text: /*
   *  The RSA public-key cryptosystem
   *
   *  Copyright (C) 2006-2011, Brainspark B.V.
   *
   *  This file is part of PolarSSL (http://www.polarssl.org)
   *  Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
   *
   *  All rights reserved.
   *
   *  This program is free software; you can redistribute it and/or modify
   *  it under the terms of the GNU General Public License as published by
   *  the Free Software Foundation; either version 2 of the License, or
   *  (at your option) any later version.
   *
   *  This program is distributed in the hope that it will be useful,
   *  but WITHOUT ANY WARRANTY; without even the implied warranty of
   *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   *  GNU General Public License for more details.
   *
   *  You should have received a copy of the GNU General Public License along
   *  with this program; if not, write to the Free Software Foundation, Inc.,
   *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
   */
  /*
   *  RSA was designed by Ron Rivest, Adi Shamir and Len Adleman.
   *
   *  http://theory.lcs.mit.edu/~rivest/rsapaper.pdf
   *  http://www.cacr.math.uwaterloo.ca/hac/about/chap8.pdf
   */
  
  #include "polarssl/config.h"
  
  
  #include "polarssl/rsa.h"
  #include "polarssl/md.h"
  
  #include <stdlib.h>
  #include <stdio.h>
  
  #if defined(POLARSSL_RSA_C)
  /*
   * Initialize an RSA context
   */
  #if WM_OPT_PORT
  void rsa_init( rsa_context *ctx,
                 int padding,
                 int hash_id )
  {
      memset( ctx, 0, sizeof( rsa_context ) );
  
      ctx->padding = padding;
      ctx->hash_id = hash_id;
  }
  #endif
  
  #if defined(POLARSSL_GENPRIME)
  
  /*
   * Generate an RSA keypair
   */
  int rsa_gen_key( rsa_context *ctx,
                   int (*f_rng)(void *, unsigned char *, size_t),
                   void *p_rng,
                   unsigned int nbits, int exponent )
  {
      int ret;
      mpi P1, Q1, H, G;
  
      if( f_rng == NULL || nbits < 128 || exponent < 3 )
          return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
  
      mpi_init( &P1 ); mpi_init( &Q1 ); mpi_init( &H ); mpi_init( &G );
  
      /*
       * find primes P and Q with Q < P so that:
       * GCD( E, (P-1)*(Q-1) ) == 1
       */
      MPI_CHK( mpi_lset( &ctx->E, exponent ) );
  
      do
      {
          MPI_CHK( mpi_gen_prime( &ctx->P, ( nbits + 1 ) >> 1, 0,
                                  f_rng, p_rng ) );
  
          MPI_CHK( mpi_gen_prime( &ctx->Q, ( nbits + 1 ) >> 1, 0,
                                  f_rng, p_rng ) );
  
          if( mpi_cmp_mpi( &ctx->P, &ctx->Q ) < 0 )
              mpi_swap( &ctx->P, &ctx->Q );
  
          if( mpi_cmp_mpi( &ctx->P, &ctx->Q ) == 0 )
              continue;
  
          MPI_CHK( mpi_mul_mpi( &ctx->N, &ctx->P, &ctx->Q ) );
          if( mpi_msb( &ctx->N ) != nbits )
              continue;
  
          MPI_CHK( mpi_sub_int( &P1, &ctx->P, 1 ) );
          MPI_CHK( mpi_sub_int( &Q1, &ctx->Q, 1 ) );
          MPI_CHK( mpi_mul_mpi( &H, &P1, &Q1 ) );
          MPI_CHK( mpi_gcd( &G, &ctx->E, &H  ) );
      }
      while( mpi_cmp_int( &G, 1 ) != 0 );
  
      /*
       * D  = E^-1 mod ((P-1)*(Q-1))
       * DP = D mod (P - 1)
       * DQ = D mod (Q - 1)
       * QP = Q^-1 mod P
       */
      MPI_CHK( mpi_inv_mod( &ctx->D , &ctx->E, &H  ) );
      MPI_CHK( mpi_mod_mpi( &ctx->DP, &ctx->D, &P1 ) );
      MPI_CHK( mpi_mod_mpi( &ctx->DQ, &ctx->D, &Q1 ) );
      MPI_CHK( mpi_inv_mod( &ctx->QP, &ctx->Q, &ctx->P ) );
  
      ctx->len = ( mpi_msb( &ctx->N ) + 7 ) >> 3;
  
  cleanup:
  
      mpi_free( &P1 ); mpi_free( &Q1 ); mpi_free( &H ); mpi_free( &G );
  
      if( ret != 0 )
      {
          rsa_free( ctx );
          return( POLARSSL_ERR_RSA_KEY_GEN_FAILED + ret );
      }
  
      return( 0 );
  }
  
  #endif
  
  /*
   * Check a public RSA key
   */
  int rsa_check_pubkey( const rsa_context *ctx )
  {
      if( !ctx->N.p || !ctx->E.p )
          return( POLARSSL_ERR_RSA_KEY_CHECK_FAILED );
  
