394 lines
12 KiB
C
394 lines
12 KiB
C
/*
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* Copyright 1995-2019 The OpenSSL Project Authors. All Rights Reserved.
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*
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* Licensed under the OpenSSL license (the "License"). You may not use
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* this file except in compliance with the License. You can obtain a copy
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* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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*/
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/*
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* NB: these functions have been "upgraded", the deprecated versions (which
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* are compatibility wrappers using these functions) are in rsa_depr.c. -
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* Geoff
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*/
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#include <stdio.h>
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#include <time.h>
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#include "internal/cryptlib.h"
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#include <openssl/bn.h>
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#include "rsa_local.h"
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static int rsa_builtin_keygen(RSA *rsa, int bits, int primes, BIGNUM *e_value,
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BN_GENCB *cb);
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/*
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* NB: this wrapper would normally be placed in rsa_lib.c and the static
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* implementation would probably be in rsa_eay.c. Nonetheless, is kept here
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* so that we don't introduce a new linker dependency. Eg. any application
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* that wasn't previously linking object code related to key-generation won't
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* have to now just because key-generation is part of RSA_METHOD.
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*/
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int RSA_generate_key_ex(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb)
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{
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if (rsa->meth->rsa_keygen != NULL)
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return rsa->meth->rsa_keygen(rsa, bits, e_value, cb);
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return RSA_generate_multi_prime_key(rsa, bits, RSA_DEFAULT_PRIME_NUM,
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e_value, cb);
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}
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int RSA_generate_multi_prime_key(RSA *rsa, int bits, int primes,
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BIGNUM *e_value, BN_GENCB *cb)
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{
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/* multi-prime is only supported with the builtin key generation */
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if (rsa->meth->rsa_multi_prime_keygen != NULL) {
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return rsa->meth->rsa_multi_prime_keygen(rsa, bits, primes,
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e_value, cb);
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} else if (rsa->meth->rsa_keygen != NULL) {
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/*
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* However, if rsa->meth implements only rsa_keygen, then we
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* have to honour it in 2-prime case and assume that it wouldn't
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* know what to do with multi-prime key generated by builtin
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* subroutine...
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*/
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if (primes == 2)
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return rsa->meth->rsa_keygen(rsa, bits, e_value, cb);
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else
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return 0;
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}
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return rsa_builtin_keygen(rsa, bits, primes, e_value, cb);
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}
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static int rsa_builtin_keygen(RSA *rsa, int bits, int primes, BIGNUM *e_value,
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BN_GENCB *cb)
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{
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BIGNUM *r0 = NULL, *r1 = NULL, *r2 = NULL, *tmp, *prime;
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int ok = -1, n = 0, bitsr[RSA_MAX_PRIME_NUM], bitse = 0;
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int i = 0, quo = 0, rmd = 0, adj = 0, retries = 0;
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RSA_PRIME_INFO *pinfo = NULL;
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STACK_OF(RSA_PRIME_INFO) *prime_infos = NULL;
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BN_CTX *ctx = NULL;
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BN_ULONG bitst = 0;
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unsigned long error = 0;
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if (bits < RSA_MIN_MODULUS_BITS) {
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ok = 0; /* we set our own err */
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RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, RSA_R_KEY_SIZE_TOO_SMALL);
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goto err;
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}
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if (primes < RSA_DEFAULT_PRIME_NUM || primes > rsa_multip_cap(bits)) {
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ok = 0; /* we set our own err */
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RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, RSA_R_KEY_PRIME_NUM_INVALID);
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goto err;
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}
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ctx = BN_CTX_new();
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if (ctx == NULL)
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goto err;
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BN_CTX_start(ctx);
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r0 = BN_CTX_get(ctx);
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r1 = BN_CTX_get(ctx);
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r2 = BN_CTX_get(ctx);
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if (r2 == NULL)
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goto err;
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/* divide bits into 'primes' pieces evenly */
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quo = bits / primes;
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rmd = bits % primes;
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for (i = 0; i < primes; i++)
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bitsr[i] = (i < rmd) ? quo + 1 : quo;
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/* We need the RSA components non-NULL */
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if (!rsa->n && ((rsa->n = BN_new()) == NULL))
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goto err;
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if (!rsa->d && ((rsa->d = BN_secure_new()) == NULL))
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goto err;
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if (!rsa->e && ((rsa->e = BN_new()) == NULL))
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goto err;
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if (!rsa->p && ((rsa->p = BN_secure_new()) == NULL))
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goto err;
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if (!rsa->q && ((rsa->q = BN_secure_new()) == NULL))
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goto err;
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if (!rsa->dmp1 && ((rsa->dmp1 = BN_secure_new()) == NULL))
