diff options
Diffstat (limited to 'gpg2ssh.c')
| -rw-r--r-- | gpg2ssh.c | 189 |
1 files changed, 189 insertions, 0 deletions
diff --git a/gpg2ssh.c b/gpg2ssh.c new file mode 100644 index 0000000..87b62a3 --- /dev/null +++ b/gpg2ssh.c @@ -0,0 +1,189 @@ +#include "gnutls-helpers.h" + +#include <gnutls/openpgp.h> +#include <gnutls/x509.h> + +/* for htonl() */ +#include <arpa/inet.h> + + +/* + Author: Daniel Kahn Gillmor <dkg@fifthhorseman.net> + 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; + + char output_data[10240]; + size_t ods = sizeof(output_data); + + init_gnutls(); + + init_datum(&data); + + init_datum(&m); + init_datum(&e); + init_datum(&p); + init_datum(&q); + init_datum(&g); + init_datum(&y); + + 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: */ + + 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; + } + + 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) { + err("the primary key can be used for authentication\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 only good for: 0x%08x. Trying subkeys...\n", usage); + + if (ret = gnutls_openpgp_crt_get_auth_subkey(openpgp_crt, keyid), ret) { + err("failed to find a subkey capable of authentication (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) { + err("could not find a subkey with authentication privileges.\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; + } + } + + /* now we have algo, and the various MPI data set. Can we export + them cleanly? */ + + + + gnutls_openpgp_crt_deinit(openpgp_crt); + gnutls_global_deinit(); + return 0; +} |