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NetBSD/dist/ntp/util/ntp-keygen.c

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/* $NetBSD: ntp-keygen.c,v 1.4 2003/12/04 17:15:26 drochner Exp $ */
/*
* Program to generate cryptographic keys for NTP clients and servers
*
* This program generates files "ntpkey_<type>_<hostname>.<filestamp>",
* where <type> is the file type, <hostname> is the generating host and
* <filestamp> is the NTP seconds in decimal format. The NTP programs
* expect generic names such as "ntpkey_<type>_whimsy.udel.edu" with the
* association maintained by soft links.
*
* Files are prefixed with a header giving the name and date of creation
* followed by a type-specific descriptive label and PEM-encoded data
* string compatible with programs of the OpenSSL library.
*
* Note that private keys can be password encrypted as per OpenSSL
* conventions.
*
* The file types include
*
* ntpkey_MD5key_<hostname>.<filestamp>
* MD5 (128-bit) keys used to compute message digests in symmetric
* key cryptography
*
* ntpkey_RSAkey_<hostname>.<filestamp>
* ntpkey_host_<hostname> (RSA) link
* RSA private/public host key pair used for public key signatures
* and data encryption
*
* ntpkey_DSAkey_<hostname>.<filestamp>
* ntpkey_sign_<hostname> (RSA or DSA) link
* DSA private/public sign key pair used for public key signatures,
* but not data encryption
*
* ntpkey_IFFpar_<hostname>.<filestamp>
* ntpkey_iff_<hostname> (IFF server/client) link
* ntpkey_iffkey_<hostname> (IFF client) link
* Schnorr (IFF) server/client identity parameters
*
* ntpkey_IFFkey_<hostname>.<filestamp>
* Schnorr (IFF) client identity parameters
*
* ntpkey_GQpar_<hostname>.<filestamp>,
* ntpkey_gq_<hostname> (GQ) link
* Guillou-Quisquater (GQ) identity parameters
*
* ntpkey_MVpar_<hostname>.<filestamp>,
* Mu-Varadharajan (MV) server identity parameters
*
* ntpkey_MVkeyX_<hostname>.<filestamp>,
* ntpkey_mv_<hostname> (MV server) link
* ntpkey_mvkey_<hostname> (MV client) link
* Mu-Varadharajan (MV) client identity parameters
*
* ntpkey_XXXcert_<hostname>.<filestamp>
* ntpkey_cert_<hostname> (RSA or DSA) link
* X509v3 certificate using RSA or DSA public keys and signatures.
* XXX is a code identifying the message digest and signature
* encryption algorithm
*
* Available digest/signature schemes
*
* RSA: RSA-MD2, RSA-MD5, RSA-SHA, RSA-SHA1, RSA-MDC2, EVP-RIPEMD160
* DSA: DSA-SHA, DSA-SHA1
*
* 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 return 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>
#if HAVE_SYS_TYPES_H
# include <sys/types.h>
#endif
#include "ntp_types.h"
#include "l_stdlib.h"
#ifdef SYS_WINNT
extern int ntp_getopt P((int, char **, const char *));
#define getopt ntp_getopt
#define optarg ntp_optarg
#endif
#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 */
/*
* Cryptodefines
*/
#define MD5KEYS 16 /* number of MD5 keys generated */
#define JAN_1970 ULONG_CONST(2208988800) /* NTP seconds */
#define YEAR ((long)60*60*24*365) /* one year in seconds */
#define MAXFILENAME 256 /* max file name length */
#define MAXHOSTNAME 256 /* max host name length */
#ifdef OPENSSL
#define PLEN 512 /* default prime modulus size (bits) */
/*
* 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 /* OPENSSL */
/*
* Prototypes
*/
FILE *fheader P((const char *, const char *));
void fslink P((const char *, const char *));
int gen_md5 P((char *));
#ifdef OPENSSL
EVP_PKEY *gen_rsa P((char *));
EVP_PKEY *gen_dsa P((char *));
EVP_PKEY *gen_iff P((char *));
EVP_PKEY *gen_gqpar P((char *));
EVP_PKEY *gen_gqkey P((char *, EVP_PKEY *));
EVP_PKEY *gen_mv P((char *));
int x509 P((EVP_PKEY *, const EVP_MD *, char *, char *));
void cb P((int, int, void *));
EVP_PKEY *genkey P((char *, char *));
u_long asn2ntp P((ASN1_TIME *));
#endif /* OPENSSL */
/*
* Program variables
*/
extern char *optarg; /* command line argument */
int debug = 0; /* debug, not de bug */
int rval; /* return status */
u_int modulus = PLEN; /* prime modulus size (bits) */
int nkeys = 0; /* MV keys */
time_t epoch; /* Unix epoch (seconds) since 1970 */
char *hostname; /* host name (subject name) */
char *trustname; /* trusted host name (issuer name) */
char filename[MAXFILENAME + 1]; /* file name */
char *passwd1 = NULL; /* input private key password */
char *passwd2 = NULL; /* output private key password */
#ifdef OPENSSL
long d0, d1, d2, d3; /* callback counters */
#endif /* OPENSSL */
#ifdef SYS_WINNT
BOOL init_randfile();
/*
* Don't try to follow symbolic links
*/
int
readlink(char * link, char * file, int len) {
return (-1);
}
/*
* Don't try to create a symbolic link for now.
