Thanks prashant!! This helped alot!!
On Thu, Dec 20, 2012 at 10:09 PM, Prashant Batra <prashant0...@gmail.com>wrote: > I have this fucntion which I use to generate public-private key pair. > > - prime : depends on the dh group, you can find these values in DH rfc - > http://www.ietf.org/rfc/rfc3526.txt > > int32_t DHInterface::GeneratePublicPrivateKeyPair(uint8_t * pub_key, > uint32_t * pub_key_length) > { > char *errbuf; > > dh = DH_new(); > > if ((dh->p = BN_bin2bn((unsigned char *)prime->v, prime->l, NULL)) == > NULL) > return -1; > > if ((dh->g = BN_new()) == NULL) > return -1; > if (!BN_set_word(dh->g, 2)) > return -1; > > > /* Now generate public and private key */ > > if (!DH_generate_key(dh)) > { > errbuf = ERR_error_string(ERR_get_error(), NULL); > printf("Error : %s", errbuf); > return -1; > } > > /* Covert keys from BN into bytes */ > > *pub_key_length = BN_bn2bin(dh->pub_key, (unsigned char *)(pub_key)); > > return 0; > } > > DH_Generate_key would generate a private key, and then a corresponding > public key value. You need to send this public key value to your peer and > then expect a public key value from the peer. > Once you get peer's public key use the same "dh" object to calculate the > secret value, which I do in this way- > peer_pub_key = BN_bin2bn((unsigned char *)peer_public_key, key_length, > NULL); > > if ((secret_key_length = DH_compute_key((unsigned char *)temp, > peer_pub_key, dh)) < 0) > { > errbuf = ERR_error_string(ERR_get_error(), NULL); > printf("Error : %s", errbuf); > return -1; > } > *secret_length = DH_size(dh); > > > I feel the variables would be self explainatory. > > > On Fri, Dec 21, 2012 at 10:19 AM, Hemayamini Kurra < > hemayaminiku...@email.arizona.edu> wrote: > >> Hello!! >> >> >> I am trying to implement Diffe-Hellman Key exchange protocol between >> Client and server. I am using openSSL dh.h library for that. The problem is >> how to send the publickey generated by DH_generate_key() function to >> client/server. >> >> My idea is to get the shared secret which I can use for further >> encryption of communication between client and server. I have followed the >> following steps >> >> 1. Generate the parameters uysing DH_generate_parameters() >> 2. DH_check() for checking the parameters generated. >> 3. Then to use DH_compute_key() I should be able to get the peer's public >> key. How can I get this? >> >> What is the private value DH_generate_key uses for generating public key? >> >> I dint find any sample programs for this problem. It would be great if >> anyone suggest some sample programs related to my above mentioned task!! >> >> >> Thanks and Regards, >> Yamini. >> > > > > -- > Prashant Batra > > >
