summaryrefslogtreecommitdiff
path: root/thirdparty/mbedtls/library/rsa.c
diff options
context:
space:
mode:
Diffstat (limited to 'thirdparty/mbedtls/library/rsa.c')
-rw-r--r--thirdparty/mbedtls/library/rsa.c490
1 files changed, 406 insertions, 84 deletions
diff --git a/thirdparty/mbedtls/library/rsa.c b/thirdparty/mbedtls/library/rsa.c
index 88c1cf1007..af1a878599 100644
--- a/thirdparty/mbedtls/library/rsa.c
+++ b/thirdparty/mbedtls/library/rsa.c
@@ -71,6 +71,12 @@
#if !defined(MBEDTLS_RSA_ALT)
+/* Parameter validation macros */
+#define RSA_VALIDATE_RET( cond ) \
+ MBEDTLS_INTERNAL_VALIDATE_RET( cond, MBEDTLS_ERR_RSA_BAD_INPUT_DATA )
+#define RSA_VALIDATE( cond ) \
+ MBEDTLS_INTERNAL_VALIDATE( cond )
+
#if defined(MBEDTLS_PKCS1_V15)
/* constant-time buffer comparison */
static inline int mbedtls_safer_memcmp( const void *a, const void *b, size_t n )
@@ -93,6 +99,7 @@ int mbedtls_rsa_import( mbedtls_rsa_context *ctx,
const mbedtls_mpi *D, const mbedtls_mpi *E )
{
int ret;
+ RSA_VALIDATE_RET( ctx != NULL );
if( ( N != NULL && ( ret = mbedtls_mpi_copy( &ctx->N, N ) ) != 0 ) ||
( P != NULL && ( ret = mbedtls_mpi_copy( &ctx->P, P ) ) != 0 ) ||
@@ -117,6 +124,7 @@ int mbedtls_rsa_import_raw( mbedtls_rsa_context *ctx,
unsigned char const *E, size_t E_len )
{
int ret = 0;
+ RSA_VALIDATE_RET( ctx != NULL );
if( N != NULL )
{
@@ -240,12 +248,16 @@ static int rsa_check_context( mbedtls_rsa_context const *ctx, int is_priv,
int mbedtls_rsa_complete( mbedtls_rsa_context *ctx )
{
int ret = 0;
+ int have_N, have_P, have_Q, have_D, have_E;
+ int n_missing, pq_missing, d_missing, is_pub, is_priv;
+
+ RSA_VALIDATE_RET( ctx != NULL );
- const int have_N = ( mbedtls_mpi_cmp_int( &ctx->N, 0 ) != 0 );
- const int have_P = ( mbedtls_mpi_cmp_int( &ctx->P, 0 ) != 0 );
- const int have_Q = ( mbedtls_mpi_cmp_int( &ctx->Q, 0 ) != 0 );
- const int have_D = ( mbedtls_mpi_cmp_int( &ctx->D, 0 ) != 0 );
- const int have_E = ( mbedtls_mpi_cmp_int( &ctx->E, 0 ) != 0 );
+ have_N = ( mbedtls_mpi_cmp_int( &ctx->N, 0 ) != 0 );
+ have_P = ( mbedtls_mpi_cmp_int( &ctx->P, 0 ) != 0 );
+ have_Q = ( mbedtls_mpi_cmp_int( &ctx->Q, 0 ) != 0 );
+ have_D = ( mbedtls_mpi_cmp_int( &ctx->D, 0 ) != 0 );
+ have_E = ( mbedtls_mpi_cmp_int( &ctx->E, 0 ) != 0 );
/*
* Check whether provided parameters are enough
@@ -257,13 +269,13 @@ int mbedtls_rsa_complete( mbedtls_rsa_context *ctx )
*
*/
- const int n_missing = have_P && have_Q && have_D && have_E;
- const int pq_missing = have_N && !have_P && !have_Q && have_D && have_E;
- const int d_missing = have_P && have_Q && !have_D && have_E;
- const int is_pub = have_N && !have_P && !have_Q && !have_D && have_E;
+ n_missing = have_P && have_Q && have_D && have_E;
+ pq_missing = have_N && !have_P && !have_Q && have_D && have_E;
+ d_missing = have_P && have_Q && !have_D && have_E;
