I also have a problem in sending the pub_key to peer. As I am using DH_generate_parameters to generate prime and generator and DH_generator_key for generating the public key , I have to send the prime, g and pub_key to the peer. Is there any function to do this??
Thanks in advance. Yamini. On Fri, Dec 21, 2012 at 9:23 AM, Hemayamini Kurra < hemayaminiku...@email.arizona.edu> wrote: > 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 >> >> >> >