      if( ( ctx->N.p[0] & 1 ) == 0 ||
          ( ctx->E.p[0] & 1 ) == 0 )
          return( POLARSSL_ERR_RSA_KEY_CHECK_FAILED );
  
      if( mpi_msb( &ctx->N ) < 128 ||
          mpi_msb( &ctx->N ) > POLARSSL_MPI_MAX_BITS )
          return( POLARSSL_ERR_RSA_KEY_CHECK_FAILED );
  
      if( mpi_msb( &ctx->E ) < 2 ||
          mpi_msb( &ctx->E ) > 64 )
          return( POLARSSL_ERR_RSA_KEY_CHECK_FAILED );
  
      return( 0 );
  }
  
  /*
   * Check a private RSA key
   */
  #if WM_OPT_PORT
  int rsa_check_privkey( const rsa_context *ctx )
  {
      int ret;
      mpi PQ, DE, P1, Q1, H, I, G, G2, L1, L2;
  
      if( ( ret = rsa_check_pubkey( ctx ) ) != 0 )
          return( ret );
  
      if( !ctx->P.p || !ctx->Q.p || !ctx->D.p )
          return( POLARSSL_ERR_RSA_KEY_CHECK_FAILED );
  
      mpi_init( &PQ ); mpi_init( &DE ); mpi_init( &P1 ); mpi_init( &Q1 );
      mpi_init( &H  ); mpi_init( &I  ); mpi_init( &G  ); mpi_init( &G2 );
      mpi_init( &L1 ); mpi_init( &L2 );
  
      MPI_CHK( mpi_mul_mpi( &PQ, &ctx->P, &ctx->Q ) );
      MPI_CHK( mpi_mul_mpi( &DE, &ctx->D, &ctx->E ) );
      MPI_CHK( mpi_sub_int( &P1, &ctx->P, 1 ) );
      MPI_CHK( mpi_sub_int( &Q1, &ctx->Q, 1 ) );
      MPI_CHK( mpi_mul_mpi( &H, &P1, &Q1 ) );
      MPI_CHK( mpi_gcd( &G, &ctx->E, &H  ) );
  
      MPI_CHK( mpi_gcd( &G2, &P1, &Q1 ) );
      MPI_CHK( mpi_div_mpi( &L1, &L2, &H, &G2 ) );
      MPI_CHK( mpi_mod_mpi( &I, &DE, &L1  ) );
  
      /*
       * Check for a valid PKCS1v2 private key
       */
      if( mpi_cmp_mpi( &PQ, &ctx->N ) != 0 ||
          mpi_cmp_int( &L2, 0 ) != 0 ||
          mpi_cmp_int( &I, 1 ) != 0 ||
          mpi_cmp_int( &G, 1 ) != 0 )
      {
          ret = POLARSSL_ERR_RSA_KEY_CHECK_FAILED;
      }
  
  
  cleanup:
  
      mpi_free( &PQ ); mpi_free( &DE ); mpi_free( &P1 ); mpi_free( &Q1 );
      mpi_free( &H  ); mpi_free( &I  ); mpi_free( &G  ); mpi_free( &G2 );
      mpi_free( &L1 ); mpi_free( &L2 );
  
      if( ret == POLARSSL_ERR_RSA_KEY_CHECK_FAILED )
          return( ret );
  
      if( ret != 0 )
          return( POLARSSL_ERR_RSA_KEY_CHECK_FAILED + ret );
  
      return( 0 );
  }
  #endif
  
  /*
   * Do an RSA public key operation
   */
  int rsa_public( rsa_context *ctx,
                  const unsigned char *input,
                  unsigned char *output )
  {
      int ret;
      size_t olen;
      mpi T;
  
      mpi_init( &T );
  
      MPI_CHK( mpi_read_binary( &T, input, ctx->len ) );
  
      if( mpi_cmp_mpi( &T, &ctx->N ) >= 0 )
      {
          mpi_free( &T );
          return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
      }
  
      olen = ctx->len;
      MPI_CHK( mpi_exp_mod( &T, &T, &ctx->E, &ctx->N, &ctx->RN ) );
      MPI_CHK( mpi_write_binary( &T, output, olen ) );
  
  cleanup:
  
      mpi_free( &T );
  
      if( ret != 0 )
          return( POLARSSL_ERR_RSA_PUBLIC_FAILED + ret );
  
      return( 0 );
  }
  
  /*
   * Do an RSA private key operation
   */
  int rsa_private( rsa_context *ctx,
                   const unsigned char *input,
                   unsigned char *output )
  {
      int ret;
      size_t olen;
      mpi T, T1, T2;
  
      mpi_init( &T ); mpi_init( &T1 ); mpi_init( &T2 );
  
      MPI_CHK( mpi_read_binary( &T, input, ctx->len ) );
  
      if( mpi_cmp_mpi( &T, &ctx->N ) >= 0 )
      {
          mpi_free( &T );
          return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
      }
  