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goto err;
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if (!rsa->dmq1 && ((rsa->dmq1 = BN_secure_new()) == NULL))
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goto err;
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if (!rsa->iqmp && ((rsa->iqmp = BN_secure_new()) == NULL))
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goto err;
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/* initialize multi-prime components */
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if (primes > RSA_DEFAULT_PRIME_NUM) {
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rsa->version = RSA_ASN1_VERSION_MULTI;
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prime_infos = sk_RSA_PRIME_INFO_new_reserve(NULL, primes - 2);
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if (prime_infos == NULL)
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goto err;
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if (rsa->prime_infos != NULL) {
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/* could this happen? */
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sk_RSA_PRIME_INFO_pop_free(rsa->prime_infos, rsa_multip_info_free);
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}
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rsa->prime_infos = prime_infos;
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/* prime_info from 2 to |primes| -1 */
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for (i = 2; i < primes; i++) {
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pinfo = rsa_multip_info_new();
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if (pinfo == NULL)
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goto err;
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(void)sk_RSA_PRIME_INFO_push(prime_infos, pinfo);
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}
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}
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if (BN_copy(rsa->e, e_value) == NULL)
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goto err;
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/* generate p, q and other primes (if any) */
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for (i = 0; i < primes; i++) {
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adj = 0;
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retries = 0;
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if (i == 0) {
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prime = rsa->p;
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} else if (i == 1) {
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prime = rsa->q;
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} else {
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pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2);
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prime = pinfo->r;
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}
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BN_set_flags(prime, BN_FLG_CONSTTIME);
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for (;;) {
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redo:
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if (!BN_generate_prime_ex(prime, bitsr[i] + adj, 0, NULL, NULL, cb))
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goto err;
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/*
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* prime should not be equal to p, q, r_3...
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* (those primes prior to this one)
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*/
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{
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int j;
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for (j = 0; j < i; j++) {
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BIGNUM *prev_prime;
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if (j == 0)
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prev_prime = rsa->p;
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else if (j == 1)
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prev_prime = rsa->q;
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else
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prev_prime = sk_RSA_PRIME_INFO_value(prime_infos,
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j - 2)->r;
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if (!BN_cmp(prime, prev_prime)) {
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goto redo;
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}
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}
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}
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if (!BN_sub(r2, prime, BN_value_one()))
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goto err;
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ERR_set_mark();
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BN_set_flags(r2, BN_FLG_CONSTTIME);
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if (BN_mod_inverse(r1, r2, rsa->e, ctx) != NULL) {
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/* GCD == 1 since inverse exists */
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break;
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}
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error = ERR_peek_last_error();
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if (ERR_GET_LIB(error) == ERR_LIB_BN
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&& ERR_GET_REASON(error) == BN_R_NO_INVERSE) {
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/* GCD != 1 */
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ERR_pop_to_mark();
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} else {
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goto err;
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}
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if (!BN_GENCB_call(cb, 2, n++))
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goto err;
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}
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bitse += bitsr[i];
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/* calculate n immediately to see if it's sufficient */
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if (i == 1) {
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/* we get at least 2 primes */
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if (!BN_mul(r1, rsa->p, rsa->q, ctx))
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goto err;
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} else if (i != 0) {
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/* modulus n = p * q * r_3 * r_4 ... */
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if (!BN_mul(r1, rsa->n, prime, ctx))
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goto err;
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} else {
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/* i == 0, do nothing */
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if (!BN_GENCB_call(cb, 3, i))
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goto err;
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continue;
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}
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/*
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* if |r1|, product of factors so far, is not as long as expected
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* (by checking the first 4 bits are less than 0x9 or greater than
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* 0xF). If so, re-generate the last prime.
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*
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* NOTE: This actually can't happen in two-prime case, because of
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* the way factors are generated.
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*
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* Besides, another consideration is, for multi-prime case, even the
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* length modulus is as long as expected, the modulus could start at
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* 0x8, which could be utilized to distinguish a multi-prime private
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* key by using the modulus in a certificate. This is also covered
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* by checking the length should not be less than 0x9.