* Just move the file to the name you need.
*/
int
symlink(char *filename, char *linkname) {
DeleteFile(linkname);
MoveFile(filename, linkname);
return 0;
}
void
InitWin32Sockets() {
WORD wVersionRequested;
WSADATA wsaData;
wVersionRequested = MAKEWORD(2,0);
if (WSAStartup(wVersionRequested, &wsaData))
{
fprintf(stderr, "No useable winsock.dll");
exit(1);
}
}
#endif /* SYS_WINNT */
/*
* Main program
*/
int
main(
int argc, /* command line options */
char **argv
)
{
struct timeval tv; /* initialization vector */
#ifdef OPENSSL
X509 *cert = NULL; /* X509 certificate */
EVP_PKEY *pkey_host = NULL; /* host key */
EVP_PKEY *pkey_sign = NULL; /* sign key */
EVP_PKEY *pkey_iff = NULL; /* IFF parameters */
EVP_PKEY *pkey_gq = NULL; /* GQ parameters */
EVP_PKEY *pkey_mv = NULL; /* MV parameters */
int md5key = 0; /* generate MD5 keys */
int hostkey = 0; /* generate RSA keys */
int iffkey = 0; /* generate IFF parameters */
int gqpar = 0; /* generate GQ parameters */
int gqkey = 0; /* update GQ keys */
int mvpar = 0; /* generate MV parameters */
int mvkey = 0; /* update MV keys */
char *sign = NULL; /* sign key */
EVP_PKEY *pkey = NULL; /* temp key */
const EVP_MD *ectx; /* EVP digest */
char hostbuf[MAXHOSTNAME + 1];
char pathbuf[MAXFILENAME + 1];
const char *scheme = NULL; /* digest/signature scheme */
char *exten = NULL; /* private extension */
char *grpkey = NULL; /* identity extension */
int nid; /* X509 digest/signature scheme */
FILE *fstr = NULL; /* file handle */
int iffsw = 0; /* IFF key switch */
const char *fnptr;
#endif /* OPENSSL */
u_int temp;
#ifdef SYS_WINNT
/* Initialize before OpenSSL checks */
InitWin32Sockets();
if(!init_randfile())
fprintf(stderr, "Unable to initialize .rnd file\n");
#endif
#ifdef OPENSSL
if (SSLeay() != OPENSSL_VERSION_NUMBER) {
fprintf(stderr,
"OpenSSL version mismatch. Built against %lx, you have %lx\n",
OPENSSL_VERSION_NUMBER, SSLeay());
return (-1);
} else {
fprintf(stderr,
"Using OpenSSL version %lx\n", SSLeay());
}
#endif /* OPENSSL */
/*
* Process options, initialize host name and timestamp.
*/
gethostname(hostbuf, MAXHOSTNAME);
hostname = hostbuf;
trustname = hostbuf;
passwd1 = hostbuf;
#ifndef SYS_WINNT
gettimeofday(&tv, 0);
#else
gettimeofday(&tv);
#endif
epoch = tv.tv_sec;
rval = 0;
while ((temp = getopt(argc, argv,
"c:deGgHIi:Mm:nPp:q:S:s:TV:v:")) != -1) {
switch(temp) {
/*
* -c select public certificate type
*/
case 'c':
scheme = optarg;
continue;
/*
* -d debug
*/
case 'd':
debug++;
continue;
/*
* -e write identity keys
*/
case 'e':
iffsw++;
continue;
/*
* -G generate GQ parameters and keys
*/
case 'G':
gqpar++;
continue;
/*
* -g update GQ keys
*/
case 'g':
gqkey++;
continue;
/*
* -H generate host key (RSA)
*/
case 'H':
hostkey++;
continue;
/*
* -I generate IFF parameters
*/
case 'I':
iffkey++;
continue;
/*
* -i set issuer name
*/
case 'i':
trustname = optarg;
continue;
/*
* -M generate MD5 keys
*/
case 'M':
md5key++;
continue;
/*
* -m select modulus (256-2048)
*/
case 'm':
if (sscanf(optarg, "%d", &modulus) != 1)
fprintf(stderr,
"invalid option -m %s\n", optarg);
continue;
/*
* -P generate PC private certificate
*/
case 'P':
exten = EXT_KEY_PRIVATE;
continue;
/*
* -p output private key password
*/
case 'p':
passwd2 = optarg;
continue;
/*
* -q input private key password
*/
case 'q':
passwd1 = optarg;
continue;
/*
* -S generate sign key (RSA or DSA)
*/
case 'S':
sign = optarg;
continue;
/*
* -s set subject name
*/
case 's':
hostname = optarg;
continue;
/*
* -T trusted certificate (TC scheme)
*/
case 'T':
exten = EXT_KEY_TRUST;
continue;
/*
* -V <keys> generate MV parameters
*/
case 'V':
mvpar++;
if (sscanf(optarg, "%d", &nkeys) != 1)
fprintf(stderr,
"invalid option -V %s\n", optarg);
continue;
/*
* -v <key> update MV keys
*/
case 'v':
mvkey++;
if (sscanf(optarg, "%d", &nkeys) != 1)
fprintf(stderr,
"invalid option -v %s\n", optarg);
continue;
/*
* None of the above.
