X-Git-Url: https://codewiz.org/gitweb?a=blobdiff_plain;f=src%2Fkeytrans%2Fpem2openpgp;h=4e6ebe71a21f47d5ab7bfe4d3d6e3d94dc60e5e2;hb=b08a2e207f22000b494fc1aabe413bea5eb8f7d5;hp=7522c8ff2abc94b296256a7a958eb0ad31c0f770;hpb=abc8c78f7053972fe55c3330cea243a4c43cbd7b;p=monkeysphere.git diff --git a/src/keytrans/pem2openpgp b/src/keytrans/pem2openpgp index 7522c8f..4e6ebe7 100755 --- a/src/keytrans/pem2openpgp +++ b/src/keytrans/pem2openpgp @@ -1,8 +1,12 @@ #!/usr/bin/perl -w -T # pem2openpgp: take a PEM-encoded RSA private-key on standard input, a -# User ID as the first argument, and generate an OpenPGP certificate -# from it. +# User ID as the first argument, and generate an OpenPGP secret key +# and certificate from it. + +# WARNING: the secret key material *will* appear on stdout (albeit in +# OpenPGP form) -- if you redirect stdout to a file, make sure the +# permissions on that file are appropriately locked down! # Usage: @@ -21,42 +25,243 @@ use strict; use warnings; use Crypt::OpenSSL::RSA; use Crypt::OpenSSL::Bignum; +use Crypt::OpenSSL::Bignum::CTX; use Digest::SHA1; use MIME::Base64; ## make sure all length() and substr() calls use bytes only: use bytes; -my $uid = shift; +my $old_format_packet_lengths = { one => 0, + two => 1, + four => 2, + indeterminate => 3, +}; + +# see RFC 4880 section 9.1 (ignoring deprecated algorithms for now) +my $asym_algos = { rsa => 1, + elgamal => 16, + dsa => 17, + }; + +# see RFC 4880 section 9.2 +my $ciphers = { plaintext => 0, + idea => 1, + tripledes => 2, + cast5 => 3, + blowfish => 4, + aes128 => 7, + aes192 => 8, + aes256 => 9, + twofish => 10, + }; + +# see RFC 4880 section 9.3 +my $zips = { uncompressed => 0, + zip => 1, + zlib => 2, + bzip2 => 3, + }; + +# see RFC 4880 section 9.4 +my $digests = { md5 => 1, + sha1 => 2, + ripemd160 => 3, + sha256 => 8, + sha384 => 9, + sha512 => 10, + sha224 => 11, + }; + +# see RFC 4880 section 5.2.3.21 +my $usage_flags = { certify => 0x01, + sign => 0x02, + encrypt_comms => 0x04, + encrypt_storage => 0x08, + encrypt => 0x0c, ## both comms and storage + split => 0x10, # the private key is split via secret sharing + authenticate => 0x20, + shared => 0x80, # more than one person holds the entire private key + }; + +# see RFC 4880 section 4.3 +my $packet_types = { pubkey_enc_session => 1, + sig => 2, + symkey_enc_session => 3, + onepass_sig => 4, + seckey => 5, + pubkey => 6, + sec_subkey => 7, + compressed_data => 8, + symenc_data => 9, + marker => 10, + literal => 11, + trust => 12, + uid => 13, + pub_subkey => 14, + uat => 17, + symenc_w_integrity => 18, + mdc => 19, + }; + +# see RFC 4880 section 5.2.1 +my $sig_types = { binary_doc => 0x00, + text_doc => 0x01, + standalone => 0x02, + generic_certification => 0x10, + persona_certification => 0x11, + casual_certification => 0x12, + positive_certification => 0x13, + subkey_binding => 0x18, + primary_key_binding => 0x19, + key_signature => 0x1f, + key_revocation => 0x20, + subkey_revocation => 0x28, + certification_revocation => 0x30, + timestamp => 0x40, + thirdparty => 0x50, + }; + + +# see RFC 4880 section 5.2.3.1 +my $subpacket_types = { sig_creation_time => 2, + sig_expiration_time => 3, + exportable => 4, + trust_sig => 5, + regex => 6, + revocable => 7, + key_expiration_time => 9, + preferred_cipher => 11, + revocation_key => 12, + issuer => 16, + notation => 20, + preferred_digest => 21, + preferred_compression => 22, + keyserver_prefs => 23, + preferred_keyserver => 24, + primary_uid => 25, + policy_uri => 26, + usage_flags => 27, + signers_uid => 28, + revocation_reason => 29, + features => 30, + signature_target => 31, + embedded_signature => 32, + }; + +# bitstring (see RFC 4880 section 5.2.3.24) +my $features = { mdc => 0x01 + }; + +# bitstring (see RFC 4880 5.2.3.17) +my $keyserver_prefs = { nomodify => 0x80 + }; + +###### end lookup tables ###### + +# FIXME: if we want to be able to interpret openpgp data as well as +# produce it, we need to produce key/value-swapped lookup tables as well. + + +########### Math/Utility Functions ############## + + +# see the bottom of page 43 of RFC 4880 +sub simple_checksum { + my $bytes = shift; + + return unpack("%32W*",$bytes) % 65536; +} + +# calculate the multiplicative inverse of a mod b this is euclid's +# extended algorithm. For more information see: +# http://en.wikipedia.org/wiki/Extended_Euclidean_algorithm the +# arguments here should be Crypt::OpenSSL::Bignum objects. $a should +# be the larger of the two values, and the two values should be +# coprime. + +sub modular_multi_inverse { + my $a = shift; + my $b = shift; + + + my $origdivisor = $b->copy(); + + my $ctx = Crypt::OpenSSL::Bignum::CTX->new(); + my $x = Crypt::OpenSSL::Bignum->zero(); + my $y = Crypt::OpenSSL::Bignum->one(); + my $lastx = Crypt::OpenSSL::Bignum->one(); + my $lasty = Crypt::OpenSSL::Bignum->zero(); + + my $finalquotient; + my $finalremainder; + + while (! $b->is_zero()) { + my ($quotient, $remainder) = $a->div($b, $ctx); + + $a = $b; + $b = $remainder; + + my $temp = $x; + $x = $lastx->sub($quotient->mul($x, $ctx)); + $lastx = $temp; + + $temp = $y; + $y = $lasty->sub($quotient->mul($y, $ctx)); + $lasty = $temp; + } + + if (!$a->is_one()) { + die "did this math wrong.\n"; + } + + # let's make sure that we return a positive value because RFC 4880, + # section 3.2 only allows unsigned values: + + ($finalquotient, $finalremainder) = $lastx->add($origdivisor)->div($origdivisor, $ctx); + + return $finalremainder; +} -# FIXME: fail if there is no given user ID; or should we default to -# hostname_long() from Sys::Hostname::Long ? + +############ OpenPGP formatting functions ############ # make an old-style packet out of the given packet type and body. # old-style (see RFC 4880 section 4.2) sub make_packet { my $type = shift; my $body = shift; + my $options = shift; my $len = length($body); + my $pseudolen = $len; + + # if the caller wants to use at least N octets of packet length, + # pretend that we're using that many. + if (defined $options && defined $options->{'packet_length'}) { + $pseudolen = 2**($options->{'packet_length'} * 8) - 1; + } + if ($pseudolen < $len) { + $pseudolen = $len; + } my $lenbytes; my $lencode; - if ($len < 2**8) { - $lenbytes = 0; + if ($pseudolen < 2**8) { + $lenbytes = $old_format_packet_lengths->{one}; $lencode = 'C'; - } elsif ($len < 2**16) { - $lenbytes = 1; + } elsif ($pseudolen < 2**16) { + $lenbytes = $old_format_packet_lengths->{two}; $lencode = 'n'; - } elsif ($len < 2**31) { + } elsif ($pseudolen < 2**31) { ## not testing against full 32 bits because i don't want to deal ## with potential overflow. - $lenbytes = 2; + $lenbytes = $old_format_packet_lengths->{four}; $lencode = 'N'; } else { ## what the hell do we do here? - $lenbytes = 3; + $lenbytes = $old_format_packet_lengths->{indeterminate}; $lencode = ''; } @@ -82,7 +287,7 @@ sub mpi_pack { return pack('n', $mpilen).