java - Determining a Private Key (Diffie-Hellman) -

java - Determining a Private Key (Diffie-Hellman) -

i've been given challenge , has testing friend's encryption process.

it's diffie-hellman exchange process, , here known variables / constants:

p, g my generated private key (variable) my generated public key(variable) the recipients public key (constant).

when looking @ private key - p , g both within it. example, first 'x' bytes seem have no relation anything, next 'y' bytes p, next 2 bytes static, , next 'z' bytes g, remainder variable.

the process encrypt file, , send device, in turn decrypt - ideas of attack this:

try duplicate secret shared key. problem here is fine long know generated private key, @ case - don't files he's given me.

try find recipients private key. here, brute forcefulness way in - take forever unless had sort of supercomputer.

are there other options @ when trying attack this?

i should maintain mouth shut, chance interested in diffie-hellman larn something:

simple implementation of diffie-hellman generate shared key vulnerable man-in-the-middle attacks. however, implementation of dh tackle issue adding authentication between alice , bob.

if implementation of dh allows declaring new set of pqg, request other peer utilize new weak set. if bob not verify quality of set, vulnerable attacks.

dh requires alice send x = g^x, if bob not check quality of x, vulnerable, since space of possible values of secret key can reduced eve in middle.

if implementation not remember compromised keys, can re-used eve.

if implementation not remember compromised certificates, can re-used eve.

if implementation not check certificates, eve have fun sure.

java diffie-hellman