*/
default:
fprintf(stderr, "Option ignored\n");
continue;
}
}
if (passwd1 != NULL && passwd2 == NULL)
passwd2 = passwd1;
#ifdef OPENSSL
/*
* Seed random number generator and grow weeds.
*/
ERR_load_crypto_strings();
OpenSSL_add_all_algorithms();
fnptr = RAND_file_name(pathbuf, MAXFILENAME);
if (fnptr == NULL) {
fprintf(stderr, "RAND_file_name %s\n",
ERR_error_string(ERR_get_error(), NULL));
return (-1);
}
temp = RAND_load_file(fnptr, -1);
if (temp == 0) {
fprintf(stderr,
"RAND_load_file %s not found or empty\n", fnptr);
return (-1);
}
fprintf(stderr,
"Random seed file %s %u bytes\n", fnptr, temp);
RAND_add(&epoch, sizeof(epoch), 4.0);
/*
* Generate new parameters and keys as requested. These replace
* any values already generated.
*/
if (md5key)
gen_md5("MD5");
if (hostkey)
pkey_host = genkey("RSA", "host");
if (sign != NULL)
pkey_sign = genkey(sign, "sign");
if (iffkey)
pkey_iff = gen_iff("iff");
if (gqpar)
pkey_gq = gen_gqpar("gq");
if (mvpar)
pkey_mv = gen_mv("mv");
/*
* If there is no new host key, look for an existing one. If not
* found, create it.
*/
while (pkey_host == NULL && rval == 0 && !iffsw) {
sprintf(filename, "ntpkey_host_%s", hostname);
if ((fstr = fopen(filename, "r")) != NULL) {
pkey_host = PEM_read_PrivateKey(fstr, NULL,
NULL, passwd1);
fclose(fstr);
readlink(filename, filename, sizeof(filename));
if (pkey_host == NULL) {
fprintf(stderr, "Host key\n%s\n",
ERR_error_string(ERR_get_error(),
NULL));
rval = -1;
} else {
fprintf(stderr,
"Using host key %s\n", filename);
}
break;
} else if ((pkey_host = genkey("RSA", "host")) ==
NULL) {
rval = -1;
break;
}
}
/*
* If there is no new sign key, look for an existing one. If not
* found, use the host key instead.
*/
pkey = pkey_sign;
while (pkey_sign == NULL && rval == 0 && !iffsw) {
sprintf(filename, "ntpkey_sign_%s", hostname);
if ((fstr = fopen(filename, "r")) != NULL) {
pkey_sign = PEM_read_PrivateKey(fstr, NULL,
NULL, passwd1);
fclose(fstr);
readlink(filename, filename, sizeof(filename));
if (pkey_sign == NULL) {
fprintf(stderr, "Sign key\n%s\n",
ERR_error_string(ERR_get_error(),
NULL));
rval = -1;
} else {
fprintf(stderr, "Using sign key %s\n",
filename);
}
break;
} else {
pkey = pkey_host;
fprintf(stderr, "Using host key as sign key\n");
break;
}
}
/*
* If there is no new IFF file, look for an existing one.
*/
if (pkey_iff == NULL && rval == 0) {
sprintf(filename, "ntpkey_iff_%s", hostname);
if ((fstr = fopen(filename, "r")) != NULL) {
pkey_iff = PEM_read_PrivateKey(fstr, NULL,
NULL, passwd1);
fclose(fstr);
readlink(filename, filename, sizeof(filename));
if (pkey_iff == NULL) {
fprintf(stderr, "IFF parameters\n%s\n",
ERR_error_string(ERR_get_error(),
NULL));
rval = -1;
} else {
fprintf(stderr,
"Using IFF parameters %s\n",
filename);
}
}
}
/*
* If there is no new GQ file, look for an existing one.
*/
if (pkey_gq == NULL && rval == 0 && !iffsw) {
sprintf(filename, "ntpkey_gq_%s", hostname);
if ((fstr = fopen(filename, "r")) != NULL) {
pkey_gq = PEM_read_PrivateKey(fstr, NULL, NULL,
passwd1);
fclose(fstr);
readlink(filename, filename, sizeof(filename));
if (pkey_gq == NULL) {
fprintf(stderr, "GQ parameters\n%s\n",
ERR_error_string(ERR_get_error(),
NULL));
rval = -1;
} else {
fprintf(stderr,
"Using GQ parameters %s\n",
filename);
}
}
}
/*
* If there is a GQ parameter file, create GQ private/public
* keys and extract the public key for the certificate.
