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Add mbedtls_rsa_validate_crt

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This commit adds the function mbedtls_rsa_validate_crt for validating a set of CRT parameters. The function
mbedtls_rsa_check_crt is simplified accordingly.
This commit is contained in:
Hanno Becker 2017-08-25 07:55:03 +01:00
parent d56d83a7f3
commit d363799a9d
2 changed files with 124 additions and 56 deletions
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34
include/mbedtls/rsa.h
View file

@ -198,6 +198,38 @@ int mbedtls_rsa_validate_params( const mbedtls_mpi *N, const mbedtls_mpi *P,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng );
/**
* \brief Check validity of RSA CRT parameters
*
* \note This is a 'static' helper function not operating on
* an RSA context. Alternative implementations need not
* overwrite it.
*
* \param P First prime factor of RSA modulus
* \param Q Second prime factor of RSA modulus
* \param D RSA private exponent
* \param DP MPI to check for D modulo P-1
* \param DQ MPI to check for D modulo P-1
* \param QP MPI to check for the modular inverse of Q modulo P.
*
* \return - 0 if the following conditions are satisfied:
* - D = DP mod P-1 if P, D, DP != NULL
* - Q = DQ mod P-1 if P, D, DQ != NULL
* - QP = Q^-1 mod P if P, Q, QP != NULL
* - MBEDTLS_ERR_RSA_KEY_CHECK_FAILED if check failed,
* potentially including MBEDTLS_ERR_MPI_XXX if some
* MPI calculations failed.
* - MBEDTLS_ERR_RSA_BAD_INPUT_DATA if insufficient
* data was provided to check DP, DQ or QP.
*
* \note The function can be used with a restricted set of arguments
* to perform specific checks only. E.g., calling it with the
* parameters (P, -, D, DP, -, -) will check DP = D mod P-1.
*/
int mbedtls_rsa_validate_crt( const mbedtls_mpi *P, const mbedtls_mpi *Q,
const mbedtls_mpi *D, const mbedtls_mpi *DP,
const mbedtls_mpi *DQ, const mbedtls_mpi *QP );
/**
* Implementation of RSA interface
*/
@ -394,7 +426,7 @@ int mbedtls_rsa_complete( mbedtls_rsa_context *ctx,
* before calling this function.
*
*/
int mbedtls_rsa_check_crt( mbedtls_rsa_context *ctx,
int mbedtls_rsa_check_crt( const mbedtls_rsa_context *ctx,
mbedtls_mpi *DP,
mbedtls_mpi *DQ,
mbedtls_mpi *QP );

146
library/rsa.c
View file

@ -304,6 +304,92 @@ cleanup:
return( ret );
}
/*
* Check that RSA CRT parameters are in accordance with core parameters.
*/
int mbedtls_rsa_validate_crt( const mbedtls_mpi *P, const mbedtls_mpi *Q,
const mbedtls_mpi *D, const mbedtls_mpi *DP,
const mbedtls_mpi *DQ, const mbedtls_mpi *QP )
{
int ret = 0;
mbedtls_mpi K, L;
mbedtls_mpi_init( &K );
mbedtls_mpi_init( &L );
/* Check that DP - P == 0 mod P - 1 */
if( DP != NULL )
{
if( P == NULL )
{
ret = MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
goto cleanup;
}
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &K, P, 1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_mpi( &L, DP, D ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &L, &L, &K ) );
if( mbedtls_mpi_cmp_int( &L, 0 ) != 0 )
{
return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED );
}
}
/* Check that DQ - Q == 0 mod Q - 1 */
if( DQ != NULL )
{
if( Q == NULL )
{
ret = MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
goto cleanup;
}
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &K, Q, 1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_mpi( &L, DQ, D ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &L, &L, &K ) );
if( mbedtls_mpi_cmp_int( &L, 0 ) != 0 )
{
return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED );
}
}
/* Check that QP * P - 1 == 0 mod P */
if( QP != NULL )
{
if( P == NULL || Q == NULL )
{
ret = MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
goto cleanup;
}
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &K, QP, Q ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &K, &K, 1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &K, &K, P ) );
if( mbedtls_mpi_cmp_int( &K, 0 ) != 0 )
{
return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED );
}
}
cleanup:
/* Wrap MPI error codes by RSA check failure error code */
if( ret != 0 &&
ret != MBEDTLS_ERR_RSA_KEY_CHECK_FAILED &&
ret != MBEDTLS_ERR_RSA_BAD_INPUT_DATA )
{
ret += MBEDTLS_ERR_RSA_KEY_CHECK_FAILED;
}
mbedtls_mpi_free( &K );
mbedtls_mpi_free( &L );
return( ret );
}
/*
* Check that core RSA parameters are sane.
*/
@ -621,8 +707,8 @@ int mbedtls_rsa_complete( mbedtls_rsa_context *ctx,
* in order to be able to validate DER encoded RSA keys,
* which always contain CRT parameters.
*/
int mbedtls_rsa_check_crt( mbedtls_rsa_context *ctx, mbedtls_mpi *DP,
mbedtls_mpi *DQ, mbedtls_mpi *QP )
int mbedtls_rsa_check_crt( const mbedtls_rsa_context *ctx,
mbedtls_mpi *DP, mbedtls_mpi *DQ, mbedtls_mpi *QP )
{
int ret = 0;
@ -648,61 +734,11 @@ int mbedtls_rsa_check_crt( mbedtls_rsa_context *ctx, mbedtls_mpi *DP,
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
}
#else /* MBEDTLS_RSA_NO_CRT */
/*
* Check that DP, DQ and QP are in accordance with core parameters.
* (1) Check that DP - P == 0 mod P - 1
* (2) Check that DQ - Q == 0 mod Q - 1
* (3) Check that QP * P - 1 == 0 mod P
* Alternative implementation also not using DP, DQ and QP
* should be able to reuse this codepath.
*/
/* Check (1) */
if( DP != NULL )
if( ( ret = mbedtls_rsa_validate_crt( &ctx->P, &ctx->Q, &ctx->D,
DP, DQ, QP ) ) != 0 )
{
/* Temporarily replace P by P-1 and compute DP - D mod P-1 */
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &ctx->P, &ctx->P, 1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_mpi( DP, DP, &ctx->D ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( DP, DP, &ctx->P ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_add_int( &ctx->P, &ctx->P, 1 ) );
if( mbedtls_mpi_cmp_int( DP, 0 ) != 0 )
{
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
}
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
}
/* Check (1) */
if( DQ != NULL )
{
/* Temporarily replace Q by Q-1 and compute DQ - D mod Q-1 */
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &ctx->Q, &ctx->Q, 1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_mpi( DQ, DQ, &ctx->D ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( DQ, DQ, &ctx->Q ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_add_int( &ctx->Q, &ctx->Q, 1 ) );
if( mbedtls_mpi_cmp_int( DQ, 0 ) != 0 )
{
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
}
}
/* Check (3) */
if( QP != NULL )
{
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( QP, QP, &ctx->Q ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( QP, QP, 1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( QP, QP, &ctx->P ) );
if( mbedtls_mpi_cmp_int( QP, 0 ) != 0 )
{
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
}
}
cleanup:
#endif
if( ret != 0 )