text: /*
   * Copyright 1995-2020 The OpenSSL Project Authors. All Rights Reserved.
   *
   * Licensed under the Apache License 2.0 (the "License").  You may not use
   * this file except in compliance with the License.  You can obtain a copy
   * in the file LICENSE in the source distribution or at
   * https://www.openssl.org/source/license.html
   */
  
  /*
   * NB: these functions have been "upgraded", the deprecated versions (which
   * are compatibility wrappers using these functions) are in rsa_depr.c. -
   * Geoff
   */
  
  /*
   * RSA low level APIs are deprecated for public use, but still ok for
   * internal use.
   */
  #include "internal/deprecated.h"
  
  #include <stdio.h>
  #include <time.h>
  #include "internal/cryptlib.h"
  #include <openssl/bn.h>
  #include <openssl/self_test.h>
  #include "rsa_local.h"
  
  static int rsa_keygen_pairwise_test(RSA *rsa, OSSL_CALLBACK *cb, void *cbarg);
  static int rsa_keygen(OPENSSL_CTX *libctx, RSA *rsa, int bits, int primes,
                        BIGNUM *e_value, BN_GENCB *cb, int pairwise_test);
  
  /*
   * NB: this wrapper would normally be placed in rsa_lib.c and the static
   * implementation would probably be in rsa_eay.c. Nonetheless, is kept here
   * so that we don't introduce a new linker dependency. Eg. any application
   * that wasn't previously linking object code related to key-generation won't
   * have to now just because key-generation is part of RSA_METHOD.
   */
  int RSA_generate_key_ex(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb)
  {
      if (rsa->meth->rsa_keygen != NULL)
          return rsa->meth->rsa_keygen(rsa, bits, e_value, cb);
  
      return RSA_generate_multi_prime_key(rsa, bits, RSA_DEFAULT_PRIME_NUM,
                                          e_value, cb);
  }
  
  int RSA_generate_multi_prime_key(RSA *rsa, int bits, int primes,
                                   BIGNUM *e_value, BN_GENCB *cb)
  {
  #ifndef FIPS_MODULE
      /* multi-prime is only supported with the builtin key generation */
      if (rsa->meth->rsa_multi_prime_keygen != NULL) {
          return rsa->meth->rsa_multi_prime_keygen(rsa, bits, primes,
                                                   e_value, cb);
      } else if (rsa->meth->rsa_keygen != NULL) {
          /*
           * However, if rsa->meth implements only rsa_keygen, then we
           * have to honour it in 2-prime case and assume that it wouldn't
           * know what to do with multi-prime key generated by builtin
           * subroutine...
           */
          if (primes == 2)
              return rsa->meth->rsa_keygen(rsa, bits, e_value, cb);
          else
              return 0;
      }
  #endif /* FIPS_MODUKE */
      return rsa_keygen(rsa->libctx, rsa, bits, primes, e_value, cb, 0);
  }
  
  #ifndef FIPS_MODULE
  static int rsa_multiprime_keygen(RSA *rsa, int bits, int primes,
                                   BIGNUM *e_value, BN_GENCB *cb)
  {
      BIGNUM *r0 = NULL, *r1 = NULL, *r2 = NULL, *tmp, *prime;
      int n = 0, bitsr[RSA_MAX_PRIME_NUM], bitse = 0;
      int i = 0, quo = 0, rmd = 0, adj = 0, retries = 0;
      RSA_PRIME_INFO *pinfo = NULL;
      STACK_OF(RSA_PRIME_INFO) *prime_infos = NULL;
      BN_CTX *ctx = NULL;
      BN_ULONG bitst = 0;
      unsigned long error = 0;
      int ok = -1;
  
      if (bits < RSA_MIN_MODULUS_BITS) {
          ok = 0;             /* we set our own err */
          RSAerr(0, RSA_R_KEY_SIZE_TOO_SMALL);
          goto err;
      }
  
      /* A bad value for e can cause infinite loops */
      if (e_value != NULL && !rsa_check_public_exponent(e_value)) {
          RSAerr(0, RSA_R_PUB_EXPONENT_OUT_OF_RANGE);
          return 0;
      }
  
      if (primes < RSA_DEFAULT_PRIME_NUM || primes > rsa_multip_cap(bits)) {
          ok = 0;             /* we set our own err */
          RSAerr(0, RSA_R_KEY_PRIME_NUM_INVALID);
          goto err;
      }
  
      ctx = BN_CTX_new();
      if (ctx == NULL)
          goto err;
      BN_CTX_start(ctx);
      r0 = BN_CTX_get(ctx);
      r1 = BN_CTX_get(ctx);
      r2 = BN_CTX_get(ctx);
      if (r2 == NULL)
          goto err;
  