*/
if (pkey_gq != NULL && rval == 0) {
gen_gqkey("gq", pkey_gq);
grpkey = BN_bn2hex(pkey_gq->pkey.rsa->q);
}
/*
* Generate a X509v3 certificate.
*/
while (scheme == NULL && rval == 0 && !iffsw) {
sprintf(filename, "ntpkey_cert_%s", hostname);
if ((fstr = fopen(filename, "r")) != NULL) {
cert = PEM_read_X509(fstr, NULL, NULL, NULL);
fclose(fstr);
readlink(filename, filename, sizeof(filename));
if (cert == NULL) {
fprintf(stderr, "Cert \n%s\n",
ERR_error_string(ERR_get_error(),
NULL));
rval = -1;
} else {
nid = OBJ_obj2nid(
cert->cert_info->signature->algorithm);
scheme = OBJ_nid2sn(nid);
fprintf(stderr,
"Using scheme %s from %s\n", scheme,
filename);
break;
}
}
scheme = "RSA-MD5";
}
if (pkey != NULL && rval == 0 && !iffsw) {
ectx = EVP_get_digestbyname(scheme);
if (ectx == NULL) {
fprintf(stderr,
"Invalid digest/signature combination %s\n",
scheme);
rval = -1;
} else {
x509(pkey, ectx, grpkey, exten);
}
}
/*
* Write the IFF client parameters and keys as a DSA private key
* encoded in PEM. Note the private key is obscured.
*/
if (pkey_iff != NULL && rval == 0 && iffsw) {
DSA *dsa;
char *sptr;
sptr = strrchr(filename, '.');
sprintf(filename, "ntpkey_IFFkey_%s.%s", trustname,
++sptr);
fprintf(stderr, "Writing new IFF key %s\n", filename);
fprintf(stdout, "# %s\n# %s", filename, ctime(&epoch));
dsa = pkey_iff->pkey.dsa;
BN_copy(dsa->priv_key, BN_value_one());
pkey = EVP_PKEY_new();
EVP_PKEY_assign_DSA(pkey, dsa);
PEM_write_PrivateKey(stdout, pkey, passwd2 ?
EVP_des_cbc() : NULL, NULL, 0, NULL, passwd2);
fclose(stdout);
if (debug)
DSA_print_fp(stdout, dsa, 0);
}
/*
* Return the marbles.
*/
if (grpkey != NULL)
OPENSSL_free(grpkey);
if (pkey_host != NULL)
EVP_PKEY_free(pkey_host);
if (pkey_sign != NULL)
EVP_PKEY_free(pkey_sign);
if (pkey_iff != NULL)
EVP_PKEY_free(pkey_iff);
if (pkey_gq != NULL)
EVP_PKEY_free(pkey_gq);
if (pkey_mv != NULL)
EVP_PKEY_free(pkey_mv);
#endif /* OPENSSL */
return (rval);
}
#if 0
/*
* Generate random MD5 key with password.
*/
int
gen_md5(
char *id /* file name id */
)
{
BIGNUM *key;
BIGNUM *keyid;
FILE *str;
u_char bin[16];
fprintf(stderr, "Generating MD5 keys...\n");
str = fheader("MD5key", hostname);
keyid = BN_new(); key = BN_new();
BN_rand(keyid, 16, -1, 0);
BN_rand(key, 128, -1, 0);
BN_bn2bin(key, bin);
PEM_write_fp(str, MD5, NULL, bin);
fclose(str);
fslink(id, hostname);
return (1);
}
#else
/*
* Generate semi-random MD5 keys compatible with NTPv3 and NTPv4
*/
int
gen_md5(
char *id /* file name id */
)
{
u_char md5key[16]; /* MD5 key */
FILE *str;
u_int temp = 0; /* Initialize to prevent warnings during compile */
int i, j;
fprintf(stderr, "Generating MD5 keys...\n");
str = fheader("MD5key", hostname);
srandom(epoch);
for (i = 1; i <= MD5KEYS; i++) {
for (j = 0; j < 16; j++) {
while (1) {
temp = random() & 0xff;
if (temp == '#')
continue;
if (temp > 0x20 && temp < 0x7f)
break;
}
md5key[j] = (u_char)temp;
}
md5key[16] = '\0';
fprintf(str, "%2d MD5 %16s # MD5 key\n", i,
md5key);
}
fclose(str);
fslink(id, hostname);
return (1);
}
#endif /* OPENSSL */
#ifdef OPENSSL
/*
* 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));
rval = -1;
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);
rval = -1;
return (NULL);
}
/*
* Write the RSA parameters and keys as a RSA private key
* encoded in PEM.