+ is_pub = have_N && !have_P && !have_Q && !have_D && have_E;
/* These three alternatives are mutually exclusive */
- const int is_priv = n_missing || pq_missing || d_missing;
+ is_priv = n_missing || pq_missing || d_missing;
if( !is_priv && !is_pub )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
@@ -336,9 +348,11 @@ int mbedtls_rsa_export_raw( const mbedtls_rsa_context *ctx,
unsigned char *E, size_t E_len )
{
int ret = 0;
+ int is_priv;
+ RSA_VALIDATE_RET( ctx != NULL );
/* Check if key is private or public */
- const int is_priv =
+ is_priv =
mbedtls_mpi_cmp_int( &ctx->N, 0 ) != 0 &&
mbedtls_mpi_cmp_int( &ctx->P, 0 ) != 0 &&
mbedtls_mpi_cmp_int( &ctx->Q, 0 ) != 0 &&
@@ -379,9 +393,11 @@ int mbedtls_rsa_export( const mbedtls_rsa_context *ctx,
mbedtls_mpi *D, mbedtls_mpi *E )
{
int ret;
+ int is_priv;
+ RSA_VALIDATE_RET( ctx != NULL );
/* Check if key is private or public */
- int is_priv =
+ is_priv =
mbedtls_mpi_cmp_int( &ctx->N, 0 ) != 0 &&
mbedtls_mpi_cmp_int( &ctx->P, 0 ) != 0 &&
mbedtls_mpi_cmp_int( &ctx->Q, 0 ) != 0 &&
@@ -421,9 +437,11 @@ int mbedtls_rsa_export_crt( const mbedtls_rsa_context *ctx,
mbedtls_mpi *DP, mbedtls_mpi *DQ, mbedtls_mpi *QP )
{
int ret;
+ int is_priv;
+ RSA_VALIDATE_RET( ctx != NULL );
/* Check if key is private or public */
- int is_priv =
+ is_priv =
mbedtls_mpi_cmp_int( &ctx->N, 0 ) != 0 &&
mbedtls_mpi_cmp_int( &ctx->P, 0 ) != 0 &&
mbedtls_mpi_cmp_int( &ctx->Q, 0 ) != 0 &&
@@ -459,6 +477,10 @@ void mbedtls_rsa_init( mbedtls_rsa_context *ctx,
int padding,
int hash_id )
{
+ RSA_VALIDATE( ctx != NULL );
+ RSA_VALIDATE( padding == MBEDTLS_RSA_PKCS_V15 ||
+ padding == MBEDTLS_RSA_PKCS_V21 );
+
memset( ctx, 0, sizeof( mbedtls_rsa_context ) );
mbedtls_rsa_set_padding( ctx, padding, hash_id );
@@ -471,8 +493,13 @@ void mbedtls_rsa_init( mbedtls_rsa_context *ctx,
/*
* Set padding for an existing RSA context
*/
-void mbedtls_rsa_set_padding( mbedtls_rsa_context *ctx, int padding, int hash_id )
+void mbedtls_rsa_set_padding( mbedtls_rsa_context *ctx, int padding,
+ int hash_id )
{
+ RSA_VALIDATE( ctx != NULL );
+ RSA_VALIDATE( padding == MBEDTLS_RSA_PKCS_V15 ||
+ padding == MBEDTLS_RSA_PKCS_V21 );
+
ctx->padding = padding;
ctx->hash_id = hash_id;
}
@@ -502,12 +529,20 @@ int mbedtls_rsa_gen_key( mbedtls_rsa_context *ctx,
{
int ret;
mbedtls_mpi H, G, L;
+ int prime_quality = 0;
+ RSA_VALIDATE_RET( ctx != NULL );
+ RSA_VALIDATE_RET( f_rng != NULL );
- if( f_rng == NULL || nbits < 128 || exponent < 3 )
+ if( nbits < 128 || exponent < 3 || nbits % 2 != 0 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
- if( nbits % 2 )
- return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+ /*
+ * If the modulus is 1024 bit long or shorter, then the security strength of
+ * the RSA algorithm is less than or equal to 80 bits and therefore an error
+ * rate of 2^-80 is sufficient.
