read from file + 1 : ");
> BN_print_fp(stdout, b);
> printf("\n");
>
> BN_free(b);
> return 1;
> }
>
> --
> Ludovic FLAMENT
>
______________________________________________________________________
> OpenSSL Project
> http://www.openssl.org
> User Support Mailing List
> openssl-users@openssl.org
> Automated List Manager
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>
Just a minor remark about the sample source:
you should not BN_free(b) before BN_hex2bn(&b, buff)
-----------------------------
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