AuroraMiddleware/mbedtls
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Fix a compliance issue in signature encoding

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The issue is not present in the normal path because asn1write_mpi() does it
automatically, but we're not using that here...
This commit is contained in:
Manuel Pégourié-Gonnard 2018-11-16 10:09:11 +01:00 committed by Hanno Becker
parent 615530728f
commit 1e48ebd306
1 changed files with 9 additions and 1 deletions
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10
library/pk_wrap.c
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@ -807,8 +807,16 @@ static int asn1_write_mpibuf( unsigned char **p, unsigned char *start,
*p -= len; *p -= len;
memmove( *p, start, len ); memmove( *p, start, len );
/* ASN.1 DER encoding requires minimal length, so skip leading 0s.
* Neither r nor s can be 0, so we can assume len > 0 at all times. */
while( **p == 0x00 )
{
++(*p);
--len;
}
/* if the msb is 1, ASN.1 requires that we prepend a 0. /* if the msb is 1, ASN.1 requires that we prepend a 0.
* we're never called with n_len == 0, so we can always read back a byte */ * Neither r nor s can be 0, so we can assume len > 0 at all times. */
if( **p & 0x80 ) if( **p & 0x80 )
{ {
if( *p - start < 1 ) if( *p - start < 1 )