+ */
+ if( nbits > 1024 )
+ prime_quality = MBEDTLS_MPI_GEN_PRIME_FLAG_LOW_ERR;
mbedtls_mpi_init( &H );
mbedtls_mpi_init( &G );
@@ -523,11 +558,11 @@ int mbedtls_rsa_gen_key( mbedtls_rsa_context *ctx,
do
{
- MBEDTLS_MPI_CHK( mbedtls_mpi_gen_prime( &ctx->P, nbits >> 1, 0,
- f_rng, p_rng ) );
+ MBEDTLS_MPI_CHK( mbedtls_mpi_gen_prime( &ctx->P, nbits >> 1,
+ prime_quality, f_rng, p_rng ) );
- MBEDTLS_MPI_CHK( mbedtls_mpi_gen_prime( &ctx->Q, nbits >> 1, 0,
- f_rng, p_rng ) );
+ MBEDTLS_MPI_CHK( mbedtls_mpi_gen_prime( &ctx->Q, nbits >> 1,
+ prime_quality, f_rng, p_rng ) );
/* make sure the difference between p and q is not too small (FIPS 186-4 §B.3.3 step 5.4) */
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_mpi( &H, &ctx->P, &ctx->Q ) );
@@ -603,6 +638,8 @@ cleanup:
*/
int mbedtls_rsa_check_pubkey( const mbedtls_rsa_context *ctx )
{
+ RSA_VALIDATE_RET( ctx != NULL );
+
if( rsa_check_context( ctx, 0 /* public */, 0 /* no blinding */ ) != 0 )
return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED );
@@ -626,6 +663,8 @@ int mbedtls_rsa_check_pubkey( const mbedtls_rsa_context *ctx )
*/
int mbedtls_rsa_check_privkey( const mbedtls_rsa_context *ctx )
{
+ RSA_VALIDATE_RET( ctx != NULL );
+
if( mbedtls_rsa_check_pubkey( ctx ) != 0 ||
rsa_check_context( ctx, 1 /* private */, 1 /* blinding */ ) != 0 )
{
@@ -655,6 +694,9 @@ int mbedtls_rsa_check_privkey( const mbedtls_rsa_context *ctx )
int mbedtls_rsa_check_pub_priv( const mbedtls_rsa_context *pub,
const mbedtls_rsa_context *prv )
{
+ RSA_VALIDATE_RET( pub != NULL );
+ RSA_VALIDATE_RET( prv != NULL );
+
if( mbedtls_rsa_check_pubkey( pub ) != 0 ||
mbedtls_rsa_check_privkey( prv ) != 0 )
{
@@ -680,6 +722,9 @@ int mbedtls_rsa_public( mbedtls_rsa_context *ctx,
int ret;
size_t olen;
mbedtls_mpi T;
+ RSA_VALIDATE_RET( ctx != NULL );
+ RSA_VALIDATE_RET( input != NULL );
+ RSA_VALIDATE_RET( output != NULL );
if( rsa_check_context( ctx, 0 /* public */, 0 /* no blinding */ ) )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
@@ -822,6 +867,10 @@ int mbedtls_rsa_private( mbedtls_rsa_context *ctx,
* checked result; should be the same in the end. */
mbedtls_mpi I, C;
+ RSA_VALIDATE_RET( ctx != NULL );
+ RSA_VALIDATE_RET( input != NULL );
+ RSA_VALIDATE_RET( output != NULL );
+
if( rsa_check_context( ctx, 1 /* private key checks */,
f_rng != NULL /* blinding y/n */ ) != 0 )
{
@@ -1082,6 +1131,13 @@ int mbedtls_rsa_rsaes_oaep_encrypt( mbedtls_rsa_context *ctx,
const mbedtls_md_info_t *md_info;
mbedtls_md_context_t md_ctx;
+ RSA_VALIDATE_RET( ctx != NULL );
+ RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE ||
+ mode == MBEDTLS_RSA_PUBLIC );
+ RSA_VALIDATE_RET( output != NULL );
+ RSA_VALIDATE_RET( input != NULL );
+ RSA_VALIDATE_RET( label_len == 0 || label != NULL );
+
if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V21 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
@@ -1158,11 +1214,13 @@ int mbedtls_rsa_rsaes_pkcs1_v15_encrypt( mbedtls_rsa_context *ctx,
int ret;
unsigned char *p = output;
- if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V15 )
- return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+ RSA_VALIDATE_RET( ctx != NULL );
+ RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE ||
+ mode == MBEDTLS_RSA_PUBLIC );
+ RSA_VALIDATE_RET( output != NULL );
+ RSA_VALIDATE_RET( input != NULL );
- // We don't check p_rng because it won't be dereferenced here
- if( f_rng == NULL || input == NULL || output == NULL )
+ if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V15 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
olen = ctx->len;