$val; } -# FIXME: genericize this to accept either RSA or DSA keys: +# FIXME: genericize these to accept either RSA or DSA keys: sub make_rsa_pub_key_body { my $key = shift; my $timestamp = shift; @@ -91,144 +296,241 @@ sub make_rsa_pub_key_body { return pack('CN', 4, $timestamp). - pack('C', 1). # RSA + pack('C', $asym_algos->{rsa}). mpi_pack($n). mpi_pack($e); - } -# expects an RSA key (public or private) and a timestamp -sub fingerprint { +sub make_rsa_sec_key_body { my $key = shift; my $timestamp = shift; - my $rsabody = make_rsa_pub_key_body($key, $timestamp); + # we're not using $a and $b, but we need them to get to $c. + my ($n, $e, $d, $p, $q) = $key->get_key_parameters(); - return Digest::SHA1::sha1(pack('Cn', 0x99, length($rsabody)).$rsabody); -} + my $c3 = modular_multi_inverse($p, $q); -# we're just not dealing with newline business right now. slurp in -# the whole file. -undef $/; -my $buf = ; + my $secret_material = mpi_pack($d). + mpi_pack($p). + mpi_pack($q). + mpi_pack($c3); + # according to Crypt::OpenSSL::RSA, the closest value we can get out + # of get_key_parameters is 1/q mod p; but according to sec 5.5.3 of + # RFC 4880, we're actually looking for u, the multiplicative inverse + # of p, mod q. This is why we're calculating the value directly + # with modular_multi_inverse. -my $rsa = Crypt::OpenSSL::RSA->new_private_key($buf); - -$rsa->use_sha1_hash(); -$rsa->use_no_padding(); - -if (! $rsa->check_key()) { - die "key does not check"; + return + pack('CN', 4, $timestamp). + pack('C', $asym_algos->{rsa}). + mpi_pack($n). + mpi_pack($e). + pack('C', 0). # seckey material is not encrypted -- see RFC 4880 sec 5.5.3 + $secret_material. + pack('n', simple_checksum($secret_material)); } -my $version = pack('C', 4); -# strong assertion of identity: -my $sigtype = pack('C', 0x13); -# RSA -my $pubkey_algo = pack('C', 1); -# SHA1 -my $hash_algo = pack('C', 2); - -# FIXME: i'm worried about generating a bazillion new OpenPGP -# certificates from the same key, which could easily happen if you run -# this script more than once against the same key. How can we prevent -# this? - -# could an environment variable (if set) override the current time? -my $timestamp = time(); - -my $creation_time_packet = pack('CCN', 5, 2, $timestamp); - - -# usage: signing and certification: -my $flags = 0x03; -my $usage_packet = pack('CCC', 2, 27, $flags); - - -# FIXME: HARDCODED: how should we determine how far off to set the -# expiration date? default is to expire in 2 days, which is insanely -# short (but good for testing). -my $expires_in = 86400*2; -my $expiration_packet = pack('CCN', 5, 9, $expires_in); +# expects an RSA key (public or private) and a timestamp +sub fingerprint { + my $key = shift; + my $timestamp = shift; + my $rsabody = make_rsa_pub_key_body($key, $timestamp); -# prefer AES-256, AES-192, AES-128, CAST5, 3DES: -my $pref_sym_algos = pack('CCCCCCC', 6, 11, 9, 8, 7, 3, 2); + return Digest::SHA1::sha1(pack('Cn', 0x99, length($rsabody)).