  #if defined(POLARSSL_RSA_NO_CRT)
      MPI_CHK( mpi_exp_mod( &T, &T, &ctx->D, &ctx->N, &ctx->RN ) );
  #else
      /*
       * faster decryption using the CRT
       *
       * T1 = input ^ dP mod P
       * T2 = input ^ dQ mod Q
       */
      MPI_CHK( mpi_exp_mod( &T1, &T, &ctx->DP, &ctx->P, &ctx->RP ) );
      MPI_CHK( mpi_exp_mod( &T2, &T, &ctx->DQ, &ctx->Q, &ctx->RQ ) );
  
      /*
       * T = (T1 - T2) * (Q^-1 mod P) mod P
       */
      MPI_CHK( mpi_sub_mpi( &T, &T1, &T2 ) );
      MPI_CHK( mpi_mul_mpi( &T1, &T, &ctx->QP ) );
      MPI_CHK( mpi_mod_mpi( &T, &T1, &ctx->P ) );
  
      /*
       * output = T2 + T * Q
       */
      MPI_CHK( mpi_mul_mpi( &T1, &T, &ctx->Q ) );
      MPI_CHK( mpi_add_mpi( &T, &T2, &T1 ) );
  #endif
  
      olen = ctx->len;
      MPI_CHK( mpi_write_binary( &T, output, olen ) );
  
  cleanup:
  
      mpi_free( &T ); mpi_free( &T1 ); mpi_free( &T2 );
  
      if( ret != 0 )
          return( POLARSSL_ERR_RSA_PRIVATE_FAILED + ret );
  
      return( 0 );
  }
  
  #if defined(POLARSSL_PKCS1_V21)
  /**
   * Generate and apply the MGF1 operation (from PKCS#1 v2.1) to a buffer.
   *
   * \param dst       buffer to mask
   * \param dlen      length of destination buffer
   * \param src       source of the mask generation
   * \param slen      length of the source buffer
   * \param md_ctx    message digest context to use
   */
  static void mgf_mask( unsigned char *dst, size_t dlen, unsigned char *src, size_t slen,
                         md_context_t *md_ctx )
  {
      unsigned char mask[POLARSSL_MD_MAX_SIZE];
      unsigned char counter[4];
      unsigned char *p;
      unsigned int hlen;
      size_t i, use_len;
  
      memset( mask, 0, POLARSSL_MD_MAX_SIZE );
      memset( counter, 0, 4 );
  
      hlen = md_ctx->md_info->size;
  
      // Generate and apply dbMask
      //
      p = dst;
  
      while( dlen > 0 )
      {
          use_len = hlen;
          if( dlen < hlen )
              use_len = dlen;
  
          md_starts( md_ctx );
          md_update( md_ctx, src, slen );
          md_update( md_ctx, counter, 4 );
          md_finish( md_ctx, mask );
  
          for( i = 0; i < use_len; ++i )
              *p++ ^= mask[i];
  
          counter[3]++;
  
          dlen -= use_len;
      }
  }
  #endif
  
  /*
   * Add the message padding, then do an RSA operation
   */
  int rsa_pkcs1_encrypt( rsa_context *ctx,
                         int (*f_rng)(void *, unsigned char *, size_t),
                         void *p_rng,
                         int mode, size_t ilen,
                         const unsigned char *input,
                         unsigned char *output )
  {
      size_t nb_pad, olen;
      int ret;
      unsigned char *p = output;
  #if defined(POLARSSL_PKCS1_V21)
      unsigned int hlen;
      const md_info_t *md_info;
      md_context_t md_ctx;
  #endif
  
      olen = ctx->len;
  
      if( f_rng == NULL )
          return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
  
      switch( ctx->padding )
      {
          case RSA_PKCS_V15:
  
              if( olen < ilen + 11 )
                  return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
  
              nb_pad = olen - 3 - ilen;
  
              *p++ = 0;
              *p++ = RSA_CRYPT;
  
              while( nb_pad-- > 0 )
              {
                  int rng_dl = 100;
  
                  do {
                      ret = f_rng( p_rng, p, 1 );
                  } while( *p == 0 && --rng_dl && ret == 0 );
  
                  // Check if RNG failed to generate data
                  //
                  if( rng_dl == 0 || ret != 0)
                      return POLARSSL_ERR_RSA_RNG_FAILED + ret;
  
                  p++;
              }
              *p++ = 0;
              memcpy( p, input, ilen );
              break;
  
  #if defined(POLARSSL_PKCS1_V21)
          case RSA_PKCS_V21:
  
              md_info = md_info_from_type( ctx->hash_id );
              if( md_info == NULL )
                  return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
  
              hlen = md_get_size( md_info );
  
              if( olen < ilen + 2 * hlen + 2 || f_rng == NULL )
                  return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
  
              memset( output, 0, olen );
              memset( &md_ctx, 0, sizeof( md_context_t ) );
  
              md_init_ctx( &md_ctx, md_info );
  
              *p++ = 0;
  
              // Generate a random octet string seed
              //
              if( ( ret = f_rng( p_rng, p, hlen ) ) != 0 )
                  return( POLARSSL_ERR_RSA_RNG_FAILED + ret );
  
              p += hlen;
  