*/
str = fheader("RSAkey", hostname);
pkey = EVP_PKEY_new();
EVP_PKEY_assign_RSA(pkey, rsa);
PEM_write_PrivateKey(str, pkey, passwd2 ? EVP_des_cbc() : NULL,
NULL, 0, NULL, passwd2);
fclose(str);
if (debug)
RSA_print_fp(stdout, rsa, 0);
fslink(id, hostname);
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));
rval = -1;
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);
rval = -1;
return (NULL);
}
/*
* Write the DSA parameters and keys as a DSA private key
* encoded in PEM.
*/
str = fheader("DSAkey", hostname);
pkey = EVP_PKEY_new();
EVP_PKEY_assign_DSA(pkey, dsa);
PEM_write_PrivateKey(str, pkey, passwd2 ? EVP_des_cbc() : NULL,
NULL, 0, NULL, passwd2);
fclose(str);
if (debug)
DSA_print_fp(stdout, dsa, 0);
fslink(id, hostname);
return (pkey);
}
/*
* Generate Schnorr (IFF) parameters and keys
*
* The Schnorr (IFF)identity scheme is intended for use when
* certificates are generated by some other trusted certificate
* authority and the parameters cannot be conveyed in the certificate
* itself. For this purpose, new generations of IFF values must be
* securely transmitted to all members of the group before use. There
* are two kinds of files: server/client files that include private and
* public parameters and client files that include only public
* parameters. 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), then computes public
* v = g^(q - a). All values except the group key are known to all group
* members; the group key is known to the group servers, but not the
* group clients. Alice challenges Bob to confirm identity using the
* protocol described below.
*/
EVP_PKEY * /* DSA cuckoo nest */
gen_iff(
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 parameters (%d bits)...\n",
modulus);
RAND_bytes(seed, sizeof(seed));
dsa = DSA_generate_parameters(modulus, 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));
rval = -1;
return (NULL);;
}
/*
* Generate the private and public keys. The DSA parameters and
* these keys are distributed to all members of the group.
*/
fprintf(stderr, "Generating IFF keys (%d bits)...\n", modulus);
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);
rval = -1;
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 r (0 < r < q) and sends it to Bob. She needs only
* modulus q.
*/
BN_rand(r, BN_num_bits(dsa->q), -1, 0); /* r */
BN_mod(r, r, dsa->q, ctx);
/*
* Bob rolls random k (0 < k < q), computes y = k + b r mod q
* and x = g^k mod p, then sends (y, x) to Alice. He needs
* moduli p, q and the group key b.
*/
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 computes g^y v^r and verifies the result is equal to x.
* She needs modulus p, generator g, and the public key v, as
* well as her original r.
*/
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);
rval = -1;
return (NULL);
}
/*
* Write the IFF server parameters and keys as a DSA private key
* encoded in PEM.
*
* p modulus p
* q modulus q
* g generator g
* priv_key b
* public_key v
*/
str = fheader("IFFpar", trustname);
pkey = EVP_PKEY_new();
EVP_PKEY_assign_DSA(pkey, dsa);
PEM_write_PrivateKey(str, pkey, passwd2 ? EVP_des_cbc() : NULL,
NULL, 0, NULL, passwd2);
fclose(str);
if (debug)
DSA_print_fp(stdout, dsa, 0);
fslink(id, trustname);
return (pkey);
}
/*
* Generate Guillou-Quisquater (GQ) parameters and keys
*
* The Guillou-Quisquater (GQ) identity scheme is intended for use when
* the parameters, keys and certificates are generated by this program.
* The scheme uses a certificate extension field do convey the public
* key of a particular group identified by a group key known only to
* members of the group. 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 member 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.
*/
EVP_PKEY * /* RSA cuckoo nest */
gen_gqpar(
char *id /* file name id */
)
{
EVP_PKEY *pkey; /* private key */
RSA *rsa; /* GQ parameters */
BN_CTX *ctx; /* BN working space */
FILE *str;
/*
* Generate RSA parameters for use as GQ parameters.
*/
fprintf(stderr,
"Generating GQ parameters (%d bits)...\n", modulus);
rsa = RSA_generate_key(modulus, 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));
rval = -1;
return (NULL);
}
/*
* Generate the group key b, which is saved in the e member of
* the RSA structure. These values are distributed to all
* members of the group, but shielded from all other groups. We
* don't use all the parameters, but set the unused ones to a
* small number to minimize the file size.
*/
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);
BN_copy(rsa->d, BN_value_one());
BN_copy(rsa->p, BN_value_one());
BN_copy(rsa->q, BN_value_one());
BN_copy(rsa->dmp1, BN_value_one());
BN_copy(rsa->dmq1, BN_value_one());
BN_copy(rsa->iqmp, BN_value_one());
/*
* Write the GQ parameters as a RSA private key encoded in PEM.
* The public and private keys are filled in later.