$rsabody); +} -# prefer SHA-1, SHA-256, RIPE-MD/160 -my $pref_hash_algos = pack('CCCCC', 4, 21, 2, 8, 3); -# prefer ZLIB, BZip2, ZIP -my $pref_zip_algos = pack('CCCCC', 4, 22, 2, 3, 1); +# FIXME: handle DSA keys as well! +sub pem2openpgp { + my $rsa = shift; + my $uid = shift; + my $args = shift; -# we support the MDC feature: -my $features = pack('CCC', 2, 30, 1); + $rsa->use_sha1_hash(); -# keyserver preference: only owner modify (???): -my $keyserver_pref = pack('CCC', 2, 23, 0x80); + # see page 22 of RFC 4880 for why i think this is the right padding + # choice to use: + $rsa->use_pkcs1_padding(); -my $subpackets_to_be_hashed = - $creation_time_packet. - $usage_packet. - $expiration_packet. - $pref_sym_algos. - $pref_hash_algos. - $pref_zip_algos. - $features. - $keyserver_pref; + if (! $rsa->check_key()) { + die "key does not check"; + } -my $subpacket_octets = pack('n', length($subpackets_to_be_hashed)); + my $version = pack('C', 4); + # strong assertion of identity: + my $sigtype = pack('C', $sig_types->{positive_certification}); + # RSA + my $pubkey_algo = pack('C', $asym_algos->{rsa}); + # SHA1 + my $hash_algo = pack('C', $digests->{sha1}); + + # FIXME: i'm worried about generating a bazillion new OpenPGP + # certificates from the same key, which could easily happen if you run + # this script more than once against the same key (because the + # timestamps will differ). How can we prevent this? + + # this environment variable (if set) overrides the current time, to + # be able to create a standard key? If we read the key from a file + # instead of stdin, should we use the creation time on the file? + my $timestamp = 0; + if (defined $args->{timestamp}) { + $timestamp = ($args->{timestamp} + 0); + } else { + $timestamp = time(); + } -my $sig_data_to_be_hashed = - $version. - $sigtype. - $pubkey_algo. - $hash_algo. - $subpacket_octets. - $subpackets_to_be_hashed; + my $creation_time_packet = pack('CCN', 5, $subpacket_types->{sig_creation_time}, $timestamp); -my $pubkey = make_rsa_pub_key_body($rsa, $timestamp); -#open(KEYFILE, "{usage_flags}) { + $flags = $usage_flags->{certify}; + } else { + my @ff = split(",", $args->{usage_flags}); + foreach my $f (@ff) { + if (! defined $usage_flags->{$f}) { + die "No such flag $f"; + } + $flags |= $usage_flags->{$f}; + } + } -# take the last 8 bytes of the fingerprint as the keyid: -my $keyid = substr(fingerprint($rsa, $timestamp), 20 - 8, 8); + my $usage_packet = pack('CCC', 2, $subpacket_types->{usage_flags}, $flags); -# the v4 signature trailer is: -# version number, literal 0xff, and then a 4-byte count of the -# signature data itself. -my $trailer = pack('CCN', 4, 0xff, length($sig_data_to_be_hashed)); + # how should we determine how far off to set the expiration date? + # default is no expiration. Specify the timestamp in seconds from the + # key creation. + my $expiration_packet = ''; + if (defined $args->{expiration}) { + my $expires_in = $args->{expiration} + 0; + $expiration_packet = pack('CCN', 5, $subpacket_types->{key_expiration_time}, $expires_in); + } -my $uid_data = - pack('CN', 0xb4, length($uid)). - $uid; -my $datatosign = - $key_data. - $uid_data. - $sig_data_to_be_hashed. - $trailer; + # prefer AES-256, AES-192, AES-128, CAST5, 3DES: + my $pref_sym_algos = pack('CCCCCCC', 6, $subpacket_types->{preferred_cipher}, + $ciphers->{aes256}, + $ciphers->{aes192}, + $ciphers->{aes128}, + $ciphers->{cast5}, + $ciphers->{tripledes} + ); + + # prefer