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Reuse Bignum core I/O functions

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Signed-off-by: Janos Follath <janos.follath@arm.com>
This commit is contained in:
Janos Follath 2022-07-22 16:18:41 +01:00
parent 91dc67d31c
commit 5f016650d7
1 changed files with 5 additions and 84 deletions
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87
library/bignum.c
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@ -659,14 +659,12 @@ int mbedtls_mpi_read_binary_le( mbedtls_mpi *X,
const unsigned char *buf, size_t buflen ) const unsigned char *buf, size_t buflen )
{ {
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t i;
size_t const limbs = CHARS_TO_LIMBS( buflen ); size_t const limbs = CHARS_TO_LIMBS( buflen );
/* Ensure that target MPI has exactly the necessary number of limbs */ /* Ensure that target MPI has exactly the necessary number of limbs */
MBEDTLS_MPI_CHK( mbedtls_mpi_resize_clear( X, limbs ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_resize_clear( X, limbs ) );
for( i = 0; i < buflen; i++ ) MBEDTLS_MPI_CHK( mbedtls_mpi_core_read_le( X->p, X->n, buf, buflen ) );
X->p[i / ciL] |= ((mbedtls_mpi_uint) buf[i]) << ((i % ciL) << 3);
cleanup: cleanup:
@ -688,8 +686,6 @@ int mbedtls_mpi_read_binary( mbedtls_mpi *X, const unsigned char *buf, size_t bu
{ {
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t const limbs = CHARS_TO_LIMBS( buflen ); size_t const limbs = CHARS_TO_LIMBS( buflen );
size_t const overhead = ( limbs * ciL ) - buflen;
unsigned char *Xp;
MPI_VALIDATE_RET( X != NULL ); MPI_VALIDATE_RET( X != NULL );
MPI_VALIDATE_RET( buflen == 0 || buf != NULL ); MPI_VALIDATE_RET( buflen == 0 || buf != NULL );
@ -697,15 +693,7 @@ int mbedtls_mpi_read_binary( mbedtls_mpi *X, const unsigned char *buf, size_t bu
/* Ensure that target MPI has exactly the necessary number of limbs */ /* Ensure that target MPI has exactly the necessary number of limbs */
MBEDTLS_MPI_CHK( mbedtls_mpi_resize_clear( X, limbs ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_resize_clear( X, limbs ) );
/* Avoid calling `memcpy` with NULL source or destination argument, MBEDTLS_MPI_CHK( mbedtls_mpi_core_read_be( X->p, X->n, buf, buflen ) );
* even if buflen is 0. */
if( buflen != 0 )
{
Xp = (unsigned char*) X->p;
memcpy( Xp + overhead, buf, buflen );
mbedtls_mpi_core_bigendian_to_host( X->p, limbs );
}
cleanup: cleanup:
@ -723,37 +711,7 @@ cleanup:
int mbedtls_mpi_write_binary_le( const mbedtls_mpi *X, int mbedtls_mpi_write_binary_le( const mbedtls_mpi *X,
unsigned char *buf, size_t buflen ) unsigned char *buf, size_t buflen )
{ {
size_t stored_bytes = X->n * ciL; return( mbedtls_mpi_core_write_le( X->p, X->n, buf, buflen) );
size_t bytes_to_copy;
size_t i;
if( stored_bytes < buflen )
{
bytes_to_copy = stored_bytes;
}
else
{
bytes_to_copy = buflen;
/* The output buffer is smaller than the allocated size of X.
* However X may fit if its leading bytes are zero. */
for( i = bytes_to_copy; i < stored_bytes; i++ )
{
if( GET_BYTE( X, i ) != 0 )
return( MBEDTLS_ERR_MPI_BUFFER_TOO_SMALL );
}
}
for( i = 0; i < bytes_to_copy; i++ )
buf[i] = GET_BYTE( X, i );
if( stored_bytes < buflen )
{
/* Write trailing 0 bytes */
memset( buf + stored_bytes, 0, buflen - stored_bytes );
}
return( 0 );
} }
/* /*
@ -762,44 +720,7 @@ int mbedtls_mpi_write_binary_le( const mbedtls_mpi *X,
int mbedtls_mpi_write_binary( const mbedtls_mpi *X, int mbedtls_mpi_write_binary( const mbedtls_mpi *X,
unsigned char *buf, size_t buflen ) unsigned char *buf, size_t buflen )
{ {
size_t stored_bytes; return( mbedtls_mpi_core_write_be( X->p, X->n, buf, buflen ) );
size_t bytes_to_copy;
unsigned char *p;
size_t i;
MPI_VALIDATE_RET( X != NULL );
MPI_VALIDATE_RET( buflen == 0 || buf != NULL );
stored_bytes = X->n * ciL;
if( stored_bytes < buflen )
{
/* There is enough space in the output buffer. Write initial
* null bytes and record the position at which to start
* writing the significant bytes. In this case, the execution
* trace of this function does not depend on the value of the
* number. */
bytes_to_copy = stored_bytes;
p = buf + buflen - stored_bytes;
memset( buf, 0, buflen - stored_bytes );
}
else
{
/* The output buffer is smaller than the allocated size of X.
* However X may fit if its leading bytes are zero. */
bytes_to_copy = buflen;
p = buf;
for( i = bytes_to_copy; i < stored_bytes; i++ )
{
if( GET_BYTE( X, i ) != 0 )
return( MBEDTLS_ERR_MPI_BUFFER_TOO_SMALL );
}
}
for( i = 0; i < bytes_to_copy; i++ )
p[bytes_to_copy - i - 1] = GET_BYTE( X, i );
return( 0 );
} }
/* /*