@@ -1176,6 +1234,9 @@ int mbedtls_rsa_rsaes_pkcs1_v15_encrypt( mbedtls_rsa_context *ctx,
*p++ = 0;
if( mode == MBEDTLS_RSA_PUBLIC )
{
+ if( f_rng == NULL )
+ return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
*p++ = MBEDTLS_RSA_CRYPT;
while( nb_pad-- > 0 )
@@ -1220,6 +1281,12 @@ int mbedtls_rsa_pkcs1_encrypt( mbedtls_rsa_context *ctx,
const unsigned char *input,
unsigned char *output )
{
+ RSA_VALIDATE_RET( ctx != NULL );
+ RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE ||
+ mode == MBEDTLS_RSA_PUBLIC );
+ RSA_VALIDATE_RET( output != NULL );
+ RSA_VALIDATE_RET( input != NULL );
+
switch( ctx->padding )
{
#if defined(MBEDTLS_PKCS1_V15)
@@ -1262,6 +1329,14 @@ int mbedtls_rsa_rsaes_oaep_decrypt( mbedtls_rsa_context *ctx,
const mbedtls_md_info_t *md_info;
mbedtls_md_context_t md_ctx;
+ RSA_VALIDATE_RET( ctx != NULL );
+ RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE ||
+ mode == MBEDTLS_RSA_PUBLIC );
+ RSA_VALIDATE_RET( output_max_len == 0 || output != NULL );
+ RSA_VALIDATE_RET( label_len == 0 || label != NULL );
+ RSA_VALIDATE_RET( input != NULL );
+ RSA_VALIDATE_RET( olen != NULL );
+
/*
* Parameters sanity checks
*/
@@ -1378,6 +1453,97 @@ cleanup:
#endif /* MBEDTLS_PKCS1_V21 */
#if defined(MBEDTLS_PKCS1_V15)
+/** Turn zero-or-nonzero into zero-or-all-bits-one, without branches.
+ *
+ * \param value The value to analyze.
+ * \return Zero if \p value is zero, otherwise all-bits-one.
+ */
+static unsigned all_or_nothing_int( unsigned value )
+{
+ /* MSVC has a warning about unary minus on unsigned, but this is
+ * well-defined and precisely what we want to do here */
+#if defined(_MSC_VER)
+#pragma warning( push )
+#pragma warning( disable : 4146 )
+#endif
+ return( - ( ( value | - value ) >> ( sizeof( value ) * 8 - 1 ) ) );
+#if defined(_MSC_VER)
+#pragma warning( pop )
+#endif
+}
+
+/** Check whether a size is out of bounds, without branches.
+ *
+ * This is equivalent to `size > max`, but is likely to be compiled to
+ * to code using bitwise operation rather than a branch.
+ *
+ * \param size Size to check.
+ * \param max Maximum desired value for \p size.
+ * \return \c 0 if `size <= max`.
+ * \return \c 1 if `size > max`.
+ */
+static unsigned size_greater_than( size_t size, size_t max )
+{
+ /* Return the sign bit (1 for negative) of (max - size). */
+ return( ( max - size ) >> ( sizeof( size_t ) * 8 - 1 ) );
+}
+
+/** Choose between two integer values, without branches.
+ *
+ * This is equivalent to `cond ? if1 : if0`, but is likely to be compiled
+ * to code using bitwise operation rather than a branch.
+ *
+ * \param cond Condition to test.
+ * \param if1 Value to use if \p cond is nonzero.
+ * \param if0 Value to use if \p cond is zero.
+ * \return \c if1 if \p cond is nonzero, otherwise \c if0.
+ */
+static unsigned if_int( unsigned cond, unsigned if1, unsigned if0 )
+{
+ unsigned mask = all_or_nothing_int( cond );
+ return( ( mask & if1 ) | (~mask & if0 ) );
+}
+
+/** Shift some data towards the left inside a buffer without leaking
+ * the length of the data through side channels.
+ *
+ * `mem_move_to_left(start, total, offset)` is functionally equivalent to
+ * ```
+ * memmove(start, start + offset, total - offset);
+ * memset(start + offset, 0, total - offset);
+ * ```
+ * but it strives to use a memory access pattern (and thus total timing)
+ * that does not depend on \p offset. This timing independence comes at
+ * the expense of performance.
+ *
+ * \param start Pointer to the start of the buffer.
+ * \param total Total size of the buffer.
+ * \param offset Offset from which to copy \p total - \p offset bytes.