              // Construct DB
              //
              md( md_info, p, 0, p );
              p += hlen;
              p += olen - 2 * hlen - 2 - ilen;
              *p++ = 1;
              memcpy( p, input, ilen );
  
              // maskedDB: Apply dbMask to DB
              //
              mgf_mask( output + hlen + 1, olen - hlen - 1, output + 1, hlen,
                         &md_ctx );
  
              // maskedSeed: Apply seedMask to seed
              //
              mgf_mask( output + 1, hlen, output + hlen + 1, olen - hlen - 1,
                         &md_ctx );
              break;
  #endif
  
          default:
  
              return( POLARSSL_ERR_RSA_INVALID_PADDING );
      }
  
      return( ( mode == RSA_PUBLIC )
              ? rsa_public(  ctx, output, output )
              : rsa_private( ctx, output, output ) );
  }
  
  /*
   * Do an RSA operation, then remove the message padding
   */
  #if WM_OPT_PORT
  int rsa_pkcs1_decrypt( rsa_context *ctx,
                         int mode, size_t *olen,
                         const unsigned char *input,
                         unsigned char *output,
                         size_t output_max_len)
  {
      int ret;
      size_t ilen;
      unsigned char *p;
      unsigned char buf[1024];
  #if defined(POLARSSL_PKCS1_V21)
      unsigned char lhash[POLARSSL_MD_MAX_SIZE];
      unsigned int hlen;
      const md_info_t *md_info;
      md_context_t md_ctx;
  #endif
  
      ilen = ctx->len;
  
      if( ilen < 16 || ilen > sizeof( buf ) )
          return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
  
      ret = ( mode == RSA_PUBLIC )
            ? rsa_public(  ctx, input, buf )
            : rsa_private( ctx, input, buf );
  
      if( ret != 0 )
          return( ret );
  
      p = buf;
  
      switch( ctx->padding )
      {
          case RSA_PKCS_V15:
  
              if( *p++ != 0 || *p++ != RSA_CRYPT )
                  return( POLARSSL_ERR_RSA_INVALID_PADDING );
  
              while( *p != 0 )
              {
                  if( p >= buf + ilen - 1 )
                      return( POLARSSL_ERR_RSA_INVALID_PADDING );
                  p++;
              }
              p++;
              break;
  
  #if defined(POLARSSL_PKCS1_V21)
          case RSA_PKCS_V21:
  
              if( *p++ != 0 )
                  return( POLARSSL_ERR_RSA_INVALID_PADDING );
  
              md_info = md_info_from_type( ctx->hash_id );
              if( md_info == NULL )
                  return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
  
              hlen = md_get_size( md_info );
              memset( &md_ctx, 0, sizeof( md_context_t ) );
  
              md_init_ctx( &md_ctx, md_info );
  
              // Generate lHash
              //
              md( md_info, lhash, 0, lhash );
  
              // seed: Apply seedMask to maskedSeed
              //
              mgf_mask( buf + 1, hlen, buf + hlen + 1, ilen - hlen - 1,
                         &md_ctx );
  
              // DB: Apply dbMask to maskedDB
              //
              mgf_mask( buf + hlen + 1, ilen - hlen - 1, buf + 1, hlen,
                         &md_ctx );
  
              p += hlen;
  
              // Check validity
              //
              if( memcmp( lhash, p, hlen ) != 0 )
                  return( POLARSSL_ERR_RSA_INVALID_PADDING );
  
              p += hlen;
  
              while( *p == 0 && p < buf + ilen )
                  p++;
  
              if( p == buf + ilen )
                  return( POLARSSL_ERR_RSA_INVALID_PADDING );
  
              if( *p++ != 0x01 )
                  return( POLARSSL_ERR_RSA_INVALID_PADDING );
  
              break;
  #endif
  
          default:
  
              return( POLARSSL_ERR_RSA_INVALID_PADDING );
      }
  
      if (ilen - (p - buf) > output_max_len)
          return( POLARSSL_ERR_RSA_OUTPUT_TOO_LARGE );
  
      *olen = ilen - (p - buf);
      memcpy( output, p, *olen );
  
      return( 0 );
  }
  #endif
  #endif //POLARSSL_RSA_C
  
  /*
   * Do an RSA operation to sign the message digest
   */
  int rsa_pkcs1_sign( rsa_context *ctx,
                      int (*f_rng)(void *, unsigned char *, size_t),
                      void *p_rng,
                      int mode,
                      int hash_id,
                      unsigned int hashlen,
                      const unsigned char *hash,
                      unsigned char *sig )
  {
      size_t nb_pad, olen;
      unsigned char *p = sig;
  #if defined(POLARSSL_PKCS1_V21)
      unsigned char salt[POLARSSL_MD_MAX_SIZE];
      unsigned int slen, hlen, offset = 0;
      int ret;
      size_t msb;
      const md_info_t *md_info;
      md_context_t md_ctx;
  #else
      (void) f_rng;
      (void) p_rng;
  #endif
  