      /* divide bits into 'primes' pieces evenly */
      quo = bits / primes;
      rmd = bits % primes;
  
      for (i = 0; i < primes; i++)
          bitsr[i] = (i < rmd) ? quo + 1 : quo;
  
      rsa->dirty_cnt++;
  
      /* We need the RSA components non-NULL */
      if (!rsa->n && ((rsa->n = BN_new()) == NULL))
          goto err;
      if (!rsa->d && ((rsa->d = BN_secure_new()) == NULL))
          goto err;
      BN_set_flags(rsa->d, BN_FLG_CONSTTIME);
      if (!rsa->e && ((rsa->e = BN_new()) == NULL))
          goto err;
      if (!rsa->p && ((rsa->p = BN_secure_new()) == NULL))
          goto err;
      BN_set_flags(rsa->p, BN_FLG_CONSTTIME);
      if (!rsa->q && ((rsa->q = BN_secure_new()) == NULL))
          goto err;
      BN_set_flags(rsa->q, BN_FLG_CONSTTIME);
      if (!rsa->dmp1 && ((rsa->dmp1 = BN_secure_new()) == NULL))
          goto err;
      BN_set_flags(rsa->dmp1, BN_FLG_CONSTTIME);
      if (!rsa->dmq1 && ((rsa->dmq1 = BN_secure_new()) == NULL))
          goto err;
      BN_set_flags(rsa->dmq1, BN_FLG_CONSTTIME);
      if (!rsa->iqmp && ((rsa->iqmp = BN_secure_new()) == NULL))
          goto err;
      BN_set_flags(rsa->iqmp, BN_FLG_CONSTTIME);
  
      /* initialize multi-prime components */
      if (primes > RSA_DEFAULT_PRIME_NUM) {
          rsa->version = RSA_ASN1_VERSION_MULTI;
          prime_infos = sk_RSA_PRIME_INFO_new_reserve(NULL, primes - 2);
          if (prime_infos == NULL)
              goto err;
          if (rsa->prime_infos != NULL) {
              /* could this happen? */
              sk_RSA_PRIME_INFO_pop_free(rsa->prime_infos, rsa_multip_info_free);
          }
          rsa->prime_infos = prime_infos;
  
          /* prime_info from 2 to |primes| -1 */
          for (i = 2; i < primes; i++) {
              pinfo = rsa_multip_info_new();
              if (pinfo == NULL)
                  goto err;
              (void)sk_RSA_PRIME_INFO_push(prime_infos, pinfo);
          }
      }
  
      if (BN_copy(rsa->e, e_value) == NULL)
          goto err;
  
      /* generate p, q and other primes (if any) */
      for (i = 0; i < primes; i++) {
          adj = 0;
          retries = 0;
  
          if (i == 0) {
              prime = rsa->p;
          } else if (i == 1) {
              prime = rsa->q;
          } else {
              pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2);
              prime = pinfo->r;
          }
          BN_set_flags(prime, BN_FLG_CONSTTIME);
  
          for (;;) {
   redo:
              if (!BN_generate_prime_ex(prime, bitsr[i] + adj, 0, NULL, NULL, cb))
                  goto err;
              /*
               * prime should not be equal to p, q, r_3...
               * (those primes prior to this one)
               */
              {
                  int j;
  
                  for (j = 0; j < i; j++) {
                      BIGNUM *prev_prime;
  
                      if (j == 0)
                          prev_prime = rsa->p;
                      else if (j == 1)
                          prev_prime = rsa->q;
                      else
                          prev_prime = sk_RSA_PRIME_INFO_value(prime_infos,
                                                               j - 2)->r;
  
                      if (!BN_cmp(prime, prev_prime)) {
                          goto redo;
                      }
                  }
              }
              if (!BN_sub(r2, prime, BN_value_one()))
                  goto err;
              ERR_set_mark();
              BN_set_flags(r2, BN_FLG_CONSTTIME);
              if (BN_mod_inverse(r1, r2, rsa->e, ctx) != NULL) {
                 /* GCD == 1 since inverse exists */
                  break;
              }
              error = ERR_peek_last_error();
              if (ERR_GET_LIB(error) == ERR_LIB_BN
                  && ERR_GET_REASON(error) == BN_R_NO_INVERSE) {
                  /* GCD != 1 */
                  ERR_pop_to_mark();
              } else {
                  goto err;
              }
              if (!BN_GENCB_call(cb, 2, n++))
                  goto err;
          }
  
          bitse += bitsr[i];
  
