From e8ac612c4bad88172c5e80fa7e813664e536a6f8 Mon Sep 17 00:00:00 2001 From: Daniel Kahn Gillmor Date: Mon, 23 Jun 2008 17:02:15 -0400 Subject: [PATCH] openpgp2ssh can now accept arbitrary-length key IDs (from the trivial 8 hex digit key IDs to 40 hex digits of a full fingerprint). This moves our build dependency on gnutls to 2.4.0, which includes subkey fingerprint calculations. --- debian/control | 2 +- man/man1/openpgp2ssh.1 | 18 +++-- src/keytrans/openpgp2ssh.c | 134 ++++++++++++++++++++++++++++--------- 3 files changed, 113 insertions(+), 41 deletions(-) diff --git a/debian/control b/debian/control index d4d25c6..85b2d3f 100644 --- a/debian/control +++ b/debian/control @@ -3,7 +3,7 @@ Section: net Priority: extra Maintainer: Daniel Kahn Gillmor Uploaders: Jameson Rollins -Build-Depends: debhelper (>= 7.0), libgnutls-dev (>= 2.3.14) +Build-Depends: debhelper (>= 7.0), libgnutls-dev (>= 2.4.0) Standards-Version: 3.8.0.1 Homepage: http://cmrg.fifthhorseman.net/wiki/OpenPGPandSSH Dm-Upload-Allowed: yes diff --git a/man/man1/openpgp2ssh.1 b/man/man1/openpgp2ssh.1 index bea1da5..6141ec5 100644 --- a/man/man1/openpgp2ssh.1 +++ b/man/man1/openpgp2ssh.1 @@ -19,11 +19,14 @@ SSH-style key on standard output. .Pp If the data on standard input contains no subkeys, you can invoke .Nm -without arguments. If the data on standard input contains -multiple keys (e.g. a primary key and associated subkeys), you must -specify a specific OpenPGP keyid (e.g. CCD2ED94D21739E9) or -fingerprint as the first argument to indicate which key to export. -The keyid must be exactly 16 hex characters. +without arguments. If the data on standard input contains multiple +keys (e.g. a primary key and associated subkeys), you must specify a +specific OpenPGP key identifier as the first argument to indicate +which key to export. The key ID is normally the 40 hex digit OpenPGP +fingerprint of the key or subkey desired, but +.Nm +will accept as few as the last 8 digits of the fingerprint as a key +ID. .Pp If the input contains an OpenPGP RSA or DSA public key, it will be converted to the OpenSSH-style single-line keystring, prefixed with @@ -78,8 +81,9 @@ Secret key output is currently not passphrase-protected. .Nm currently cannot handle passphrase-protected secret keys on input. .Pp -It would be nice to be able to use keyids shorter or longer than 16 -hex characters. +Key identifiers consisting of an odd number of hex digits are not +accepted. Users who use a key ID with a standard length of 8, 16, or +40 hex digits should not be affected by this. .Pp .Nm only acts on keys associated with the first primary key diff --git a/src/keytrans/openpgp2ssh.c b/src/keytrans/openpgp2ssh.c index 92bdc19..5cc6cfa 100644 --- a/src/keytrans/openpgp2ssh.c +++ b/src/keytrans/openpgp2ssh.c @@ -35,15 +35,16 @@ /* FIXME: keyid should be const as well */ -int convert_private_pgp_to_x509(gnutls_x509_privkey_t* output, const gnutls_openpgp_privkey_t* pgp_privkey, gnutls_openpgp_keyid_t* keyid) { +int convert_private_pgp_to_x509(gnutls_x509_privkey_t* output, const gnutls_openpgp_privkey_t* pgp_privkey, const unsigned char* keyfpr, unsigned int fprlen) { gnutls_datum_t m, e, d, p, q, u, g, y, x; gnutls_pk_algorithm_t pgp_algo; unsigned int pgp_bits; int ret; - gnutls_openpgp_keyid_t curkeyid; int subkeyidx; int subkeycount; int found = 0; + unsigned char fingerprint[20]; + size_t fingerprint_length = sizeof(fingerprint); init_datum(&m); init_datum(&e); @@ -61,20 +62,27 @@ int convert_private_pgp_to_x509(gnutls_x509_privkey_t* output, const gnutls_open return 1; } - if ((keyid == NULL) && + if ((keyfpr == NULL) && (subkeycount > 0)) { - err(0,"No keyid passed in, but there were %d keys to choose from\n", subkeycount + 1); + err(0,"No key identifier passed in, but there were %d keys to choose from\n", subkeycount + 1); return 1; } - if (keyid != NULL) { - ret = gnutls_openpgp_privkey_get_key_id(*pgp_privkey, curkeyid); + if (keyfpr != NULL) { + ret = gnutls_openpgp_privkey_get_fingerprint(*pgp_privkey, fingerprint, &fingerprint_length); if (ret) { - err(0,"Could not get keyid (error: %d)\n", ret); + err(0,"Could not get fingerprint (error: %d)\n", ret); return 1; } + if (fprlen > fingerprint_length) { + err(0, "Requested key identifier is longer than computed fingerprint\n"); + return 1; + } + if (fingerprint_length > fprlen) { + err(0, "Only comparing last %d bits of key fingerprint\n", fprlen*8); + } } - if ((keyid == NULL) || (memcmp(*keyid, curkeyid, sizeof(gnutls_openpgp_keyid_t)) == 0)) { + if ((keyfpr == NULL) || (memcmp(fingerprint + (fingerprint_length - fprlen), keyfpr, fprlen) == 0)) { /* we want to export the primary key: */ err(0,"exporting primary key\n"); @@ -106,12 +114,19 @@ int convert_private_pgp_to_x509(gnutls_x509_privkey_t* output, const gnutls_open } else { /* lets trawl through the subkeys until we find the one we want: */ for (subkeyidx = 0; (subkeyidx < subkeycount) && !found; subkeyidx++) { - ret = gnutls_openpgp_privkey_get_subkey_id(*pgp_privkey, subkeyidx, curkeyid); + ret = gnutls_openpgp_privkey_get_subkey_fingerprint(*pgp_privkey, subkeyidx, fingerprint, &fingerprint_length); if (ret) { - err(0,"Could not get keyid of subkey with index %d (error: %d)\n", subkeyidx, ret); + err(0,"Could not get fingerprint of subkey with index %d (error: %d)\n", subkeyidx, ret); return 1; } - if (memcmp(*keyid, curkeyid, sizeof(gnutls_openpgp_keyid_t)) == 0) { + if (fprlen > fingerprint_length) { + err(0, "Requested key identifier is longer than computed fingerprint\n"); + return 1; + } + if (fingerprint_length > fprlen) { + err(1, "Only comparing last %d bits of key fingerprint\n", fprlen*8); + } + if (memcmp(fingerprint + (fingerprint_length - fprlen), keyfpr, fprlen) == 0) { err(0,"exporting subkey index %d\n", subkeyidx); /* FIXME: this is almost identical to the block above for the @@ -172,8 +187,7 @@ int convert_private_pgp_to_x509(gnutls_x509_privkey_t* output, const gnutls_open } /* FIXME: keyid should be const also */ -int emit_public_openssh_from_pgp(const gnutls_openpgp_crt_t* pgp_crt, gnutls_openpgp_keyid_t* keyid) { - gnutls_openpgp_keyid_t curkeyid; +int emit_public_openssh_from_pgp(const gnutls_openpgp_crt_t* pgp_crt, const unsigned char* keyfpr, size_t fprlen) { int ret; int subkeyidx; int subkeycount; @@ -188,6 +202,9 @@ int emit_public_openssh_from_pgp(const gnutls_openpgp_crt_t* pgp_crt, gnutls_ope algorithm name: */ char output_data[20]; + unsigned char fingerprint[20]; + size_t fingerprint_length = sizeof(fingerprint); + /* variables for the output conversion: */ int pipestatus; int pipefd, child_pid; @@ -208,20 +225,27 @@ int emit_public_openssh_from_pgp(const gnutls_openpgp_crt_t* pgp_crt, gnutls_ope return 1; } - if ((keyid == NULL) && + if ((keyfpr == NULL) && (subkeycount > 0)) { - err(0,"No keyid passed in, but there were %d keys to choose from\n", subkeycount + 1); + err(0,"No key identifier passed in, but there were %d keys to choose from\n", subkeycount + 1); return 1; } - if (keyid != NULL) { - ret = gnutls_openpgp_crt_get_key_id(*pgp_crt, curkeyid); + if (keyfpr != NULL) { + ret = gnutls_openpgp_crt_get_fingerprint(*pgp_crt, fingerprint, &fingerprint_length); if (ret) { - err(0,"Could not get keyid (error: %d)\n", ret); + err(0,"Could not get key fingerprint (error: %d)\n", ret); return 1; } + if (fprlen > fingerprint_length) { + err(0, "Requested key identifier is longer than computed fingerprint\n"); + return 1; + } + if (fingerprint_length > fprlen) { + err(0, "Only comparing last %d bits of key fingerprint\n", fprlen*8); + } } - if ((keyid == NULL) || (memcmp(*keyid, curkeyid, sizeof(gnutls_openpgp_keyid_t)) == 0)) { + if ((keyfpr == NULL) || (memcmp(fingerprint + (fingerprint_length - fprlen), keyfpr, fprlen) == 0)) { /* we want to export the primary key: */ err(0,"exporting primary key\n"); @@ -252,12 +276,19 @@ int emit_public_openssh_from_pgp(const gnutls_openpgp_crt_t* pgp_crt, gnutls_ope } else { /* lets