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mozilla-nss.27762
nss-fips-rsa-keygen-strictness.patch
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File nss-fips-rsa-keygen-strictness.patch of Package mozilla-nss.27762
# HG changeset patch # User M. Sirringhaus <msirringhaus@suse.de> # Date 1584305670 -3600 # Sun Mar 15 21:54:30 2020 +0100 # Node ID 2f570c6952d8edfc1ad9061cd3830f202eec1960 # Parent 557f9009507c9e70941dbe39965028049e1ef5a2 commit 4b8c0eac6b092717157b4141c82b4d76ccdc91b3 Author: Hans Petter Jansson <hpj@cl.no> Patch 16: nss-fips-rsa-keygen-strictness.patch 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 @@ -14,6 +14,8 @@ #include <stdlib.h> #include <string.h> +#include "../fips.h" + #define SMALL_TABLE 0 /* determines size of hard-wired prime table */ #define RANDOM() rand() @@ -451,6 +453,25 @@ } 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)); diff --git a/lib/freebl/rsa.c b/lib/freebl/rsa.c --- a/lib/freebl/rsa.c +++ b/lib/freebl/rsa.c @@ -16,11 +16,13 @@ #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 @@ -143,11 +145,24 @@ 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); @@ -280,10 +295,12 @@ mp_int q = { 0, 0, 0, NULL }; mp_int e = { 0, 0, 0, NULL }; mp_int d = { 0, 0, 0, NULL }; + mp_int u = { 0, 0, 0, NULL }; + mp_int v = { 0, 0, 0, NULL }; int kiter; int max_attempts; mp_err err = MP_OKAY; - SECStatus rv = SECSuccess; + SECStatus rv = SECFailure; int prerr = 0; RSAPrivateKey *key = NULL; PLArenaPool *arena = NULL; @@ -301,11 +318,40 @@ PORT_SetError(SEC_ERROR_INVALID_ARGS); goto cleanup; } + + MP_DIGITS(&p) = 0; + MP_DIGITS(&q) = 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(&d)); + CHECK_MPI_OK(mp_init(&u)); + CHECK_MPI_OK(mp_init(&v)); + #ifndef NSS_FIPS_DISABLED - /* Check that the exponent is not smaller than 65537 */ - if (mp_cmp_d(&e, 0x10001) < 0) { - PORT_SetError(SEC_ERROR_INVALID_ARGS); - goto cleanup; + if (FIPS_mode()) { + /* Check that the exponent is not smaller than 65537 */ + if (mp_cmp_d(&e, 0x10001) < 0) { + PORT_SetError(SEC_ERROR_INVALID_ARGS); + goto cleanup; + } + + /* FIPS 186-4 requires 2^16 < e < 2^256 (B.3.1.1.b) */ + CHECK_MPI_OK( mp_2expt(&v, 256) ); + if (!(mp_cmp(&e, &v) < 0 )) { + err = MP_BADARG; + goto cleanup; + } + + /* FIPS 186-4 mandates keys to be either 2048, 3072 or 4096 bits long. + * We also allow a key length of 4096, since this is needed in order to + * pass the CAVS RSA SigGen test. */ + if (keySizeInBits < 2048) { + PORT_SetError(SEC_ERROR_INVALID_ARGS); + goto cleanup; + } } #endif @@ -323,12 +369,7 @@ 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(&d) = 0; - CHECK_MPI_OK(mp_init(&p)); - CHECK_MPI_OK(mp_init(&q)); - CHECK_MPI_OK(mp_init(&d)); + /* 3. Set the version number (PKCS1 v1.5 says it should be zero) */ SECITEM_AllocItem(arena, &key->version, 1); key->version.data[0] = 0; @@ -339,13 +380,64 @@ 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 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()) { + /* 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: + * 1518500250 * 2^(n/2 - 31) = v < q + * p < u = 2^(n/2 - 1) + */ + 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)) { + prerr = SEC_ERROR_NEED_RANDOM; /* retry with different values */ + 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) { + prerr = SEC_ERROR_NEED_RANDOM; /* retry with different values */ + kiter++; + continue; + } + } + /* Attempt to use these primes to generate a key */ rv = rsa_build_from_primes(&p, &q, &e, PR_FALSE, /* needPublicExponent=false */ @@ -368,7 +460,9 @@ mp_clear(&q); mp_clear(&e); mp_clear(&d); - if (err) { + mp_clear(&u); + mp_clear(&v); + if (err != MP_OKAY) { MP_TO_SEC_ERROR(err); rv = SECFailure; }
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