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*/
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if (!BN_rshift(r2, r1, bitse - 4))
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goto err;
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bitst = BN_get_word(r2);
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if (bitst < 0x9 || bitst > 0xF) {
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/*
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* For keys with more than 4 primes, we attempt longer factor to
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* meet length requirement.
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*
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* Otherwise, we just re-generate the prime with the same length.
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*
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* This strategy has the following goals:
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*
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* 1. 1024-bit factors are efficient when using 3072 and 4096-bit key
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* 2. stay the same logic with normal 2-prime key
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*/
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bitse -= bitsr[i];
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if (!BN_GENCB_call(cb, 2, n++))
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goto err;
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if (primes > 4) {
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if (bitst < 0x9)
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adj++;
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else
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adj--;
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} else if (retries == 4) {
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/*
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* re-generate all primes from scratch, mainly used
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* in 4 prime case to avoid long loop. Max retry times
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* is set to 4.
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*/
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i = -1;
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bitse = 0;
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continue;
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}
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retries++;
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goto redo;
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}
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/* save product of primes for further use, for multi-prime only */
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if (i > 1 && BN_copy(pinfo->pp, rsa->n) == NULL)
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goto err;
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if (BN_copy(rsa->n, r1) == NULL)
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goto err;
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if (!BN_GENCB_call(cb, 3, i))
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goto err;
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}
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if (BN_cmp(rsa->p, rsa->q) < 0) {
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tmp = rsa->p;
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rsa->p = rsa->q;
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rsa->q = tmp;
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}
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/* calculate d */
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/* p - 1 */
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if (!BN_sub(r1, rsa->p, BN_value_one()))
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goto err;
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/* q - 1 */
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if (!BN_sub(r2, rsa->q, BN_value_one()))
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goto err;
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/* (p - 1)(q - 1) */
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if (!BN_mul(r0, r1, r2, ctx))
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goto err;
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/* multi-prime */
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for (i = 2; i < primes; i++) {
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pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2);
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/* save r_i - 1 to pinfo->d temporarily */
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if (!BN_sub(pinfo->d, pinfo->r, BN_value_one()))
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goto err;
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if (!BN_mul(r0, r0, pinfo->d, ctx))
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goto err;
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}
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{
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BIGNUM *pr0 = BN_new();
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if (pr0 == NULL)
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goto err;
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BN_with_flags(pr0, r0, BN_FLG_CONSTTIME);
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if (!BN_mod_inverse(rsa->d, rsa->e, pr0, ctx)) {
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BN_free(pr0);
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goto err; /* d */
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}
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/* We MUST free pr0 before any further use of r0 */
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BN_free(pr0);
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}
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{
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BIGNUM *d = BN_new();
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if (d == NULL)
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goto err;
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BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
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/* calculate d mod (p-1) and d mod (q - 1) */
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if (!BN_mod(rsa->dmp1, d, r1, ctx)
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|| !BN_mod(rsa->dmq1, d, r2, ctx)) {
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BN_free(d);
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goto err;
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}
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/* calculate CRT exponents */
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for (i = 2; i < primes; i++) {
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pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2);
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/* pinfo->d == r_i - 1 */
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if (!BN_mod(pinfo->d, d, pinfo->d, ctx)) {
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BN_free(d);
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goto err;
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}
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}
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/* We MUST free d before any further use of rsa->d */
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BN_free(d);
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}
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{
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BIGNUM *p = BN_new();
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if (p == NULL)
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goto err;
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BN_with_flags(p, rsa->p, BN_FLG_CONSTTIME);
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/* calculate inverse of q mod p */
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if (!BN_mod_inverse(rsa->iqmp, rsa->q, p, ctx)) {
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BN_free(p);
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goto err;
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}
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/* calculate CRT coefficient for other primes */
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for (i = 2; i < primes; i++) {
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pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2);
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BN_with_flags(p, pinfo->r, BN_FLG_CONSTTIME);
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if (!BN_mod_inverse(pinfo->t, pinfo->pp, p, ctx)) {
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BN_free(p);
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goto err;
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}
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}
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/* We MUST free p before any further use of rsa->p */
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BN_free(p);
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}
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ok = 1;
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err:
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if (ok == -1) {
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RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, ERR_LIB_BN);
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ok = 0;
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}
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BN_CTX_end(ctx);
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BN_CTX_free(ctx);
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return ok;
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}
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