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New function mbedtls_rsa_get_bitlen
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Add a new function mbedtls_rsa_get_bitlen which returns the RSA key
size, i.e. the bit size of the modulus. In the pk module, call
mbedtls_rsa_get_bitlen instead of mbedtls_rsa_get_len, which gave the
wrong result for key sizes that are not a multiple of 8.

This commit adds one non-regression test in the pk suite. More tests
are needed for RSA key sizes that are a multiple of 8.

This commit does not address RSA alternative implementations, which
only provide an interface that return the modulus size in bytes.
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@gilles-peskine-arm
gilles-peskine-arm authored and itayzafrir committed Sep 5, 2018
1 parent 4a6aaa4 commit 1d26709
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Showing 6 changed files with 80 additions and 18 deletions.
10 changes: 10 additions & 0 deletions include/mbedtls/rsa.h
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Original file line number Diff line number Diff line change
Expand Up @@ -403,6 +403,16 @@ void mbedtls_rsa_set_padding( mbedtls_rsa_context *ctx, int padding,
*/
size_t mbedtls_rsa_get_len( const mbedtls_rsa_context *ctx );

/**
* \brief This function retrieves the length of the RSA modulus in bits.
*
* \param ctx The initialized RSA context.
*
* \return The length of the RSA modulus in bits.
*
*/
size_t mbedtls_rsa_get_bitlen( const mbedtls_rsa_context *ctx );

/**
* \brief This function generates an RSA keypair.
*
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2 changes: 1 addition & 1 deletion library/pk_wrap.c
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Expand Up @@ -66,7 +66,7 @@ static int rsa_can_do( mbedtls_pk_type_t type )
static size_t rsa_get_bitlen( const void *ctx )
{
const mbedtls_rsa_context * rsa = (const mbedtls_rsa_context *) ctx;
return( 8 * mbedtls_rsa_get_len( rsa ) );
return( mbedtls_rsa_get_bitlen( rsa ) );
}

static int rsa_verify_wrap( void *ctx, mbedtls_md_type_t md_alg,
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9 changes: 8 additions & 1 deletion library/rsa.c
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Original file line number Diff line number Diff line change
Expand Up @@ -480,12 +480,19 @@ void mbedtls_rsa_set_padding( mbedtls_rsa_context *ctx, int padding, int hash_id
/*
* Get length in bytes of RSA modulus
*/

size_t mbedtls_rsa_get_len( const mbedtls_rsa_context *ctx )
{
return( ctx->len );
}

/*
* Get length in bits of RSA modulus
*/
size_t mbedtls_rsa_get_bitlen( const mbedtls_rsa_context *ctx )
{
return( mbedtls_mpi_bitlen( &ctx->N ) );
}


#if defined(MBEDTLS_GENPRIME)

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11 changes: 10 additions & 1 deletion tests/suites/test_suite_pk.data
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Original file line number Diff line number Diff line change
@@ -1,7 +1,16 @@
PK utils: RSA
PK utils: RSA, 512 bits
depends_on:MBEDTLS_RSA_C:MBEDTLS_GENPRIME
pk_utils:MBEDTLS_PK_RSA:512:64:"RSA"

## RSA key generation only supports even bit sizes
#PK utils: RSA, 511 bits
#depends_on:MBEDTLS_RSA_C:MBEDTLS_GENPRIME
#pk_utils:MBEDTLS_PK_RSA:511:64:"RSA"
#
PK utils: RSA, 510 bits
depends_on:MBEDTLS_RSA_C:MBEDTLS_GENPRIME
pk_utils:MBEDTLS_PK_RSA:510:64:"RSA"

PK utils: ECKEY
depends_on:MBEDTLS_ECP_C:MBEDTLS_ECP_DP_SECP192R1_ENABLED
pk_utils:MBEDTLS_PK_ECKEY:192:24:"EC"
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39 changes: 33 additions & 6 deletions tests/suites/test_suite_pk.function
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Original file line number Diff line number Diff line change
Expand Up @@ -13,22 +13,49 @@ static int rnd_std_rand( void *rng_state, unsigned char *output, size_t len );
#define RSA_KEY_SIZE 512
#define RSA_KEY_LEN 64

static int pk_genkey( mbedtls_pk_context *pk )
static int pk_genkey( mbedtls_pk_context *pk, int size )
{
((void) pk);

