ECDSA Nonce Recovery

Nonce reuse leading to private key recovery, this time with elliptic curves

Discuss The Problem

As part of signing something using DSA (digital signature algorithm) one must select a secret, cryptographically secure random number $k$ to be used as a nonce. $k$ must never be reused. Why you ask? Well you could ask Sony, or I could just tell you that you can recover $k$ given two signature / message pairs that used the same $k$ and signing key, which can lead to the signing key being compromised. I've signed two messages $(z_1, z_2)$ with the same $k$ (using the NIST curve P-192), resulting in the signatures $(s_1, r_1)$ and $(s_2, r_2)$. Your job is to recover $k$ (submit your answer in hex). Some reading to get started (of most relevance is section 2.3).

z1 = 78963682628359021178354263774457319969002651313568557216154777320971976772376
s1 = 5416854926380100427833180746305766840425542218870878667299
r1 = 5568285309948811794296918647045908208072077338037998537885
z2 = 62159883521253885305257821420764054581335542629545274203255594975380151338879
s2 = 1063435989394679868923901244364688588218477569545628548100
r2 = 5568285309948811794296918647045908208072077338037998537885
n = 6277101735386680763835789423176059013767194773182842284081