PolarSSL v1.1.4
rsa.c
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00001 /*
00002  *  The RSA public-key cryptosystem
00003  *
00004  *  Copyright (C) 2006-2011, Brainspark B.V.
00005  *
00006  *  This file is part of PolarSSL (http://www.polarssl.org)
00007  *  Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
00008  *
00009  *  All rights reserved.
00010  *
00011  *  This program is free software; you can redistribute it and/or modify
00012  *  it under the terms of the GNU General Public License as published by
00013  *  the Free Software Foundation; either version 2 of the License, or
00014  *  (at your option) any later version.
00015  *
00016  *  This program is distributed in the hope that it will be useful,
00017  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
00018  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00019  *  GNU General Public License for more details.
00020  *
00021  *  You should have received a copy of the GNU General Public License along
00022  *  with this program; if not, write to the Free Software Foundation, Inc.,
00023  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
00024  */
00025 /*
00026  *  RSA was designed by Ron Rivest, Adi Shamir and Len Adleman.
00027  *
00028  *  http://theory.lcs.mit.edu/~rivest/rsapaper.pdf
00029  *  http://www.cacr.math.uwaterloo.ca/hac/about/chap8.pdf
00030  */
00031 
00032 #include "polarssl/config.h"
00033 
00034 #if defined(POLARSSL_RSA_C)
00035 
00036 #include "polarssl/rsa.h"
00037 #include "polarssl/md.h"
00038 
00039 #include <stdlib.h>
00040 #include <stdio.h>
00041 
00042 /*
00043  * Initialize an RSA context
00044  */
00045 void rsa_init( rsa_context *ctx,
00046                int padding,
00047                int hash_id )
00048 {
00049     memset( ctx, 0, sizeof( rsa_context ) );
00050 
00051     ctx->padding = padding;
00052     ctx->hash_id = hash_id;
00053 }
00054 
00055 #if defined(POLARSSL_GENPRIME)
00056 
00057 /*
00058  * Generate an RSA keypair
00059  */
00060 int rsa_gen_key( rsa_context *ctx,
00061                  int (*f_rng)(void *, unsigned char *, size_t),
00062                  void *p_rng,
00063                  unsigned int nbits, int exponent )
00064 {
00065     int ret;
00066     mpi P1, Q1, H, G;
00067 
00068     if( f_rng == NULL || nbits < 128 || exponent < 3 )
00069         return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
00070 
00071     mpi_init( &P1 ); mpi_init( &Q1 ); mpi_init( &H ); mpi_init( &G );
00072 
00073     /*
00074      * find primes P and Q with Q < P so that:
00075      * GCD( E, (P-1)*(Q-1) ) == 1
00076      */
00077     MPI_CHK( mpi_lset( &ctx->E, exponent ) );
00078 
00079     do
00080     {
00081         MPI_CHK( mpi_gen_prime( &ctx->P, ( nbits + 1 ) >> 1, 0, 
00082                                 f_rng, p_rng ) );
00083 
00084         MPI_CHK( mpi_gen_prime( &ctx->Q, ( nbits + 1 ) >> 1, 0,
00085                                 f_rng, p_rng ) );
00086 
00087         if( mpi_cmp_mpi( &ctx->P, &ctx->Q ) < 0 )
00088             mpi_swap( &ctx->P, &ctx->Q );
00089 
00090         if( mpi_cmp_mpi( &ctx->P, &ctx->Q ) == 0 )
00091             continue;
00092 
00093         MPI_CHK( mpi_mul_mpi( &ctx->N, &ctx->P, &ctx->Q ) );
00094         if( mpi_msb( &ctx->N ) != nbits )
00095             continue;
00096 
00097         MPI_CHK( mpi_sub_int( &P1, &ctx->P, 1 ) );
00098         MPI_CHK( mpi_sub_int( &Q1, &ctx->Q, 1 ) );
00099         MPI_CHK( mpi_mul_mpi( &H, &P1, &Q1 ) );
00100         MPI_CHK( mpi_gcd( &G, &ctx->E, &H  ) );
00101     }
00102     while( mpi_cmp_int( &G, 1 ) != 0 );
00103 
00104     /*
00105      * D  = E^-1 mod ((P-1)*(Q-1))
00106      * DP = D mod (P - 1)
00107      * DQ = D mod (Q - 1)
00108      * QP = Q^-1 mod P
00109      */
00110     MPI_CHK( mpi_inv_mod( &ctx->D , &ctx->E, &H  ) );
00111     MPI_CHK( mpi_mod_mpi( &ctx->DP, &ctx->D, &P1 ) );
00112     MPI_CHK( mpi_mod_mpi( &ctx->DQ, &ctx->D, &Q1 ) );
00113     MPI_CHK( mpi_inv_mod( &ctx->QP, &ctx->Q, &ctx->P ) );
00114 
00115     ctx->len = ( mpi_msb( &ctx->N ) + 7 ) >> 3;
00116 
00117 cleanup:
00118 
00119     mpi_free( &P1 ); mpi_free( &Q1 ); mpi_free( &H ); mpi_free( &G );
00120 
00121     if( ret != 0 )
00122     {
00123         rsa_free( ctx );
00124         return( POLARSSL_ERR_RSA_KEY_GEN_FAILED + ret );
00125     }
00126 
00127     return( 0 );   
00128 }
00129 
00130 #endif
00131 
00132 /*
00133  * Check a public RSA key
00134  */
00135 int rsa_check_pubkey( const rsa_context *ctx )
00136 {
00137     if( !ctx->N.p || !ctx->E.p )
00138         return( POLARSSL_ERR_RSA_KEY_CHECK_FAILED );
00139 
00140     if( ( ctx->N.p[0] & 1 ) == 0 || 
00141         ( ctx->E.p[0] & 1 ) == 0 )
00142         return( POLARSSL_ERR_RSA_KEY_CHECK_FAILED );
00143 
00144     if( mpi_msb( &ctx->N ) < 128 ||
00145         mpi_msb( &ctx->N ) > POLARSSL_MPI_MAX_BITS )
00146         return( POLARSSL_ERR_RSA_KEY_CHECK_FAILED );
00147 
00148     if( mpi_msb( &ctx->E ) < 2 ||
00149         mpi_msb( &ctx->E ) > 64 )