*
* n modulus n
* e group key b
* (remaining values are not used)
*/
str = fheader("GQpar", trustname);
pkey = EVP_PKEY_new();
EVP_PKEY_assign_RSA(pkey, rsa);
PEM_write_PrivateKey(str, pkey, passwd2 ? EVP_des_cbc() : NULL,
NULL, 0, NULL, passwd2);
fclose(str);
if (debug)
RSA_print_fp(stdout, rsa, 0);
fslink(id, trustname);
return (pkey);
}
/*
* Update Guillou-Quisquater (GQ) parameters
*/
EVP_PKEY * /* RSA cuckoo nest */
gen_gqkey(
char *id, /* file name id */
EVP_PKEY *gqpar /* GQ parameters */
)
{
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 GQ keys. Note that the group key b is the e member
* of
* the GQ parameters.
*/
fprintf(stderr, "Updating GQ keys (%d bits)...\n", modulus);
ctx = BN_CTX_new(); u = BN_new(); v = BN_new();
g = BN_new(); k = BN_new(); r = BN_new(); y = BN_new();
/*
* When generating his certificate, Bob rolls random private key
* u.
*/
rsa = gqpar->pkey.rsa;
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);
rval = -1;
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 r (0 < r < n) and sends it to Bob. She needs only
* modulus n from the parameters.
*/
BN_rand(r, BN_num_bits(rsa->n), -1, 0); /* r */
BN_mod(r, r, rsa->n, ctx);
/*
* Bob rolls random k (0 < k < n), computes y = k u^r mod n and
* g = k^b mod n, then sends (y, g) to Alice. He needs modulus n
* from the parameters and his private key u.
*/
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 computes v^r y^b mod n and verifies the result is equal
* to g. She needs modulus n, generator g and group key b from
* the parameters and Bob's public key v = (u^-1)^b from his
* certificate.
*/
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);
rval = -1;
return (NULL);
}
/*
* Write the GQ parameters and keys as a RSA private key encoded
* in PEM.
*
* n modulus n
* e group key b
* p private key u
* q public key (u^-1)^b
* (remaining values are not used)
*/
str = fheader("GQpar", trustname);
pkey = EVP_PKEY_new();
EVP_PKEY_assign_RSA(pkey, rsa);
PEM_write_PrivateKey(str, pkey, passwd2 ? EVP_des_cbc() : NULL,
NULL, 0, NULL, passwd2);
fclose(str);
if (debug)
RSA_print_fp(stdout, rsa, 0);
fslink(id, trustname);
return (pkey);
}
/*
* Generate Mu-Varadharajan (MV) parameters and keys
*
* The Mu-Varadharajan (MV) cryptosystem is useful 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 operates 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. We don't use it this way, but read on.
*
* 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 s'[j] (j = 1...n), where
* each s'[j] has m significant bits. Let p be a prime p = 2 * q + 1, so
* that q and each s'[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. Associated with each s'[j] is an element
* s[j] such that s[j] s'[j] = s'[j] mod q. We find s[j] as the quotient
* (q + s'[j]) / s'[j]. 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 encryption file including the
* private encryption key E and public key (gbar, ghat). It then
* generates decryption files including the private key (xbar[j],
* xhat[j]) for each client. E is a permutation that encrypts a block
* y = E x. The jth client computes the inverse permutation E^-1 =
* gbar^xhat[j] ghat^xbar[j] and decrypts the block x = E^-1 y.
*
* 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(s'[j]) (j = 1...n) above. If the factor s'[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 block.
*/
EVP_PKEY * /* DSA cuckoo nest */
gen_mv(
char *id /* file name id */
)
{
EVP_PKEY *pkey, *pkey1; /* private key */
DSA *dsa; /* DSA parameters */
DSA *sdsa; /* DSA parameters */
BN_CTX *ctx; /* BN working space */
BIGNUM **x; /* polynomial zeros vector */
BIGNUM **a; /* polynomial coefficient vector */
BIGNUM **g; /* public key vector */
BIGNUM **s, **s1; /* private enabling keys */
BIGNUM **xbar, **xhat; /* private keys vector */
BIGNUM *b; /* group key */
BIGNUM *b1; /* inverse group key */
BIGNUM *ss; /* 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;
char ident[20];
/*
* 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 s'[j] (j = 1...n) and q divides p - 1. We
* first generate n distinct primes, which may have to be
* regenerated later. As a practical matter, it is tough to find
* more than 31 distinct primes for modulus 512 or 61 primes for
* modulus 1024. 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,
modulus / 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();
s = malloc((n + 1) * sizeof(BIGNUM));
s1 = malloc((n + 1) * sizeof(BIGNUM));
for (j = 1; j <= n; j++)
s1[j] = BN_new();
temp = 0;
for (j = 1; j <= n; j++) {
while (1) {
fprintf(stderr, "Birthdays %d\r", temp);
BN_generate_prime(s1[j], modulus / 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 rejected %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 and 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) {
fprintf(stderr, "Duplicate keys rejected %d\r", ++temp);
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;
j = temp % n + 1;
while (1) {
BN_generate_prime(u, modulus / 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, "Duplicate keys rejected %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.
