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/*
* Program to generate cryptographic keys for ntp clients and servers
*
* This program generates password encrypted data files for use with the
* Autokey security protocol and Network Time Protocol Version 4. Files
* are prefixed with a header giving the name and date of creation
* followed by a type-specific descriptive label and PEM-encoded data
* structure compatible with programs of the OpenSSL library.
*
* All file names are like "ntpkey_<type>_<hostname>.<filestamp>", where
* <type> is the file type, <hostname> the generating host name and
* <filestamp> the generation time in NTP seconds. The NTP programs
* expect generic names such as "ntpkey_<type>_whimsy.udel.edu" with the
* association maintained by soft links. Following is a list of file
* types; the first line is the file name and the second link name.
*
* ntpkey_MD5key_<hostname>.<filestamp>
* MD5 (128-bit) keys used to compute message digests in symmetric
* key cryptography
*
* ntpkey_RSAhost_<hostname>.<filestamp>
* ntpkey_host_<hostname>
* RSA private/public host key pair used for public key signatures
*
* ntpkey_RSAsign_<hostname>.<filestamp>
* ntpkey_sign_<hostname>
* RSA private/public sign key pair used for public key signatures
*
* ntpkey_DSAsign_<hostname>.<filestamp>
* ntpkey_sign_<hostname>
* DSA Private/public sign key pair used for public key signatures
*
* Available digest/signature schemes
*
* RSA: RSA-MD2, RSA-MD5, RSA-SHA, RSA-SHA1, RSA-MDC2, EVP-RIPEMD160
* DSA: DSA-SHA, DSA-SHA1
*
* ntpkey_XXXcert_<hostname>.<filestamp>
* ntpkey_cert_<hostname>
* X509v3 certificate using RSA or DSA public keys and signatures.
* XXX is a code identifying the message digest and signature
* encryption algorithm
*
* Identity schemes. The key type par is used for the challenge; the key
* type key is used for the response.
*
* ntpkey_IFFkey_<groupname>.<filestamp>
* ntpkey_iffkey_<groupname>
* Schnorr (IFF) identity parameters and keys
*
* ntpkey_GQkey_<groupname>.<filestamp>,
* ntpkey_gqkey_<groupname>
* Guillou-Quisquater (GQ) identity parameters and keys
*
* ntpkey_MVkeyX_<groupname>.<filestamp>,
* ntpkey_mvkey_<groupname>
* Mu-Varadharajan (MV) identity parameters and keys
*
* Note: Once in a while because of some statistical fluke this program
* fails to generate and verify some cryptographic data, as indicated by
* exit status -1. In this case simply run the program again. If the
* program does complete with exit code 0, the data are correct as
* verified.
*
* These cryptographic routines are characterized by the prime modulus
* size in bits. The default value of 512 bits is a compromise between
* cryptographic strength and computing time and is ordinarily
* considered adequate for this application. The routines have been
* tested with sizes of 256, 512, 1024 and 2048 bits. Not all message
* digest and signature encryption schemes work with sizes less than 512
* bits. The computing time for sizes greater than 2048 bits is
* prohibitive on all but the fastest processors. An UltraSPARC Blade
* 1000 took something over nine minutes to generate and verify the
* values with size 2048. An old SPARC IPC would take a week.
*
* The OpenSSL library used by this program expects a random seed file.
* As described in the OpenSSL documentation, the file name defaults to
* first the RANDFILE environment variable in the user's home directory
* and then .rnd in the user's home directory.
*/
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include "ntp.h"
#include "ntp_random.h"
#include "ntp_stdlib.h"
#include "ntp_assert.h"
#include "ntp_libopts.h"
#include "ntp_unixtime.h"
#include "ntp-keygen-opts.h"
#ifdef OPENSSL
#include "openssl/bn.h"
#include "openssl/evp.h"
#include "openssl/err.h"
#include "openssl/rand.h"
#include "openssl/pem.h"
#include "openssl/x509v3.h"
#include <openssl/objects.h>
#endif /* OPENSSL */
#include <ssl_applink.c>
/*
* Cryptodefines
*/
#define MD5KEYS 10 /* number of keys generated of each type */
#define MD5SIZE 20 /* maximum key size */
#define YEAR ((long)365) /* one year in days */
#ifdef AUTOKEY
#define PLEN 512 /* default prime modulus size (bits) */
#define ILEN 256 /* default identity modulus size (bits) */
#define MVMAX 100 /* max MV parameters */
/*
* Strings used in X509v3 extension fields
*/
#define KEY_USAGE "digitalSignature,keyCertSign"
#define BASIC_CONSTRAINTS "critical,CA:TRUE"
#define EXT_KEY_PRIVATE "private"
#define EXT_KEY_TRUST "trustRoot"
#endif /* AUTOKEY */
/*
* Prototypes
*/
FILE *fheader (const char *, const char *, const char *);
int gen_md5 (char *);
void followlink (char *, size_t);
#ifdef AUTOKEY
EVP_PKEY *gen_rsa (char *);
EVP_PKEY *gen_dsa (char *);
EVP_PKEY *gen_iffkey (char *);
EVP_PKEY *gen_gqkey (char *);
EVP_PKEY *gen_mvkey (char *, EVP_PKEY **);
void gen_mvserv (char *, EVP_PKEY **);
int x509 (EVP_PKEY *, const EVP_MD *, char *, char *,
char *);
void cb (int, int, void *);
EVP_PKEY *genkey (char *, char *);
EVP_PKEY *readkey (char *, char *, u_int *, EVP_PKEY **);
void writekey (char *, char *, u_int *, EVP_PKEY **);
u_long asn2ntp (ASN1_TIME *);
#endif /* AUTOKEY */
/*
* Program variables
*/
extern char *optarg; /* command line argument */
char *progname;
u_int lifetime = YEAR; /* certificate lifetime (days) */
int nkeys; /* MV keys */
time_t epoch; /* Unix epoch (seconds) since 1970 */
u_int fstamp; /* NTP filestamp */
char hostbuf[MAXHOSTNAME + 1];
char *hostname = NULL; /* host, used in cert filenames */
char *groupname = NULL; /* group name */
char certnamebuf[2 * sizeof(hostbuf)];
char *certname = NULL; /* certificate subject/issuer name */
char *passwd1 = NULL; /* input private key password */
char *passwd2 = NULL; /* output private key password */
char filename[MAXFILENAME + 1]; /* file name */
#ifdef AUTOKEY
u_int modulus = PLEN; /* prime modulus size (bits) */
u_int modulus2 = ILEN; /* identity modulus size (bits) */
long d0, d1, d2, d3; /* callback counters */
const EVP_CIPHER * cipher = NULL;
#endif /* AUTOKEY */
#ifdef SYS_WINNT
BOOL init_randfile();
/*
* Don't try to follow symbolic links on Windows. Assume link == file.
*/
int
readlink(
char * link,
char * file,
int len
)
{
return strlen(file);
}
/*
* Don't try to create symbolic links on Windows, that is supported on
* Vista and later only. Instead, if CreateHardLink is available (XP
* and later), hardlink the linkname to the original filename. On
* earlier systems, user must rename file to match expected link for
* ntpd to find it. To allow building a ntp-keygen.exe which loads on
* Windows pre-XP, runtime link to CreateHardLinkA().
*/
int
symlink(
char * filename,
char* linkname
)
{
typedef BOOL (WINAPI *PCREATEHARDLINKA)(
__in LPCSTR lpFileName,
__in LPCSTR lpExistingFileName,
__reserved LPSECURITY_ATTRIBUTES lpSA
);
static PCREATEHARDLINKA pCreateHardLinkA;
static int tried;
HMODULE hDll;
FARPROC pfn;
int link_created;
int saved_errno;
if (!tried) {
tried = TRUE;
hDll = LoadLibrary("kernel32");
pfn = GetProcAddress(hDll, "CreateHardLinkA");
pCreateHardLinkA = (PCREATEHARDLINKA)pfn;
}
if (NULL == pCreateHardLinkA) {
errno = ENOSYS;
return -1;
}
link_created = (*pCreateHardLinkA)(linkname, filename, NULL);
if (link_created)
return 0;
saved_errno = GetLastError(); /* yes we play loose */
mfprintf(stderr, "Create hard link %s to %s failed: %m\n",
linkname, filename);
errno = saved_errno;
return -1;
}
void
InitWin32Sockets() {
WORD wVersionRequested;
WSADATA wsaData;
wVersionRequested = MAKEWORD(2,0);
if (WSAStartup(wVersionRequested, &wsaData))
{
fprintf(stderr, "No useable winsock.dll\n");
exit(1);
}
}
#endif /* SYS_WINNT */
/*
* followlink() - replace filename with its target if symlink.
*
* Some readlink() implementations do not null-terminate the result.