#if defined(MBEDTLS_RSA_C) && defined(MBEDTLS_GENPRIME)
if( mbedtls_pk_get_type( pk ) == MBEDTLS_PK_RSA )
return mbedtls_rsa_gen_key( mbedtls_pk_rsa( *pk ), rnd_std_rand, NULL, RSA_KEY_SIZE, 3 );
{
if( size == 0 )
size = RSA_KEY_SIZE;
return( mbedtls_rsa_gen_key( mbedtls_pk_rsa( *pk ),
rnd_std_rand, NULL, size, 3 ) );
}
#endif
#if defined(MBEDTLS_ECP_C)
if( mbedtls_pk_get_type( pk ) == MBEDTLS_PK_ECKEY ||
mbedtls_pk_get_type( pk ) == MBEDTLS_PK_ECKEY_DH ||
mbedtls_pk_get_type( pk ) == MBEDTLS_PK_ECDSA )
{
int ret;
mbedtls_ecp_group_id curve;
switch( size )
{
case 0:
case 192:
curve = MBEDTLS_ECP_DP_SECP192R1;
break;
case 224:
curve = MBEDTLS_ECP_DP_SECP224R1;
break;
case 256:
curve = MBEDTLS_ECP_DP_SECP256R1;
break;
case 384:
curve = MBEDTLS_ECP_DP_SECP384R1;
break;
case 521:
curve = MBEDTLS_ECP_DP_SECP521R1;
break;
default:
return( -1 );
}
if( ( ret = mbedtls_ecp_group_load( &mbedtls_pk_ec( *pk )->grp,
MBEDTLS_ECP_DP_SECP192R1 ) ) != 0 )
curve ) ) != 0 )
return( ret );

return mbedtls_ecp_gen_keypair( &mbedtls_pk_ec( *pk )->grp, &mbedtls_pk_ec( *pk )->d,
Expand Down Expand Up @@ -77,7 +104,7 @@ void pk_utils( int type, int size, int len, char * name )
mbedtls_pk_init( &pk );

TEST_ASSERT( mbedtls_pk_setup( &pk, mbedtls_pk_info_from_type( type ) ) == 0 );
TEST_ASSERT( pk_genkey( &pk ) == 0 );
TEST_ASSERT( pk_genkey( &pk, size ) == 0 );

TEST_ASSERT( (int) mbedtls_pk_get_type( &pk ) == type );
TEST_ASSERT( mbedtls_pk_can_do( &pk, type ) );
Expand Down Expand Up @@ -252,7 +279,7 @@ void pk_sign_verify( int type, int sign_ret, int verify_ret )
memset( sig, 0, sizeof sig );

TEST_ASSERT( mbedtls_pk_setup( &pk, mbedtls_pk_info_from_type( type ) ) == 0 );
TEST_ASSERT( pk_genkey( &pk ) == 0 );
TEST_ASSERT( pk_genkey( &pk, 0 ) == 0 );

TEST_ASSERT( mbedtls_pk_sign( &pk, MBEDTLS_MD_SHA256, hash, sizeof hash,
sig, &sig_len, rnd_std_rand, NULL ) == sign_ret );
Expand Down Expand Up @@ -447,7 +474,7 @@ void pk_rsa_alt( )
/* Initiliaze PK RSA context with random key */
TEST_ASSERT( mbedtls_pk_setup( &rsa,
mbedtls_pk_info_from_type( MBEDTLS_PK_RSA ) ) == 0 );
TEST_ASSERT( pk_genkey( &rsa ) == 0 );
TEST_ASSERT( pk_genkey( &rsa, RSA_KEY_SIZE ) == 0 );

