+ kex->we_need = need;
+
+ /* ignore the next message if the proposals do not match */
+ if (first_kex_follows && !proposals_match(my, peer) &&
+ !(datafellows & SSH_BUG_FIRSTKEX)) {
+ type = packet_read();
+ debug2("skipping next packet (type %u)", type);
+ }
+
+ kex_prop_free(my);
+ kex_prop_free(peer);
+}
+
+static u_char *
+derive_key(Kex *kex, int id, u_int need, u_char *hash, u_int hashlen,
+ BIGNUM *shared_secret)
+{
+ Buffer b;
+ EVP_MD_CTX md;
+ char c = id;
+ u_int have;
+ int mdsz;
+ u_char *digest;
+
+ if ((mdsz = EVP_MD_size(kex->evp_md)) <= 0)
+ fatal("bad kex md size %d", mdsz);
+ digest = xmalloc(roundup(need, mdsz));
+
+ buffer_init(&b);
+ buffer_put_bignum2(&b, shared_secret);
+
+ /* K1 = HASH(K || H || "A" || session_id) */
+ EVP_DigestInit(&md, kex->evp_md);
+ if (!(datafellows & SSH_BUG_DERIVEKEY))
+ EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
+ EVP_DigestUpdate(&md, hash, hashlen);
+ EVP_DigestUpdate(&md, &c, 1);
+ EVP_DigestUpdate(&md, kex->session_id, kex->session_id_len);
+ EVP_DigestFinal(&md, digest, NULL);
+
+ /*
+ * expand key:
+ * Kn = HASH(K || H || K1 || K2 || ... || Kn-1)
+ * Key = K1 || K2 || ... || Kn
+ */
+ for (have = mdsz; need > have; have += mdsz) {
+ EVP_DigestInit(&md, kex->evp_md);
+ if (!(datafellows & SSH_BUG_DERIVEKEY))
+ EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
+ EVP_DigestUpdate(&md, hash, hashlen);
+ EVP_DigestUpdate(&md, digest, have);
+ EVP_DigestFinal(&md, digest + have, NULL);
+ }
+ buffer_free(&b);
+#ifdef DEBUG_KEX
+ fprintf(stderr, "key '%c'== ", c);
+ dump_digest("key", digest, need);
+#endif
+ return digest;