*/
void
followlink(
char * fname,
size_t bufsiz
)
{
int len;
REQUIRE(bufsiz > 0);
len = readlink(fname, fname, (int)bufsiz);
if (len < 0 ) {
fname[0] = '\0';
return;
}
if (len > (int)bufsiz - 1)
len = (int)bufsiz - 1;
fname[len] = '\0';
}
/*
* Main program
*/
int
main(
int argc, /* command line options */
char **argv
)
{
struct timeval tv; /* initialization vector */
int md5key = 0; /* generate MD5 keys */
int optct; /* option count */
#ifdef AUTOKEY
X509 *cert = NULL; /* X509 certificate */
X509_EXTENSION *ext; /* X509v3 extension */
EVP_PKEY *pkey_host = NULL; /* host key */
EVP_PKEY *pkey_sign = NULL; /* sign key */
EVP_PKEY *pkey_iffkey = NULL; /* IFF sever keys */
EVP_PKEY *pkey_gqkey = NULL; /* GQ server keys */
EVP_PKEY *pkey_mvkey = NULL; /* MV trusted agen keys */
EVP_PKEY *pkey_mvpar[MVMAX]; /* MV cleient keys */
int hostkey = 0; /* generate RSA keys */
int iffkey = 0; /* generate IFF keys */
int gqkey = 0; /* generate GQ keys */
int mvkey = 0; /* update MV keys */
int mvpar = 0; /* generate MV parameters */
char *sign = NULL; /* sign key */
EVP_PKEY *pkey = NULL; /* temp key */
const EVP_MD *ectx; /* EVP digest */
char pathbuf[MAXFILENAME + 1];
const char *scheme = NULL; /* digest/signature scheme */
const char *ciphername = NULL; /* to encrypt priv. key */
char *exten = NULL; /* private extension */
char *grpkey = NULL; /* identity extension */
int nid; /* X509 digest/signature scheme */
FILE *fstr = NULL; /* file handle */
char groupbuf[MAXHOSTNAME + 1];
u_int temp;
BIO * bp;
int i, cnt;
char * ptr;
#endif /* AUTOKEY */
progname = argv[0];
#ifdef SYS_WINNT
/* Initialize before OpenSSL checks */
InitWin32Sockets();
if (!init_randfile())
fprintf(stderr, "Unable to initialize .rnd file\n");
ssl_applink();
#endif
#ifdef OPENSSL
ssl_check_version();
#endif /* OPENSSL */
/*
* Process options, initialize host name and timestamp.
* gethostname() won't null-terminate if hostname is exactly the
* length provided for the buffer.
*/
gethostname(hostbuf, sizeof(hostbuf) - 1);
hostbuf[COUNTOF(hostbuf) - 1] = '\0';
hostname = hostbuf;
groupname = hostbuf;
passwd1 = hostbuf;
passwd2 = NULL;
GETTIMEOFDAY(&tv, NULL);
ntp_srandom((u_long)(tv.tv_sec + tv.tv_usec));
epoch = tv.tv_sec;
fstamp = (u_int)(epoch + JAN_1970);
optct = ntpOptionProcess(&ntp_keygenOptions, argc, argv);
argc -= optct;
argv += optct;
#ifdef OPENSSL
if (SSLeay() == SSLEAY_VERSION_NUMBER)
fprintf(stderr, "Using OpenSSL version %s\n",
SSLeay_version(SSLEAY_VERSION));
else
fprintf(stderr, "Built against OpenSSL %s, using version %s\n",
OPENSSL_VERSION_TEXT, SSLeay_version(SSLEAY_VERSION));
#endif /* OPENSSL */
debug = OPT_VALUE_SET_DEBUG_LEVEL;
if (HAVE_OPT( MD5KEY ))
md5key++;
#ifdef AUTOKEY
if (HAVE_OPT( PVT_PASSWD ))
passwd1 = estrdup(OPT_ARG( PVT_PASSWD ));
if (HAVE_OPT( GET_PVT_PASSWD ))
passwd2 = estrdup(OPT_ARG( GET_PVT_PASSWD ));
if (HAVE_OPT( HOST_KEY ))
hostkey++;
if (HAVE_OPT( SIGN_KEY ))
sign = estrdup(OPT_ARG( SIGN_KEY ));
if (HAVE_OPT( GQ_PARAMS ))
gqkey++;
if (HAVE_OPT( IFFKEY ))
iffkey++;
if (HAVE_OPT( MV_PARAMS )) {
mvkey++;
nkeys = OPT_VALUE_MV_PARAMS;
}
if (HAVE_OPT( MV_KEYS )) {
mvpar++;
nkeys = OPT_VALUE_MV_KEYS;
}
if (HAVE_OPT( IMBITS ))
modulus2 = OPT_VALUE_IMBITS;
if (HAVE_OPT( MODULUS ))
modulus = OPT_VALUE_MODULUS;
if (HAVE_OPT( CERTIFICATE ))
scheme = OPT_ARG( CERTIFICATE );
if (HAVE_OPT( CIPHER ))
ciphername = OPT_ARG( CIPHER );
if (HAVE_OPT( SUBJECT_NAME ))
hostname = estrdup(OPT_ARG( SUBJECT_NAME ));
if (HAVE_OPT( IDENT ))
groupname = estrdup(OPT_ARG( IDENT ));
if (HAVE_OPT( LIFETIME ))
lifetime = OPT_VALUE_LIFETIME;
if (HAVE_OPT( PVT_CERT ))
exten = EXT_KEY_PRIVATE;
if (HAVE_OPT( TRUSTED_CERT ))
exten = EXT_KEY_TRUST;
/*
* Remove the group name from the hostname variable used
* in host and sign certificate file names.
*/
if (hostname != hostbuf)
ptr = strchr(hostname, '@');
else
ptr = NULL;
if (ptr != NULL) {
*ptr = '\0';
groupname = estrdup(ptr + 1);
/* -s @group is equivalent to -i group, host unch. */
if (ptr == hostname)
hostname = hostbuf;
}
/*
* Derive host certificate issuer/subject names from host name
* and optional group. If no groupname is provided, the issuer
* and subject is the hostname with no '@group', and the
* groupname variable is pointed to hostname for use in IFF, GQ,
* and MV parameters file names.
*/
if (groupname == hostbuf) {
certname = hostname;
} else {
snprintf(certnamebuf, sizeof(certnamebuf), "%s@%s",
hostname, groupname);
certname = certnamebuf;
}
/*
* Seed random number generator and grow weeds.
*/
ERR_load_crypto_strings();
OpenSSL_add_all_algorithms();
if (!RAND_status()) {
if (RAND_file_name(pathbuf, sizeof(pathbuf)) == NULL) {
fprintf(stderr, "RAND_file_name %s\n",
ERR_error_string(ERR_get_error(), NULL));
exit (-1);
}
temp = RAND_load_file(pathbuf, -1);
if (temp == 0) {
fprintf(stderr,
"RAND_load_file %s not found or empty\n",
pathbuf);
exit (-1);
}
fprintf(stderr,
"Random seed file %s %u bytes\n", pathbuf, temp);
RAND_add(&epoch, sizeof(epoch), 4.0);
}
#endif /* AUTOKEY */
/*
* Create new unencrypted MD5 keys file if requested. If this
* option is selected, ignore all other options.
*/
if (md5key) {
gen_md5("md5");
exit (0);
}
#ifdef AUTOKEY
/*
* Load previous certificate if available.
*/
snprintf(filename, sizeof(filename), "ntpkey_cert_%s", hostname);
if ((fstr = fopen(filename, "r")) != NULL) {
cert = PEM_read_X509(fstr, NULL, NULL, NULL);
fclose(fstr);
}
if (cert != NULL) {
/*
* Extract subject name.
*/
X509_NAME_oneline(X509_get_subject_name(cert), groupbuf,
MAXFILENAME);
/*
* Extract digest/signature scheme.
*/
if (scheme == NULL) {
nid = OBJ_obj2nid(cert->cert_info->
signature->algorithm);
scheme = OBJ_nid2sn(nid);
}
/*
* If a key_usage extension field is present, determine
* whether this is a trusted or private certificate.
*/
if (exten == NULL) {
ptr = strstr(groupbuf, "CN=");
cnt = X509_get_ext_count(cert);
for (i = 0; i < cnt; i++) {
ext = X509_get_ext(cert, i);
if (OBJ_obj2nid(ext->object) ==
NID_ext_key_usage) {
bp = BIO_new(BIO_s_mem());
X509V3_EXT_print(bp, ext, 0, 0);
BIO_gets(bp, pathbuf,
MAXFILENAME);
BIO_free(bp);
if (strcmp(pathbuf,
"Trust Root") == 0)
exten = EXT_KEY_TRUST;
else if (strcmp(pathbuf,
"Private") == 0)
exten = EXT_KEY_PRIVATE;
certname = estrdup(ptr + 3);
}
}
}
}
if (scheme == NULL)
scheme = "RSA-MD5";
if (ciphername == NULL)
ciphername = "des-ede3-cbc";
cipher = EVP_get_cipherbyname(ciphername);
if (cipher == NULL) {
fprintf(stderr, "Unknown cipher %s\n", ciphername);
exit(-1);
}
fprintf(stderr, "Using host %s group %s\n", hostname,
groupname);
/*
* Create a new encrypted RSA host key file if requested;
* otherwise, look for an existing host key file. If not found,
* create a new encrypted RSA host key file. If that fails, go
* no further.
*/
if (hostkey)
pkey_host = genkey("RSA", "host");
if (pkey_host == NULL) {
snprintf(filename, sizeof(filename), "ntpkey_host_%s", hostname);
pkey_host = readkey(filename, passwd1, &fstamp, NULL);
if (pkey_host != NULL) {
followlink(filename, sizeof(filename));
fprintf(stderr, "Using host key %s\n",
filename);
} else {
pkey_host = genkey("RSA", "host");
}
}
if (pkey_host == NULL) {
fprintf(stderr, "Generating host key fails\n");
exit(-1);
}
/*
* Create new encrypted RSA or DSA sign keys file if requested;
* otherwise, look for an existing sign key file. If not found,
* use the host key instead.
