diff --git a/ChangeLog b/ChangeLog index cfe27f3eb..439f1a88a 100644 --- a/ChangeLog +++ b/ChangeLog @@ -17,6 +17,8 @@ Security implementation allowed an offline 2^80 brute force attack on the HMAC key of a single, uninterrupted connection (with no resumption of the session). + * Verify results of RSA private key operations to defend + against Bellcore glitch attack. Features * Extend PKCS#8 interface by introducing support for the entire SHA diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h index 1c98558eb..c7ba1743b 100644 --- a/include/mbedtls/config.h +++ b/include/mbedtls/config.h @@ -1049,7 +1049,8 @@ /** * \def MBEDTLS_RSA_NO_CRT * - * Do not use the Chinese Remainder Theorem for the RSA private operation. + * Do not use the Chinese Remainder Theorem + * for the RSA private operation. * * Uncomment this macro to disable the use of CRT in RSA. * diff --git a/include/mbedtls/rsa.h b/include/mbedtls/rsa.h index fb2f77f94..5548f3c12 100644 --- a/include/mbedtls/rsa.h +++ b/include/mbedtls/rsa.h @@ -518,6 +518,18 @@ int mbedtls_rsa_public( mbedtls_rsa_context *ctx, * * \note The input and output buffers must be large * enough. For example, 128 Bytes if RSA-1024 is used. + * + * \note Blinding is used if and only if a PRNG is provided. + * + * \note If blinding is used, both the base of exponentation + * and the exponent are blinded, providing protection + * against some side-channel attacks. + * + * \warning It is deprecated and a security risk to not provide + * a PRNG here and thereby prevent the use of blinding. + * Future versions of the library may enforce the presence + * of a PRNG. + * */ int mbedtls_rsa_private( mbedtls_rsa_context *ctx, int (*f_rng)(void *, unsigned char *, size_t), diff --git a/library/bignum.c b/library/bignum.c index d27c130bc..9f13da442 100644 --- a/library/bignum.c +++ b/library/bignum.c @@ -1623,7 +1623,7 @@ int mbedtls_mpi_exp_mod( mbedtls_mpi *X, const mbedtls_mpi *A, const mbedtls_mpi mbedtls_mpi RR, T, W[ 2 << MBEDTLS_MPI_WINDOW_SIZE ], Apos; int neg; - if( mbedtls_mpi_cmp_int( N, 0 ) < 0 || ( N->p[0] & 1 ) == 0 ) + if( mbedtls_mpi_cmp_int( N, 0 ) <= 0 || ( N->p[0] & 1 ) == 0 ) return( MBEDTLS_ERR_MPI_BAD_INPUT_DATA ); if( mbedtls_mpi_cmp_int( E, 0 ) < 0 ) diff --git a/library/rsa.c b/library/rsa.c index 6526978e2..c9f7ba91b 100644 --- a/library/rsa.c +++ b/library/rsa.c @@ -773,16 +773,38 @@ 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; -#endif +#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 /* MBEDTLS_RSA_NO_CRT */ + + /* Temporaries holding the initial input and the double + * checked result; should be the same in the end. */ + mbedtls_mpi I, C; if( rsa_check_context( ctx, 1 /* private key checks */, f_rng != NULL /* blinding y/n */ ) != 0 ) @@ -790,8 +812,17 @@ int mbedtls_rsa_private( mbedtls_rsa_context *ctx, 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 ) { @@ -803,12 +834,15 @@ 