00150         return( POLARSSL_ERR_RSA_KEY_CHECK_FAILED );
00151 
00152     return( 0 );
00153 }
00154 
00155 /*
00156  * Check a private RSA key
00157  */
00158 int rsa_check_privkey( const rsa_context *ctx )
00159 {
00160     int ret;
00161     mpi PQ, DE, P1, Q1, H, I, G, G2, L1, L2;
00162 
00163     if( ( ret = rsa_check_pubkey( ctx ) ) != 0 )
00164         return( ret );
00165 
00166     if( !ctx->P.p || !ctx->Q.p || !ctx->D.p )
00167         return( POLARSSL_ERR_RSA_KEY_CHECK_FAILED );
00168 
00169     mpi_init( &PQ ); mpi_init( &DE ); mpi_init( &P1 ); mpi_init( &Q1 );
00170     mpi_init( &H  ); mpi_init( &I  ); mpi_init( &G  ); mpi_init( &G2 );
00171     mpi_init( &L1 ); mpi_init( &L2 );
00172 
00173     MPI_CHK( mpi_mul_mpi( &PQ, &ctx->P, &ctx->Q ) );
00174     MPI_CHK( mpi_mul_mpi( &DE, &ctx->D, &ctx->E ) );
00175     MPI_CHK( mpi_sub_int( &P1, &ctx->P, 1 ) );
00176     MPI_CHK( mpi_sub_int( &Q1, &ctx->Q, 1 ) );
00177     MPI_CHK( mpi_mul_mpi( &H, &P1, &Q1 ) );
00178     MPI_CHK( mpi_gcd( &G, &ctx->E, &H  ) );
00179 
00180     MPI_CHK( mpi_gcd( &G2, &P1, &Q1 ) );
00181     MPI_CHK( mpi_div_mpi( &L1, &L2, &H, &G2 ) );  
00182     MPI_CHK( mpi_mod_mpi( &I, &DE, &L1  ) );
00183 
00184     /*
00185      * Check for a valid PKCS1v2 private key
00186      */
00187     if( mpi_cmp_mpi( &PQ, &ctx->N ) != 0 ||
00188         mpi_cmp_int( &L2, 0 ) != 0 ||
00189         mpi_cmp_int( &I, 1 ) != 0 ||
00190         mpi_cmp_int( &G, 1 ) != 0 )
00191     {
00192         ret = POLARSSL_ERR_RSA_KEY_CHECK_FAILED;
00193     }
00194 
00195     
00196 cleanup:
00197 
00198     mpi_free( &PQ ); mpi_free( &DE ); mpi_free( &P1 ); mpi_free( &Q1 );
00199     mpi_free( &H  ); mpi_free( &I  ); mpi_free( &G  ); mpi_free( &G2 );
00200     mpi_free( &L1 ); mpi_free( &L2 );
00201 
00202     if( ret == POLARSSL_ERR_RSA_KEY_CHECK_FAILED )
00203         return( ret );
00204 
00205     if( ret != 0 )
00206         return( POLARSSL_ERR_RSA_KEY_CHECK_FAILED + ret );
00207 
00208     return( 0 );
00209 }
00210 
00211 /*
00212  * Do an RSA public key operation
00213  */
00214 int rsa_public( rsa_context *ctx,
00215                 const unsigned char *input,
00216                 unsigned char *output )
00217 {
00218     int ret;
00219     size_t olen;
00220     mpi T;
00221 
00222     mpi_init( &T );
00223 
00224     MPI_CHK( mpi_read_binary( &T, input, ctx->len ) );
00225 
00226     if( mpi_cmp_mpi( &T, &ctx->N ) >= 0 )
00227     {
00228         mpi_free( &T );
00229         return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
00230     }
00231 
00232     olen = ctx->len;
00233     MPI_CHK( mpi_exp_mod( &T, &T, &ctx->E, &ctx->N, &ctx->RN ) );
00234     MPI_CHK( mpi_write_binary( &T, output, olen ) );
00235 
00236 cleanup:
00237 
00238     mpi_free( &T );
00239 
00240     if( ret != 0 )
00241         return( POLARSSL_ERR_RSA_PUBLIC_FAILED + ret );
00242 
00243     return( 0 );
00244 }
00245 
00246 /*
00247  * Do an RSA private key operation
00248  */
00249 int rsa_private( rsa_context *ctx,
00250                  const unsigned char *input,
00251                  unsigned char *output )
00252 {
00253     int ret;
00254     size_t olen;
00255     mpi T, T1, T2;
00256 
00257     mpi_init( &T ); mpi_init( &T1 ); mpi_init( &T2 );
00258 
00259     MPI_CHK( mpi_read_binary( &T, input, ctx->len ) );
00260 
00261     if( mpi_cmp_mpi( &T, &ctx->N ) >= 0 )
00262     {
00263         mpi_free( &T );
00264         return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
00265     }
00266 
00267 #if defined(POLARSSL_RSA_NO_CRT)
00268     MPI_CHK( mpi_exp_mod( &T, &T, &ctx->D, &ctx->N, &ctx->RN ) );
00269 #else
00270     /*
00271      * faster decryption using the CRT
00272      *
00273      * T1 = input ^ dP mod P
00274      * T2 = input ^ dQ mod Q
00275      */
00276     MPI_CHK( mpi_exp_mod( &T1, &T, &ctx->DP, &ctx->P, &ctx->RP ) );
00277     MPI_CHK( mpi_exp_mod( &T2, &T, &ctx->DQ, &ctx->Q, &ctx->RQ ) );
00278 
00279     /*
00280      * T = (T1 - T2) * (Q^-1 mod P) mod P
00281      */
00282     MPI_CHK( mpi_sub_mpi( &T, &T1, &T2 ) );
00283     MPI_CHK( mpi_mul_mpi( &T1, &T, &ctx->QP ) );
00284     MPI_CHK( mpi_mod_mpi( &T, &T1, &ctx->P ) );
00285 
00286     /*
00287      * output = T2 + T * Q
00288      */
00289     MPI_CHK( mpi_mul_mpi( &T1, &T, &ctx->Q ) );
00290     MPI_CHK( mpi_add_mpi( &T, &T2, &T1 ) );
00291 #endif
00292 
00293     olen = ctx->len;
00294     MPI_CHK( mpi_write_binary( &T, output, olen ) );
00295 
00296 cleanup:
00297 
00298     mpi_free( &T ); mpi_free( &T1 ); mpi_free( &T2 );
00299 
00300     if( ret != 0 )
00301         return( POLARSSL_ERR_RSA_PRIVATE_FAILED + ret );
00302 
00303     return( 0 );
00304 }
00305 
00306 #if defined(POLARSSL_PKCS1_V21)
00307 
00316 static void mgf_mask( unsigned char *dst, size_t dlen, unsigned char *src, size_t slen,  
00317                        md_context_t *md_ctx )
00318 {
00319     unsigned char mask[POLARSSL_MD_MAX_SIZE];
00320     unsigned char counter[4];
00321     unsigned char *p;