*/
if (sign != NULL)
pkey_sign = genkey(sign, "sign");
if (pkey_sign == NULL) {
snprintf(filename, sizeof(filename), "ntpkey_sign_%s",
hostname);
pkey_sign = readkey(filename, passwd1, &fstamp, NULL);
if (pkey_sign != NULL) {
followlink(filename, sizeof(filename));
fprintf(stderr, "Using sign key %s\n",
filename);
} else {
pkey_sign = pkey_host;
fprintf(stderr, "Using host key as sign key\n");
}
}
/*
* Create new encrypted GQ server keys file if requested;
* otherwise, look for an exisiting file. If found, fetch the
* public key for the certificate.
*/
if (gqkey)
pkey_gqkey = gen_gqkey("gqkey");
if (pkey_gqkey == NULL) {
snprintf(filename, sizeof(filename), "ntpkey_gqkey_%s",
groupname);
pkey_gqkey = readkey(filename, passwd1, &fstamp, NULL);
if (pkey_gqkey != NULL) {
followlink(filename, sizeof(filename));
fprintf(stderr, "Using GQ parameters %s\n",
filename);
}
}
if (pkey_gqkey != NULL)
grpkey = BN_bn2hex(pkey_gqkey->pkey.rsa->q);
/*
* Write the nonencrypted GQ client parameters to the stdout
* stream. The parameter file is the server key file with the
* private key obscured.
*/
if (pkey_gqkey != NULL && HAVE_OPT(ID_KEY)) {
RSA *rsa;
snprintf(filename, sizeof(filename),
"ntpkey_gqpar_%s.%u", groupname, fstamp);
fprintf(stderr, "Writing GQ parameters %s to stdout\n",
filename);
fprintf(stdout, "# %s\n# %s\n", filename,
ctime(&epoch));
rsa = pkey_gqkey->pkey.rsa;
BN_copy(rsa->p, BN_value_one());
BN_copy(rsa->q, BN_value_one());
pkey = EVP_PKEY_new();
EVP_PKEY_assign_RSA(pkey, rsa);
PEM_write_PKCS8PrivateKey(stdout, pkey, NULL, NULL, 0,
NULL, NULL);
fflush(stdout);
if (debug)
RSA_print_fp(stderr, rsa, 0);
}
/*
* Write the encrypted GQ server keys to the stdout stream.
*/
if (pkey_gqkey != NULL && passwd2 != NULL) {
RSA *rsa;
snprintf(filename, sizeof(filename),
"ntpkey_gqkey_%s.%u", groupname, fstamp);
fprintf(stderr, "Writing GQ keys %s to stdout\n",
filename);
fprintf(stdout, "# %s\n# %s\n", filename,
ctime(&epoch));
rsa = pkey_gqkey->pkey.rsa;
pkey = EVP_PKEY_new();
EVP_PKEY_assign_RSA(pkey, rsa);
PEM_write_PKCS8PrivateKey(stdout, pkey, cipher, NULL, 0,
NULL, passwd2);
fflush(stdout);
if (debug)
RSA_print_fp(stderr, rsa, 0);
}
/*
* Create new encrypted IFF server keys file if requested;
* otherwise, look for existing file.
*/
if (iffkey)
pkey_iffkey = gen_iffkey("iffkey");
if (pkey_iffkey == NULL) {
snprintf(filename, sizeof(filename), "ntpkey_iffkey_%s",
groupname);
pkey_iffkey = readkey(filename, passwd1, &fstamp, NULL);
if (pkey_iffkey != NULL) {
followlink(filename, sizeof(filename));
fprintf(stderr, "Using IFF keys %s\n",
filename);
}
}
/*
* Write the nonencrypted IFF client parameters to the stdout
* stream. The parameter file is the server key file with the
* private key obscured.
*/
if (pkey_iffkey != NULL && HAVE_OPT(ID_KEY)) {
DSA *dsa;
snprintf(filename, sizeof(filename),
"ntpkey_iffpar_%s.%u", groupname, fstamp);
fprintf(stderr, "Writing IFF parameters %s to stdout\n",
filename);
fprintf(stdout, "# %s\n# %s\n", filename,
ctime(&epoch));
dsa = pkey_iffkey->pkey.dsa;
BN_copy(dsa->priv_key, BN_value_one());
pkey = EVP_PKEY_new();
EVP_PKEY_assign_DSA(pkey, dsa);
PEM_write_PKCS8PrivateKey(stdout, pkey, NULL, NULL, 0,
NULL, NULL);
fflush(stdout);
if (debug)
DSA_print_fp(stderr, dsa, 0);
}
/*
* Write the encrypted IFF server keys to the stdout stream.
*/
if (pkey_iffkey != NULL && passwd2 != NULL) {
DSA *dsa;
snprintf(filename, sizeof(filename),
"ntpkey_iffkey_%s.%u", groupname, fstamp);
fprintf(stderr, "Writing IFF keys %s to stdout\n",
filename);
fprintf(stdout, "# %s\n# %s\n", filename,
ctime(&epoch));
dsa = pkey_iffkey->pkey.dsa;
pkey = EVP_PKEY_new();
EVP_PKEY_assign_DSA(pkey, dsa);
PEM_write_PKCS8PrivateKey(stdout, pkey, cipher, NULL, 0,
NULL, passwd2);
fflush(stdout);
if (debug)
DSA_print_fp(stderr, dsa, 0);
}
/*
* Create new encrypted MV trusted-authority keys file if
* requested; otherwise, look for existing keys file.
*/
if (mvkey)
pkey_mvkey = gen_mvkey("mv", pkey_mvpar);
if (pkey_mvkey == NULL) {
snprintf(filename, sizeof(filename), "ntpkey_mvta_%s",
groupname);
pkey_mvkey = readkey(filename, passwd1, &fstamp,
pkey_mvpar);
if (pkey_mvkey != NULL) {
followlink(filename, sizeof(filename));
fprintf(stderr, "Using MV keys %s\n",
filename);
}
}
/*
* Write the nonencrypted MV client parameters to the stdout
* stream. For the moment, we always use the client parameters
* associated with client key 1.
*/
if (pkey_mvkey != NULL && HAVE_OPT(ID_KEY)) {
snprintf(filename, sizeof(filename),
"ntpkey_mvpar_%s.%u", groupname, fstamp);
fprintf(stderr, "Writing MV parameters %s to stdout\n",
filename);
fprintf(stdout, "# %s\n# %s\n", filename,
ctime(&epoch));
pkey = pkey_mvpar[2];
PEM_write_PKCS8PrivateKey(stdout, pkey, NULL, NULL, 0,
NULL, NULL);
fflush(stdout);
if (debug)
DSA_print_fp(stderr, pkey->pkey.dsa, 0);
}
/*
* Write the encrypted MV server keys to the stdout stream.
*/
if (pkey_mvkey != NULL && passwd2 != NULL) {
snprintf(filename, sizeof(filename),
"ntpkey_mvkey_%s.%u", groupname, fstamp);
fprintf(stderr, "Writing MV keys %s to stdout\n",
filename);
fprintf(stdout, "# %s\n# %s\n", filename,
ctime(&epoch));
pkey = pkey_mvpar[1];
PEM_write_PKCS8PrivateKey(stdout, pkey, cipher, NULL, 0,
NULL, passwd2);
fflush(stdout);
if (debug)
DSA_print_fp(stderr, pkey->pkey.dsa, 0);
}
/*
* Decode the digest/signature scheme and create the
* certificate. Do this every time we run the program.
*/
ectx = EVP_get_digestbyname(scheme);
if (ectx == NULL) {
fprintf(stderr,
"Invalid digest/signature combination %s\n",
scheme);
exit (-1);
}
x509(pkey_sign, ectx, grpkey, exten, certname);
#endif /* AUTOKEY */
exit(0);
}
/*
* Generate semi-random MD5 keys compatible with NTPv3 and NTPv4. Also,
* if OpenSSL is around, generate random SHA1 keys compatible with
* symmetric key cryptography.
*/
int
gen_md5(
char *id /* file name id */
)
{
u_char md5key[MD5SIZE + 1]; /* MD5 key */
FILE *str;
int i, j;
#ifdef OPENSSL
u_char keystr[MD5SIZE];
u_char hexstr[2 * MD5SIZE + 1];
u_char hex[] = "0123456789abcdef";
#endif /* OPENSSL */
str = fheader("MD5key", id, groupname);
for (i = 1; i <= MD5KEYS; i++) {
for (j = 0; j < MD5SIZE; j++) {
int temp;
while (1) {
temp = ntp_random() & 0xff;
if (temp == '#')
continue;
if (temp > 0x20 && temp < 0x7f)
break;
}
md5key[j] = (u_char)temp;
}
md5key[j] = '\0';
fprintf(str, "%2d MD5 %s # MD5 key\n", i,
md5key);
}
#ifdef OPENSSL
for (i = 1; i <= MD5KEYS; i++) {
RAND_bytes(keystr, 20);
for (j = 0; j < MD5SIZE; j++) {
hexstr[2 * j] = hex[keystr[j] >> 4];
hexstr[2 * j + 1] = hex[keystr[j] & 0xf];
}
hexstr[2 * MD5SIZE] = '\0';
fprintf(str, "%2d SHA1 %s # SHA1 key\n", i + MD5KEYS,
hexstr);
}
#endif /* OPENSSL */
fclose(str);
return (1);
}
#ifdef AUTOKEY
/*
* readkey - load cryptographic parameters and keys
*
* This routine loads a PEM-encoded file of given name and password and
* extracts the filestamp from the file name. It returns a pointer to
* the first key if valid, NULL if not.