          /* calculate n immediately to see if it's sufficient */
          if (i == 1) {
              /* we get at least 2 primes */
              if (!BN_mul(r1, rsa->p, rsa->q, ctx))
                  goto err;
          } else if (i != 0) {
              /* modulus n = p * q * r_3 * r_4 ... */
              if (!BN_mul(r1, rsa->n, prime, ctx))
                  goto err;
          } else {
              /* i == 0, do nothing */
              if (!BN_GENCB_call(cb, 3, i))
                  goto err;
              continue;
          }
          /*
           * if |r1|, product of factors so far, is not as long as expected
           * (by checking the first 4 bits are less than 0x9 or greater than
           * 0xF). If so, re-generate the last prime.
           *
           * NOTE: This actually can't happen in two-prime case, because of
           * the way factors are generated.
           *
           * Besides, another consideration is, for multi-prime case, even the
           * length modulus is as long as expected, the modulus could start at
           * 0x8, which could be utilized to distinguish a multi-prime private
           * key by using the modulus in a certificate. This is also covered
           * by checking the length should not be less than 0x9.
           */
          if (!BN_rshift(r2, r1, bitse - 4))
              goto err;
          bitst = BN_get_word(r2);
  
          if (bitst < 0x9 || bitst > 0xF) {
              /*
               * For keys with more than 4 primes, we attempt longer factor to
               * meet length requirement.
               *
               * Otherwise, we just re-generate the prime with the same length.
               *
               * This strategy has the following goals:
               *
               * 1. 1024-bit factors are efficient when using 3072 and 4096-bit key
               * 2. stay the same logic with normal 2-prime key
               */
              bitse -= bitsr[i];
              if (!BN_GENCB_call(cb, 2, n++))
                  goto err;
              if (primes > 4) {
                  if (bitst < 0x9)
                      adj++;
                  else
                      adj--;
              } else if (retries == 4) {
                  /*
                   * re-generate all primes from scratch, mainly used
                   * in 4 prime case to avoid long loop. Max retry times
                   * is set to 4.
                   */
                  i = -1;
                  bitse = 0;
                  continue;
              }
              retries++;
              goto redo;
          }
          /* save product of primes for further use, for multi-prime only */
          if (i > 1 && BN_copy(pinfo->pp, rsa->n) == NULL)
              goto err;
          if (BN_copy(rsa->n, r1) == NULL)
              goto err;
          if (!BN_GENCB_call(cb, 3, i))
              goto err;
      }
  
      if (BN_cmp(rsa->p, rsa->q) < 0) {
          tmp = rsa->p;
          rsa->p = rsa->q;
          rsa->q = tmp;
      }
  
      /* calculate d */
  
      /* p - 1 */
      if (!BN_sub(r1, rsa->p, BN_value_one()))
          goto err;
      /* q - 1 */
      if (!BN_sub(r2, rsa->q, BN_value_one()))
          goto err;
      /* (p - 1)(q - 1) */
      if (!BN_mul(r0, r1, r2, ctx))
          goto err;
      /* multi-prime */
      for (i = 2; i < primes; i++) {
          pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2);
          /* save r_i - 1 to pinfo->d temporarily */
          if (!BN_sub(pinfo->d, pinfo->r, BN_value_one()))
              goto err;
          if (!BN_mul(r0, r0, pinfo->d, ctx))
              goto err;
      }
  
      {
          BIGNUM *pr0 = BN_new();
  
          if (pr0 == NULL)
              goto err;
  
          BN_with_flags(pr0, r0, BN_FLG_CONSTTIME);
          if (!BN_mod_inverse(rsa->d, rsa->e, pr0, ctx)) {
              BN_free(pr0);
              goto err;               /* d */
          }
          /* We MUST free pr0 before any further use of r0 */
          BN_free(pr0);
      }
  
      {
          BIGNUM *d = BN_new();
  
          if (d == NULL)
              goto err;
  
          BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
  
          /* calculate d mod (p-1) and d mod (q - 1) */
          if (!BN_mod(rsa->dmp1, d, r1, ctx)
              || !BN_mod(rsa->dmq1, d, r2, ctx)) {
              BN_free(d);
              goto err;
          }
  
          /* calculate CRT exponents */
          for (i = 2; i < primes; i++) {
              pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2);
              /* pinfo->d == r_i - 1 */
              if (!BN_mod(pinfo->d, d, pinfo->d, ctx)) {
                  BN_free(d);
                  goto err;
              }
          }
  
          /* We MUST free d before any further use of rsa->d */
          BN_free(d);
      }
  
      {
          BIGNUM *p = BN_new();
  
          if (p == NULL)
              goto err;
          BN_with_flags(p, rsa->p, BN_FLG_CONSTTIME);
  
          /* calculate inverse of q mod p */
          if (!BN_mod_inverse(rsa->iqmp, rsa->q, p, ctx)) {
              BN_free(p);
              goto err;
          }
  
