Suchindra Chandrahas wrote:
> Hi Jimmy,
> RFC-2246 is for TLS v1. However, i am going for SSL
> v3. I don't know whether there is any function for the same. I went
> through ssl3_enc.c in openssl code:
>
ssl3_generate_master_secret() is the equivalent one for ssl3. Although
it takes some of the needed parameters from the SSL structure passed to
it; so you can't use it the same way as tls1_PRF(). But you could use
the code as reference for your PRF code.
> int ssl3_generate_master_secret(SSL *s, unsigned char *out, unsigned
> char *p,
> int len)
> {
> static const unsigned char *salt[3]={
> #ifndef CHARSET_EBCDIC
> (const unsigned char *)"A",
> (const unsigned char *)"BB",
> (const unsigned char *)"CCC",
> #else
> (const unsigned char *)"\x41",
> (const unsigned char *)"\x42\x42",
> (const unsigned char *)"\x43\x43\x43",
> #endif
> };
> unsigned char buf[EVP_MAX_MD_SIZE];
> EVP_MD_CTX ctx;
> int i,ret=0;
> unsigned int n;
>
> EVP_MD_CTX_init(&ctx);
> for (i=0; i<3; i++)
> {
> EVP_DigestInit_ex(&ctx,s->ctx->sha1, NULL);
> EVP_DigestUpdate(&ctx,salt[i],strlen((const char
> *)salt[i]));
> EVP_DigestUpdate(&ctx,p,len);
> EVP_DigestUpdate(&ctx,&(s->s3->client_random[0]),
> SSL3_RANDOM_SIZE);
> EVP_DigestUpdate(&ctx,&(s->s3->server_random[0]),
> SSL3_RANDOM_SIZE);
> EVP_DigestFinal_ex(&ctx,buf,&n);
>
> EVP_DigestInit_ex(&ctx,s->ctx->md5, NULL);
> EVP_DigestUpdate(&ctx,p,len);
> EVP_DigestUpdate(&ctx,buf,n);
> EVP_DigestFinal_ex(&ctx,out,&n);
> out+=n;
> ret+=n;
> }
> EVP_MD_CTX_cleanup(&ctx);
> return(ret);
> }
>
>
> I guess *p above is pointer to premaster secret. I am doing the same
> thing here, only that EVP_Digest_Update is replaced
> MD5_Update/SHA_Update. I am not still sure whether my algorithm is
> correct or not!
>
you can call the specific _Update functions; provided you don't forget
to also call the corresponding _Init function.
-jb
--
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