lib/mbedtls
1
0
Fork 0
mirror of https://github.com/Mbed-TLS/mbedtls.git synced 2025-07-29 11:41:15 +03:00
Code Activity

Merge remote-tracking branch 'restricted/pr/535' into development

Browse Source
This commit is contained in:
Simon Butcher
2018-11-29 16:54:51 +00:00
parent 658618b6b2 50da016e5c
commit b9eb7866eb
2 changed files with 46 additions and 13 deletions
Download Patch File Download Diff File Expand all files Collapse all files

45
library/bignum.c
View File

@ -321,6 +321,10 @@ int mbedtls_mpi_get_bit( const mbedtls_mpi *X, size_t pos )
return( ( X->p[pos / biL] >> ( pos % biL ) ) & 0x01 );
}
/* Get a specific byte, without range checks. */
#define GET_BYTE( X, i ) \
( ( ( X )->p[( i ) / ciL] >> ( ( ( i ) % ciL ) * 8 ) ) & 0xff )
/*
* Set a bit to a specific value of 0 or 1
*/
@ -704,19 +708,40 @@ cleanup:
/*
* Export X into unsigned binary data, big endian
*/
int mbedtls_mpi_write_binary( const mbedtls_mpi *X, unsigned char *buf, size_t buflen )
int mbedtls_mpi_write_binary( const mbedtls_mpi *X,
unsigned char *buf, size_t buflen )
{
size_t i, j, n;
size_t stored_bytes = X->n * ciL;
size_t bytes_to_copy;
unsigned char *p;
size_t i;
n = mbedtls_mpi_size( X );
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 );
}
}
if( buflen < n )
return( MBEDTLS_ERR_MPI_BUFFER_TOO_SMALL );
memset( buf, 0, buflen );
for( i = buflen - 1, j = 0; n > 0; i--, j++, n-- )
buf[i] = (unsigned char)( X->p[j / ciL] >> ((j % ciL) << 3) );
for( i = 0; i < bytes_to_copy; i++ )
p[bytes_to_copy - i - 1] = GET_BYTE( X, i );
return( 0 );
}