+ */
+static void mem_move_to_left( void *start,
+ size_t total,
+ size_t offset )
+{
+ volatile unsigned char *buf = start;
+ size_t i, n;
+ if( total == 0 )
+ return;
+ for( i = 0; i < total; i++ )
+ {
+ unsigned no_op = size_greater_than( total - offset, i );
+ /* The first `total - offset` passes are a no-op. The last
+ * `offset` passes shift the data one byte to the left and
+ * zero out the last byte. */
+ for( n = 0; n < total - 1; n++ )
+ {
+ unsigned char current = buf[n];
+ unsigned char next = buf[n+1];
+ buf[n] = if_int( no_op, current, next );
+ }
+ buf[total-1] = if_int( no_op, buf[total-1], 0 );
+ }
+}
+
/*
* Implementation of the PKCS#1 v2.1 RSAES-PKCS1-V1_5-DECRYPT function
*/
@@ -1387,18 +1553,42 @@ int mbedtls_rsa_rsaes_pkcs1_v15_decrypt( mbedtls_rsa_context *ctx,
int mode, size_t *olen,
const unsigned char *input,
unsigned char *output,
- size_t output_max_len)
+ size_t output_max_len )
{
int ret;
- size_t ilen, pad_count = 0, i;
- unsigned char *p, bad, pad_done = 0;
+ size_t ilen, i, plaintext_max_size;
unsigned char buf[MBEDTLS_MPI_MAX_SIZE];
+ /* The following variables take sensitive values: their value must
+ * not leak into the observable behavior of the function other than
+ * the designated outputs (output, olen, return value). Otherwise
+ * this would open the execution of the function to
+ * side-channel-based variants of the Bleichenbacher padding oracle
+ * attack. Potential side channels include overall timing, memory
+ * access patterns (especially visible to an adversary who has access
+ * to a shared memory cache), and branches (especially visible to
+ * an adversary who has access to a shared code cache or to a shared
+ * branch predictor). */
+ size_t pad_count = 0;
+ unsigned bad = 0;
+ unsigned char pad_done = 0;
+ size_t plaintext_size = 0;
+ unsigned output_too_large;
+
+ RSA_VALIDATE_RET( ctx != NULL );
+ RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE ||
+ mode == MBEDTLS_RSA_PUBLIC );
+ RSA_VALIDATE_RET( output_max_len == 0 || output != NULL );
+ RSA_VALIDATE_RET( input != NULL );
+ RSA_VALIDATE_RET( olen != NULL );
+
+ ilen = ctx->len;
+ plaintext_max_size = ( output_max_len > ilen - 11 ?
+ ilen - 11 :
+ output_max_len );
if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V15 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
- ilen = ctx->len;
-
if( ilen < 16 || ilen > sizeof( buf ) )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
@@ -1409,63 +1599,109 @@ int mbedtls_rsa_rsaes_pkcs1_v15_decrypt( mbedtls_rsa_context *ctx,
if( ret != 0 )
goto cleanup;
- p = buf;
- bad = 0;
-
- /*
- * Check and get padding len in "constant-time"
- */
- bad |= *p++; /* First byte must be 0 */
+ /* Check and get padding length in constant time and constant
+ * memory trace. The first byte must be 0. */
+ bad |= buf[0];
- /* This test does not depend on secret data */
if( mode == MBEDTLS_RSA_PRIVATE )
{
- bad |= *p++ ^ MBEDTLS_RSA_CRYPT;
+ /* Decode EME-PKCS1-v1_5 padding: 0x00 || 0x02 || PS || 0x00
+ * where PS must be at least 8 nonzero bytes. */
+ bad |= buf[1] ^ MBEDTLS_RSA_CRYPT;
- /* Get padding len, but always read till end of buffer
- * (minus one, for the 00 byte) */
- for( i = 0; i < ilen - 3; i++ )
+ /* Read the whole buffer. Set pad_done to nonzero if we find
+ * the 0x00 byte and remember the padding length in pad_count. */
+ for( i = 2; i < ilen; i++ )
{
- pad_done |= ((p[i] | (unsigned char)-p[i]) >> 7) ^ 1;
+ pad_done |= ((buf[i] | (unsigned char)-buf[i]) >> 7) ^ 1;
pad_count += ((pad_done | (unsigned char)-pad_done) >> 7) ^ 1;
}
-
- p += pad_count;
- bad |= *p++; /* Must be zero */
}
else
{
- bad |= *p++ ^ MBEDTLS_RSA_SIGN;
+ /* Decode EMSA-PKCS1-v1_5 padding: 0x00 || 0x01 || PS || 0x00
+ * where PS must be at least 8 bytes with the value 0xFF. */
+ bad |= buf[1] ^ MBEDTLS_RSA_SIGN;
- /* Get padding len, but always read till end of buffer
- * (minus one, for the 00 byte) */
- for( i = 0; i < ilen - 3; i++ )
+ /* Read the whole buffer. Set pad_done to nonzero if we find
+ * the 0x00 byte and remember the padding length in pad_count.