00322     unsigned int hlen;
00323     size_t i, use_len;
00324 
00325     memset( mask, 0, POLARSSL_MD_MAX_SIZE );
00326     memset( counter, 0, 4 );
00327 
00328     hlen = md_ctx->md_info->size;
00329 
00330     // Generate and apply dbMask
00331     //
00332     p = dst;
00333 
00334     while( dlen > 0 )
00335     {
00336         use_len = hlen;
00337         if( dlen < hlen )
00338             use_len = dlen;
00339 
00340         md_starts( md_ctx );
00341         md_update( md_ctx, src, slen );
00342         md_update( md_ctx, counter, 4 );
00343         md_finish( md_ctx, mask );
00344 
00345         for( i = 0; i < use_len; ++i )
00346             *p++ ^= mask[i];
00347 
00348         counter[3]++;
00349 
00350         dlen -= use_len;
00351     }
00352 }
00353 #endif
00354 
00355 /*
00356  * Add the message padding, then do an RSA operation
00357  */
00358 int rsa_pkcs1_encrypt( rsa_context *ctx,
00359                        int (*f_rng)(void *, unsigned char *, size_t),
00360                        void *p_rng,
00361                        int mode, size_t ilen,
00362                        const unsigned char *input,
00363                        unsigned char *output )
00364 {
00365     size_t nb_pad, olen;
00366     int ret;
00367     unsigned char *p = output;
00368 #if defined(POLARSSL_PKCS1_V21)
00369     unsigned int hlen;
00370     const md_info_t *md_info;
00371     md_context_t md_ctx;
00372 #endif
00373 
00374     olen = ctx->len;
00375 
00376     if( f_rng == NULL )
00377         return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
00378 
00379     switch( ctx->padding )
00380     {
00381         case RSA_PKCS_V15:
00382 
00383             if( olen < ilen + 11 )
00384                 return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
00385 
00386             nb_pad = olen - 3 - ilen;
00387 
00388             *p++ = 0;
00389             *p++ = RSA_CRYPT;
00390 
00391             while( nb_pad-- > 0 )
00392             {
00393                 int rng_dl = 100;
00394 
00395                 do {
00396                     ret = f_rng( p_rng, p, 1 );
00397                 } while( *p == 0 && --rng_dl && ret == 0 );
00398 
00399                 // Check if RNG failed to generate data
00400                 //
00401                 if( rng_dl == 0 || ret != 0)
00402                     return POLARSSL_ERR_RSA_RNG_FAILED + ret;
00403 
00404                 p++;
00405             }
00406             *p++ = 0;
00407             memcpy( p, input, ilen );
00408             break;
00409         
00410 #if defined(POLARSSL_PKCS1_V21)
00411         case RSA_PKCS_V21:
00412 
00413             md_info = md_info_from_type( ctx->hash_id );
00414             if( md_info == NULL )
00415                 return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
00416 
00417             hlen = md_get_size( md_info );
00418 
00419             if( olen < ilen + 2 * hlen + 2 || f_rng == NULL )
00420                 return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
00421 
00422             memset( output, 0, olen );
00423             memset( &md_ctx, 0, sizeof( md_context_t ) );
00424 
00425             md_init_ctx( &md_ctx, md_info );
00426 
00427             *p++ = 0;
00428 
00429             // Generate a random octet string seed
00430             //
00431             if( ( ret = f_rng( p_rng, p, hlen ) ) != 0 )
00432                 return( POLARSSL_ERR_RSA_RNG_FAILED + ret );
00433 
00434             p += hlen;
00435 
00436             // Construct DB
00437             //
00438             md( md_info, p, 0, p );
00439             p += hlen;
00440             p += olen - 2 * hlen - 2 - ilen;
00441             *p++ = 1;
00442             memcpy( p, input, ilen ); 
00443 
00444             // maskedDB: Apply dbMask to DB
00445             //
00446             mgf_mask( output + hlen + 1, olen - hlen - 1, output + 1, hlen,  
00447                        &md_ctx );
00448 
00449             // maskedSeed: Apply seedMask to seed
00450             //
00451             mgf_mask( output + 1, hlen, output + hlen + 1, olen - hlen - 1,  
00452                        &md_ctx );
00453             break;
00454 #endif
00455 
00456         default:
00457 
00458             return( POLARSSL_ERR_RSA_INVALID_PADDING );
00459     }
00460 
00461     return( ( mode == RSA_PUBLIC )
00462             ? rsa_public(  ctx, output, output )
00463             : rsa_private( ctx, output, output ) );
00464 }
00465 
00466 /*
00467  * Do an RSA operation, then remove the message padding
00468  */
00469 int rsa_pkcs1_decrypt( rsa_context *ctx,
00470                        int mode, size_t *olen,
00471                        const unsigned char *input,
00472                        unsigned char *output,
00473                        size_t output_max_len)
00474 {
00475     int ret;
00476     size_t ilen;
00477     unsigned char *p;
00478     unsigned char buf[1024];
00479 #if defined(POLARSSL_PKCS1_V21)