trawl through the subkeys until we find the one we want: */ for (subkeyidx = 0; (subkeyidx < subkeycount) && !found; subkeyidx++) { - ret = gnutls_openpgp_crt_get_subkey_id(*pgp_crt, subkeyidx, curkeyid); + ret = gnutls_openpgp_crt_get_subkey_fingerprint(*pgp_crt, subkeyidx, fingerprint, &fingerprint_length); if (ret) { - err(0,"Could not get keyid of subkey with index %d (error: %d)\n", subkeyidx, ret); + err(0,"Could not get fingerprint of subkey with index %d (error: %d)\n", subkeyidx, ret); return 1; } - if (memcmp(*keyid, curkeyid, sizeof(gnutls_openpgp_keyid_t)) == 0) { + if (fprlen > fingerprint_length) { + err(0, "Requested key identifier is longer than computed fingerprint\n"); + return 1; + } + if (fingerprint_length > fprlen) { + err(1, "Only comparing last %d bits of key fingerprint\n", fprlen*8); + } + if (memcmp(fingerprint + (fingerprint_length - fprlen), keyfpr, fprlen) == 0) { err(0,"exporting subkey index %d\n", subkeyidx); /* FIXME: this is almost identical to the block above for the @@ -351,7 +382,7 @@ int emit_public_openssh_from_pgp(const gnutls_openpgp_crt_t* pgp_crt, gnutls_ope int main(int argc, char* argv[]) { gnutls_datum_t data; - int ret; + int ret = 0; gnutls_x509_privkey_t x509_privkey; gnutls_openpgp_privkey_t pgp_privkey; gnutls_openpgp_crt_t pgp_crt; @@ -359,18 +390,54 @@ int main(int argc, char* argv[]) { char output_data[10240]; size_t ods = sizeof(output_data); - gnutls_openpgp_keyid_t keyid; - gnutls_openpgp_keyid_t* use_keyid; + unsigned char * fingerprint = NULL; + size_t fpr_size; + char * prettyfpr = NULL; init_gnutls(); - /* figure out what keyid we should be looking for: */ - use_keyid = NULL; + /* figure out what key we should be looking for: */ if (argv[1] != NULL) { - ret = convert_string_to_keyid(keyid, argv[1]); - if (ret != 0) - return ret; - use_keyid = &keyid; + if (strlen(argv[1]) > 81) { + /* safety check to avoid some sort of wacky overflow situation: + there's no reason that the key id should be longer than twice + a sane fingerprint (one byte between chars, and then another + two at the beginning and end) */ + err(0, "Key identifier is way too long. Please use at most 40 hex digits.\n"); + return 1; + } + + fpr_size = hexstring2bin(NULL, argv[1]); + if (fpr_size > 40*4) { + err(0, "Key identifier is longer than 40 hex digits\n"); + return 1; + } + /* since fpr_size is initially in bits: */ + if (fpr_size % 8 != 0) { + err(0, "Please provide an even number of hex digits for the key identifier\n"); + return 1; + } + fpr_size /= 8; + + fingerprint = malloc(sizeof(unsigned char) * fpr_size); + bzero(fingerprint, sizeof(unsigned char) * fpr_size); + hexstring2bin(fingerprint, argv[1]); + + prettyfpr = malloc(sizeof(unsigned char)*fpr_size*2 + 1); + if (prettyfpr != NULL) { + hex_print_data(prettyfpr, fingerprint, fpr_size); + prettyfpr[sizeof(unsigned char)*fpr_size*2] = '\0'; + err(1, "searching for key with fingerprint '%s'\n", prettyfpr); + free(prettyfpr); + } + + if (fpr_size < 4) { + err(0, "You MUST provide at least 8 hex digits in any key identifier\n"); + return 1; + } + if (fpr_size < 8) + err(0, "You should provide at least 16 hex digits in any key identifier (proceeding with %d digits anyway)\n", fpr_size*2); + } @@ -397,7 +464,7 @@ int main(int argc, char* argv[]) { return 1; } - ret = convert_private_pgp_to_x509(&x509_privkey, &pgp_privkey, use_keyid); + ret = convert_private_pgp_to_x509(&x509_privkey, &pgp_privkey, fingerprint, fpr_size); gnutls_openpgp_privkey_deinit(pgp_privkey); if (ret) @@ -423,7 +490,7 @@ int main(int argc, char* argv[]) { /* we're dealing with a public key */ err(0,"Translating public key\n"); - ret = emit_public_openssh_from_pgp(&pgp_crt, use_keyid); + ret = emit_public_openssh_from_pgp(&pgp_crt, fingerprint, fpr_size); } else { /* we have no idea what kind of key this is at all anyway! */ @@ -433,5 +500,6 @@ int main(int argc, char* argv[]) { } gnutls_global_deinit(); + free(fingerprint); return 0; } -- 2.25.1