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Put configuration options for RSA blinding and verification to work.

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This commit is contained in:
Hanno Becker 2017-05-03 15:10:34 +01:00
parent a540068a56
commit 06811ced27
1 changed files with 108 additions and 24 deletions
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132
library/rsa.c
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@ -398,24 +398,68 @@ int mbedtls_rsa_private( mbedtls_rsa_context *ctx,
{
int ret;
size_t olen;
mbedtls_mpi T, T1, T2;
/* Temporary holding the result */
mbedtls_mpi T;
/* Temporaries holding P-1, Q-1 and the
* exponent blinding factor, respectively. */
mbedtls_mpi P1, Q1, R;
#if defined(MBEDTLS_RSA_NO_CRT)
mbedtls_mpi D_blind;
mbedtls_mpi *D = &ctx->D;
#else
#if !defined(MBEDTLS_RSA_NO_CRT)
/* Temporaries holding the results mod p resp. mod q. */
mbedtls_mpi TP, TQ;
/* Temporaries holding the blinded exponents for
* the mod p resp. mod q computation (if used). */
mbedtls_mpi DP_blind, DQ_blind;
/* Pointers to actual exponents to be used - either the unblinded
* or the blinded ones, depending on the presence of a PRNG. */
mbedtls_mpi *DP = &ctx->DP;
mbedtls_mpi *DQ = &ctx->DQ;
#else
/* Temporary holding the blinded exponent (if used). */
mbedtls_mpi D_blind;
/* Pointer to actual exponent to be used - either the unblinded
* or the blinded one, depending on the presence of a PRNG. */
mbedtls_mpi *D = &ctx->D;
#endif
#if defined(MBEDTLS_RSA_REQUIRE_VERIFICATION)
/* Temporaries holding input mod p resp. mod q. */
mbedtls_mpi IP, IQ;
/* Temporaries holding double check results mod p resp. mod q;
* should in the end have the same values as IP and IQ. */
mbedtls_mpi CP, CQ;
/* Comparison results */
int check = 0;
#endif
#if defined(MBEDTLS_RSA_FORCE_BLINDING)
if( f_rng == NULL )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
#endif
/* Make sure we have private key info, prevent possible misuse */
if( ctx->P.p == NULL || ctx->Q.p == NULL || ctx->D.p == NULL )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
mbedtls_mpi_init( &T ); mbedtls_mpi_init( &T1 ); mbedtls_mpi_init( &T2 );
mbedtls_mpi_init( &P1 ); mbedtls_mpi_init( &Q1 ); mbedtls_mpi_init( &R );
#if defined(MBEDTLS_THREADING_C)
if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 )
return( ret );
#endif
/* MPI Initialization */
mbedtls_mpi_init( &T );
mbedtls_mpi_init( &P1 );
mbedtls_mpi_init( &Q1 );
mbedtls_mpi_init( &R );
if( f_rng != NULL )
{
@ -427,12 +471,17 @@ int mbedtls_rsa_private( mbedtls_rsa_context *ctx,
#endif
}
#if defined(MBEDTLS_THREADING_C)
if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 )
return( ret );
#if !defined(MBEDTLS_RSA_NO_CRT)
mbedtls_mpi_init( &TP ); mbedtls_mpi_init( &TQ );
#endif
#if defined(MBEDTLS_RSA_REQUIRE_VERIFICATION)
mbedtls_mpi_init( &IP ); mbedtls_mpi_init( &IQ );
mbedtls_mpi_init( &CP ); mbedtls_mpi_init( &CQ );
#endif
/* End of MPI initialization */
MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &T, input, ctx->len ) );
if( mbedtls_mpi_cmp_mpi( &T, &ctx->N ) >= 0 )
{
@ -440,6 +489,11 @@ int mbedtls_rsa_private( mbedtls_rsa_context *ctx,
goto cleanup;
}
#if defined(MBEDTLS_RSA_REQUIRE_VERIFICATION)
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &IP, &T, &ctx->P ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &IQ, &T, &ctx->Q ) );
#endif
if( f_rng != NULL )
{
/*
@ -498,24 +552,25 @@ int mbedtls_rsa_private( mbedtls_rsa_context *ctx,
/*
* Faster decryption using the CRT
*
* T1 = input ^ dP mod P
* T2 = input ^ dQ mod Q
* TP = input ^ dP mod P
* TQ = input ^ dQ mod Q
*/
MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &T1, &T, DP, &ctx->P, &ctx->RP ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &T2, &T, DQ, &ctx->Q, &ctx->RQ ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &TP, &T, DP, &ctx->P, &ctx->RP ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &TQ, &T, DQ, &ctx->Q, &ctx->RQ ) );
/*
* T = (T1 - T2) * (Q^-1 mod P) mod P
* T = (TP - TQ) * (Q^-1 mod P) mod P
*/
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_mpi( &T, &T1, &T2 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &T1, &T, &ctx->QP ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &T, &T1, &ctx->P ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_mpi( &T, &TP, &TQ ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &TP, &T, &ctx->QP ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &T, &TP, &ctx->P ) );
/*
* T = T2 + T * Q
* T = TQ + T * Q
*/
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &T1, &T, &ctx->Q ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( &T, &T2, &T1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &TP, &T, &ctx->Q ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( &T, &TQ, &TP ) );
#endif /* MBEDTLS_RSA_NO_CRT */
if( f_rng != NULL )
@ -528,6 +583,23 @@ int mbedtls_rsa_private( mbedtls_rsa_context *ctx,
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &T, &T, &ctx->N ) );
}
/* If requested by the config, verify the result to prevent glitching attacks.
* For that, check the two prime moduli separately. */
#if defined(MBEDTLS_RSA_REQUIRE_VERIFICATION)
MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &CP, &T, &ctx->E, &ctx->P, &ctx->RP ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &CQ, &T, &ctx->E, &ctx->Q, &ctx->RQ ) );
check |= mbedtls_mpi_cmp_mpi( &CP, &IP );
check |= mbedtls_mpi_cmp_mpi( &CQ, &IQ );
if( check != 0 )
{
/* Verification failed */
ret = MBEDTLS_ERR_RSA_VERIFY_FAILED;
goto cleanup;
}
#endif /* MBEDTLS_RSA_REQUIRE_VERIFICATION */
olen = ctx->len;
MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &T, output, olen ) );
@ -537,8 +609,9 @@ cleanup:
return( MBEDTLS_ERR_THREADING_MUTEX_ERROR );
#endif
mbedtls_mpi_free( &T ); mbedtls_mpi_free( &T1 ); mbedtls_mpi_free( &T2 );
mbedtls_mpi_free( &P1 ); mbedtls_mpi_free( &Q1 ); mbedtls_mpi_free( &R );
mbedtls_mpi_free( &P1 );
mbedtls_mpi_free( &Q1 );
mbedtls_mpi_free( &R );
if( f_rng != NULL )
{
@ -550,6 +623,17 @@ cleanup:
#endif
}
mbedtls_mpi_free( &T );
#if !defined(MBEDTLS_RSA_NO_CRT)
mbedtls_mpi_free( &TP ); mbedtls_mpi_free( &TQ );
#endif
#if defined(MBEDTLS_RSA_REQUIRE_VERIFICATION)
mbedtls_mpi_free( &IP ); mbedtls_mpi_free( &IQ );
mbedtls_mpi_free( &CP ); mbedtls_mpi_free( &CQ );
#endif
if( ret != 0 )
return( MBEDTLS_ERR_RSA_PRIVATE_FAILED + ret );