00480     unsigned char lhash[POLARSSL_MD_MAX_SIZE];
00481     unsigned int hlen;
00482     const md_info_t *md_info;
00483     md_context_t md_ctx;
00484 #endif
00485 
00486     ilen = ctx->len;
00487 
00488     if( ilen < 16 || ilen > sizeof( buf ) )
00489         return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
00490 
00491     ret = ( mode == RSA_PUBLIC )
00492           ? rsa_public(  ctx, input, buf )
00493           : rsa_private( ctx, input, buf );
00494 
00495     if( ret != 0 )
00496         return( ret );
00497 
00498     p = buf;
00499 
00500     switch( ctx->padding )
00501     {
00502         case RSA_PKCS_V15:
00503 
00504             if( *p++ != 0 || *p++ != RSA_CRYPT )
00505                 return( POLARSSL_ERR_RSA_INVALID_PADDING );
00506 
00507             while( *p != 0 )
00508             {
00509                 if( p >= buf + ilen - 1 )
00510                     return( POLARSSL_ERR_RSA_INVALID_PADDING );
00511                 p++;
00512             }
00513             p++;
00514             break;
00515 
00516 #if defined(POLARSSL_PKCS1_V21)
00517         case RSA_PKCS_V21:
00518             
00519             if( *p++ != 0 )
00520                 return( POLARSSL_ERR_RSA_INVALID_PADDING );
00521 
00522             md_info = md_info_from_type( ctx->hash_id );
00523             if( md_info == NULL )
00524                 return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
00525                 
00526             hlen = md_get_size( md_info );
00527             memset( &md_ctx, 0, sizeof( md_context_t ) );
00528 
00529             md_init_ctx( &md_ctx, md_info );
00530             
00531             // Generate lHash
00532             //
00533             md( md_info, lhash, 0, lhash );
00534 
00535             // seed: Apply seedMask to maskedSeed
00536             //
00537             mgf_mask( buf + 1, hlen, buf + hlen + 1, ilen - hlen - 1,
00538                        &md_ctx );
00539 
00540             // DB: Apply dbMask to maskedDB
00541             //
00542             mgf_mask( buf + hlen + 1, ilen - hlen - 1, buf + 1, hlen,  
00543                        &md_ctx );
00544 
00545             p += hlen;
00546 
00547             // Check validity
00548             //
00549             if( memcmp( lhash, p, hlen ) != 0 )
00550                 return( POLARSSL_ERR_RSA_INVALID_PADDING );
00551 
00552             p += hlen;
00553 
00554             while( *p == 0 && p < buf + ilen )
00555                 p++;
00556 
00557             if( p == buf + ilen )
00558                 return( POLARSSL_ERR_RSA_INVALID_PADDING );
00559 
00560             if( *p++ != 0x01 )
00561                 return( POLARSSL_ERR_RSA_INVALID_PADDING );
00562 
00563             break;
00564 #endif
00565 
00566         default:
00567 
00568             return( POLARSSL_ERR_RSA_INVALID_PADDING );
00569     }
00570 
00571     if (ilen - (p - buf) > output_max_len)
00572         return( POLARSSL_ERR_RSA_OUTPUT_TOO_LARGE );
00573 
00574     *olen = ilen - (p - buf);
00575     memcpy( output, p, *olen );
00576 
00577     return( 0 );
00578 }
00579 
00580 /*
00581  * Do an RSA operation to sign the message digest
00582  */
00583 int rsa_pkcs1_sign( rsa_context *ctx,
00584                     int (*f_rng)(void *, unsigned char *, size_t),
00585                     void *p_rng,
00586                     int mode,
00587                     int hash_id,
00588                     unsigned int hashlen,
00589                     const unsigned char *hash,
00590                     unsigned char *sig )
00591 {
00592     size_t nb_pad, olen;
00593     unsigned char *p = sig;
00594 #if defined(POLARSSL_PKCS1_V21)
00595     unsigned char salt[POLARSSL_MD_MAX_SIZE];
00596     unsigned int slen, hlen, offset = 0;
00597     int ret;
00598     size_t msb;
00599     const md_info_t *md_info;
00600     md_context_t md_ctx;
00601 #else
00602     (void) f_rng;
00603     (void) p_rng;
00604 #endif
00605 
00606     olen = ctx->len;
00607 
00608     switch( ctx->padding )
00609     {
00610         case RSA_PKCS_V15:
00611 
00612             switch( hash_id )
00613             {
00614                 case SIG_RSA_RAW:
00615                     nb_pad = olen - 3 - hashlen;
00616                     break;
00617 
00618                 case SIG_RSA_MD2:
00619                 case SIG_RSA_MD4:
00620                 case SIG_RSA_MD5:
00621                     nb_pad = olen - 3 - 34;
00622                     break;
00623 
00624                 case SIG_RSA_SHA1:
00625                     nb_pad = olen - 3 - 35;
00626                     break;
00627 
00628                 case SIG_RSA_SHA224:
00629                     nb_pad = olen - 3 - 47;
00630                     break;
00631 
00632                 case SIG_RSA_SHA256:
00633                     nb_pad = olen - 3 - 51;
00634                     break;
00635 
00636                 case SIG_RSA_SHA384:
00637                     nb_pad = olen - 3 - 67;
00638                     break;
00639 