SHA-1, SHA-256, RIPE-MD/160 + my $pref_hash_algos = pack('CCCCC', 4, $subpacket_types->{preferred_digest}, + $digests->{sha1}, + $digests->{sha256}, + $digests->{ripemd160} + ); + + # prefer ZLIB, BZip2, ZIP + my $pref_zip_algos = pack('CCCCC', 4, $subpacket_types->{preferred_compression}, + $zips->{zlib}, + $zips->{bzip2}, + $zips->{zip} + ); + + # we support the MDC feature: + my $feature_subpacket = pack('CCC', 2, $subpacket_types->{features}, + $features->{mdc}); + + # keyserver preference: only owner modify (???): + my $keyserver_pref = pack('CCC', 2, $subpacket_types->{keyserver_prefs}, + $keyserver_prefs->{nomodify}); + + my $subpackets_to_be_hashed = + $creation_time_packet. + $usage_packet. + $expiration_packet. + $pref_sym_algos. + $pref_hash_algos. + $pref_zip_algos. + $feature_subpacket. + $keyserver_pref; + + my $subpacket_octets = pack('n', length($subpackets_to_be_hashed)); + + my $sig_data_to_be_hashed = + $version. + $sigtype. + $pubkey_algo. + $hash_algo. + $subpacket_octets. + $subpackets_to_be_hashed; + + my $pubkey = make_rsa_pub_key_body($rsa, $timestamp); + my $seckey = make_rsa_sec_key_body($rsa, $timestamp); + + # this is for signing. it needs to be an old-style header with a + # 2-packet octet count. + + my $key_data = make_packet($packet_types->{pubkey}, $pubkey, {'packet_length'=>2}); + + # take the last 8 bytes of the fingerprint as the keyid: + my $keyid = substr(fingerprint($rsa, $timestamp), 20 - 8, 8); + + # the v4 signature trailer is: + + # version number, literal 0xff, and then a 4-byte count of the + # signature data itself. + my $trailer = pack('CCN', 4, 0xff, length($sig_data_to_be_hashed)); + + my $uid_data = + pack('CN', 0xb4, length($uid)). + $uid; + + my $datatosign = + $key_data. + $uid_data. + $sig_data_to_be_hashed. + $trailer; + + my $data_hash = Digest::SHA1::sha1_hex($datatosign); + + my $issuer_packet = pack('CCa8', 9, $subpacket_types->{issuer}, $keyid); + + my $sig = Crypt::OpenSSL::Bignum->new_from_bin($rsa->sign($datatosign)); + + my $sig_body = + $sig_data_to_be_hashed. + pack('n', length($issuer_packet)). + $issuer_packet. + pack('n', hex(substr($data_hash, 0, 4))). + mpi_pack($sig); -my $data_hash = Digest::SHA1::sha1_hex($datatosign); + return + make_packet($packet_types->{seckey}, $seckey). + make_packet($packet_types->{uid}, $uid). + make_packet($packet_types->{sig}, $sig_body); +} -my $issuer_packet = pack('CCa8', 9, 16, $keyid); +my $rsa; +my $stdin; +if (defined $ENV{PEM2OPENPGP_NEWKEY}) { + $rsa = Crypt::OpenSSL::RSA->generate_key($ENV{PEM2OPENPGP_NEWKEY}); +} else { + $stdin = do { + local $/; # slurp! + ; + }; -my $sig = Crypt::OpenSSL::Bignum->new_from_bin($rsa->sign($datatosign)); + $rsa = Crypt::OpenSSL::RSA->new_private_key($stdin); +} -my $sig_body = - $sig_data_to_be_hashed. - pack('n', length($issuer_packet)). - $issuer_packet. - pack('n', hex(substr($data_hash, 0, 4))). - mpi_pack($sig); +my $uid = shift; -print - make_packet(6, $pubkey). - make_packet(13, $uid). - make_packet(2, $sig_body); +# FIXME: fail if there is no given user ID; or should we default to +# hostname_long() from Sys::Hostname::Long ? +print pem2openpgp($rsa, + $uid, + { timestamp => $ENV{PEM2OPENPGP_TIMESTAMP}, + expiration => $ENV{PEM2OPENPGP_EXPIRATION}, + usage_flags => $ENV{PEM2OPENPGP_USAGE_FLAGS}, + } + );