*/
EVP_PKEY * /* public/private key pair */
readkey(
char *cp, /* file name */
char *passwd, /* password */
u_int *estamp, /* file stamp */
EVP_PKEY **evpars /* parameter list pointer */
)
{
FILE *str; /* file handle */
EVP_PKEY *pkey = NULL; /* public/private key */
u_int gstamp; /* filestamp */
char linkname[MAXFILENAME]; /* filestamp buffer) */
EVP_PKEY *parkey;
char *ptr;
int i;
/*
* Open the key file.
*/
str = fopen(cp, "r");
if (str == NULL)
return (NULL);
/*
* Read the filestamp, which is contained in the first line.
*/
if ((ptr = fgets(linkname, MAXFILENAME, str)) == NULL) {
fprintf(stderr, "Empty key file %s\n", cp);
fclose(str);
return (NULL);
}
if ((ptr = strrchr(ptr, '.')) == NULL) {
fprintf(stderr, "No filestamp found in %s\n", cp);
fclose(str);
return (NULL);
}
if (sscanf(++ptr, "%u", &gstamp) != 1) {
fprintf(stderr, "Invalid filestamp found in %s\n", cp);
fclose(str);
return (NULL);
}
/*
* Read and decrypt PEM-encoded private keys. The first one
* found is returned. If others are expected, add them to the
* parameter list.
*/
for (i = 0; i <= MVMAX - 1;) {
parkey = PEM_read_PrivateKey(str, NULL, NULL, passwd);
if (evpars != NULL) {
evpars[i++] = parkey;
evpars[i] = NULL;
}
if (parkey == NULL)
break;
if (pkey == NULL)
pkey = parkey;
if (debug) {
if (parkey->type == EVP_PKEY_DSA)
DSA_print_fp(stderr, parkey->pkey.dsa,
0);
else if (parkey->type == EVP_PKEY_RSA)
RSA_print_fp(stderr, parkey->pkey.rsa,
0);
}
}
fclose(str);
if (pkey == NULL) {
fprintf(stderr, "Corrupt file %s or wrong key %s\n%s\n",
cp, passwd, ERR_error_string(ERR_get_error(),
NULL));
exit (-1);
}
*estamp = gstamp;
return (pkey);
}
/*
* Generate RSA public/private key pair
*/
EVP_PKEY * /* public/private key pair */
gen_rsa(
char *id /* file name id */
)
{
EVP_PKEY *pkey; /* private key */
RSA *rsa; /* RSA parameters and key pair */
FILE *str;
fprintf(stderr, "Generating RSA keys (%d bits)...\n", modulus);
rsa = RSA_generate_key(modulus, 3, cb, "RSA");
fprintf(stderr, "\n");
if (rsa == NULL) {
fprintf(stderr, "RSA generate keys fails\n%s\n",
ERR_error_string(ERR_get_error(), NULL));
return (NULL);
}
/*
* For signature encryption it is not necessary that the RSA
* parameters be strictly groomed and once in a while the
* modulus turns out to be non-prime. Just for grins, we check
* the primality.
*/
if (!RSA_check_key(rsa)) {
fprintf(stderr, "Invalid RSA key\n%s\n",
ERR_error_string(ERR_get_error(), NULL));
RSA_free(rsa);
return (NULL);
}
/*
* Write the RSA parameters and keys as a RSA private key
* encoded in PEM.
*/
if (strcmp(id, "sign") == 0)
str = fheader("RSAsign", id, hostname);
else
str = fheader("RSAhost", id, hostname);
pkey = EVP_PKEY_new();
EVP_PKEY_assign_RSA(pkey, rsa);
PEM_write_PKCS8PrivateKey(str, pkey, cipher, NULL, 0, NULL,
passwd1);
fclose(str);
if (debug)
RSA_print_fp(stderr, rsa, 0);
return (pkey);
}
/*
* Generate DSA public/private key pair
*/
EVP_PKEY * /* public/private key pair */
gen_dsa(
char *id /* file name id */
)
{
EVP_PKEY *pkey; /* private key */
DSA *dsa; /* DSA parameters */
u_char seed[20]; /* seed for parameters */
FILE *str;
/*
* Generate DSA parameters.
*/
fprintf(stderr,
"Generating DSA parameters (%d bits)...\n", modulus);
RAND_bytes(seed, sizeof(seed));
dsa = DSA_generate_parameters(modulus, seed, sizeof(seed), NULL,
NULL, cb, "DSA");
fprintf(stderr, "\n");
if (dsa == NULL) {
fprintf(stderr, "DSA generate parameters fails\n%s\n",
ERR_error_string(ERR_get_error(), NULL));
return (NULL);
}
/*
* Generate DSA keys.
*/
fprintf(stderr, "Generating DSA keys (%d bits)...\n", modulus);
if (!DSA_generate_key(dsa)) {
fprintf(stderr, "DSA generate keys fails\n%s\n",
ERR_error_string(ERR_get_error(), NULL));
DSA_free(dsa);
return (NULL);
}
/*
* Write the DSA parameters and keys as a DSA private key
* encoded in PEM.
*/
str = fheader("DSAsign", id, hostname);
pkey = EVP_PKEY_new();
EVP_PKEY_assign_DSA(pkey, dsa);
PEM_write_PKCS8PrivateKey(str, pkey, cipher, NULL, 0, NULL,
passwd1);
fclose(str);
if (debug)
DSA_print_fp(stderr, dsa, 0);
return (pkey);
}
/*
***********************************************************************
* *
* The following routines implement the Schnorr (IFF) identity scheme *
* *
***********************************************************************
*
* The Schnorr (IFF) identity scheme is intended for use when
* certificates are generated by some other trusted certificate
* authority and the certificate cannot be used to convey public
* parameters. There are two kinds of files: encrypted server files that
* contain private and public values and nonencrypted client files that
* contain only public values. New generations of server files must be
* securely transmitted to all servers of the group; client files can be
* distributed by any means. The scheme is self contained and
* independent of new generations of host keys, sign keys and
* certificates.
*
* The IFF values hide in a DSA cuckoo structure which uses the same
* parameters. The values are used by an identity scheme based on DSA
* cryptography and described in Stimson p. 285. The p is a 512-bit
* prime, g a generator of Zp* and q a 160-bit prime that divides p - 1
* and is a qth root of 1 mod p; that is, g^q = 1 mod p. The TA rolls a
* private random group key b (0 < b < q) and public key v = g^b, then
* sends (p, q, g, b) to the servers and (p, q, g, v) to the clients.
* Alice challenges Bob to confirm identity using the protocol described
* below.
*
* How it works
*
* The scheme goes like this. Both Alice and Bob have the public primes
* p, q and generator g. The TA gives private key b to Bob and public
* key v to Alice.
*
* Alice rolls new random challenge r (o < r < q) and sends to Bob in
* the IFF request message. Bob rolls new random k (0 < k < q), then
* computes y = k + b r mod q and x = g^k mod p and sends (y, hash(x))
* to Alice in the response message. Besides making the response
* shorter, the hash makes it effectivey impossible for an intruder to
* solve for b by observing a number of these messages.
*
* Alice receives the response and computes g^y v^r mod p. After a bit
* of algebra, this simplifies to g^k. If the hash of this result
* matches hash(x), Alice knows that Bob has the group key b. The signed
* response binds this knowledge to Bob's private key and the public key
* previously received in his certificate.
*/
/*
* Generate Schnorr (IFF) keys.
*/
EVP_PKEY * /* DSA cuckoo nest */
gen_iffkey(
char *id /* file name id */
)
{
EVP_PKEY *pkey; /* private key */
DSA *dsa; /* DSA parameters */
u_char seed[20]; /* seed for parameters */
BN_CTX *ctx; /* BN working space */
BIGNUM *b, *r, *k, *u, *v, *w; /* BN temp */
FILE *str;
u_int temp;
/*
* Generate DSA parameters for use as IFF parameters.
*/
fprintf(stderr, "Generating IFF keys (%d bits)...\n",
modulus2);
RAND_bytes(seed, sizeof(seed));
dsa = DSA_generate_parameters(modulus2, seed, sizeof(seed), NULL,
NULL, cb, "IFF");
fprintf(stderr, "\n");
if (dsa == NULL) {
fprintf(stderr, "DSA generate parameters fails\n%s\n",
ERR_error_string(ERR_get_error(), NULL));
return (NULL);;
}
/*
* Generate the private and public keys. The DSA parameters and
* private key are distributed to the servers, while all except
* the private key are distributed to the clients.
*/
b = BN_new(); r = BN_new(); k = BN_new();
u = BN_new(); v = BN_new(); w = BN_new(); ctx = BN_CTX_new();
BN_rand(b, BN_num_bits(dsa->q), -1, 0); /* a */
BN_mod(b, b, dsa->q, ctx);
BN_sub(v, dsa->q, b);
BN_mod_exp(v, dsa->g, v, dsa->p, ctx); /* g^(q - b) mod p */
BN_mod_exp(u, dsa->g, b, dsa->p, ctx); /* g^b mod p */
BN_mod_mul(u, u, v, dsa->p, ctx);
temp = BN_is_one(u);
fprintf(stderr,
"Confirm g^(q - b) g^b = 1 mod p: %s\n", temp == 1 ?