00640                 case SIG_RSA_SHA512:
00641                     nb_pad = olen - 3 - 83;
00642                     break;
00643 
00644 
00645                 default:
00646                     return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
00647             }
00648 
00649             if( nb_pad < 8 )
00650                 return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
00651 
00652             *p++ = 0;
00653             *p++ = RSA_SIGN;
00654             memset( p, 0xFF, nb_pad );
00655             p += nb_pad;
00656             *p++ = 0;
00657 
00658             switch( hash_id )
00659             {
00660                 case SIG_RSA_RAW:
00661                     memcpy( p, hash, hashlen );
00662                     break;
00663 
00664                 case SIG_RSA_MD2:
00665                     memcpy( p, ASN1_HASH_MDX, 18 );
00666                     memcpy( p + 18, hash, 16 );
00667                     p[13] = 2; break;
00668 
00669                 case SIG_RSA_MD4:
00670                     memcpy( p, ASN1_HASH_MDX, 18 );
00671                     memcpy( p + 18, hash, 16 );
00672                     p[13] = 4; break;
00673 
00674                 case SIG_RSA_MD5:
00675                     memcpy( p, ASN1_HASH_MDX, 18 );
00676                     memcpy( p + 18, hash, 16 );
00677                     p[13] = 5; break;
00678 
00679                 case SIG_RSA_SHA1:
00680                     memcpy( p, ASN1_HASH_SHA1, 15 );
00681                     memcpy( p + 15, hash, 20 );
00682                     break;
00683 
00684                 case SIG_RSA_SHA224:
00685                     memcpy( p, ASN1_HASH_SHA2X, 19 );
00686                     memcpy( p + 19, hash, 28 );
00687                     p[1] += 28; p[14] = 4; p[18] += 28; break;
00688 
00689                 case SIG_RSA_SHA256:
00690                     memcpy( p, ASN1_HASH_SHA2X, 19 );
00691                     memcpy( p + 19, hash, 32 );
00692                     p[1] += 32; p[14] = 1; p[18] += 32; break;
00693 
00694                 case SIG_RSA_SHA384:
00695                     memcpy( p, ASN1_HASH_SHA2X, 19 );
00696                     memcpy( p + 19, hash, 48 );
00697                     p[1] += 48; p[14] = 2; p[18] += 48; break;
00698 
00699                 case SIG_RSA_SHA512:
00700                     memcpy( p, ASN1_HASH_SHA2X, 19 );
00701                     memcpy( p + 19, hash, 64 );
00702                     p[1] += 64; p[14] = 3; p[18] += 64; break;
00703 
00704                 default:
00705                     return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
00706             }
00707 
00708             break;
00709 
00710 #if defined(POLARSSL_PKCS1_V21)
00711         case RSA_PKCS_V21:
00712 
00713             if( f_rng == NULL )
00714                 return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
00715 
00716             switch( hash_id )
00717             {
00718                 case SIG_RSA_MD2:
00719                 case SIG_RSA_MD4:
00720                 case SIG_RSA_MD5:
00721                     hashlen = 16;
00722                     break;
00723 
00724                 case SIG_RSA_SHA1:
00725                     hashlen = 20;
00726                     break;
00727 
00728                 case SIG_RSA_SHA224:
00729                     hashlen = 28;
00730                     break;
00731 
00732                 case SIG_RSA_SHA256:
00733                     hashlen = 32;
00734                     break;
00735 
00736                 case SIG_RSA_SHA384:
00737                     hashlen = 48;
00738                     break;
00739 
00740                 case SIG_RSA_SHA512:
00741                     hashlen = 64;
00742                     break;
00743 
00744                 default:
00745                     return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
00746             }
00747 
00748             md_info = md_info_from_type( ctx->hash_id );
00749             if( md_info == NULL )
00750                 return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
00751                 
00752             hlen = md_get_size( md_info );
00753             slen = hlen;
00754 
00755             memset( sig, 0, olen );
00756             memset( &md_ctx, 0, sizeof( md_context_t ) );
00757 
00758             md_init_ctx( &md_ctx, md_info );
00759 
00760             msb = mpi_msb( &ctx->N ) - 1;
00761 
00762             // Generate salt of length slen
00763             //
00764             if( ( ret = f_rng( p_rng, salt, slen ) ) != 0 )
00765                 return( POLARSSL_ERR_RSA_RNG_FAILED + ret );
00766 
00767             // Note: EMSA-PSS encoding is over the length of N - 1 bits
00768             //
00769             msb = mpi_msb( &ctx->N ) - 1;
00770             p += olen - hlen * 2 - 2;
00771             *p++ = 0x01;
00772             memcpy( p, salt, slen );
00773             p += slen;
00774 
00775             // Generate H = Hash( M' )
00776             //
00777             md_starts( &md_ctx );