+ * If there's a non-0xff byte in the padding, the padding is bad. */
+ for( i = 2; i < ilen; i++ )
{
- pad_done |= ( p[i] != 0xFF );
- pad_count += ( pad_done == 0 );
+ pad_done |= if_int( buf[i], 0, 1 );
+ pad_count += if_int( pad_done, 0, 1 );
+ bad |= if_int( pad_done, 0, buf[i] ^ 0xFF );
}
-
- p += pad_count;
- bad |= *p++; /* Must be zero */
}
- bad |= ( pad_count < 8 );
-
- if( bad )
- {
- ret = MBEDTLS_ERR_RSA_INVALID_PADDING;
- goto cleanup;
- }
-
- if( ilen - ( p - buf ) > output_max_len )
- {
- ret = MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE;
- goto cleanup;
- }
-
- *olen = ilen - (p - buf);
- memcpy( output, p, *olen );
- ret = 0;
+ /* If pad_done is still zero, there's no data, only unfinished padding. */
+ bad |= if_int( pad_done, 0, 1 );
+
+ /* There must be at least 8 bytes of padding. */
+ bad |= size_greater_than( 8, pad_count );
+
+ /* If the padding is valid, set plaintext_size to the number of
+ * remaining bytes after stripping the padding. If the padding
+ * is invalid, avoid leaking this fact through the size of the
+ * output: use the maximum message size that fits in the output
+ * buffer. Do it without branches to avoid leaking the padding
+ * validity through timing. RSA keys are small enough that all the
+ * size_t values involved fit in unsigned int. */
+ plaintext_size = if_int( bad,
+ (unsigned) plaintext_max_size,
+ (unsigned) ( ilen - pad_count - 3 ) );
+
+ /* Set output_too_large to 0 if the plaintext fits in the output
+ * buffer and to 1 otherwise. */
+ output_too_large = size_greater_than( plaintext_size,
+ plaintext_max_size );
+
+ /* Set ret without branches to avoid timing attacks. Return:
+ * - INVALID_PADDING if the padding is bad (bad != 0).
+ * - OUTPUT_TOO_LARGE if the padding is good but the decrypted
+ * plaintext does not fit in the output buffer.
+ * - 0 if the padding is correct. */
+ ret = - (int) if_int( bad, - MBEDTLS_ERR_RSA_INVALID_PADDING,
+ if_int( output_too_large, - MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE,
+ 0 ) );
+
+ /* If the padding is bad or the plaintext is too large, zero the
+ * data that we're about to copy to the output buffer.
+ * We need to copy the same amount of data
+ * from the same buffer whether the padding is good or not to
+ * avoid leaking the padding validity through overall timing or
+ * through memory or cache access patterns. */
+ bad = all_or_nothing_int( bad | output_too_large );
+ for( i = 11; i < ilen; i++ )
+ buf[i] &= ~bad;
+
+ /* If the plaintext is too large, truncate it to the buffer size.
+ * Copy anyway to avoid revealing the length through timing, because
+ * revealing the length is as bad as revealing the padding validity
+ * for a Bleichenbacher attack. */
+ plaintext_size = if_int( output_too_large,
+ (unsigned) plaintext_max_size,
+ (unsigned) plaintext_size );
+
+ /* Move the plaintext to the leftmost position where it can start in
+ * the working buffer, i.e. make it start plaintext_max_size from
+ * the end of the buffer. Do this with a memory access trace that
+ * does not depend on the plaintext size. After this move, the
+ * starting location of the plaintext is no longer sensitive
+ * information. */
+ mem_move_to_left( buf + ilen - plaintext_max_size,
+ plaintext_max_size,
+ plaintext_max_size - plaintext_size );
+
+ /* Finally copy the decrypted plaintext plus trailing zeros
+ * into the output buffer. */
+ memcpy( output, buf + ilen - plaintext_max_size, plaintext_max_size );
+
+ /* Report the amount of data we copied to the output buffer. In case