  #ifdef POLARSSL_RSA_C
      olen = ctx->len;
  
      switch( ctx->padding )
  #endif
      {
          case RSA_PKCS_V15:
  
              switch( hash_id )
              {
                  case SIG_RSA_RAW:
                      nb_pad = olen - 3 - hashlen;
                      break;
  
                  case SIG_RSA_MD2:
                  case SIG_RSA_MD4:
                  case SIG_RSA_MD5:
                      nb_pad = olen - 3 - 34;
                      break;
  
                  case SIG_RSA_SHA1:
                      nb_pad = olen - 3 - 35;
                      break;
  
                  case SIG_RSA_SHA224:
                      nb_pad = olen - 3 - 47;
                      break;
  
                  case SIG_RSA_SHA256:
                      nb_pad = olen - 3 - 51;
                      break;
  
                  case SIG_RSA_SHA384:
                      nb_pad = olen - 3 - 67;
                      break;
  
                  case SIG_RSA_SHA512:
                      nb_pad = olen - 3 - 83;
                      break;
  
  
                  default:
                      return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
              }
  
              if( nb_pad < 8 )
                  return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
  
              *p++ = 0;
              *p++ = RSA_SIGN;
              memset( p, 0xFF, nb_pad );
              p += nb_pad;
              *p++ = 0;
  
              switch( hash_id )
              {
                  case SIG_RSA_RAW:
                      memcpy( p, hash, hashlen );
                      break;
  
                  case SIG_RSA_MD2:
                      memcpy( p, ASN1_HASH_MDX, 18 );
                      memcpy( p + 18, hash, 16 );
                      p[13] = 2; break;
  
                  case SIG_RSA_MD4:
                      memcpy( p, ASN1_HASH_MDX, 18 );
                      memcpy( p + 18, hash, 16 );
                      p[13] = 4; break;
  
                  case SIG_RSA_MD5:
                      memcpy( p, ASN1_HASH_MDX, 18 );
                      memcpy( p + 18, hash, 16 );
                      p[13] = 5; break;
  
                  case SIG_RSA_SHA1:
                      memcpy( p, ASN1_HASH_SHA1, 15 );
                      memcpy( p + 15, hash, 20 );
                      break;
  
                  case SIG_RSA_SHA224:
                      memcpy( p, ASN1_HASH_SHA2X, 19 );
                      memcpy( p + 19, hash, 28 );
                      p[1] += 28; p[14] = 4; p[18] += 28; break;
  
                  case SIG_RSA_SHA256:
                      memcpy( p, ASN1_HASH_SHA2X, 19 );
                      memcpy( p + 19, hash, 32 );
                      p[1] += 32; p[14] = 1; p[18] += 32; break;
  
                  case SIG_RSA_SHA384:
                      memcpy( p, ASN1_HASH_SHA2X, 19 );
                      memcpy( p + 19, hash, 48 );
                      p[1] += 48; p[14] = 2; p[18] += 48; break;
  
                  case SIG_RSA_SHA512:
                      memcpy( p, ASN1_HASH_SHA2X, 19 );
                      memcpy( p + 19, hash, 64 );
                      p[1] += 64; p[14] = 3; p[18] += 64; break;
  
                  default:
                      return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
              }
  
              break;
  
  #if defined(POLARSSL_PKCS1_V21)
          case RSA_PKCS_V21:
  
              if( f_rng == NULL )
                  return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
  
              switch( hash_id )
              {
                  case SIG_RSA_MD2:
                  case SIG_RSA_MD4:
                  case SIG_RSA_MD5:
                      hashlen = 16;
                      break;
  
                  case SIG_RSA_SHA1:
                      hashlen = 20;
                      break;
  
                  case SIG_RSA_SHA224:
                      hashlen = 28;
                      break;
  
                  case SIG_RSA_SHA256:
                      hashlen = 32;
                      break;
  
                  case SIG_RSA_SHA384:
                      hashlen = 48;
                      break;
  
                  case SIG_RSA_SHA512:
                      hashlen = 64;
                      break;
  
                  default:
                      return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
              }
  
              md_info = md_info_from_type( ctx->hash_id );
              if( md_info == NULL )
                  return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
  
              hlen = md_get_size( md_info );
              slen = hlen;
  
              memset( sig, 0, olen );
              memset( &md_ctx, 0, sizeof( md_context_t ) );
  
              md_init_ctx( &md_ctx, md_info );
  
              msb = mpi_msb( &ctx->N ) - 1;
  
              // Generate salt of length slen
              //
              if( ( ret = f_rng( p_rng, salt, slen ) ) != 0 )
                  return( POLARSSL_ERR_RSA_RNG_FAILED + ret );
  
              // Note: EMSA-PSS encoding is over the length of N - 1 bits
              //
              msb = mpi_msb( &ctx->N ) - 1;
              p += olen - hlen * 2 - 2;
              *p++ = 0x01;
              memcpy( p, salt, slen );
              p += slen;
  
              // Generate H = Hash( M' )
              //
              md_starts( &md_ctx );
              md_update( &md_ctx, p, 8 );
              md_update( &md_ctx, hash, hashlen );
              md_update( &md_ctx, salt, slen );
              md_finish( &md_ctx, p );
  
