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mbedtls/library/rsa.c

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/*
* 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"
#if defined(POLARSSL_RSA_C)
#include "polarssl/rsa.h"
#if defined(POLARSSL_PKCS1_V21)
#include "polarssl/md.h"
#endif
#include <stdlib.h>
#include <stdio.h>
/*
* Initialize an RSA context
*/
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;
}
#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
*/
int rsa_check_privkey( const rsa_context *ctx )
{
int ret;
mpi PQ, DE, P1, Q1, H, I, G, G2, L1, L2, DP, DQ, QP;
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_init( &DP ); mpi_init( &DQ );
mpi_init( &QP );
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 ) );
MPI_CHK( mpi_mod_mpi( &DP, &ctx->D, &P1 ) );
MPI_CHK( mpi_mod_mpi( &DQ, &ctx->D, &Q1 ) );
MPI_CHK( mpi_inv_mod( &QP, &ctx->Q, &ctx->P ) );
/*
* Check for a valid PKCS1v2 private key
*/
if( mpi_cmp_mpi( &PQ, &ctx->N ) != 0 ||
mpi_cmp_mpi( &DP, &ctx->DP ) != 0 ||
mpi_cmp_mpi( &DQ, &ctx->DQ ) != 0 ||
mpi_cmp_mpi( &QP, &ctx->QP ) != 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 ); mpi_free( &DP ); mpi_free( &DQ );
mpi_free( &QP );
if( ret == POLARSSL_ERR_RSA_KEY_CHECK_FAILED )
return( ret );
if( ret != 0 )
return( POLARSSL_ERR_RSA_KEY_CHECK_FAILED + ret );
return( 0 );
}
/*
* 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;
if( mode == RSA_PUBLIC )
{
*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++;
}
}
else
{
*p++ = RSA_SIGN;
while( nb_pad-- > 0 )
*p++ = 0xFF;
}
*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 );
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 );
md_free_ctx( &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
*/
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 bt;
unsigned char buf[POLARSSL_MPI_MAX_SIZE];
#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 )
return( POLARSSL_ERR_RSA_INVALID_PADDING );
bt = *p++;
if( ( bt != RSA_CRYPT && mode == RSA_PRIVATE ) ||
( bt != RSA_SIGN && mode == RSA_PUBLIC ) )
{
return( POLARSSL_ERR_RSA_INVALID_PADDING );
}
if( bt == RSA_CRYPT )
{
while( *p != 0 && p < buf + ilen - 1 )
p++;
if( *p != 0 || p >= buf + ilen - 1 )
return( POLARSSL_ERR_RSA_INVALID_PADDING );
p++;
}
else
{
while( *p == 0xFF && p < buf + ilen - 1 )
p++;
if( *p != 0 || p >= buf + ilen - 1 )
return( POLARSSL_ERR_RSA_INVALID_PADDING );
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 );
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;
md_free_ctx( &md_ctx );
// 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 );
}
/*
* 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
olen = ctx->len;
switch( ctx->padding )
{
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 ) || ( nb_pad > olen ) )
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;
if( olen < hlen + slen + 2 )
return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
memset( sig, 0, olen );
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 );
md_free_ctx( &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[POLARSSL_MPI_MAX_SIZE];
#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
siglen = ctx->len;
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;
switch( ctx->padding )
{
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 == 33 && hash_id == SIG_RSA_SHA1 )
{
if( memcmp( p, ASN1_HASH_SHA1_ALT, 13 ) == 0 &&
memcmp( p + 13, hash, 20 ) == 0 )
return( 0 );
else
return( POLARSSL_ERR_RSA_VERIFY_FAILED );
}
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( 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 );
md_free_ctx( &md_ctx );
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 );
}
/*
* 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 : " );
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
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