File nss-CC-RSA_keygen_FIPS186-4.patch of Package mozilla-nss.972
# HG changeset patch
# Parent 1362ec425ba175fc9a316a0e81f297007f5c60e9
Make RSA key generation compliant with FIPS 186-4, section B.3.1
(and following).
bsc#917319
diff --git a/lib/freebl/mpi/mpprime.c b/lib/freebl/mpi/mpprime.c
--- a/lib/freebl/mpi/mpprime.c
+++ b/lib/freebl/mpi/mpprime.c
@@ -9,16 +9,18 @@
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "mpi-priv.h"
#include "mpprime.h"
#include "mplogic.h"
#include <stdlib.h>
#include <string.h>
+#include "../fips.h"
+
#define SMALL_TABLE 0 /* determines size of hard-wired prime table */
#define RANDOM() rand()
#include "primes.c" /* pull in the prime digit table */
/*
Test if any of a given vector of digits divides a. If not, MP_NO
@@ -433,16 +435,35 @@ mp_err mpp_make_prime(mp_int *start, mp_
num_tests = 15;
} else if (nBits >= 150) {
num_tests = 18;
} else if (nBits >= 100) {
num_tests = 27;
} else
num_tests = 50;
+ /* FIPS 186-4 mandates more M-R tests for probable primes generation - make
+ * sure the minimums are observed (see Appendix C, tables C.1 and C.2).
+ * For DSA this is handled in pqg_ParamGen() through the use of
+ * prime_testcount_p() and prime_testcount_q() respectively.
+ * For RSA this unfortunately seems to be the right place to prevent larger
+ * code changes. On the other hand, it seems to generally speed things up,
+ * since there are measurably less errors while calculating inverse modulo in
+ * rsa_build_from_primes().
+ */
+ if (FIPS_mode()) {
+ if (nBits >= 1536)
+ i = 4;
+ else
+ i = 5;
+ if (i > num_tests)
+ num_tests = i;
+ i = 0;
+ }
+
if (strong)
--nBits;
MP_CHECKOK( mpl_set_bit(start, nBits - 1, 1) );
MP_CHECKOK( mpl_set_bit(start, 0, 1) );
for (i = mpl_significant_bits(start) - 1; i >= nBits; --i) {
MP_CHECKOK( mpl_set_bit(start, i, 0) );
}
/* start sieveing with prime value of 3. */
diff --git a/lib/freebl/rsa.c b/lib/freebl/rsa.c
--- a/lib/freebl/rsa.c
+++ b/lib/freebl/rsa.c
@@ -11,32 +11,35 @@
#include "secerr.h"
#include "prclist.h"
#include "nssilock.h"
#include "prinit.h"
#include "blapi.h"
#include "mpi.h"
+#include "mpi-priv.h"
#include "mpprime.h"
#include "mplogic.h"
#include "secmpi.h"
#include "secitem.h"
#include "blapii.h"
+#include "fips.h"
/*
** Number of times to attempt to generate a prime (p or q) from a random
** seed (the seed changes for each iteration).
*/
#define MAX_PRIME_GEN_ATTEMPTS 10
/*
** Number of times to attempt to generate a key. The primes p and q change
** for each attempt.
*/
#define MAX_KEY_GEN_ATTEMPTS 10
+#define MAX_KEY_GEN_ATTEMPTS_FIPS (5 * MAX_KEY_GEN_ATTEMPTS)
/* Blinding Parameters max cache size */
#define RSA_BLINDING_PARAMS_MAX_CACHE_SIZE 20
/* exponent should not be greater than modulus */
#define BAD_RSA_KEY_SIZE(modLen, expLen) \
((expLen) > (modLen) || (modLen) > RSA_MAX_MODULUS_BITS/8 || \
(expLen) > RSA_MAX_EXPONENT_BITS/8)
@@ -133,28 +136,41 @@ rsa_build_from_primes(const mp_int *p, c
/* at least one exponent must be given */
PORT_Assert(!(needPublicExponent && needPrivateExponent));
/* 2. Compute phi = (p-1)*(q-1) */
CHECK_MPI_OK( mp_sub_d(p, 1, &psub1) );
CHECK_MPI_OK( mp_sub_d(q, 1, &qsub1) );
if (needPublicExponent || needPrivateExponent) {
- CHECK_MPI_OK( mp_mul(&psub1, &qsub1, &phi) );
+ CHECK_MPI_OK( mp_lcm(&psub1, &qsub1, &phi) );
/* 3. Compute d = e**-1 mod(phi) */
/* or e = d**-1 mod(phi) as necessary */
if (needPublicExponent) {
err = mp_invmod(d, &phi, e);
} else {
err = mp_invmod(e, &phi, d);
+ /* FIPS 186-4 (B.3.1.3.a) places additional requirements on the
+ * private exponent d:
+ * 2^(n/2) < d < lcm(p-1, q-1) = phi
+ */
+ if (FIPS_mode() && (MP_OKAY == err)) {
+ CHECK_MPI_OK( mp_2expt(&tmp, keySizeInBits / 2) );
+ if ((mp_cmp(d, &tmp) <= 0) || (mp_cmp(d, &phi) >= 0)) {
+ /* new set of p, q is needed for another calculation of d */
+ err = MP_UNDEF;
+ }
+ }
}
} else {
err = MP_OKAY;
}
- /* Verify that phi(n) and e have no common divisors */
+ /* Verify that phi(n) and e have no common divisors
+ * This is also the coprimality constraint from FIPS 186-4 (B.3.1.2.a)
+ */
if (err != MP_OKAY) {
if (err == MP_UNDEF) {
PORT_SetError(SEC_ERROR_NEED_RANDOM);
err = MP_OKAY; /* to keep PORT_SetError from being called again */
rv = SECFailure;
}
goto cleanup;
}
@@ -234,29 +250,36 @@ cleanup:
** "publicExponent" when not NULL is a pointer to some data that
** represents the public exponent to use. The data is a byte
** encoded integer, in "big endian" order.
*/
RSAPrivateKey *
RSA_NewKey(int keySizeInBits, SECItem *publicExponent)
{
unsigned int primeLen;
+ unsigned int retrials;
mp_int p, q, e, d;
+ mp_int u, v;
int kiter;
mp_err err = MP_OKAY;
- SECStatus rv = SECSuccess;
+ SECStatus rv = SECFailure;
int prerr = 0;
RSAPrivateKey *key = NULL;
PLArenaPool *arena = NULL;
/* Require key size to be a multiple of 16 bits. */
if (!publicExponent || keySizeInBits % 16 != 0 ||
BAD_RSA_KEY_SIZE(keySizeInBits/8, publicExponent->len)) {
PORT_SetError(SEC_ERROR_INVALID_ARGS);
return NULL;
}
+ /* FIPS 186-4 mandates keys to be either 2048 or 3072 bits long */
+ if (FIPS_mode() && (keySizeInBits != 2048) && (keySizeInBits != 3072)) {
+ PORT_SetError(SEC_ERROR_INVALID_ARGS);
+ return NULL;
+ }
/* 1. Allocate arena & key */
arena = PORT_NewArena(NSS_FREEBL_DEFAULT_CHUNKSIZE);
if (!arena) {
PORT_SetError(SEC_ERROR_NO_MEMORY);
return NULL;
}
key = PORT_ArenaZNew(arena, RSAPrivateKey);
if (!key) {
@@ -266,56 +289,132 @@ RSA_NewKey(int keySizeInBits, SECItem *p
}
key->arena = arena;
/* length of primes p and q (in bytes) */
primeLen = keySizeInBits / (2 * PR_BITS_PER_BYTE);
MP_DIGITS(&p) = 0;
MP_DIGITS(&q) = 0;
MP_DIGITS(&e) = 0;
MP_DIGITS(&d) = 0;
+ MP_DIGITS(&u) = 0;
+ MP_DIGITS(&v) = 0;
CHECK_MPI_OK( mp_init(&p) );
CHECK_MPI_OK( mp_init(&q) );
CHECK_MPI_OK( mp_init(&e) );
CHECK_MPI_OK( mp_init(&d) );
+ CHECK_MPI_OK( mp_init(&u) );
+ CHECK_MPI_OK( mp_init(&v) );
/* 2. Set the version number (PKCS1 v1.5 says it should be zero) */
SECITEM_AllocItem(arena, &key->version, 1);
key->version.data[0] = 0;
/* 3. Set the public exponent */
SECITEM_TO_MPINT(*publicExponent, &e);
+
+ /* FIPS 186-4 requires 2^16 < e < 2^256 (B.3.1.1.b) */
+ if (FIPS_mode()) {
+ CHECK_MPI_OK( mp_2expt(&u, 16) );
+ CHECK_MPI_OK( mp_2expt(&v, 256) );
+ if (!((mp_cmp(&u, &e) < 0) && (mp_cmp(&e, &v) < 0 ))) {
+ err = MP_BADARG;
+ goto cleanup;
+ }
+ }
+
kiter = 0;
+ /* allow more retrials in FIPS mode, since there are more chances for a
+ * respin due to additional checks */
+ retrials = FIPS_mode() ? MAX_KEY_GEN_ATTEMPTS_FIPS : MAX_KEY_GEN_ATTEMPTS;
do {
- prerr = 0;
- PORT_SetError(0);
CHECK_SEC_OK( generate_prime(&p, primeLen) );
CHECK_SEC_OK( generate_prime(&q, primeLen) );
- /* Assure p > q */
+ /* Assure p >= q */
/* NOTE: PKCS #1 does not require p > q, and NSS doesn't use any
* implementation optimization that requires p > q. We can remove
* this code in the future.