              // Compensate for boundary condition when applying mask
              //
              if( msb % 8 == 0 )
                  offset = 1;
  
              // maskedDB: Apply dbMask to DB
              //
              mgf_mask( sig + offset, olen - hlen - 1 - offset, p, hlen, &md_ctx );
  
              msb = mpi_msb( &ctx->N ) - 1;
              sig[0] &= 0xFF >> ( olen * 8 - msb );
  
              p += hlen;
              *p++ = 0xBC;
              break;
  #endif
  
          default:
  
              return( POLARSSL_ERR_RSA_INVALID_PADDING );
      }
  
      return( ( mode == RSA_PUBLIC )
              ? rsa_public(  ctx, sig, sig )
              : rsa_private( ctx, sig, sig ) );
  }
  
  /*
   * Do an RSA operation and check the message digest
   */
  int rsa_pkcs1_verify( rsa_context *ctx,
                        int mode,
                        int hash_id,
                        unsigned int hashlen,
                        const unsigned char *hash,
                        unsigned char *sig )
  {
      int ret;
      size_t len, siglen;
      unsigned char *p, c;
      unsigned char buf[1024];
  #if defined(POLARSSL_PKCS1_V21)
      unsigned char result[POLARSSL_MD_MAX_SIZE];
      unsigned char zeros[8];
      unsigned int hlen;
      size_t slen, msb;
      const md_info_t *md_info;
      md_context_t md_ctx;
  #endif
  
  #ifdef POLARSSL_RSA_C
  	siglen = ctx->len;
  #endif
  
  
      if( siglen < 16 || siglen > sizeof( buf ) )
          return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
  
      ret = ( mode == RSA_PUBLIC )
            ? rsa_public(  ctx, sig, buf )
            : rsa_private( ctx, sig, buf );
  
      if( ret != 0 )
          return( ret );
  
      p = buf;
  
  #ifdef POLARSSL_RSA_C
      switch( ctx->padding )
  #endif
      {
          case RSA_PKCS_V15:
  
              if( *p++ != 0 || *p++ != RSA_SIGN )
                  return( POLARSSL_ERR_RSA_INVALID_PADDING );
  
              while( *p != 0 )
              {
                  if( p >= buf + siglen - 1 || *p != 0xFF )
                      return( POLARSSL_ERR_RSA_INVALID_PADDING );
                  p++;
              }
              p++;
  
              len = siglen - ( p - buf );
  
              if( len == 34 )
              {
                  c = p[13];
                  p[13] = 0;
  
                  if( memcmp( p, ASN1_HASH_MDX, 18 ) != 0 )
                      return( POLARSSL_ERR_RSA_VERIFY_FAILED );
  
                  if( ( c == 2 && hash_id == SIG_RSA_MD2 ) ||
                          ( c == 4 && hash_id == SIG_RSA_MD4 ) ||
                          ( c == 5 && hash_id == SIG_RSA_MD5 ) )
                  {
                      if( memcmp( p + 18, hash, 16 ) == 0 )
                          return( 0 );
                      else
                          return( POLARSSL_ERR_RSA_VERIFY_FAILED );
                  }
              }
  
              if( len == 35 && hash_id == SIG_RSA_SHA1 )
              {
                  if( memcmp( p, ASN1_HASH_SHA1, 15 ) == 0 &&
                          memcmp( p + 15, hash, 20 ) == 0 )
                      return( 0 );
                  else
                      return( POLARSSL_ERR_RSA_VERIFY_FAILED );
              }
              if( ( len == 19 + 28 && p[14] == 4 && hash_id == SIG_RSA_SHA224 ) ||
                      ( len == 19 + 32 && p[14] == 1 && hash_id == SIG_RSA_SHA256 ) ||
                      ( len == 19 + 48 && p[14] == 2 && hash_id == SIG_RSA_SHA384 ) ||
                      ( len == 19 + 64 && p[14] == 3 && hash_id == SIG_RSA_SHA512 ) )
              {
                  c = p[1] - 17;
                  p[1] = 17;
                  p[14] = 0;
  
                  if( p[18] == c &&
                          memcmp( p, ASN1_HASH_SHA2X, 18 ) == 0 &&
                          memcmp( p + 19, hash, c ) == 0 )
                      return( 0 );
                  else
                      return( POLARSSL_ERR_RSA_VERIFY_FAILED );
              }
  
              if( len == hashlen && hash_id == SIG_RSA_RAW )
              {
                  if( memcmp( p, hash, hashlen ) == 0 )
                      return( 0 );
                  else
                      return( POLARSSL_ERR_RSA_VERIFY_FAILED );
              }
  
              break;
  
