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Rm ecp_add() and add ecp_muladd()

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This commit is contained in:
Manuel Pégourié-Gonnard 2015-05-11 18:40:45 +02:00
parent 6dde596a03
commit 56cc88a796
4 changed files with 66 additions and 52 deletions
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3
ChangeLog
View File

@ -61,7 +61,8 @@ API Changes
Removals
* Removed mbedtls_ecp_group_read_string(). Only named groups are supported.
* Removed mbedtls_ecp_sub().
* Removed mbedtls_ecp_sub() and mbedtls_ecp_add(), use
mbedtls_ecp_muladd().
* Removed individual mdX_hmac and shaX_hmac functions (use generic
md_hmac functions from md.h)
* Removed the PBKDF2 module (use PKCS5).

61
include/mbedtls/ecp.h
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@ -481,27 +481,20 @@ int mbedtls_ecp_tls_read_group( mbedtls_ecp_group *grp, const unsigned char **bu
int mbedtls_ecp_tls_write_group( const mbedtls_ecp_group *grp, size_t *olen,
unsigned char *buf, size_t blen );
/**
* \brief Addition: R = P + Q
*
* \param grp ECP group
* \param R Destination point
* \param P Left-hand point
* \param Q Right-hand point
*
* \return 0 if successful,
* MBEDTLS_ERR_MPI_MALLOC_FAILED if memory allocation failed
*
* \note This function does not support Montgomery curves, such as
* Curve25519.
*/
int mbedtls_ecp_add( const mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
const mbedtls_ecp_point *P, const mbedtls_ecp_point *Q );
/**
* \brief Multiplication by an integer: R = m * P
* (Not thread-safe to use same group in multiple threads)
*
* \note In order to prevent timing attacks, this function
* executes the exact same sequence of (base field)
* operations for any valid m. It avoids any if-branch or
* array index depending on the value of m.
*
* \note If f_rng is not NULL, it is used to randomize intermediate
* results in order to prevent potential timing attacks
* targeting these results. It is recommended to always
* provide a non-NULL f_rng (the overhead is negligible).
*
* \param grp ECP group
* \param R Destination point
* \param m Integer by which to multiply
@ -513,21 +506,35 @@ int mbedtls_ecp_add( const mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
* MBEDTLS_ERR_ECP_INVALID_KEY if m is not a valid privkey
* or P is not a valid pubkey,
* MBEDTLS_ERR_MPI_MALLOC_FAILED if memory allocation failed
*
* \note In order to prevent timing attacks, this function
* executes the exact same sequence of (base field)
* operations for any valid m. It avoids any if-branch or
* array index depending on the value of m.
*
* \note If f_rng is not NULL, it is used to randomize intermediate
* results in order to prevent potential timing attacks
* targeting these results. It is recommended to always
* provide a non-NULL f_rng (the overhead is negligible).
*/
int mbedtls_ecp_mul( mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
const mbedtls_mpi *m, const mbedtls_ecp_point *P,
int (*f_rng)(void *, unsigned char *, size_t), void *p_rng );
/**
* \brief Multiplication and addition of two points by integers:
* R = m * P + n * Q
* (Not thread-safe to use same group in multiple threads)
*
* \note In contrast to ecp_mul(), this function does not guarantee
* a constant execution flow and timing.
*
* \param grp ECP group
* \param R Destination point
* \param m Integer by which to multiply P
* \param P Point to multiply by m
* \param n Integer by which to multiply Q
* \param Q Point to be multiplied by n
*
* \return 0 if successful,
* MBEDTLS_ERR_ECP_INVALID_KEY if m or n is not a valid privkey
* or P or Q is not a valid pubkey,
* MBEDTLS_ERR_MPI_MALLOC_FAILED if memory allocation failed
*/
int mbedtls_ecp_muladd( mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
const mbedtls_mpi *m, const mbedtls_ecp_point *P,
const mbedtls_mpi *n, const mbedtls_ecp_point *Q );
/**
* \brief Check that a point is a valid public key on this curve
*

