On Thu, Jul 21, 2011, Prashant Batra wrote: > Hello, > > I am using DH exchange in ikev2 for generating secret key b/w 2 parties. > I am observing some awkward thing, > in some of the cases, the secret calculated by both the parties is not the > same, although the input (public key, private key and peer public key ) is > same. > > Hexdump: Length [128] > [0] 00 1c ad b2 96 d2 2f b5 25 81 df ac 59 65 2d 01 0a 29 2b 51 27 20 61 49 > 14 f1 80 f7 e3 53 cc 20 > [32] d4 be f8 b5 44 33 1d 25 d2 d2 b0 be b0 93 93 04 6f ec af c1 09 f3 d3 59 > d4 21 5d 01 a4 70 b6 9e > [64] ab 49 6e ff a4 3d 02 1e 51 ec 76 20 e1 c1 12 f4 3f ba ca 70 d1 41 75 bd > de 73 e0 aa 40 32 f4 da > [96] 69 d5 a2 b8 01 4f 31 8b 9e a8 40 e9 fe 9c 2f ea 5c 34 fd ed ea b5 63 93 > a3 be 78 61 6f 50 96 b6 } > > Hexdump: Length [128] > [0] 1c ad b2 96 d2 2f b5 25 81 df ac 59 65 2d 01 0a 29 2b 51 27 20 61 49 14 > f1 80 f7 e3 53 cc 20 > [32] d4 be f8 b5 44 33 1d 25 d2 d2 b0 be [32] b0 93 93 04 6f ec af c1 09 f3 > d3 59 d4 21 5d 01 a4 70 b6 9e > [64] ab 49 6e ff a4 3d 02 1e 51 ec 76 20 e1 c1 12 f4 3f ba ca 70 d1 41 75 bd > de 73 e0 aa 40 32 f4 da > [96] 69 d5 a2 b8 01 4f 31 8b 9e a8 40 e9 fe 9c 2f ea 5c 34 fd ed ea b5 63 93 > a3 be 78 61 6f 50 96 b6 00 } > > So, there is a problem of 1 byte. > > The exchange is working properly for other users and the key is also > matching. > > Can someone point out the problem, or any clue, where I may be doing wrong, > as the same code is getting hit for all the users. >
OpenSSLs DH implementation is compliant with the SSL/TLS requirements that skips leading zeroes on the output. It looks like the other implementation includes leading zeroes. The return value of DH_compute_key is the length of the returned key, if it is less than DH_size(key) then prepend zeroes. Steve. -- Dr Stephen N. Henson. OpenSSL project core developer. Commercial tech support now available see: http://www.openssl.org ______________________________________________________________________ OpenSSL Project http://www.openssl.org User Support Mailing List openssl-users@openssl.org Automated List Manager majord...@openssl.org