  #if defined(POLARSSL_PKCS1_V21)
          case RSA_PKCS_V21:
  
              if( buf[siglen - 1] != 0xBC )
                  return( POLARSSL_ERR_RSA_INVALID_PADDING );
  
              switch( hash_id )
              {
                  case SIG_RSA_MD2:
                  case SIG_RSA_MD4:
                  case SIG_RSA_MD5:
                      hashlen = 16;
                      break;
  
                  case SIG_RSA_SHA1:
                      hashlen = 20;
                      break;
  
                  case SIG_RSA_SHA224:
                      hashlen = 28;
                      break;
  
                  case SIG_RSA_SHA256:
                      hashlen = 32;
                      break;
  
                  case SIG_RSA_SHA384:
                      hashlen = 48;
                      break;
  
                  case SIG_RSA_SHA512:
                      hashlen = 64;
                      break;
  
                  default:
                      return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
              }
  
              md_info = md_info_from_type( ctx->hash_id );
              if( md_info == NULL )
                  return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
  
              hlen = md_get_size( md_info );
              slen = siglen - hlen - 1;
  
              memset( &md_ctx, 0, sizeof( md_context_t ) );
              memset( zeros, 0, 8 );
  
              md_init_ctx( &md_ctx, md_info );
  
              // Note: EMSA-PSS verification is over the length of N - 1 bits
              //
              msb = mpi_msb( &ctx->N ) - 1;
  
              // Compensate for boundary condition when applying mask
              //
              if( msb % 8 == 0 )
              {
                  p++;
                  siglen -= 1;
              }
              if( buf[0] >> ( 8 - siglen * 8 + msb ) )
                  return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
  
              mgf_mask( p, siglen - hlen - 1, p + siglen - hlen - 1, hlen, &md_ctx );
  
              buf[0] &= 0xFF >> ( siglen * 8 - msb );
  
              while( *p == 0 && p < buf + siglen )
                  p++;
  
              if( p == buf + siglen )
                  return( POLARSSL_ERR_RSA_INVALID_PADDING );
  
              if( *p++ != 0x01 )
                  return( POLARSSL_ERR_RSA_INVALID_PADDING );
  
              slen -= p - buf;
  
              // Generate H = Hash( M' )
              //
              md_starts( &md_ctx );
              md_update( &md_ctx, zeros, 8 );
              md_update( &md_ctx, hash, hashlen );
              md_update( &md_ctx, p, slen );
              md_finish( &md_ctx, result );
  
              if( memcmp( p + slen, result, hlen ) == 0 )
                  return( 0 );
              else
                  return( POLARSSL_ERR_RSA_VERIFY_FAILED );
  #endif
  
          default:
  
              return( POLARSSL_ERR_RSA_INVALID_PADDING );
      }
  
      return( POLARSSL_ERR_RSA_INVALID_PADDING );
  }
  
  #if defined(POLARSSL_RSA_C)
  /*
   * Free the components of an RSA key
   */
  void rsa_free( rsa_context *ctx )
  {
      mpi_free( &ctx->RQ ); mpi_free( &ctx->RP ); mpi_free( &ctx->RN );
      mpi_free( &ctx->QP ); mpi_free( &ctx->DQ ); mpi_free( &ctx->DP );
      mpi_free( &ctx->Q  ); mpi_free( &ctx->P  ); mpi_free( &ctx->D );
      mpi_free( &ctx->E  ); mpi_free( &ctx->N  );
  }
  
  #if defined(POLARSSL_SELF_TEST)
  
  #include "polarssl/sha1.h"
  
  /*
   * Example RSA-1024 keypair, for test purposes
   */
  #define KEY_LEN 128
  
  #define RSA_N   "9292758453063D803DD603D5E777D788" \
                  "8ED1D5BF35786190FA2F23EBC0848AEA" \
                  "DDA92CA6C3D80B32C4D109BE0F36D6AE" \
                  "7130B9CED7ACDF54CFC7555AC14EEBAB" \
                  "93A89813FBF3C4F8066D2D800F7C38A8" \
                  "1AE31942917403FF4946B0A83D3D3E05" \
                  "EE57C6F5F5606FB5D4BC6CD34EE0801A" \
                  "5E94BB77B07507233A0BC7BAC8F90F79"
  
  #define RSA_E   "10001"
  
  #define RSA_D   "24BF6185468786FDD303083D25E64EFC" \
                  "66CA472BC44D253102F8B4A9D3BFA750" \
                  "91386C0077937FE33FA3252D28855837" \
                  "AE1B484A8A9A45F7EE8C0C634F99E8CD" \
                  "DF79C5CE07EE72C7F123142198164234" \
                  "CABB724CF78B8173B9F880FC86322407" \
                  "AF1FEDFDDE2BEB674CA15F3E81A1521E" \
                  "071513A1E85B5DFA031F21ECAE91A34D"
  
  #define RSA_P   "C36D0EB7FCD285223CFB5AABA5BDA3D8" \
                  "2C01CAD19EA484A87EA4377637E75500" \
                  "FCB2005C5C7DD6EC4AC023CDA285D796" \
                  "C3D9E75E1EFC42488BB4F1D13AC30A57"
  
  #define RSA_Q   "C000DF51A7C77AE8D7C7370C1FF55B69" \
                  "E211C2B9E5DB1ED0BF61D0D9899620F4" \
                  "910E4168387E3C30AA1E00C339A79508" \
                  "8452DD96A9A5EA5D9DCA68DA636032AF"
  