          /* calculate CRT coefficient for other primes */
          for (i = 2; i < primes; i++) {
              pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2);
              BN_with_flags(p, pinfo->r, BN_FLG_CONSTTIME);
              if (!BN_mod_inverse(pinfo->t, pinfo->pp, p, ctx)) {
                  BN_free(p);
                  goto err;
              }
          }
  
          /* We MUST free p before any further use of rsa->p */
          BN_free(p);
      }
  
      ok = 1;
   err:
      if (ok == -1) {
          RSAerr(0, ERR_LIB_BN);
          ok = 0;
      }
      BN_CTX_end(ctx);
      BN_CTX_free(ctx);
      return ok;
  }
  #endif /* FIPS_MODULE */
  
  static int rsa_keygen(OPENSSL_CTX *libctx, RSA *rsa, int bits, int primes,
                        BIGNUM *e_value, BN_GENCB *cb, int pairwise_test)
  {
      int ok = 0;
  
      /*
       * Only multi-prime keys or insecure keys with a small key length will use
       * the older rsa_multiprime_keygen().
       */
      if (primes == 2 && bits >= 2048)
          ok = rsa_sp800_56b_generate_key(rsa, bits, e_value, cb);
  #ifndef FIPS_MODULE
      else
          ok = rsa_multiprime_keygen(rsa, bits, primes, e_value, cb);
  #endif /* FIPS_MODULE */
  
  #ifdef FIPS_MODULE
      pairwise_test = 1; /* FIPS MODE needs to always run the pairwise test */
  #endif
      if (pairwise_test && ok > 0) {
          OSSL_CALLBACK *stcb = NULL;
          void *stcbarg = NULL;
  
          OSSL_SELF_TEST_get_callback(libctx, &stcb, &stcbarg);
          ok = rsa_keygen_pairwise_test(rsa, stcb, stcbarg);
          if (!ok) {
              /* Clear intermediate results */
              BN_clear_free(rsa->d);
              BN_clear_free(rsa->p);
              BN_clear_free(rsa->q);
              BN_clear_free(rsa->dmp1);
              BN_clear_free(rsa->dmq1);
              BN_clear_free(rsa->iqmp);
              rsa->d = NULL;
              rsa->p = NULL;
              rsa->q = NULL;
              rsa->dmp1 = NULL;
              rsa->dmq1 = NULL;
              rsa->iqmp = NULL;
          }
      }
      return ok;
  }
  
  /*
   * For RSA key generation it is not known whether the key pair will be used
   * for key transport or signatures. FIPS 140-2 IG 9.9 states that in this case
   * either a signature verification OR an encryption operation may be used to
   * perform the pairwise consistency check. The simpler encrypt/decrypt operation
   * has been chosen for this case.
   */
  static int rsa_keygen_pairwise_test(RSA *rsa, OSSL_CALLBACK *cb, void *cbarg)
  {
      int ret = 0;
      unsigned int ciphertxt_len;
      unsigned char *ciphertxt = NULL;
      const unsigned char plaintxt[16] = {0};
      unsigned char decoded[256];
      unsigned int decoded_len;
      unsigned int plaintxt_len = (unsigned int)sizeof(plaintxt_len);
      int padding = RSA_PKCS1_PADDING;
      OSSL_SELF_TEST *st = NULL;
  
      st = OSSL_SELF_TEST_new(cb, cbarg);
      if (st == NULL)
          goto err;
      OSSL_SELF_TEST_onbegin(st, OSSL_SELF_TEST_TYPE_PCT,
                             OSSL_SELF_TEST_DESC_PCT_RSA_PKCS1);
  
      ciphertxt_len = RSA_size(rsa);
      ciphertxt = (unsigned char *)OPENSSL_zalloc(ciphertxt_len);
      if (ciphertxt == NULL)
          goto err;
  
      ciphertxt_len = RSA_public_encrypt(plaintxt_len, plaintxt, ciphertxt, rsa,
                                         padding);
      if (ciphertxt_len <= 0)
          goto err;
      if (ciphertxt_len == plaintxt_len
          && memcmp(ciphertxt, plaintxt, plaintxt_len) == 0)
          goto err;
  
      OSSL_SELF_TEST_oncorrupt_byte(st, ciphertxt);
  
      decoded_len = RSA_private_decrypt(ciphertxt_len, ciphertxt, decoded, rsa,
                                        padding);
      if (decoded_len != plaintxt_len
          || memcmp(decoded, plaintxt,  decoded_len) != 0)
          goto err;
  
      ret = 1;
  err:
      OSSL_SELF_TEST_onend(st, ret);
      OSSL_SELF_TEST_free(st);
      OPENSSL_free(ciphertxt);
  
      return ret;
  }
  