"yes" : "no");
if (!temp) {
BN_free(b); BN_free(r); BN_free(k);
BN_free(u); BN_free(v); BN_free(w); BN_CTX_free(ctx);
return (NULL);
}
dsa->priv_key = BN_dup(b); /* private key */
dsa->pub_key = BN_dup(v); /* public key */
/*
* Here is a trial round of the protocol. First, Alice rolls
* random nonce r mod q and sends it to Bob. She needs only
* q from parameters.
*/
BN_rand(r, BN_num_bits(dsa->q), -1, 0); /* r */
BN_mod(r, r, dsa->q, ctx);
/*
* Bob rolls random nonce k mod q, computes y = k + b r mod q
* and x = g^k mod p, then sends (y, x) to Alice. He needs
* p, q and b from parameters and r from Alice.
*/
BN_rand(k, BN_num_bits(dsa->q), -1, 0); /* k, 0 < k < q */
BN_mod(k, k, dsa->q, ctx);
BN_mod_mul(v, dsa->priv_key, r, dsa->q, ctx); /* b r mod q */
BN_add(v, v, k);
BN_mod(v, v, dsa->q, ctx); /* y = k + b r mod q */
BN_mod_exp(u, dsa->g, k, dsa->p, ctx); /* x = g^k mod p */
/*
* Alice verifies x = g^y v^r to confirm that Bob has group key
* b. She needs p, q, g from parameters, (y, x) from Bob and the
* original r. We omit the detail here thatt only the hash of y
* is sent.
*/
BN_mod_exp(v, dsa->g, v, dsa->p, ctx); /* g^y mod p */
BN_mod_exp(w, dsa->pub_key, r, dsa->p, ctx); /* v^r */
BN_mod_mul(v, w, v, dsa->p, ctx); /* product mod p */
temp = BN_cmp(u, v);
fprintf(stderr,
"Confirm g^k = g^(k + b r) g^(q - b) r: %s\n", temp ==
0 ? "yes" : "no");
BN_free(b); BN_free(r); BN_free(k);
BN_free(u); BN_free(v); BN_free(w); BN_CTX_free(ctx);
if (temp != 0) {
DSA_free(dsa);
return (NULL);
}
/*
* Write the IFF keys as an encrypted DSA private key encoded in
* PEM.
*
* p modulus p
* q modulus q
* g generator g
* priv_key b
* public_key v
* kinv not used
* r not used
*/
str = fheader("IFFkey", id, groupname);
pkey = EVP_PKEY_new();
EVP_PKEY_assign_DSA(pkey, dsa);
PEM_write_PKCS8PrivateKey(str, pkey, cipher, NULL, 0, NULL,
passwd1);
fclose(str);
if (debug)
DSA_print_fp(stderr, dsa, 0);
return (pkey);
}
/*
***********************************************************************
* *
* The following routines implement the Guillou-Quisquater (GQ) *
* identity scheme *
* *
***********************************************************************
*
* The Guillou-Quisquater (GQ) identity scheme is intended for use when
* the certificate can be used to convey public parameters. The scheme
* uses a X509v3 certificate extension field do convey the public key of
* a private key known only to servers. There are two kinds of files:
* encrypted server files that contain private and public values and
* nonencrypted client files that contain only public values. New
* generations of server files must be securely transmitted to all
* servers of the group; client files can be distributed by any means.
* The scheme is self contained and independent of new generations of
* host keys and sign keys. The scheme is self contained and independent
* of new generations of host keys and sign keys.
*
* The GQ parameters hide in a RSA cuckoo structure which uses the same
* parameters. The values are used by an identity scheme based on RSA
* cryptography and described in Stimson p. 300 (with errors). The 512-
* bit public modulus is n = p q, where p and q are secret large primes.
* The TA rolls private random group key b as RSA exponent. These values
* are known to all group members.
*
* When rolling new certificates, a server recomputes the private and
* public keys. The private key u is a random roll, while the public key
* is the inverse obscured by the group key v = (u^-1)^b. These values
* replace the private and public keys normally generated by the RSA
* scheme. Alice challenges Bob to confirm identity using the protocol
* described below.
*
* How it works
*
* The scheme goes like this. Both Alice and Bob have the same modulus n
* and some random b as the group key. These values are computed and
* distributed in advance via secret means, although only the group key
* b is truly secret. Each has a private random private key u and public
* key (u^-1)^b, although not necessarily the same ones. Bob and Alice
* can regenerate the key pair from time to time without affecting
* operations. The public key is conveyed on the certificate in an
* extension field; the private key is never revealed.
*
* Alice rolls new random challenge r and sends to Bob in the GQ
* request message. Bob rolls new random k, then computes y = k u^r mod
* n and x = k^b mod n and sends (y, hash(x)) to Alice in the response
* message. Besides making the response shorter, the hash makes it
* effectivey impossible for an intruder to solve for b by observing
* a number of these messages.
*
* Alice receives the response and computes y^b v^r mod n. After a bit
* of algebra, this simplifies to k^b. If the hash of this result
* matches hash(x), Alice knows that Bob has the group key b. The signed
* response binds this knowledge to Bob's private key and the public key
* previously received in his certificate.
*/
/*
* Generate Guillou-Quisquater (GQ) parameters file.
*/
EVP_PKEY * /* RSA cuckoo nest */
gen_gqkey(
char *id /* file name id */
)
{
EVP_PKEY *pkey; /* private key */
RSA *rsa; /* RSA parameters */
BN_CTX *ctx; /* BN working space */
BIGNUM *u, *v, *g, *k, *r, *y; /* BN temps */
FILE *str;
u_int temp;
/*
* Generate RSA parameters for use as GQ parameters.
*/
fprintf(stderr,
"Generating GQ parameters (%d bits)...\n",
modulus2);
rsa = RSA_generate_key(modulus2, 3, cb, "GQ");
fprintf(stderr, "\n");
if (rsa == NULL) {
fprintf(stderr, "RSA generate keys fails\n%s\n",
ERR_error_string(ERR_get_error(), NULL));
return (NULL);
}
u = BN_new(); v = BN_new(); g = BN_new();
k = BN_new(); r = BN_new(); y = BN_new();
/*
* Generate the group key b, which is saved in the e member of
* the RSA structure. The group key is transmitted to each group
* member encrypted by the member private key.
*/
ctx = BN_CTX_new();
BN_rand(rsa->e, BN_num_bits(rsa->n), -1, 0); /* b */
BN_mod(rsa->e, rsa->e, rsa->n, ctx);
/*
* When generating his certificate, Bob rolls random private key
* u, then computes inverse v = u^-1.
*/
BN_rand(u, BN_num_bits(rsa->n), -1, 0); /* u */
BN_mod(u, u, rsa->n, ctx);
BN_mod_inverse(v, u, rsa->n, ctx); /* u^-1 mod n */
BN_mod_mul(k, v, u, rsa->n, ctx);
/*
* Bob computes public key v = (u^-1)^b, which is saved in an
* extension field on his certificate. We check that u^b v =
* 1 mod n.
*/
BN_mod_exp(v, v, rsa->e, rsa->n, ctx);
BN_mod_exp(g, u, rsa->e, rsa->n, ctx); /* u^b */
BN_mod_mul(g, g, v, rsa->n, ctx); /* u^b (u^-1)^b */
temp = BN_is_one(g);
fprintf(stderr,
"Confirm u^b (u^-1)^b = 1 mod n: %s\n", temp ? "yes" :
"no");
if (!temp) {
BN_free(u); BN_free(v);
BN_free(g); BN_free(k); BN_free(r); BN_free(y);
BN_CTX_free(ctx);
RSA_free(rsa);
return (NULL);
}
BN_copy(rsa->p, u); /* private key */
BN_copy(rsa->q, v); /* public key */
/*
* Here is a trial run of the protocol. First, Alice rolls
* random nonce r mod n and sends it to Bob. She needs only n
* from parameters.
*/
BN_rand(r, BN_num_bits(rsa->n), -1, 0); /* r */
BN_mod(r, r, rsa->n, ctx);
/*
* Bob rolls random nonce k mod n, computes y = k u^r mod n and
* g = k^b mod n, then sends (y, g) to Alice. He needs n, u, b
* from parameters and r from Alice.
*/
BN_rand(k, BN_num_bits(rsa->n), -1, 0); /* k */
BN_mod(k, k, rsa->n, ctx);
BN_mod_exp(y, rsa->p, r, rsa->n, ctx); /* u^r mod n */
BN_mod_mul(y, k, y, rsa->n, ctx); /* y = k u^r mod n */
BN_mod_exp(g, k, rsa->e, rsa->n, ctx); /* g = k^b mod n */
/*
* Alice verifies g = v^r y^b mod n to confirm that Bob has
* private key u. She needs n, g from parameters, public key v =
* (u^-1)^b from the certificate, (y, g) from Bob and the
* original r. We omit the detaul here that only the hash of g
* is sent.
*/
BN_mod_exp(v, rsa->q, r, rsa->n, ctx); /* v^r mod n */
BN_mod_exp(y, y, rsa->e, rsa->n, ctx); /* y^b mod n */
BN_mod_mul(y, v, y, rsa->n, ctx); /* v^r y^b mod n */
temp = BN_cmp(y, g);
fprintf(stderr, "Confirm g^k = v^r y^b mod n: %s\n", temp == 0 ?
