+ *len = 20;
+ memcpy(fingerprint, buff, *len);
+ break;
+ default:
+ fprintf(stderr, "Unknown key type: %d\n",
+ packet->data[0]);
+ }
+
+ return fingerprint;
+}
+
+
+/**
+ * get_packetid - Given a PGP packet returns the keyid.
+ * @packet: The packet to calculate the id for.
+ */
+uint64_t get_packetid(struct openpgp_packet *packet)
+{
+ uint64_t keyid = 0;
+ int offset = 0;
+ int i = 0;
+ size_t length = 0;
+ unsigned char buff[20];
+
+ assert(packet != NULL);
+
+ switch (packet->data[0]) {
+ case 2:
+ case 3:
+ /*
+ * For a type 2 or 3 key the keyid is the last 64 bits of the
+ * public modulus n, which is stored as an MPI from offset 8
+ * onwards.
+ *
+ * We need to ensure it's an RSA key.
+ */
+ if (packet->data[7] == 1) {
+ offset = (packet->data[8] << 8) +
+ packet->data[9];
+ offset = ((offset + 7) / 8) + 2;
+
+ for (keyid = 0, i = 0; i < 8; i++) {
+ keyid <<= 8;
+ keyid += packet->data[offset++];
+ }
+ } else {
+ fputs("Type 2 or 3 key, but not RSA.\n", stderr);
+ }
+ break;
+ case 4:
+ get_fingerprint(packet, buff, &length);