+ * of errors (bad padding or output too large), the value of *olen
+ * when this function returns is not specified. Making it equivalent
+ * to the good case limits the risks of leaking the padding validity. */
+ *olen = plaintext_size;
cleanup:
mbedtls_platform_zeroize( buf, sizeof( buf ) );
@@ -1485,6 +1721,13 @@ int mbedtls_rsa_pkcs1_decrypt( mbedtls_rsa_context *ctx,
unsigned char *output,
size_t output_max_len)
{
+ RSA_VALIDATE_RET( ctx != NULL );
+ RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE ||
+ mode == MBEDTLS_RSA_PUBLIC );
+ RSA_VALIDATE_RET( output_max_len == 0 || output != NULL );
+ RSA_VALIDATE_RET( input != NULL );
+ RSA_VALIDATE_RET( olen != NULL );
+
switch( ctx->padding )
{
#if defined(MBEDTLS_PKCS1_V15)
@@ -1521,11 +1764,18 @@ int mbedtls_rsa_rsassa_pss_sign( mbedtls_rsa_context *ctx,
size_t olen;
unsigned char *p = sig;
unsigned char salt[MBEDTLS_MD_MAX_SIZE];
- unsigned int slen, hlen, offset = 0;
+ size_t slen, min_slen, hlen, offset = 0;
int ret;
size_t msb;
const mbedtls_md_info_t *md_info;
mbedtls_md_context_t md_ctx;
+ RSA_VALIDATE_RET( ctx != NULL );
+ RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE ||
+ mode == MBEDTLS_RSA_PUBLIC );
+ RSA_VALIDATE_RET( ( md_alg == MBEDTLS_MD_NONE &&
+ hashlen == 0 ) ||
+ hash != NULL );
+ RSA_VALIDATE_RET( sig != NULL );
if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V21 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
@@ -1550,10 +1800,20 @@ int mbedtls_rsa_rsassa_pss_sign( mbedtls_rsa_context *ctx,
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
hlen = mbedtls_md_get_size( md_info );
- slen = hlen;
- if( olen < hlen + slen + 2 )
+ /* Calculate the largest possible salt length. Normally this is the hash
+ * length, which is the maximum length the salt can have. If there is not
+ * enough room, use the maximum salt length that fits. The constraint is
+ * that the hash length plus the salt length plus 2 bytes must be at most
+ * the key length. This complies with FIPS 186-4 §5.5 (e) and RFC 8017
+ * (PKCS#1 v2.2) §9.1.1 step 3. */
+ min_slen = hlen - 2;
+ if( olen < hlen + min_slen + 2 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+ else if( olen >= hlen + hlen + 2 )
+ slen = hlen;
+ else
+ slen = olen - hlen - 2;
memset( sig, 0, olen );
@@ -1563,7 +1823,7 @@ int mbedtls_rsa_rsassa_pss_sign( mbedtls_rsa_context *ctx,
/* Note: EMSA-PSS encoding is over the length of N - 1 bits */
msb = mbedtls_mpi_bitlen( &ctx->N ) - 1;
- p += olen - hlen * 2 - 2;
+ p += olen - hlen - slen - 2;
*p++ = 0x01;
memcpy( p, salt, slen );
p += slen;
@@ -1763,6 +2023,14 @@ int mbedtls_rsa_rsassa_pkcs1_v15_sign( mbedtls_rsa_context *ctx,
int ret;
unsigned char *sig_try = NULL, *verif = NULL;
+ RSA_VALIDATE_RET( ctx != NULL );
+ RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE ||
+ mode == MBEDTLS_RSA_PUBLIC );
+ RSA_VALIDATE_RET( ( md_alg == MBEDTLS_MD_NONE &&
+ hashlen == 0 ) ||
+ hash != NULL );
+ RSA_VALIDATE_RET( sig != NULL );
+
if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V15 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
@@ -1832,6 +2100,14 @@ int mbedtls_rsa_pkcs1_sign( mbedtls_rsa_context *ctx,
const unsigned char *hash,
unsigned char *sig )
{
+ RSA_VALIDATE_RET( ctx != NULL );
+ RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE ||
+ mode == MBEDTLS_RSA_PUBLIC );
+ RSA_VALIDATE_RET( ( md_alg == MBEDTLS_MD_NONE &&
+ hashlen == 0 ) ||
+ hash != NULL );
+ RSA_VALIDATE_RET( sig != NULL );
+
switch( ctx->padding )
{
#if defined(MBEDTLS_PKCS1_V15)