"yes" : "no");
BN_CTX_free(ctx); BN_free(u); BN_free(v);
BN_free(g); BN_free(k); BN_free(r); BN_free(y);
if (temp != 0) {
RSA_free(rsa);
return (NULL);
}
/*
* Write the GQ parameter file as an encrypted RSA private key
* encoded in PEM.
*
* n modulus n
* e group key b
* d not used
* p private key u
* q public key (u^-1)^b
* dmp1 not used
* dmq1 not used
* iqmp not used
*/
BN_copy(rsa->d, BN_value_one());
BN_copy(rsa->dmp1, BN_value_one());
BN_copy(rsa->dmq1, BN_value_one());
BN_copy(rsa->iqmp, BN_value_one());
str = fheader("GQkey", id, groupname);
pkey = EVP_PKEY_new();
EVP_PKEY_assign_RSA(pkey, rsa);
PEM_write_PKCS8PrivateKey(str, pkey, cipher, NULL, 0, NULL,
passwd1);
fclose(str);
if (debug)
RSA_print_fp(stderr, rsa, 0);
return (pkey);
}
/*
***********************************************************************
* *
* The following routines implement the Mu-Varadharajan (MV) identity *
* scheme *
* *
***********************************************************************
*
* The Mu-Varadharajan (MV) cryptosystem was originally intended when
* servers broadcast messages to clients, but clients never send
* messages to servers. There is one encryption key for the server and a
* separate decryption key for each client. It operated something like a
* pay-per-view satellite broadcasting system where the session key is
* encrypted by the broadcaster and the decryption keys are held in a
* tamperproof set-top box.
*
* The MV parameters and private encryption key hide in a DSA cuckoo
* structure which uses the same parameters, but generated in a
* different way. The values are used in an encryption scheme similar to
* El Gamal cryptography and a polynomial formed from the expansion of
* product terms (x - x[j]), as described in Mu, Y., and V.
* Varadharajan: Robust and Secure Broadcasting, Proc. Indocrypt 2001,
* 223-231. The paper has significant errors and serious omissions.
*
* Let q be the product of n distinct primes s1[j] (j = 1...n), where
* each s1[j] has m significant bits. Let p be a prime p = 2 * q + 1, so
* that q and each s1[j] divide p - 1 and p has M = n * m + 1
* significant bits. Let g be a generator of Zp; that is, gcd(g, p - 1)
* = 1 and g^q = 1 mod p. We do modular arithmetic over Zq and then
* project into Zp* as exponents of g. Sometimes we have to compute an
* inverse b^-1 of random b in Zq, but for that purpose we require
* gcd(b, q) = 1. We expect M to be in the 500-bit range and n
* relatively small, like 30. These are the parameters of the scheme and
* they are expensive to compute.
*
* We set up an instance of the scheme as follows. A set of random
* values x[j] mod q (j = 1...n), are generated as the zeros of a
* polynomial of order n. The product terms (x - x[j]) are expanded to
* form coefficients a[i] mod q (i = 0...n) in powers of x. These are
* used as exponents of the generator g mod p to generate the private
* encryption key A. The pair (gbar, ghat) of public server keys and the
* pairs (xbar[j], xhat[j]) (j = 1...n) of private client keys are used
* to construct the decryption keys. The devil is in the details.
*
* This routine generates a private server encryption file including the
* private encryption key E and partial decryption keys gbar and ghat.
* It then generates public client decryption files including the public
* keys xbar[j] and xhat[j] for each client j. The partial decryption
* files are used to compute the inverse of E. These values are suitably
* blinded so secrets are not revealed.
*
* The distinguishing characteristic of this scheme is the capability to
* revoke keys. Included in the calculation of E, gbar and ghat is the
* product s = prod(s1[j]) (j = 1...n) above. If the factor s1[j] is
* subsequently removed from the product and E, gbar and ghat
* recomputed, the jth client will no longer be able to compute E^-1 and
* thus unable to decrypt the messageblock.
*
* How it works
*
* The scheme goes like this. Bob has the server values (p, E, q,
* gbar, ghat) and Alice has the client values (p, xbar, xhat).
*
* Alice rolls new random nonce r mod p and sends to Bob in the MV
* request message. Bob rolls random nonce k mod q, encrypts y = r E^k
* mod p and sends (y, gbar^k, ghat^k) to Alice.
*
* Alice receives the response and computes the inverse (E^k)^-1 from
* the partial decryption keys gbar^k, ghat^k, xbar and xhat. She then
* decrypts y and verifies it matches the original r. The signed
* response binds this knowledge to Bob's private key and the public key
* previously received in his certificate.
*/
EVP_PKEY * /* DSA cuckoo nest */
gen_mvkey(
char *id, /* file name id */
EVP_PKEY **evpars /* parameter list pointer */
)
{
EVP_PKEY *pkey, *pkey1; /* private keys */
DSA *dsa, *dsa2, *sdsa; /* DSA parameters */
BN_CTX *ctx; /* BN working space */
BIGNUM *a[MVMAX]; /* polynomial coefficient vector */
BIGNUM *g[MVMAX]; /* public key vector */
BIGNUM *s1[MVMAX]; /* private enabling keys */
BIGNUM *x[MVMAX]; /* polynomial zeros vector */
BIGNUM *xbar[MVMAX], *xhat[MVMAX]; /* private keys vector */
BIGNUM *b; /* group key */
BIGNUM *b1; /* inverse group key */
BIGNUM *s; /* enabling key */
BIGNUM *biga; /* master encryption key */
BIGNUM *bige; /* session encryption key */
BIGNUM *gbar, *ghat; /* public key */
BIGNUM *u, *v, *w; /* BN scratch */
int i, j, n;
FILE *str;
u_int temp;
/*
* Generate MV parameters.
*
* The object is to generate a multiplicative group Zp* modulo a
* prime p and a subset Zq mod q, where q is the product of n
* distinct primes s1[j] (j = 1...n) and q divides p - 1. We
* first generate n m-bit primes, where the product n m is in
* the order of 512 bits. One or more of these may have to be
* replaced later. As a practical matter, it is tough to find
* more than 31 distinct primes for 512 bits or 61 primes for
* 1024 bits. The latter can take several hundred iterations
* and several minutes on a Sun Blade 1000.
*/
n = nkeys;
fprintf(stderr,
"Generating MV parameters for %d keys (%d bits)...\n", n,
modulus2 / n);
ctx = BN_CTX_new(); u = BN_new(); v = BN_new(); w = BN_new();
b = BN_new(); b1 = BN_new();
dsa = DSA_new();
dsa->p = BN_new(); dsa->q = BN_new(); dsa->g = BN_new();
dsa->priv_key = BN_new(); dsa->pub_key = BN_new();
temp = 0;
for (j = 1; j <= n; j++) {
s1[j] = BN_new();
while (1) {
BN_generate_prime(s1[j], modulus2 / n, 0, NULL,
NULL, NULL, NULL);
for (i = 1; i < j; i++) {
if (BN_cmp(s1[i], s1[j]) == 0)
break;
}
if (i == j)
break;
temp++;
}
}
fprintf(stderr, "Birthday keys regenerated %d\n", temp);
/*
* Compute the modulus q as the product of the primes. Compute
* the modulus p as 2 * q + 1 and test p for primality. If p
* is composite, replace one of the primes with a new distinct
* one and try again. Note that q will hardly be a secret since
* we have to reveal p to servers, but not clients. However,
* factoring q to find the primes should be adequately hard, as
* this is the same problem considered hard in RSA. Question: is
* it as hard to find n small prime factors totalling n bits as
* it is to find two large prime factors totalling n bits?
* Remember, the bad guy doesn't know n.
*/
temp = 0;
while (1) {
BN_one(dsa->q);
for (j = 1; j <= n; j++)
BN_mul(dsa->q, dsa->q, s1[j], ctx);
BN_copy(dsa->p, dsa->q);
BN_add(dsa->p, dsa->p, dsa->p);
BN_add_word(dsa->p, 1);
if (BN_is_prime(dsa->p, BN_prime_checks, NULL, ctx,
NULL))
break;
temp++;
j = temp % n + 1;
while (1) {
BN_generate_prime(u, modulus2 / n, 0, 0, NULL,
NULL, NULL);
for (i = 1; i <= n; i++) {
if (BN_cmp(u, s1[i]) == 0)
break;
}
if (i > n)
break;
}
BN_copy(s1[j], u);
}
fprintf(stderr, "Defective keys regenerated %d\n", temp);
/*
* Compute the generator g using a random roll such that
* gcd(g, p - 1) = 1 and g^q = 1. This is a generator of p, not
* q. This may take several iterations.
*/
BN_copy(v, dsa->p);
BN_sub_word(v, 1);
while (1) {
BN_rand(dsa->g, BN_num_bits(dsa->p) - 1, 0, 0);
BN_mod(dsa->g, dsa->g, dsa->p, ctx);
BN_gcd(u, dsa->g, v, ctx);
if (!BN_is_one(u))
continue;
BN_mod_exp(u, dsa->g, dsa->q, dsa->p, ctx);
if (BN_is_one(u))
break;
}
/*
* Setup is now complete. Roll random polynomial roots x[j]
* (j = 1...n) for all j. While it may not be strictly
* necessary, Make sure each root has no factors in common with
* q.