  #define RSA_DP  "C1ACF567564274FB07A0BBAD5D26E298" \
                  "3C94D22288ACD763FD8E5600ED4A702D" \
                  "F84198A5F06C2E72236AE490C93F07F8" \
                  "3CC559CD27BC2D1CA488811730BB5725"
  
  #define RSA_DQ  "4959CBF6F8FEF750AEE6977C155579C7" \
                  "D8AAEA56749EA28623272E4F7D0592AF" \
                  "7C1F1313CAC9471B5C523BFE592F517B" \
                  "407A1BD76C164B93DA2D32A383E58357"
  
  #define RSA_QP  "9AE7FBC99546432DF71896FC239EADAE" \
                  "F38D18D2B2F0E2DD275AA977E2BF4411" \
                  "F5A3B2A5D33605AEBBCCBA7FEB9F2D2F" \
                  "A74206CEC169D74BF5A8C50D6F48EA08"
  
  #define PT_LEN  24
  #define RSA_PT  "\xAA\xBB\xCC\x03\x02\x01\x00\xFF\xFF\xFF\xFF\xFF" \
                  "\x11\x22\x33\x0A\x0B\x0C\xCC\xDD\xDD\xDD\xDD\xDD"
  
  static int myrand( void *rng_state, unsigned char *output, size_t len )
  {
      size_t i;
  
      if( rng_state != NULL )
          rng_state  = NULL;
  
      for( i = 0; i < len; ++i )
          output[i] = rand();
  
      return( 0 );
  }
  
  /*
   * Checkup routine
   */
  int rsa_self_test( int verbose )
  {
      size_t len;
      rsa_context rsa;
      unsigned char rsa_plaintext[PT_LEN];
      unsigned char rsa_decrypted[PT_LEN];
      unsigned char rsa_ciphertext[KEY_LEN];
  #if defined(POLARSSL_SHA1_C)
      unsigned char sha1sum[20];
  #endif
  
      rsa_init( &rsa, RSA_PKCS_V15, 0 );
  
      rsa.len = KEY_LEN;
      mpi_read_string( &rsa.N , 16, RSA_N  );
      mpi_read_string( &rsa.E , 16, RSA_E  );
      mpi_read_string( &rsa.D , 16, RSA_D  );
      mpi_read_string( &rsa.P , 16, RSA_P  );
      mpi_read_string( &rsa.Q , 16, RSA_Q  );
      mpi_read_string( &rsa.DP, 16, RSA_DP );
      mpi_read_string( &rsa.DQ, 16, RSA_DQ );
      mpi_read_string( &rsa.QP, 16, RSA_QP );
  
      if( verbose != 0 )
          printf( "  RSA key validation: " );
  
      if( rsa_check_pubkey(  &rsa ) != 0 ||
          rsa_check_privkey( &rsa ) != 0 )
      {
          if( verbose != 0 )
              printf( "failed\n" );
  
          return( 1 );
      }
  
      if( verbose != 0 )
          printf( "passed\n  PKCS#1 encryption : " );
  
      memcpy( rsa_plaintext, RSA_PT, PT_LEN );
  
      if( rsa_pkcs1_encrypt( &rsa, &myrand, NULL, RSA_PUBLIC, PT_LEN,
                             rsa_plaintext, rsa_ciphertext ) != 0 )
      {
          if( verbose != 0 )
              printf( "failed\n" );
  
          return( 1 );
      }
  
      if( verbose != 0 )
          printf( "passed\n  PKCS#1 decryption : " );
  
      if( rsa_pkcs1_decrypt( &rsa, RSA_PRIVATE, &len,
                             rsa_ciphertext, rsa_decrypted,
                             sizeof(rsa_decrypted) ) != 0 )
      {
          if( verbose != 0 )
              printf( "failed\n" );
  
          return( 1 );
      }
  
      if( memcmp( rsa_decrypted, rsa_plaintext, len ) != 0 )
      {
          if( verbose != 0 )
              printf( "failed\n" );
  
          return( 1 );
      }
  
  #if defined(POLARSSL_SHA1_C)
      if( verbose != 0 )
          printf( "passed\n  PKCS#1 data sign  : " );
  
      p_sha1( rsa_plaintext, PT_LEN, sha1sum );
  
      if( rsa_pkcs1_sign( &rsa, NULL, NULL, RSA_PRIVATE, SIG_RSA_SHA1, 20,
                          sha1sum, rsa_ciphertext ) != 0 )
      {
          if( verbose != 0 )
              printf( "failed\n" );
  
          return( 1 );
      }
  
      if( verbose != 0 )
          printf( "passed\n  PKCS#1 sig. verify: " );
  
      if( rsa_pkcs1_verify( &rsa, RSA_PUBLIC, SIG_RSA_SHA1, 20,
                            sha1sum, rsa_ciphertext ) != 0 )
      {
          if( verbose != 0 )
              printf( "failed\n" );
  
          return( 1 );
      }
  
      if( verbose != 0 )
          printf( "passed\n\n" );
  #endif /* POLARSSL_SHA1_C */
  
      rsa_free( &rsa );
  
      return( 0 );
  }
  
  #endif
  
  #endif
  