10
library/ecdsa.c
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@ -203,9 +203,9 @@ int mbedtls_ecdsa_verify( mbedtls_ecp_group *grp,
{
int ret;
mbedtls_mpi e, s_inv, u1, u2;
mbedtls_ecp_point R, P;
mbedtls_ecp_point R;
mbedtls_ecp_point_init( &R ); mbedtls_ecp_point_init( &P );
mbedtls_ecp_point_init( &R );
mbedtls_mpi_init( &e ); mbedtls_mpi_init( &s_inv ); mbedtls_mpi_init( &u1 ); mbedtls_mpi_init( &u2 );
/* Fail cleanly on curves such as Curve25519 that can't be used for ECDSA */
@ -249,9 +249,7 @@ int mbedtls_ecdsa_verify( mbedtls_ecp_group *grp,
* Since we're not using any secret data, no need to pass a RNG to
* mbedtls_ecp_mul() for countermesures.
*/
MBEDTLS_MPI_CHK( mbedtls_ecp_mul( grp, &R, &u1, &grp->G, NULL, NULL ) );
MBEDTLS_MPI_CHK( mbedtls_ecp_mul( grp, &P, &u2, Q, NULL, NULL ) );
MBEDTLS_MPI_CHK( mbedtls_ecp_add( grp, &R, &R, &P ) );
MBEDTLS_MPI_CHK( mbedtls_ecp_muladd( grp, &R, &u1, &grp->G, &u2, Q ) );
if( mbedtls_ecp_is_zero( &R ) )
{
@ -275,7 +273,7 @@ int mbedtls_ecdsa_verify( mbedtls_ecp_group *grp,
}
cleanup:
mbedtls_ecp_point_free( &R ); mbedtls_ecp_point_free( &P );
mbedtls_ecp_point_free( &R );
mbedtls_mpi_free( &e ); mbedtls_mpi_free( &s_inv ); mbedtls_mpi_free( &u1 ); mbedtls_mpi_free( &u2 );
return( ret );

44
library/ecp.c
View File

@ -1048,24 +1048,6 @@ cleanup:
return( ret );
}
/*
* Addition: R = P + Q, result's coordinates normalized
*/
int mbedtls_ecp_add( const mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
const mbedtls_ecp_point *P, const mbedtls_ecp_point *Q )
{
int ret;
if( ecp_get_type( grp ) != ECP_TYPE_SHORT_WEIERSTRASS )
return( MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE );
MBEDTLS_MPI_CHK( ecp_add_mixed( grp, R, P, Q ) );
MBEDTLS_MPI_CHK( ecp_normalize_jac( grp, R ) );
cleanup:
return( ret );
}
/*
* Randomize jacobian coordinates:
* (X, Y, Z) -> (l^2 X, l^3 Y, l Z) for random l
@ -1684,6 +1666,32 @@ cleanup:
}
#endif /* ECP_SHORTWEIERSTRASS */
/*
* Linear combination
*/
int mbedtls_ecp_muladd( mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
const mbedtls_mpi *m, const mbedtls_ecp_point *P,
const mbedtls_mpi *n, const mbedtls_ecp_point *Q )
{
int ret;
mbedtls_ecp_point mP;
if( ecp_get_type( grp ) != ECP_TYPE_SHORT_WEIERSTRASS )
return( MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE );
mbedtls_ecp_point_init( &mP );
MBEDTLS_MPI_CHK( mbedtls_ecp_mul( grp, &mP, m, P, NULL, NULL ) );
MBEDTLS_MPI_CHK( mbedtls_ecp_mul( grp, R, n, Q, NULL, NULL ) );
MBEDTLS_MPI_CHK( ecp_add_mixed( grp, R, &mP, R ) );
MBEDTLS_MPI_CHK( ecp_normalize_jac( grp, R ) );
cleanup:
mbedtls_ecp_point_free( &mP );
return( ret );
}
#if defined(ECP_MONTGOMERY)
/*