#include "gnutls-helpers.h" #include #include /* for waitpid() */ #include #include /* Author: Daniel Kahn Gillmor Date: Tue, 08 Apr 2008 License: GPL v3 or later monkeysphere public key translator: execute this with an GPG certificate (public key(s) + userid(s)) on stdin. It currently only works with RSA keys. It will spit out a version of the first key capable of being used for authentication on stdout. The output format should be suitable for appending a known_hosts file. Requirements: I've only built this so far with GnuTLS v2.3.4 -- version 2.2.0 does not contain the appropriate pieces. */ int main(int argc, char* argv[]) { gnutls_datum_t data; int ret; gnutls_openpgp_crt_t openpgp_crt; gnutls_openpgp_keyid_t keyid; printable_keyid p_keyid; unsigned int keyidx; unsigned int usage, bits; gnutls_pk_algorithm_t algo; gnutls_datum_t m, e, p, q, g, y; gnutls_datum_t algolabel; char output_data[10240]; char userid[10240]; size_t uidsz = sizeof(userid); const gnutls_datum_t* all[5]; int pipefd; pid_t child_pid; char* const args[] = {"/usr/bin/base64", "--wrap=0", NULL}; const char* algoname; int mpicount; int pipestatus; init_gnutls(); init_datum(&data); init_datum(&m); init_datum(&e); init_datum(&p); init_datum(&q); init_datum(&g); init_datum(&y); init_datum(&algolabel); init_keyid(keyid); /* slurp in the private key from stdin */ if (ret = set_datum_fd(&data, 0), ret) { err("didn't read file descriptor 0\n"); return 1; } if (ret = gnutls_openpgp_crt_init(&openpgp_crt), ret) { err("Failed to initialize OpenPGP certificate (error: %d)\n", ret); return 1; } /* format could be either: GNUTLS_OPENPGP_FMT_RAW, GNUTLS_OPENPGP_FMT_BASE64; if MONKEYSPHERE_RAW is set, use RAW, otherwise, use BASE64: */ /* FIXME: we should be auto-detecting the input format, and translating it as needed. */ if (getenv("MONKEYSPHERE_RAW")) { err("assuming RAW formatted certificate\n"); if (ret = gnutls_openpgp_crt_import(openpgp_crt, &data, GNUTLS_OPENPGP_FMT_RAW), ret) { err("failed to import the OpenPGP certificate in RAW format (error: %d)\n", ret); return ret; } } else { err("assuming BASE64 formatted certificate\n"); if (ret = gnutls_openpgp_crt_import (openpgp_crt, &data, GNUTLS_OPENPGP_FMT_BASE64), ret) { err("failed to import the OpenPGP certificate in BASE64 format (error: %d)\n", ret); return ret; } } if (gnutls_openpgp_crt_get_revoked_status(openpgp_crt)) { err("the primary key was revoked!\n"); return 1; } /* FIXME: We're currently looking at the primary key or maybe the first authentication-capable subkey. Instead, we should be iterating through the primary key and all subkeys: for each one with the authentication usage flag set of a algorithm we can handle, we should output matching UserIDs and the SSH version of the key. */ if (ret = gnutls_openpgp_crt_get_key_usage(openpgp_crt, &usage), ret) { err("failed to get the usage flags for the primary key (error: %d)\n", ret); return ret; } if (usage & GNUTLS_KEY_KEY_AGREEMENT && usage & GNUTLS_KEY_KEY_ENCIPHERMENT) { err("the primary key can be used for authentication and communication encryption!\n"); algo = gnutls_openpgp_crt_get_pk_algorithm(openpgp_crt, &bits); if (algo < 0) { err("failed to get the algorithm of the OpenPGP public key (error: %d)\n", algo); return algo; } else if (algo == GNUTLS_PK_RSA) { err("OpenPGP RSA certificate, with %d bits\n", bits); ret = gnutls_openpgp_crt_get_pk_rsa_raw(openpgp_crt, &m, &e); if (GNUTLS_E_SUCCESS != ret) { err ("failed to export RSA key parameters (error: %d)\n", ret); return 1; } } else if (algo == GNUTLS_PK_DSA) { err("OpenPGP DSA Key, with %d bits\n", bits); ret = gnutls_openpgp_crt_get_pk_dsa_raw(openpgp_crt, &p, &q, &g, &y); if (GNUTLS_E_SUCCESS != ret) { err ("failed to export DSA key parameters (error: %d)\n", ret); return 1; } } else { err("OpenPGP Key was not RSA or DSA -- can't deal! (actual algorithm was: %d)\n", algo); return 1; } } else { err("primary key is not good for authentication and communication encryption. Trying subkeys...