00778             md_update( &md_ctx, p, 8 );
00779             md_update( &md_ctx, hash, hashlen );
00780             md_update( &md_ctx, salt, slen );
00781             md_finish( &md_ctx, p );
00782 
00783             // Compensate for boundary condition when applying mask
00784             //
00785             if( msb % 8 == 0 )
00786                 offset = 1;
00787 
00788             // maskedDB: Apply dbMask to DB
00789             //
00790             mgf_mask( sig + offset, olen - hlen - 1 - offset, p, hlen, &md_ctx );
00791 
00792             msb = mpi_msb( &ctx->N ) - 1;
00793             sig[0] &= 0xFF >> ( olen * 8 - msb );
00794 
00795             p += hlen;
00796             *p++ = 0xBC;
00797             break;
00798 #endif
00799 
00800         default:
00801 
00802             return( POLARSSL_ERR_RSA_INVALID_PADDING );
00803     }
00804 
00805     return( ( mode == RSA_PUBLIC )
00806             ? rsa_public(  ctx, sig, sig )
00807             : rsa_private( ctx, sig, sig ) );
00808 }
00809 
00810 /*
00811  * Do an RSA operation and check the message digest
00812  */
00813 int rsa_pkcs1_verify( rsa_context *ctx,
00814                       int mode,
00815                       int hash_id,
00816                       unsigned int hashlen,
00817                       const unsigned char *hash,
00818                       unsigned char *sig )
00819 {
00820     int ret;
00821     size_t len, siglen;
00822     unsigned char *p, c;
00823     unsigned char buf[1024];
00824 #if defined(POLARSSL_PKCS1_V21)
00825     unsigned char result[POLARSSL_MD_MAX_SIZE];
00826     unsigned char zeros[8];
00827     unsigned int hlen;
00828     size_t slen, msb;
00829     const md_info_t *md_info;
00830     md_context_t md_ctx;
00831 #endif
00832     siglen = ctx->len;
00833 
00834     if( siglen < 16 || siglen > sizeof( buf ) )
00835         return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
00836 
00837     ret = ( mode == RSA_PUBLIC )
00838           ? rsa_public(  ctx, sig, buf )
00839           : rsa_private( ctx, sig, buf );
00840 
00841     if( ret != 0 )
00842         return( ret );
00843 
00844     p = buf;
00845 
00846     switch( ctx->padding )
00847     {
00848         case RSA_PKCS_V15:
00849 
00850             if( *p++ != 0 || *p++ != RSA_SIGN )
00851                 return( POLARSSL_ERR_RSA_INVALID_PADDING );
00852 
00853             while( *p != 0 )
00854             {
00855                 if( p >= buf + siglen - 1 || *p != 0xFF )
00856                     return( POLARSSL_ERR_RSA_INVALID_PADDING );
00857                 p++;
00858             }
00859             p++;
00860 
00861             len = siglen - ( p - buf );
00862 
00863             if( len == 34 )
00864             {
00865                 c = p[13];
00866                 p[13] = 0;
00867 
00868                 if( memcmp( p, ASN1_HASH_MDX, 18 ) != 0 )
00869                     return( POLARSSL_ERR_RSA_VERIFY_FAILED );
00870 
00871                 if( ( c == 2 && hash_id == SIG_RSA_MD2 ) ||
00872                         ( c == 4 && hash_id == SIG_RSA_MD4 ) ||
00873                         ( c == 5 && hash_id == SIG_RSA_MD5 ) )
00874                 {
00875                     if( memcmp( p + 18, hash, 16 ) == 0 ) 
00876                         return( 0 );
00877                     else
00878                         return( POLARSSL_ERR_RSA_VERIFY_FAILED );
00879                 }
00880             }
00881 
00882             if( len == 35 && hash_id == SIG_RSA_SHA1 )
00883             {
00884                 if( memcmp( p, ASN1_HASH_SHA1, 15 ) == 0 &&
00885                         memcmp( p + 15, hash, 20 ) == 0 )
00886                     return( 0 );
00887                 else
00888                     return( POLARSSL_ERR_RSA_VERIFY_FAILED );
00889             }
00890             if( ( len == 19 + 28 && p[14] == 4 && hash_id == SIG_RSA_SHA224 ) ||
00891                     ( len == 19 + 32 && p[14] == 1 && hash_id == SIG_RSA_SHA256 ) ||
00892                     ( len == 19 + 48 && p[14] == 2 && hash_id == SIG_RSA_SHA384 ) ||
00893                     ( len == 19 + 64 && p[14] == 3 && hash_id == SIG_RSA_SHA512 ) )
00894             {
00895                 c = p[1] - 17;
00896                 p[1] = 17;
00897                 p[14] = 0;
00898 
00899                 if( p[18] == c &&
00900                         memcmp( p, ASN1_HASH_SHA2X, 18 ) == 0 &&
00901                         memcmp( p + 19, hash, c ) == 0 )
00902                     return( 0 );
00903                 else
00904                     return( POLARSSL_ERR_RSA_VERIFY_FAILED );
00905             }
00906 
00907             if( len == hashlen && hash_id == SIG_RSA_RAW )
00908             {
00909                 if( memcmp( p, hash, hashlen ) == 0 )
00910                     return( 0 );
00911                 else
00912                     return( POLARSSL_ERR_RSA_VERIFY_FAILED );
00913             }
00914 
00915             break;
00916 