*/
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;
}
/*
* Compute s[j] such that s[j] * s'[j] = s'[j] for all j. The
* easy way to do this is to compute q + s'[j] and divide the
* result by s'[j]. Exercise for the student: prove the
* remainder is always zero.
*/
for (j = 1; j <= n; j++) {
s[j] = BN_new();
BN_add(s[j], dsa->q, s1[j]);
BN_div(s[j], u, s[j], s1[j], ctx);
}
/*
* Setup is now complete. Roll random polynomial roots x[j]
* (0 < x[j] < q) 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));
x = malloc((n + 1) * sizeof(BIGNUM));
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.
*/
a = malloc((n + 1) * sizeof(BIGNUM));
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.
*/
fprintf(stderr, "Generating g[i] parameters\n");
g = malloc((n + 1) * sizeof(BIGNUM));
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; otherwise,
* exit. 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) {
rval = -1;
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 involve s[j], but not s'[j]
* or the product s = prod(s'[j]) mod q, which is the enabling
* key.
*/
xbar = malloc((n + 1) * sizeof(BIGNUM));
xhat = malloc((n + 1) * sizeof(BIGNUM));
for (j = 1; j <= n; j++) {
xbar[j] = BN_new(); xhat[j] = BN_new();
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], s[j], dsa->q, ctx);
}
/*
* The enabling key is initially q by construction. We can
* revoke client j by dividing q by s'[j]. The quotient becomes
* the enabling key s. Note we always have to revoke one key;
* otherwise, the plaintext and cryptotext would be identical.
*/
ss = BN_new();
BN_copy(ss, dsa->q);
BN_div(ss, u, dsa->q, s1[n], ctx);
/*
* Make private server encryption key E = A^s and public server
* keys gbar = g^s mod p and ghat = g^(s b) mod p. The (gbar,
* ghat) is the public key provided to the server, which uses it
* to compute the session encryption key and public key included
* in its messages. 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, ss, dsa->p, ctx);
BN_mod_exp(gbar, dsa->g, ss, dsa->p, ctx);
BN_mod_mul(v, ss, b, dsa->q, ctx);
BN_mod_exp(ghat, dsa->g, v, dsa->p, ctx);
/*
* We produce the key media in three steps. The first step is to
* generate the private values that do not depend on the
* enabling key. These include the server values p, q, g, b, A
* and the client values s'[j], xbar[j] and xhat[j] for each j.
* The p, xbar[j] and xhat[j] values are encoded in private
* files which are distributed to respective clients. The p, q,
* g, A and s'[j] values (will be) written to a secret file to
* be read back later.
*
* The secret file (will be) read back at some later time to
* enable/disable individual keys and generate/regenerate the
* enabling key s. The p, q, E, gbar and ghat values are written
* to a secret file to be read back later by the server.
*
* The server reads the secret file and rolls the session key
* k, which is used only once, then computes E^k, gbar^k and
* ghat^k. The E^k is the session encryption key. The encrypted
* data, gbar^k and ghat^k are transmtted to clients in an
* extension field. The client receives the message and computes
* x = (gbar^k)^xbar[j] (ghat^k)^xhat[j], finds the session
* encryption key E^k as the inverse x^-1 and decrypts the data.
*/
BN_copy(dsa->g, bige);
dsa->priv_key = BN_dup(gbar);
dsa->pub_key = BN_dup(ghat);
/*
* Write the MV server parameters and keys as a DSA private key
* encoded in PEM.
*
* p modulus p
* q modulus q (used only to generate k)
* g E mod p
* priv_key gbar mod p
* pub_key ghat mod p
*/
str = fheader("MVpar", trustname);
pkey = EVP_PKEY_new();
EVP_PKEY_assign_DSA(pkey, dsa);
PEM_write_PrivateKey(str, pkey, passwd2 ? EVP_des_cbc() : NULL,
NULL, 0, NULL, passwd2);
fclose(str);
if (debug)
DSA_print_fp(stdout, dsa, 0);
fslink(id, trustname);
/*
* Write the parameters and private key (xbar[j], xhat[j]) for
* all j as a DSA private key encoded in PEM. It is used only by
* the designated recipient(s) who pay a suitably outrageous fee
* for its use.
*/
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_new();
sdsa->pub_key = BN_new();
for (j = 1; j <= n; j++) {
BN_copy(sdsa->priv_key, xbar[j]);
BN_copy(sdsa->pub_key, xhat[j]);
BN_mod_exp(v, dsa->priv_key, sdsa->pub_key, dsa->p,
ctx);
BN_mod_exp(u, dsa->pub_key, sdsa->priv_key, dsa->p,
ctx);
BN_mod_mul(u, u, v, dsa->p, ctx);
BN_mod_mul(u, u, dsa->g, dsa->p, ctx);
BN_free(xbar[j]); BN_free(xhat[j]);
BN_free(x[j]); BN_free(s[j]); BN_free(s1[j]);
if (!BN_is_one(u)) {
fprintf(stderr, "Revoke key %d\n", j);
continue;
}
/*
* Write the client parameters as a DSA private key
* encoded in PEM. We don't make links for these.