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 + mbedtls_mpi_init( &I ); + mbedtls_mpi_init( &C ); + + /* End of MPI initialization */ + MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &T, input, ctx->len ) ); if( mbedtls_mpi_cmp_mpi( &T, &ctx->N ) >= 0 ) { @@ -816,6 +850,8 @@ int mbedtls_rsa_private( mbedtls_rsa_context *ctx, goto cleanup; } + MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &I, &T ) ); + if( f_rng != NULL ) { /* @@ -874,24 +910,25 @@ 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 ) @@ -904,6 +941,15 @@ int mbedtls_rsa_private( mbedtls_rsa_context *ctx, MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &T, &T, &ctx->N ) ); } + /* Verify the result to prevent glitching attacks. */ + MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &C, &T, &ctx->E, + &ctx->N, &ctx->RN ) ); + if( mbedtls_mpi_cmp_mpi( &C, &I ) != 0 ) + { + ret = MBEDTLS_ERR_RSA_VERIFY_FAILED; + goto cleanup; + } + olen = ctx->len; MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &T, output, olen ) ); @@ -913,8 +959,9 @@ 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 ) { @@ -926,6 +973,15 @@ cleanup: #endif } + mbedtls_mpi_free( &T ); + +#if !defined(MBEDTLS_RSA_NO_CRT) + mbedtls_mpi_free( &TP ); mbedtls_mpi_free( &TQ ); +#endif + + mbedtls_mpi_free( &C ); + mbedtls_mpi_free( &I ); + if( ret != 0 ) return( MBEDTLS_ERR_RSA_PRIVATE_FAILED + ret ); @@ -2222,7 +2278,8 @@ int mbedtls_rsa_self_test( int verbose ) if( verbose != 0 ) mbedtls_printf( "failed\n" ); - return( 1 ); + ret = 1; + goto cleanup; } if( verbose != 0 ) @@ -2237,7 +2294,8 @@ int mbedtls_rsa_self_test( int verbose ) if( verbose != 0 ) mbedtls_printf( "failed\n" ); - return( 1 ); + ret = 1; + goto cleanup; } if( verbose != 0 ) @@ -2250,7 +2308,8 @@ int mbedtls_rsa_self_test( int verbose ) if( verbose != 0 ) mbedtls_printf( "failed\n" ); - return( 1 ); + ret = 1; + goto cleanup; } if( memcmp( rsa_decrypted, rsa_plaintext, len ) != 0 ) @@ -2258,7 +2317,8 @@ int mbedtls_rsa_self_test( int verbose ) if( verbose != 0 ) mbedtls_printf( "failed\n" ); - return( 1 ); + ret = 1; + goto cleanup; } if( verbose != 0 ) @@ -2283,7 +2343,8 @@ int mbedtls_rsa_self_test( int verbose ) if( verbose != 0 ) mbedtls_printf( "failed\n" ); - return( 1 ); + ret = 1; + goto cleanup; } if( verbose != 0 ) @@ -2296,7 +2357,8 @@ int mbedtls_rsa_self_test( int verbose ) if( verbose != 0 ) mbedtls_printf( "failed\n" ); - return( 1 ); + ret = 1; + goto cleanup; } if( verbose != 0 ) diff --git a/scripts/config.pl b/scripts/config.pl index 76ca4709c..5bf27859a 100755 --- a/scripts/config.pl +++ b/scripts/config.pl @@ -17,7 +17,7 @@ # # Full usage description provided below. # -# Things that shouldn't be enabled with "full". +# The following options are disabled instead of enabled with "full". # # MBEDTLS_TEST_NULL_ENTROPY # MBEDTLS_DEPRECATED_REMOVED @@ -30,6 +30,7 @@ # MBEDTLS_NO_PLATFORM_ENTROPY # MBEDTLS_REMOVE_ARC4_CIPHERSUITES # MBEDTLS_SSL_HW_RECORD_ACCEL +# MBEDTLS_RSA_NO_CRT # MBEDTLS_X509_ALLOW_EXTENSIONS_NON_V3 # MBEDTLS_X509_ALLOW_UNSUPPORTED_CRITICAL_EXTENSION # - this could be enabled if the respective tests were adapted @@ -86,6 +87,7 @@ MBEDTLS_ECP_DP_M383_ENABLED MBEDTLS_ECP_DP_M511_ENABLED MBEDTLS_NO_DEFAULT_ENTROPY_SOURCES MBEDTLS_NO_PLATFORM_ENTROPY +MBEDTLS_RSA_NO_CRT MBEDTLS_REMOVE_ARC4_CIPHERSUITES MBEDTLS_SSL_HW_RECORD_ACCEL MBEDTLS_X509_ALLOW_EXTENSIONS_NON_V3 diff --git a/tests/scripts/all.sh b/tests/scripts/all.sh index 67b22cdbd..fdb99be3c 100755 --- a/tests/scripts/all.sh +++ b/tests/scripts/all.sh @@ -530,6 +530,22 @@ make test msg "test: !MBEDTLS_SSL_RENEGOTIATION - ssl-opt.sh (ASan build)" # ~ 6 min if_build_succeeded tests/ssl-opt.sh +msg "build: Default + RSA_NO_CRT (ASan build)" # ~ 6 min +cleanup +cp "$CONFIG_H" "$CONFIG_BAK" +scripts/config.pl set MBEDTLS_RSA_NO_CRT +CC=gcc cmake -D CMAKE_BUILD_TYPE:String=Asan . +make + +msg "test: RSA_NO_CRT - main suites (inc. selftests) (ASan build)" # ~ 50s +make test + +msg "test: RSA_NO_CRT - RSA-related part of ssl-opt.sh (ASan build)" # ~ 5s +tests/ssl-opt.sh -f RSA + +msg "test: RSA_NO_CRT - RSA-related part of compat.sh (ASan build)" # ~ 3 min +tests/compat.sh -t RSA + msg "build: cmake, full config, clang, C99" # ~ 50s cleanup cp "$CONFIG_H" "$CONFIG_BAK" diff --git a/tests/suites/test_suite_pk.function b/tests/suites/test_suite_pk.function index 421227f5e..c0c987d5c 100644 --- a/tests/suites/test_suite_pk.function +++ b/tests/suites/test_suite_pk.function @@ -43,15 +43,18 @@ int mbedtls_rsa_decrypt_func( void *ctx, int mode, size_t *olen, const unsigned char *input, unsigned char *output, size_t output_max_len ) { - return( mbedtls_rsa_pkcs1_decrypt( (mbedtls_rsa_context *) ctx, NULL, NULL, mode, olen, - input, output, output_max_len ) ); + return( mbedtls_rsa_pkcs1_decrypt( (mbedtls_rsa_context *) ctx, + rnd_std_rand, NULL, mode, olen, + input, output, output_max_len ) ); } int mbedtls_rsa_sign_func( void *ctx, int (*f_rng)(void *, unsigned char *, size_t), void *p_rng, int mode, mbedtls_md_type_t md_alg, unsigned int hashlen, const unsigned char *hash, unsigned char *sig ) { - return( mbedtls_rsa_pkcs1_sign( (mbedtls_rsa_context *) ctx, f_rng, p_rng, mode, + ((void) f_rng); + ((void) p_rng); + return( mbedtls_rsa_pkcs1_sign( (mbedtls_rsa_context *) ctx, rnd_std_rand, NULL, mode, md_alg, hashlen, hash, sig ) ); } size_t mbedtls_rsa_key_len_func( void *ctx ) @@ -105,7 +108,8 @@ void mbedtls_pk_check_pair( char *pub_file, char *prv_file, int ret ) if( mbedtls_pk_get_type( &prv ) == MBEDTLS_PK_RSA ) { TEST_ASSERT( mbedtls_pk_setup_rsa_alt( &alt, mbedtls_pk_rsa( prv ), - mbedtls_rsa_decrypt_func, mbedtls_rsa_sign_func, mbedtls_rsa_key_len_func ) == 0 ); + mbedtls_rsa_decrypt_func, mbedtls_rsa_sign_func, + mbedtls_rsa_key_len_func ) == 0 ); TEST_ASSERT( mbedtls_pk_check_pair( &pub, &alt ) == ret ); } #endif