\n"); if (ret = gnutls_openpgp_crt_get_auth_subkey(openpgp_crt, keyid, 0), ret) { err("failed to find a subkey capable of authentication and communication encryption (error: %d)\n", ret); return ret; } make_keyid_printable(p_keyid, keyid); err("found authentication subkey %.16s\n", p_keyid); ret = gnutls_openpgp_crt_get_subkey_idx(openpgp_crt, keyid); if (ret < 0) { err("could not get the index of subkey %.16s (error: %d)\n", ret); return ret; } keyidx = ret; if (gnutls_openpgp_crt_get_subkey_revoked_status(openpgp_crt, keyidx)) { err("The authentication subkey was revoked!\n"); return 1; } if (ret = gnutls_openpgp_crt_get_subkey_usage(openpgp_crt, keyidx, &usage), ret) { err("could not figure out usage of subkey %.16s (error: %d)\n", p_keyid, ret); return ret; } if ((usage & GNUTLS_KEY_KEY_AGREEMENT) == 0 && usage & GNUTLS_KEY_KEY_ENCIPHERMENT) { err("could not find a subkey with authentication and communication encryption.\n"); return 1; } /* switch, based on the algorithm in question, to extract the MPI components: */ algo = gnutls_openpgp_crt_get_subkey_pk_algorithm(openpgp_crt, keyidx, &bits); if (algo < 0) { err("failed to get the algorithm of the authentication subkey (error: %d)\n", algo); return algo; } else if (algo == GNUTLS_PK_RSA) { err("OpenPGP RSA subkey, with %d bits\n", bits); ret = gnutls_openpgp_crt_get_subkey_pk_rsa_raw(openpgp_crt, keyidx, &m, &e); if (GNUTLS_E_SUCCESS != ret) { err ("failed to export RSA subkey parameters (error: %d)\n", ret); return 1; } } else if (algo == GNUTLS_PK_DSA) { err("OpenPGP DSA subkey, with %d bits\n", bits); ret = gnutls_openpgp_crt_get_subkey_pk_dsa_raw(openpgp_crt, keyidx, &p, &q, &g, &y); if (GNUTLS_E_SUCCESS != ret) { err ("failed to export DSA subkey parameters (error: %d)\n", ret); return 1; } } else { err("OpenPGP subkey was not RSA or DSA -- can't deal! (actual algorithm was: %d)\n", algo); return 1; } } /* make sure userid is NULL-terminated */ userid[sizeof(userid) - 1] = 0; uidsz--; /* FIXME: we're just choosing the first UserID from the certificate: instead, we should be selecting every User ID that is adequately signed and matches the spec, and aggregating them with commas for known_hosts output */ if (ret = gnutls_openpgp_crt_get_name(openpgp_crt, 0, userid, &uidsz), ret) { err("Failed to fetch the first UserID (error: %d)\n", ret); return ret; } if (ret = validate_ssh_host_userid(userid), ret) { err("bad userid: not a valid ssh host.\n"); return ret; } /* remove ssh:// from the beginning of userid */ memmove(userid, userid + strlen("ssh://"), 1 + strlen(userid) - strlen("ssh://")); /* now we have algo, and the various MPI data are set. Can we export them cleanly? */ /* for the moment, we'll just dump the info raw, and pipe it externally through coreutils' /usr/bin/base64 */ if (algo == GNUTLS_PK_RSA) { algoname = "ssh-rsa"; mpicount = 3; all[0] = &algolabel; all[1] = &e; all[2] = &m; } else if (algo == GNUTLS_PK_DSA) { algoname = "ssh-dss"; mpicount = 5; all[0] = &algolabel; all[1] = &p; all[2] = &q; all[3] = &g; all[4] = &y; } else { err("no idea what this algorithm is: %d\n", algo); return 1; } if (ret = datum_from_string(&algolabel, algoname), ret) { err("couldn't label string (error: %d)\n", ret); return ret; } snprintf(output_data, sizeof(output_data), "%s %s ", userid, algoname); pipefd = create_writing_pipe(&child_pid, args[0], args); if (pipefd < 0) { err("failed to create a writing pipe (returned %d)\n", pipefd); return pipefd; } write(1, output_data, strlen(output_data)); if (0 != write_data_fd_with_length(pipefd, all, mpicount)) { err("was not able to write out RSA key data\n"); return 1; } close(pipefd); if (child_pid != waitpid(child_pid, &pipestatus, 0)) { err("could not wait for child process to return for some reason.\n"); return 1; } if (pipestatus != 0) { err("base64 pipe died with return code %d\n", pipestatus); return pipestatus; } write(1, "\n", 1); gnutls_openpgp_crt_deinit(openpgp_crt); gnutls_global_deinit(); return 0; }