00917 #if defined(POLARSSL_PKCS1_V21)
00918         case RSA_PKCS_V21:
00919             
00920             if( buf[siglen - 1] != 0xBC )
00921                 return( POLARSSL_ERR_RSA_INVALID_PADDING );
00922 
00923             switch( hash_id )
00924             {
00925                 case SIG_RSA_MD2:
00926                 case SIG_RSA_MD4:
00927                 case SIG_RSA_MD5:
00928                     hashlen = 16;
00929                     break;
00930 
00931                 case SIG_RSA_SHA1:
00932                     hashlen = 20;
00933                     break;
00934 
00935                 case SIG_RSA_SHA224:
00936                     hashlen = 28;
00937                     break;
00938 
00939                 case SIG_RSA_SHA256:
00940                     hashlen = 32;
00941                     break;
00942 
00943                 case SIG_RSA_SHA384:
00944                     hashlen = 48;
00945                     break;
00946 
00947                 case SIG_RSA_SHA512:
00948                     hashlen = 64;
00949                     break;
00950 
00951                 default:
00952                     return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
00953             }
00954 
00955             md_info = md_info_from_type( ctx->hash_id );
00956             if( md_info == NULL )
00957                 return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
00958                 
00959             hlen = md_get_size( md_info );
00960             slen = siglen - hlen - 1;
00961 
00962             memset( &md_ctx, 0, sizeof( md_context_t ) );
00963             memset( zeros, 0, 8 );
00964 
00965             md_init_ctx( &md_ctx, md_info );
00966 
00967             // Note: EMSA-PSS verification is over the length of N - 1 bits
00968             //
00969             msb = mpi_msb( &ctx->N ) - 1;
00970 
00971             // Compensate for boundary condition when applying mask
00972             //
00973             if( msb % 8 == 0 )
00974             {
00975                 p++;
00976                 siglen -= 1;
00977             }
00978             if( buf[0] >> ( 8 - siglen * 8 + msb ) )
00979                 return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
00980 
00981             mgf_mask( p, siglen - hlen - 1, p + siglen - hlen - 1, hlen, &md_ctx );
00982 
00983             buf[0] &= 0xFF >> ( siglen * 8 - msb );
00984 
00985             while( *p == 0 && p < buf + siglen )
00986                 p++;
00987 
00988             if( p == buf + siglen )
00989                 return( POLARSSL_ERR_RSA_INVALID_PADDING );
00990 
00991             if( *p++ != 0x01 )
00992                 return( POLARSSL_ERR_RSA_INVALID_PADDING );
00993 
00994             slen -= p - buf;
00995 
00996             // Generate H = Hash( M' )
00997             //
00998             md_starts( &md_ctx );
00999             md_update( &md_ctx, zeros, 8 );
01000             md_update( &md_ctx, hash, hashlen );
01001             md_update( &md_ctx, p, slen );
01002             md_finish( &md_ctx, result );
01003 
01004             if( memcmp( p + slen, result, hlen ) == 0 )
01005                 return( 0 );
01006             else
01007                 return( POLARSSL_ERR_RSA_VERIFY_FAILED );
01008 #endif
01009 
01010         default:
01011 
01012             return( POLARSSL_ERR_RSA_INVALID_PADDING );
01013     }
01014 
01015     return( POLARSSL_ERR_RSA_INVALID_PADDING );
01016 }
01017 
01018 /*
01019  * Free the components of an RSA key
01020  */
01021 void rsa_free( rsa_context *ctx )
01022 {
01023     mpi_free( &ctx->RQ ); mpi_free( &ctx->RP ); mpi_free( &ctx->RN );
01024     mpi_free( &ctx->QP ); mpi_free( &ctx->DQ ); mpi_free( &ctx->DP );
01025     mpi_free( &ctx->Q  ); mpi_free( &ctx->P  ); mpi_free( &ctx->D );
01026     mpi_free( &ctx->E  ); mpi_free( &ctx->N  );
01027 }
01028 
01029 #if defined(POLARSSL_SELF_TEST)
01030 
01031 #include "polarssl/sha1.h"
01032 
01033 /*
01034  * Example RSA-1024 keypair, for test purposes
01035  */
01036 #define KEY_LEN 128
01037 
01038 #define RSA_N   "9292758453063D803DD603D5E777D788" \
01039                 "8ED1D5BF35786190FA2F23EBC0848AEA" \
01040                 "DDA92CA6C3D80B32C4D109BE0F36D6AE" \
01041                 "7130B9CED7ACDF54CFC7555AC14EEBAB" \
01042                 "93A89813FBF3C4F8066D2D800F7C38A8" \
01043                 "1AE31942917403FF4946B0A83D3D3E05" \
01044                 "EE57C6F5F5606FB5D4BC6CD34EE0801A" \
01045                 "5E94BB77B07507233A0BC7BAC8F90F79"
01046 
01047 #define RSA_E   "10001"
01048 
01049 #define RSA_D   "24BF6185468786FDD303083D25E64EFC" \
01050                 "66CA472BC44D253102F8B4A9D3BFA750" \
01051                 "91386C0077937FE33FA3252D28855837" \
01052                 "AE1B484A8A9A45F7EE8C0C634F99E8CD" \
01053                 "DF79C5CE07EE72C7F123142198164234" \
01054                 "CABB724CF78B8173B9F880FC86322407" \
01055                 "AF1FEDFDDE2BEB674CA15F3E81A1521E" \
01056                 "071513A1E85B5DFA031F21ECAE91A34D"