*/
fprintf(stderr,
"Generating polynomial coefficients for %d roots (%d bits)\n",
n, BN_num_bits(dsa->q));
for (j = 1; j <= n; j++) {
x[j] = BN_new();
while (1) {
BN_rand(x[j], BN_num_bits(dsa->q), 0, 0);
BN_mod(x[j], x[j], dsa->q, ctx);
BN_gcd(u, x[j], dsa->q, ctx);
if (BN_is_one(u))
break;
}
}
/*
* Generate polynomial coefficients a[i] (i = 0...n) from the
* expansion of root products (x - x[j]) mod q for all j. The
* method is a present from Charlie Boncelet.
*/
for (i = 0; i <= n; i++) {
a[i] = BN_new();
BN_one(a[i]);
}
for (j = 1; j <= n; j++) {
BN_zero(w);
for (i = 0; i < j; i++) {
BN_copy(u, dsa->q);
BN_mod_mul(v, a[i], x[j], dsa->q, ctx);
BN_sub(u, u, v);
BN_add(u, u, w);
BN_copy(w, a[i]);
BN_mod(a[i], u, dsa->q, ctx);
}
}
/*
* Generate g[i] = g^a[i] mod p for all i and the generator g.
*/
for (i = 0; i <= n; i++) {
g[i] = BN_new();
BN_mod_exp(g[i], dsa->g, a[i], dsa->p, ctx);
}
/*
* Verify prod(g[i]^(a[i] x[j]^i)) = 1 for all i, j. Note the
* a[i] x[j]^i exponent is computed mod q, but the g[i] is
* computed mod p. also note the expression given in the paper
* is incorrect.
*/
temp = 1;
for (j = 1; j <= n; j++) {
BN_one(u);
for (i = 0; i <= n; i++) {
BN_set_word(v, i);
BN_mod_exp(v, x[j], v, dsa->q, ctx);
BN_mod_mul(v, v, a[i], dsa->q, ctx);
BN_mod_exp(v, dsa->g, v, dsa->p, ctx);
BN_mod_mul(u, u, v, dsa->p, ctx);
}
if (!BN_is_one(u))
temp = 0;
}
fprintf(stderr,
"Confirm prod(g[i]^(x[j]^i)) = 1 for all i, j: %s\n", temp ?
"yes" : "no");
if (!temp) {
return (NULL);
}
/*
* Make private encryption key A. Keep it around for awhile,
* since it is expensive to compute.
*/
biga = BN_new();
BN_one(biga);
for (j = 1; j <= n; j++) {
for (i = 0; i < n; i++) {
BN_set_word(v, i);
BN_mod_exp(v, x[j], v, dsa->q, ctx);
BN_mod_exp(v, g[i], v, dsa->p, ctx);
BN_mod_mul(biga, biga, v, dsa->p, ctx);
}
}
/*
* Roll private random group key b mod q (0 < b < q), where
* gcd(b, q) = 1 to guarantee b^-1 exists, then compute b^-1
* mod q. If b is changed, the client keys must be recomputed.
*/
while (1) {
BN_rand(b, BN_num_bits(dsa->q), 0, 0);
BN_mod(b, b, dsa->q, ctx);
BN_gcd(u, b, dsa->q, ctx);
if (BN_is_one(u))
break;
}
BN_mod_inverse(b1, b, dsa->q, ctx);
/*
* Make private client keys (xbar[j], xhat[j]) for all j. Note
* that the keys for the jth client do not s1[j] or the product
* s1[j]) (j = 1...n) which is q by construction.
*
* Compute the factor w such that w s1[j] = s1[j] for all j. The
* easy way to do this is to compute (q + s1[j]) / s1[j].
* Exercise for the student: prove the remainder is always zero.
*/
for (j = 1; j <= n; j++) {
xbar[j] = BN_new(); xhat[j] = BN_new();
BN_add(w, dsa->q, s1[j]);
BN_div(w, u, w, s1[j], ctx);
BN_zero(xbar[j]);
BN_set_word(v, n);
for (i = 1; i <= n; i++) {
if (i == j)
continue;
BN_mod_exp(u, x[i], v, dsa->q, ctx);
BN_add(xbar[j], xbar[j], u);
}
BN_mod_mul(xbar[j], xbar[j], b1, dsa->q, ctx);
BN_mod_exp(xhat[j], x[j], v, dsa->q, ctx);
BN_mod_mul(xhat[j], xhat[j], w, dsa->q, ctx);
}
/*
* We revoke client j by dividing q by s1[j]. The quotient
* becomes the enabling key s. Note we always have to revoke
* one key; otherwise, the plaintext and cryptotext would be
* identical. For the present there are no provisions to revoke
* additional keys, so we sail on with only token revocations.
*/
s = BN_new();
BN_copy(s, dsa->q);
BN_div(s, u, s, s1[n], ctx);
/*
* For each combination of clients to be revoked, make private
* encryption key E = A^s and partial decryption keys gbar = g^s
* and ghat = g^(s b), all mod p. The servers use these keys to
* compute the session encryption key and partial decryption
* keys. These values must be regenerated if the enabling key is
* changed.
*/
bige = BN_new(); gbar = BN_new(); ghat = BN_new();
BN_mod_exp(bige, biga, s, dsa->p, ctx);
BN_mod_exp(gbar, dsa->g, s, dsa->p, ctx);
BN_mod_mul(v, s, b, dsa->q, ctx);
BN_mod_exp(ghat, dsa->g, v, dsa->p, ctx);
/*
* Notes: We produce the key media in three steps. The first
* step is to generate the system parameters p, q, g, b, A and
* the enabling keys s1[j]. Associated with each s1[j] are
* parameters xbar[j] and xhat[j]. All of these parameters are
* retained in a data structure protecteted by the trusted-agent
* password. The p, xbar[j] and xhat[j] paremeters are
* distributed to the j clients. When the client keys are to be
* activated, the enabled keys are multipied together to form
* the master enabling key s. This and the other parameters are
* used to compute the server encryption key E and the partial
* decryption keys gbar and ghat.
*
* In the identity exchange the client rolls random r and sends
* it to the server. The server rolls random k, which is used
* only once, then computes the session key E^k and partial
* decryption keys gbar^k and ghat^k. The server sends the
* encrypted r along with gbar^k and ghat^k to the client. The
* client completes the decryption and verifies it matches r.
*/
/*
* Write the MV trusted-agent parameters and keys as a DSA
* private key encoded in PEM.
*
* p modulus p
* q modulus q
* g generator g
* priv_key A mod p
* pub_key b mod q
* (remaining values are not used)
*/
i = 0;
str = fheader("MVta", "mvta", groupname);
fprintf(stderr, "Generating MV trusted-authority keys\n");
BN_copy(dsa->priv_key, biga);
BN_copy(dsa->pub_key, b);
pkey = EVP_PKEY_new();
EVP_PKEY_assign_DSA(pkey, dsa);
PEM_write_PKCS8PrivateKey(str, pkey, cipher, NULL, 0, NULL,
passwd1);
evpars[i++] = pkey;
if (debug)
DSA_print_fp(stderr, dsa, 0);
/*
* Append the MV server parameters and keys as a DSA key encoded
* in PEM.
*
* p modulus p
* q modulus q (used only when generating k)
* g bige
* priv_key gbar
* pub_key ghat
* (remaining values are not used)
*/
fprintf(stderr, "Generating MV server keys\n");
dsa2 = DSA_new();
dsa2->p = BN_dup(dsa->p);
dsa2->q = BN_dup(dsa->q);
dsa2->g = BN_dup(bige);
dsa2->priv_key = BN_dup(gbar);
dsa2->pub_key = BN_dup(ghat);
pkey1 = EVP_PKEY_new();
EVP_PKEY_assign_DSA(pkey1, dsa2);
PEM_write_PKCS8PrivateKey(str, pkey1, cipher, NULL, 0, NULL,
passwd1);
evpars[i++] = pkey1;
if (debug)
DSA_print_fp(stderr, dsa2, 0);
/*
* Append the MV client parameters for each client j as DSA keys
* encoded in PEM.
*
* p modulus p
* priv_key xbar[j] mod q
* pub_key xhat[j] mod q
* (remaining values are not used)
*/
fprintf(stderr, "Generating %d MV client keys\n", n);
for (j = 1; j <= n; j++) {
sdsa = DSA_new();
sdsa->p = BN_dup(dsa->p);
sdsa->q = BN_dup(BN_value_one());
sdsa->g = BN_dup(BN_value_one());
sdsa->priv_key = BN_dup(xbar[j]);
sdsa->pub_key = BN_dup(xhat[j]);
pkey1 = EVP_PKEY_new();
EVP_PKEY_set1_DSA(pkey1, sdsa);
PEM_write_PKCS8PrivateKey(str, pkey1, cipher, NULL, 0,
NULL, passwd1);
evpars[i++] = pkey1;
if (debug)
DSA_print_fp(stderr, sdsa, 0);
/*
* The product gbar^k)^xbar[j] (ghat^k)^xhat[j] and E
* are inverses of each other. We check that the product
* is one for each client except the ones that have been
* revoked.
*/
BN_mod_exp(v, dsa2->priv_key, sdsa->pub_key, dsa->p,
ctx);
BN_mod_exp(u, dsa2->pub_key, sdsa->priv_key, dsa->p,
ctx);
BN_mod_mul(u, u, v, dsa->p, ctx);
BN_mod_mul(u, u, bige, dsa->p, ctx);
if (!BN_is_one(u)) {
fprintf(stderr, "Revoke key %d\n", j);
continue;
}
}
evpars[i++] = NULL;
fclose(str);
/*
* Free the countries.