*/
if (mp_cmp(&p, &q) < 0)
mp_exch(&p, &q);
+
+ /* FIPS 186-4 puts additional requirements on the primes (B.3.1.2.a-d)
+ * (n = key bit length):
+ * 1) both (p-1) and (q-1) are coprime to e (B.3.1.2.a), i.e.:
+ * gcd(p-1,e) = 1, gcd(q-1,e) = 1
+ * this is ensured in rsa_build_from_primes(), where
+ * phi = lcm(p-1)(q-1) is tested for coprimality to e
+ * 2) magnitude constraint (B.3.1.2.b and B.3.1.2.c):
+ * both p and q are from open the (closed) interval
+ * I = < sqrt(2) * 2^(n/2 - 1) , 2^(n/2) - 1) >
+ * 3) minimum distance (B.3.1.2.d): abs(p-q) > 2 ^ (n/2 - 100)
+ */
+ if (FIPS_mode()) {
+ /* set default error which will cause the loop to re-iterate if we
+ * bail out because of unfulfilled FIPS conditions; the value is
+ * reset to 0 when the FIPS checks pass
+ */
+ prerr = SEC_ERROR_NEED_RANDOM;
+ /* 2 */
+ /* in order not to constrain the selection too much,
+ * expand the inequality:
+ * x >= 2^(1/2) * 2^(n/2 - 1)
+ * = 2^(1/2 + k) * 2^(n/2 - k - 1)
+ * = y(k) * r(k)
+ * for z(k) >= y(k) it clearly holds:
+ * x >= z(k) * r(k)
+ * one suitable z(k) such that z(k)/y(k) - 1 = o(1) is
+ * ceil(y(k)) for big-enough k
+ * ceil(y(30))/y(30) - 1 < 10^-10, so lets use that
+ * 2^30.5 = 1518500249.98802484622388101120...
+ * the magic constant is thus z(30) = 1518500250 < 2^31
+ *
+ * Additionally, since p >= q is required above, the
+ * condtitions can be shortened to:
+ * sqrt(2) * 2^(n/2 - 1) < 1518500250 * 2^(n/2 - 31) = v <= q
+ * and:
+ * p <= 2^(n/2) - 1 < 2^(n/2) = u
+ */
+ CHECK_MPI_OK( mp_2expt(&u, keySizeInBits / 2 - 31) );
+ CHECK_MPI_OK( mp_mul_d(&u, 1518500250, &v) );
+ CHECK_MPI_OK( mp_2expt(&u, keySizeInBits / 2) );
+ if ((mp_cmp(&q, &v) < 0) || (mp_cmp(&p, &u) >= 0)) {
+ kiter++;
+ continue;
+ }
+ /* 3 */
+ CHECK_MPI_OK( mp_sub(&p, &q, &u) );
+ CHECK_MPI_OK( mp_abs(&u, &u) );
+ CHECK_MPI_OK( mp_2expt(&v, keySizeInBits / 2 - 100) );
+ if (mp_cmp(&u, &v) < 0) {
+ kiter++;
+ continue;
+ }
+ }
+
+ prerr = 0;
+ PORT_SetError(0);
+
/* Attempt to use these primes to generate a key */
rv = rsa_build_from_primes(&p, &q,
&e, PR_FALSE, /* needPublicExponent=false */
&d, PR_TRUE, /* needPrivateExponent=true */
key, keySizeInBits);
if (rv == SECSuccess)
break; /* generated two good primes */
prerr = PORT_GetError();
kiter++;
/* loop until have primes */
- } while (prerr == SEC_ERROR_NEED_RANDOM && kiter < MAX_KEY_GEN_ATTEMPTS);
+ } while (prerr == SEC_ERROR_NEED_RANDOM && kiter < retrials);
if (prerr)
goto cleanup;
cleanup:
mp_clear(&p);
mp_clear(&q);
mp_clear(&e);
mp_clear(&d);
+ mp_clear(&u);
+ mp_clear(&v);
if (err) {
MP_TO_SEC_ERROR(err);
rv = SECFailure;
}
if (rv && arena) {
PORT_FreeArena(arena, PR_TRUE);
key = NULL;
}