01057 
01058 #define RSA_P   "C36D0EB7FCD285223CFB5AABA5BDA3D8" \
01059                 "2C01CAD19EA484A87EA4377637E75500" \
01060                 "FCB2005C5C7DD6EC4AC023CDA285D796" \
01061                 "C3D9E75E1EFC42488BB4F1D13AC30A57"
01062 
01063 #define RSA_Q   "C000DF51A7C77AE8D7C7370C1FF55B69" \
01064                 "E211C2B9E5DB1ED0BF61D0D9899620F4" \
01065                 "910E4168387E3C30AA1E00C339A79508" \
01066                 "8452DD96A9A5EA5D9DCA68DA636032AF"
01067 
01068 #define RSA_DP  "C1ACF567564274FB07A0BBAD5D26E298" \
01069                 "3C94D22288ACD763FD8E5600ED4A702D" \
01070                 "F84198A5F06C2E72236AE490C93F07F8" \
01071                 "3CC559CD27BC2D1CA488811730BB5725"
01072 
01073 #define RSA_DQ  "4959CBF6F8FEF750AEE6977C155579C7" \
01074                 "D8AAEA56749EA28623272E4F7D0592AF" \
01075                 "7C1F1313CAC9471B5C523BFE592F517B" \
01076                 "407A1BD76C164B93DA2D32A383E58357"
01077 
01078 #define RSA_QP  "9AE7FBC99546432DF71896FC239EADAE" \
01079                 "F38D18D2B2F0E2DD275AA977E2BF4411" \
01080                 "F5A3B2A5D33605AEBBCCBA7FEB9F2D2F" \
01081                 "A74206CEC169D74BF5A8C50D6F48EA08"
01082 
01083 #define PT_LEN  24
01084 #define RSA_PT  "\xAA\xBB\xCC\x03\x02\x01\x00\xFF\xFF\xFF\xFF\xFF" \
01085                 "\x11\x22\x33\x0A\x0B\x0C\xCC\xDD\xDD\xDD\xDD\xDD"
01086 
01087 static int myrand( void *rng_state, unsigned char *output, size_t len )
01088 {
01089     size_t i;
01090 
01091     if( rng_state != NULL )
01092         rng_state  = NULL;
01093 
01094     for( i = 0; i < len; ++i )
01095         output[i] = rand();
01096     
01097     return( 0 );
01098 }
01099 
01100 /*
01101  * Checkup routine
01102  */
01103 int rsa_self_test( int verbose )
01104 {
01105     size_t len;
01106     rsa_context rsa;
01107     unsigned char rsa_plaintext[PT_LEN];
01108     unsigned char rsa_decrypted[PT_LEN];
01109     unsigned char rsa_ciphertext[KEY_LEN];
01110 #if defined(POLARSSL_SHA1_C)
01111     unsigned char sha1sum[20];
01112 #endif
01113 
01114     rsa_init( &rsa, RSA_PKCS_V15, 0 );
01115 
01116     rsa.len = KEY_LEN;
01117     mpi_read_string( &rsa.N , 16, RSA_N  );
01118     mpi_read_string( &rsa.E , 16, RSA_E  );
01119     mpi_read_string( &rsa.D , 16, RSA_D  );
01120     mpi_read_string( &rsa.P , 16, RSA_P  );
01121     mpi_read_string( &rsa.Q , 16, RSA_Q  );
01122     mpi_read_string( &rsa.DP, 16, RSA_DP );
01123     mpi_read_string( &rsa.DQ, 16, RSA_DQ );
01124     mpi_read_string( &rsa.QP, 16, RSA_QP );
01125 
01126     if( verbose != 0 )
01127         printf( "  RSA key validation: " );
01128 
01129     if( rsa_check_pubkey(  &rsa ) != 0 ||
01130         rsa_check_privkey( &rsa ) != 0 )
01131     {
01132         if( verbose != 0 )
01133             printf( "failed\n" );
01134 
01135         return( 1 );
01136     }
01137 
01138     if( verbose != 0 )
01139         printf( "passed\n  PKCS#1 encryption : " );
01140 
01141     memcpy( rsa_plaintext, RSA_PT, PT_LEN );
01142 
01143     if( rsa_pkcs1_encrypt( &rsa, &myrand, NULL, RSA_PUBLIC, PT_LEN,
01144                            rsa_plaintext, rsa_ciphertext ) != 0 )
01145     {
01146         if( verbose != 0 )
01147             printf( "failed\n" );
01148 
01149         return( 1 );
01150     }
01151 
01152     if( verbose != 0 )
01153         printf( "passed\n  PKCS#1 decryption : " );
01154 
01155     if( rsa_pkcs1_decrypt( &rsa, RSA_PRIVATE, &len,
01156                            rsa_ciphertext, rsa_decrypted,
01157                            sizeof(rsa_decrypted) ) != 0 )
01158     {
01159         if( verbose != 0 )
01160             printf( "failed\n" );
01161 
01162         return( 1 );
01163     }
01164 
01165     if( memcmp( rsa_decrypted, rsa_plaintext, len ) != 0 )
01166     {
01167         if( verbose != 0 )
01168             printf( "failed\n" );
01169 
01170         return( 1 );
01171     }
01172 
01173 #if defined(POLARSSL_SHA1_C)
01174     if( verbose != 0 )
01175         printf( "passed\n  PKCS#1 data sign  : " );
01176 
01177     sha1( rsa_plaintext, PT_LEN, sha1sum );
01178 
01179     if( rsa_pkcs1_sign( &rsa, NULL, NULL, RSA_PRIVATE, SIG_RSA_SHA1, 20,
01180                         sha1sum, rsa_ciphertext ) != 0 )
01181     {
01182         if( verbose != 0 )
01183             printf( "failed\n" );
01184 
01185         return( 1 );
01186     }
01187 
01188     if( verbose != 0 )
01189         printf( "passed\n  PKCS#1 sig. verify: " );
01190 
01191     if( rsa_pkcs1_verify( &rsa, RSA_PUBLIC, SIG_RSA_SHA1, 20,
01192                           sha1sum, rsa_ciphertext ) != 0 )
01193     {
01194         if( verbose != 0 )
01195             printf( "failed\n" );
01196 
01197         return( 1 );
01198     }
01199 
01200     if( verbose != 0 )
01201         printf( "passed\n\n" );
01202 #endif /* POLARSSL_SHA1_C */
01203 
01204     rsa_free( &rsa );
01205 
01206     return( 0 );
01207 }
01208 
01209 #endif
01210 
01211 #endif