*/
for (i = 0; i <= n; i++) {
BN_free(a[i]); BN_free(g[i]);
}
for (j = 1; j <= n; j++) {
BN_free(x[j]); BN_free(xbar[j]); BN_free(xhat[j]);
BN_free(s1[j]);
}
return (pkey);
}
/*
* Generate X509v3 certificate.
*
* The certificate consists of the version number, serial number,
* validity interval, issuer name, subject name and public key. For a
* self-signed certificate, the issuer name is the same as the subject
* name and these items are signed using the subject private key. The
* validity interval extends from the current time to the same time one
* year hence. For NTP purposes, it is convenient to use the NTP seconds
* of the current time as the serial number.
*/
int
x509 (
EVP_PKEY *pkey, /* signing key */
const EVP_MD *md, /* signature/digest scheme */
char *gqpub, /* identity extension (hex string) */
char *exten, /* private cert extension */
char *name /* subject/issuer name */
)
{
X509 *cert; /* X509 certificate */
X509_NAME *subj; /* distinguished (common) name */
X509_EXTENSION *ex; /* X509v3 extension */
FILE *str; /* file handle */
ASN1_INTEGER *serial; /* serial number */
const char *id; /* digest/signature scheme name */
char pathbuf[MAXFILENAME + 1];
/*
* Generate X509 self-signed certificate.
*
* Set the certificate serial to the NTP seconds for grins. Set
* the version to 3. Set the initial validity to the current
* time and the finalvalidity one year hence.
*/
id = OBJ_nid2sn(md->pkey_type);
fprintf(stderr, "Generating new certificate %s %s\n", name, id);
cert = X509_new();
X509_set_version(cert, 2L);
serial = ASN1_INTEGER_new();
ASN1_INTEGER_set(serial, (long)epoch + JAN_1970);
X509_set_serialNumber(cert, serial);
ASN1_INTEGER_free(serial);
X509_time_adj(X509_get_notBefore(cert), 0L, &epoch);
X509_time_adj(X509_get_notAfter(cert), lifetime * DAY, &epoch);
subj = X509_get_subject_name(cert);
X509_NAME_add_entry_by_txt(subj, "commonName", MBSTRING_ASC,
(u_char *)name, strlen(name), -1, 0);
subj = X509_get_issuer_name(cert);
X509_NAME_add_entry_by_txt(subj, "commonName", MBSTRING_ASC,
(u_char *)name, strlen(name), -1, 0);
if (!X509_set_pubkey(cert, pkey)) {
fprintf(stderr, "Assign certificate signing key fails\n%s\n",
ERR_error_string(ERR_get_error(), NULL));
X509_free(cert);
return (0);
}
/*
* Add X509v3 extensions if present. These represent the minimum
* set defined in RFC3280 less the certificate_policy extension,
* which is seriously obfuscated in OpenSSL.
*/
/*
* The basic_constraints extension CA:TRUE allows servers to
* sign client certficitates.
*/
fprintf(stderr, "%s: %s\n", LN_basic_constraints,
BASIC_CONSTRAINTS);
ex = X509V3_EXT_conf_nid(NULL, NULL, NID_basic_constraints,
BASIC_CONSTRAINTS);
if (!X509_add_ext(cert, ex, -1)) {
fprintf(stderr, "Add extension field fails\n%s\n",
ERR_error_string(ERR_get_error(), NULL));
return (0);
}
X509_EXTENSION_free(ex);
/*
* The key_usage extension designates the purposes the key can
* be used for.
*/
fprintf(stderr, "%s: %s\n", LN_key_usage, KEY_USAGE);
ex = X509V3_EXT_conf_nid(NULL, NULL, NID_key_usage, KEY_USAGE);
if (!X509_add_ext(cert, ex, -1)) {
fprintf(stderr, "Add extension field fails\n%s\n",
ERR_error_string(ERR_get_error(), NULL));
return (0);
}
X509_EXTENSION_free(ex);
/*
* The subject_key_identifier is used for the GQ public key.
* This should not be controversial.
*/
if (gqpub != NULL) {
fprintf(stderr, "%s\n", LN_subject_key_identifier);
ex = X509V3_EXT_conf_nid(NULL, NULL,
NID_subject_key_identifier, gqpub);
if (!X509_add_ext(cert, ex, -1)) {
fprintf(stderr,
"Add extension field fails\n%s\n",
ERR_error_string(ERR_get_error(), NULL));
return (0);
}
X509_EXTENSION_free(ex);
}
/*
* The extended key usage extension is used for special purpose
* here. The semantics probably do not conform to the designer's
* intent and will likely change in future.
*
* "trustRoot" designates a root authority
* "private" designates a private certificate
*/
if (exten != NULL) {
fprintf(stderr, "%s: %s\n", LN_ext_key_usage, exten);
ex = X509V3_EXT_conf_nid(NULL, NULL,
NID_ext_key_usage, exten);
if (!X509_add_ext(cert, ex, -1)) {
fprintf(stderr,
"Add extension field fails\n%s\n",
ERR_error_string(ERR_get_error(), NULL));
return (0);
}
X509_EXTENSION_free(ex);
}
/*
* Sign and verify.
*/
X509_sign(cert, pkey, md);
if (X509_verify(cert, pkey) <= 0) {
fprintf(stderr, "Verify %s certificate fails\n%s\n", id,
ERR_error_string(ERR_get_error(), NULL));
X509_free(cert);
return (0);
}
/*
* Write the certificate encoded in PEM.
*/
snprintf(pathbuf, sizeof(pathbuf), "%scert", id);
str = fheader(pathbuf, "cert", hostname);
PEM_write_X509(str, cert);
fclose(str);
if (debug)
X509_print_fp(stderr, cert);
X509_free(cert);
return (1);
}
#if 0 /* asn2ntp is used only with commercial certificates */
/*
* asn2ntp - convert ASN1_TIME time structure to NTP time
*/
u_long
asn2ntp (
ASN1_TIME *asn1time /* pointer to ASN1_TIME structure */
)
{
char *v; /* pointer to ASN1_TIME string */
struct tm tm; /* time decode structure time */
/*
* Extract time string YYMMDDHHMMSSZ from ASN.1 time structure.
* Note that the YY, MM, DD fields start with one, the HH, MM,
* SS fiels start with zero and the Z character should be 'Z'
* for UTC. Also note that years less than 50 map to years
* greater than 100. Dontcha love ASN.1?
*/
if (asn1time->length > 13)
return (-1);
v = (char *)asn1time->data;
tm.tm_year = (v[0] - '0') * 10 + v[1] - '0';
if (tm.tm_year < 50)
tm.tm_year += 100;
tm.tm_mon = (v[2] - '0') * 10 + v[3] - '0' - 1;
tm.tm_mday = (v[4] - '0') * 10 + v[5] - '0';
tm.tm_hour = (v[6] - '0') * 10 + v[7] - '0';
tm.tm_min = (v[8] - '0') * 10 + v[9] - '0';
tm.tm_sec = (v[10] - '0') * 10 + v[11] - '0';
tm.tm_wday = 0;
tm.tm_yday = 0;
tm.tm_isdst = 0;
return (mktime(&tm) + JAN_1970);
}
#endif
/*
* Callback routine
*/
void
cb (
int n1, /* arg 1 */
int n2, /* arg 2 */
void *chr /* arg 3 */
)
{
switch (n1) {
case 0:
d0++;
fprintf(stderr, "%s %d %d %lu\r", (char *)chr, n1, n2,
d0);
break;
case 1:
d1++;
fprintf(stderr, "%s\t\t%d %d %lu\r", (char *)chr, n1,
n2, d1);
break;
case 2:
d2++;
fprintf(stderr, "%s\t\t\t\t%d %d %lu\r", (char *)chr,
n1, n2, d2);
break;
case 3:
d3++;
fprintf(stderr, "%s\t\t\t\t\t\t%d %d %lu\r",
(char *)chr, n1, n2, d3);
break;
}
}
/*
* Generate key
*/
EVP_PKEY * /* public/private key pair */
genkey(
char *type, /* key type (RSA or DSA) */
char *id /* file name id */
)
{
if (type == NULL)
return (NULL);
if (strcmp(type, "RSA") == 0)
return (gen_rsa(id));
else if (strcmp(type, "DSA") == 0)
return (gen_dsa(id));
fprintf(stderr, "Invalid %s key type %s\n", id, type);
return (NULL);
}
#endif /* AUTOKEY */
/*
* Generate file header and link
*/
FILE *
fheader (
const char *file, /* file name id */
const char *ulink, /* linkname */
const char *owner /* owner name */
)
{
FILE *str; /* file handle */
char linkname[MAXFILENAME]; /* link name */
int temp;
snprintf(filename, sizeof(filename), "ntpkey_%s_%s.%u", file,
owner, fstamp);
if ((str = fopen(filename, "w")) == NULL) {
perror("Write");
exit (-1);
}
snprintf(linkname, sizeof(linkname), "ntpkey_%s_%s", ulink,
hostname);
(void)remove(linkname); /* The symlink() line below matters */
temp = symlink(filename, linkname);
if (temp < 0)
perror(file);
fprintf(stderr, "Generating new %s file and link\n", ulink);
fprintf(stderr, "%s->%s\n", linkname, filename);
fprintf(str, "# %s\n# %s\n", filename, ctime(&epoch));
return (str);
}