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Add ecdh_calc_secret()

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Manuel Pégourié-Gonnard 2013-02-11 22:05:42 +01:00
parent 5cceb41d2c
commit 424fda5d7b
3 changed files with 35 additions and 1 deletions
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13
include/polarssl/ecdh.h
View File

@ -149,6 +149,19 @@ int ecdh_make_public( ecdh_context *ctx, size_t *olen,
int ecdh_read_public( ecdh_context *ctx,
const unsigned char *buf, size_t blen );
/**
* \brief Derive and export the shared secret
*
* \param ctx ECDH context
* \param olen number of bytes written
* \param buf destination buffer
* \param blen buffer length
*
* \return 0 if successful, or an POLARSSL_ERR_ECP_XXX error code
*/
int ecdh_calc_secret( ecdh_context *ctx, size_t *olen,
unsigned char *buf, size_t blen );
/**
* \brief Checkup routine
*

17
library/ecdh.c
View File

@ -186,6 +186,23 @@ int ecdh_read_public( ecdh_context *ctx,
return ecp_tls_read_point( &ctx->grp, &ctx->Qp, &buf, blen );
}
/*
* Derive and export the shared secret
*/
int ecdh_calc_secret( ecdh_context *ctx, size_t *olen,
unsigned char *buf, size_t blen )
{
int ret;
if( ( ret = ecdh_compute_shared( &ctx->grp, &ctx->z, &ctx->Qp, &ctx->d ) )
!= 0 )
return( ret );
*olen = mpi_size( &ctx->z );
return mpi_write_binary( &ctx->z, buf, blen );
}
#if defined(POLARSSL_SELF_TEST)
/*

6
tests/suites/test_suite_ecdh.function
View File

@ -99,11 +99,15 @@ ecdh_exchange:id
&rnd_pseudo_rand, &rnd_info ) == 0 );
TEST_ASSERT( ecdh_read_params( &cli, &vbuf, buf + len ) == 0 );
memset( buf, 0x00, sizeof( buf ) ); vbuf = buf;
memset( buf, 0x00, sizeof( buf ) );
TEST_ASSERT( ecdh_make_public( &cli, &len, buf, 1000,
&rnd_pseudo_rand, &rnd_info ) == 0 );
TEST_ASSERT( ecdh_read_public( &srv, buf, len ) == 0 );
TEST_ASSERT( ecdh_calc_secret( &srv, &len, buf, 1000 ) == 0 );
TEST_ASSERT( ecdh_calc_secret( &cli, &len, buf, 1000 ) == 0 );
TEST_ASSERT( mpi_cmp_mpi( &srv.z, &cli.z ) == 0 );
ecdh_free( &srv );
ecdh_free( &cli );
}