/* Extract key to the raw rsa context */
TEST_ASSERT( mbedtls_rsa_copy( &raw, mbedtls_pk_rsa( rsa ) ) == 0 );
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27 changes: 18 additions & 9 deletions tests/suites/test_suite_rsa.function
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Original file line number Diff line number Diff line change
Expand Up @@ -44,7 +44,8 @@ void mbedtls_rsa_pkcs1_sign( data_t * message_str, int padding_mode,
TEST_ASSERT( mbedtls_mpi_read_string( &E, radix_E, input_E ) == 0 );

TEST_ASSERT( mbedtls_rsa_import( &ctx, &N, &P, &Q, NULL, &E ) == 0 );
TEST_ASSERT( mbedtls_rsa_get_len( &ctx ) == (size_t) ( mod / 8 ) );
TEST_ASSERT( mbedtls_rsa_get_bitlen( &ctx ) == (size_t) mod );
TEST_ASSERT( mbedtls_rsa_get_len( &ctx ) == (size_t) ( mod + 7 ) / 8 );
TEST_ASSERT( mbedtls_rsa_complete( &ctx ) == 0 );
TEST_ASSERT( mbedtls_rsa_check_privkey( &ctx ) == 0 );

Expand Down Expand Up @@ -86,7 +87,8 @@ void mbedtls_rsa_pkcs1_verify( data_t * message_str, int padding_mode,
TEST_ASSERT( mbedtls_mpi_read_string( &N, radix_N, input_N ) == 0 );
TEST_ASSERT( mbedtls_mpi_read_string( &E, radix_E, input_E ) == 0 );
TEST_ASSERT( mbedtls_rsa_import( &ctx, &N, NULL, NULL, NULL, &E ) == 0 );
TEST_ASSERT( mbedtls_rsa_get_len( &ctx ) == (size_t) ( mod / 8 ) );
TEST_ASSERT( mbedtls_rsa_get_bitlen( &ctx ) == (size_t) mod );
TEST_ASSERT( mbedtls_rsa_get_len( &ctx ) == (size_t) ( mod + 7 ) / 8 );
TEST_ASSERT( mbedtls_rsa_check_pubkey( &ctx ) == 0 );


Expand Down Expand Up @@ -127,7 +129,8 @@ void rsa_pkcs1_sign_raw( data_t * hash_result,
TEST_ASSERT( mbedtls_mpi_read_string( &E, radix_E, input_E ) == 0 );

TEST_ASSERT( mbedtls_rsa_import( &ctx, &N, &P, &Q, NULL, &E ) == 0 );
TEST_ASSERT( mbedtls_rsa_get_len( &ctx ) == (size_t) ( mod / 8 ) );
TEST_ASSERT( mbedtls_rsa_get_bitlen( &ctx ) == (size_t) mod );
TEST_ASSERT( mbedtls_rsa_get_len( &ctx ) == (size_t) ( mod + 7 ) / 8 );
TEST_ASSERT( mbedtls_rsa_complete( &ctx ) == 0 );
TEST_ASSERT( mbedtls_rsa_check_privkey( &ctx ) == 0 );

Expand Down Expand Up @@ -192,7 +195,8 @@ void rsa_pkcs1_verify_raw( data_t * hash_result,
TEST_ASSERT( mbedtls_mpi_read_string( &E, radix_E, input_E ) == 0 );

TEST_ASSERT( mbedtls_rsa_import( &ctx, &N, NULL, NULL, NULL, &E ) == 0 );
TEST_ASSERT( mbedtls_rsa_get_len( &ctx ) == (size_t) ( mod / 8 ) );
TEST_ASSERT( mbedtls_rsa_get_bitlen( &ctx ) == (size_t) mod );
TEST_ASSERT( mbedtls_rsa_get_len( &ctx ) == (size_t) ( mod + 7 ) / 8 );
TEST_ASSERT( mbedtls_rsa_check_pubkey( &ctx ) == 0 );


Expand Down Expand Up @@ -256,7 +260,8 @@ void mbedtls_rsa_pkcs1_encrypt( data_t * message_str, int padding_mode,
TEST_ASSERT( mbedtls_mpi_read_string( &E, radix_E, input_E ) == 0 );