@@ -1878,6 +2154,14 @@ int mbedtls_rsa_rsassa_pss_verify_ext( mbedtls_rsa_context *ctx,
mbedtls_md_context_t md_ctx;
unsigned char buf[MBEDTLS_MPI_MAX_SIZE];
+ RSA_VALIDATE_RET( ctx != NULL );
+ RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE ||
+ mode == MBEDTLS_RSA_PUBLIC );
+ RSA_VALIDATE_RET( sig != NULL );
+ RSA_VALIDATE_RET( ( md_alg == MBEDTLS_MD_NONE &&
+ hashlen == 0 ) ||
+ hash != NULL );
+
if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V21 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
@@ -2006,7 +2290,16 @@ int mbedtls_rsa_rsassa_pss_verify( mbedtls_rsa_context *ctx,
const unsigned char *hash,
const unsigned char *sig )
{
- mbedtls_md_type_t mgf1_hash_id = ( ctx->hash_id != MBEDTLS_MD_NONE )
+ mbedtls_md_type_t mgf1_hash_id;
+ RSA_VALIDATE_RET( ctx != NULL );
+ RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE ||
+ mode == MBEDTLS_RSA_PUBLIC );
+ RSA_VALIDATE_RET( sig != NULL );
+ RSA_VALIDATE_RET( ( md_alg == MBEDTLS_MD_NONE &&
+ hashlen == 0 ) ||
+ hash != NULL );
+
+ mgf1_hash_id = ( ctx->hash_id != MBEDTLS_MD_NONE )
? (mbedtls_md_type_t) ctx->hash_id
: md_alg;
@@ -2032,9 +2325,19 @@ int mbedtls_rsa_rsassa_pkcs1_v15_verify( mbedtls_rsa_context *ctx,
const unsigned char *sig )
{
int ret = 0;
- const size_t sig_len = ctx->len;
+ size_t sig_len;
unsigned char *encoded = NULL, *encoded_expected = NULL;
+ RSA_VALIDATE_RET( ctx != NULL );
+ RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE ||
+ mode == MBEDTLS_RSA_PUBLIC );
+ RSA_VALIDATE_RET( sig != NULL );
+ RSA_VALIDATE_RET( ( md_alg == MBEDTLS_MD_NONE &&
+ hashlen == 0 ) ||
+ hash != NULL );
+
+ sig_len = ctx->len;
+
if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V15 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
@@ -2104,6 +2407,14 @@ int mbedtls_rsa_pkcs1_verify( mbedtls_rsa_context *ctx,
const unsigned char *hash,
const unsigned char *sig )
{
+ RSA_VALIDATE_RET( ctx != NULL );
+ RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE ||
+ mode == MBEDTLS_RSA_PUBLIC );
+ RSA_VALIDATE_RET( sig != NULL );
+ RSA_VALIDATE_RET( ( md_alg == MBEDTLS_MD_NONE &&
+ hashlen == 0 ) ||
+ hash != NULL );
+
switch( ctx->padding )
{
#if defined(MBEDTLS_PKCS1_V15)
@@ -2129,6 +2440,8 @@ int mbedtls_rsa_pkcs1_verify( mbedtls_rsa_context *ctx,
int mbedtls_rsa_copy( mbedtls_rsa_context *dst, const mbedtls_rsa_context *src )
{
int ret;
+ RSA_VALIDATE_RET( dst != NULL );
+ RSA_VALIDATE_RET( src != NULL );
dst->ver = src->ver;
dst->len = src->len;
@@ -2168,14 +2481,23 @@ cleanup:
*/
void mbedtls_rsa_free( mbedtls_rsa_context *ctx )
{
- mbedtls_mpi_free( &ctx->Vi ); mbedtls_mpi_free( &ctx->Vf );
- mbedtls_mpi_free( &ctx->RN ); mbedtls_mpi_free( &ctx->D );
- mbedtls_mpi_free( &ctx->Q ); mbedtls_mpi_free( &ctx->P );
- mbedtls_mpi_free( &ctx->E ); mbedtls_mpi_free( &ctx->N );
+ if( ctx == NULL )
+ return;
+
+ mbedtls_mpi_free( &ctx->Vi );
+ mbedtls_mpi_free( &ctx->Vf );
+ mbedtls_mpi_free( &ctx->RN );
+ mbedtls_mpi_free( &ctx->D );
+ mbedtls_mpi_free( &ctx->Q );
+ mbedtls_mpi_free( &ctx->P );
+ mbedtls_mpi_free( &ctx->E );
+ mbedtls_mpi_free( &ctx->N );
#if !defined(MBEDTLS_RSA_NO_CRT)
- mbedtls_mpi_free( &ctx->RQ ); mbedtls_mpi_free( &ctx->RP );
- mbedtls_mpi_free( &ctx->QP ); mbedtls_mpi_free( &ctx->DQ );
+ mbedtls_mpi_free( &ctx->RQ );
+ mbedtls_mpi_free( &ctx->RP );
+ mbedtls_mpi_free( &ctx->QP );
+ mbedtls_mpi_free( &ctx->DQ );
mbedtls_mpi_free( &ctx->DP );
#endif /* MBEDTLS_RSA_NO_CRT */
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-07 17:35:06 +0000