*
* p modulus p
* priv_key xbar[j] mod q
* pub_key xhat[j] mod q
* (remaining values are not used)
*/
sprintf(ident, "MVkey%d", j);
str = fheader(ident, trustname);
pkey1 = EVP_PKEY_new();
EVP_PKEY_set1_DSA(pkey1, sdsa);
PEM_write_PrivateKey(str, pkey1, passwd2 ?
EVP_des_cbc() : NULL, NULL, 0, NULL, passwd2);
fclose(str);
fprintf(stderr, "ntpkey_%s_%s.%lu\n", ident, trustname,
epoch + JAN_1970);
if (debug)
DSA_print_fp(stdout, sdsa, 0);
EVP_PKEY_free(pkey1);
}
/*
* Free the countries.
*/
for (i = 0; i <= n; i++) {
BN_free(a[i]);
BN_free(g[i]);
}
BN_free(u); BN_free(v); BN_free(w); BN_CTX_free(ctx);
BN_free(b); BN_free(b1); BN_free(biga); BN_free(bige);
BN_free(ss); BN_free(gbar); BN_free(ghat);
DSA_free(sdsa);
/*
* Free the world.
*/
free(x); free(a); free(g); free(s); free(s1);
free(xbar); free(xhat);
return (pkey);
}
/*
* Generate X509v3 scertificate.
*
* 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, /* generic signature algorithm */
const EVP_MD *md, /* generic digest algorithm */
char *gqpub, /* identity extension (hex string) */
char *exten /* private cert extension */
)
{
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 subject name and issuer name to the
* subject name in the request. Set the initial validity to the
* current time and the final validity one year hence.
*/
id = OBJ_nid2sn(md->pkey_type);
fprintf(stderr, "Generating certificate %s\n", id);
cert = X509_new();
X509_set_version(cert, 2L);
serial = ASN1_INTEGER_new();
ASN1_INTEGER_set(serial, epoch + JAN_1970);
X509_set_serialNumber(cert, serial);
ASN1_INTEGER_free(serial);
X509_gmtime_adj(X509_get_notBefore(cert), 0L);
X509_gmtime_adj(X509_get_notAfter(cert), YEAR);
subj = X509_get_subject_name(cert);
X509_NAME_add_entry_by_txt(subj, "commonName", MBSTRING_ASC,
(unsigned char *) hostname, strlen(hostname), -1, 0);
subj = X509_get_issuer_name(cert);
X509_NAME_add_entry_by_txt(subj, "commonName", MBSTRING_ASC,
(unsigned char *) trustname, strlen(trustname), -1, 0);
if (!X509_set_pubkey(cert, pkey)) {
fprintf(stderr, "Assign key fails\n%s\n",
ERR_error_string(ERR_get_error(), NULL));
X509_free(cert);
rval = -1;
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));
rval = -1;
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));
rval = -1;
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));
rval = -1;
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));
rval = -1;
return (0);
}
X509_EXTENSION_free(ex);
}
/*
* Sign and verify.
*/
X509_sign(cert, pkey, md);
if (!X509_verify(cert, pkey)) {
fprintf(stderr, "Verify %s certificate fails\n%s\n", id,
ERR_error_string(ERR_get_error(), NULL));
X509_free(cert);
rval = -1;
return (0);
}
/*
* Write the certificate encoded in PEM.
*/
sprintf(pathbuf, "%scert", id);
str = fheader(pathbuf, hostname);
PEM_write_X509(str, cert);
fclose(str);
if (debug)
X509_print_fp(stdout, cert);
X509_free(cert);
fslink("cert", hostname);
return (1);
}
#if 0 /* asn2ntp is not used */
/*
* 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;
}
}
#endif /* OPENSSL */
/*
* 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);
rval = -1;
return (NULL);
}
/*
* Generate file header
*/
FILE *
fheader (
const char *id, /* file name id */
const char *name /* owner name */
)
{
FILE *str; /* file handle */
sprintf(filename, "ntpkey_%s_%s.%lu", id, name, epoch +
JAN_1970);
if ((str = fopen(filename, "w")) == NULL) {
perror("Write");
exit (-1);
}
fprintf(str, "# %s\n# %s", filename, ctime(&epoch));
return (str);
}
/*
* Generate symbolic links
*/
void
fslink(
const char *id, /* file name id */
const char *name /* owner name */
)
{
char linkname[MAXFILENAME]; /* link name */
int temp;
sprintf(linkname, "ntpkey_%s_%s", id, name);
remove(linkname);
temp = symlink(filename, linkname);
if (temp < 0)
perror(id);
fprintf(stderr, "Generating new %s file and link\n", id);
fprintf(stderr, "%s->%s\n", linkname, filename);
}
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