TEST_ASSERT( mbedtls_rsa_import( &ctx, &N, NULL, NULL, NULL, &E ) == 0 );
TEST_ASSERT( mbedtls_rsa_get_len( &ctx ) == (size_t) ( mod / 8 ) );
TEST_ASSERT( mbedtls_rsa_get_bitlen( &ctx ) == (size_t) mod );
TEST_ASSERT( mbedtls_rsa_get_len( &ctx ) == (size_t) ( mod + 7 ) / 8 );
TEST_ASSERT( mbedtls_rsa_check_pubkey( &ctx ) == 0 );


Expand Down Expand Up @@ -294,7 +299,8 @@ void rsa_pkcs1_encrypt_bad_rng( data_t * message_str, int padding_mode,
TEST_ASSERT( mbedtls_mpi_read_string( &E, radix_E, input_E ) == 0 );

TEST_ASSERT( mbedtls_rsa_import( &ctx, &N, NULL, NULL, NULL, &E ) == 0 );
TEST_ASSERT( mbedtls_rsa_get_len( &ctx ) == (size_t) ( mod / 8 ) );
TEST_ASSERT( mbedtls_rsa_get_bitlen( &ctx ) == (size_t) mod );
TEST_ASSERT( mbedtls_rsa_get_len( &ctx ) == (size_t) ( mod + 7 ) / 8 );
TEST_ASSERT( mbedtls_rsa_check_pubkey( &ctx ) == 0 );


Expand Down Expand Up @@ -342,7 +348,8 @@ void mbedtls_rsa_pkcs1_decrypt( data_t * message_str, int padding_mode,
TEST_ASSERT( mbedtls_mpi_read_string( &E, radix_E, input_E ) == 0 );

TEST_ASSERT( mbedtls_rsa_import( &ctx, &N, &P, &Q, NULL, &E ) == 0 );
TEST_ASSERT( mbedtls_rsa_get_len( &ctx ) == (size_t) ( mod / 8 ) );
TEST_ASSERT( mbedtls_rsa_get_bitlen( &ctx ) == (size_t) mod );
TEST_ASSERT( mbedtls_rsa_get_len( &ctx ) == (size_t) ( mod + 7 ) / 8 );
TEST_ASSERT( mbedtls_rsa_complete( &ctx ) == 0 );
TEST_ASSERT( mbedtls_rsa_check_privkey( &ctx ) == 0 );

Expand Down Expand Up @@ -381,7 +388,8 @@ void mbedtls_rsa_public( data_t * message_str, int mod, int radix_N,
TEST_ASSERT( mbedtls_mpi_read_string( &E, radix_E, input_E ) == 0 );

TEST_ASSERT( mbedtls_rsa_import( &ctx, &N, NULL, NULL, NULL, &E ) == 0 );
TEST_ASSERT( mbedtls_rsa_get_len( &ctx ) == (size_t) ( mod / 8 ) );
TEST_ASSERT( mbedtls_rsa_get_bitlen( &ctx ) == (size_t) mod );
TEST_ASSERT( mbedtls_rsa_get_len( &ctx ) == (size_t) ( mod + 7 ) / 8 );
TEST_ASSERT( mbedtls_rsa_check_pubkey( &ctx ) == 0 );


Expand Down Expand Up @@ -440,7 +448,8 @@ void mbedtls_rsa_private( data_t * message_str, int mod, int radix_P,
TEST_ASSERT( mbedtls_mpi_read_string( &E, radix_E, input_E ) == 0 );

TEST_ASSERT( mbedtls_rsa_import( &ctx, &N, &P, &Q, NULL, &E ) == 0 );
TEST_ASSERT( mbedtls_rsa_get_len( &ctx ) == (size_t) ( mod / 8 ) );
TEST_ASSERT( mbedtls_rsa_get_bitlen( &ctx ) == (size_t) mod );
TEST_ASSERT( mbedtls_rsa_get_len( &ctx ) == (size_t) ( mod + 7 ) / 8 );
TEST_ASSERT( mbedtls_rsa_complete( &ctx ) == 0 );
TEST_ASSERT( mbedtls_rsa_check_privkey( &ctx ) == 0 );

Expand Down

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