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Deprecate the old deterministic ECDSA function

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The current interface does not allow passing an RNG, which is needed for
blinding. Using the scheme's internal HMAC-DRBG results the same
blinding values for the same key and message, diminishing the
effectiveness of the countermeasure. A new function
`mbedtls_ecdsa_det_ext` is available to address this problem.
This commit is contained in:
Janos Follath 2019-01-04 15:55:43 +00:00 committed by Darryl Green
parent 651eac8c5e
commit e65e0597a8
2 changed files with 15 additions and 2 deletions
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14
include/mbedtls/ecdsa.h
View file

@ -176,6 +176,12 @@ int mbedtls_ecdsa_sign( mbedtls_ecp_group *grp, mbedtls_mpi *r, mbedtls_mpi *s,
int (*f_rng)(void *, unsigned char *, size_t), void *p_rng );
#if defined(MBEDTLS_ECDSA_DETERMINISTIC)
#if ! defined(MBEDTLS_DEPRECATED_REMOVED)
#if defined(MBEDTLS_DEPRECATED_WARNING)
#define MBEDTLS_DEPRECATED __attribute__((deprecated))
#else
#define MBEDTLS_DEPRECATED
#endif
/**
* \brief This function computes the ECDSA signature of a
* previously-hashed message, deterministic version.
@ -214,7 +220,10 @@ int mbedtls_ecdsa_sign( mbedtls_ecp_group *grp, mbedtls_mpi *r, mbedtls_mpi *s,
int mbedtls_ecdsa_sign_det( mbedtls_ecp_group *grp, mbedtls_mpi *r,
mbedtls_mpi *s, const mbedtls_mpi *d,
const unsigned char *buf, size_t blen,
mbedtls_md_type_t md_alg );
mbedtls_md_type_t md_alg ) MBEDTLS_DEPRECATED;
#undef MBEDTLS_DEPRECATED
#endif /* MBEDTLS_DEPRECATED_REMOVED */
/**
* \brief This function computes the ECDSA signature of a
* previously-hashed message, deterministic version.
@ -338,7 +347,8 @@ int mbedtls_ecdsa_verify( mbedtls_ecp_group *grp,
* the signature written. Must not be \c NULL.
* \param f_rng The RNG function. This must not be \c NULL if
* #MBEDTLS_ECDSA_DETERMINISTIC is unset. Otherwise,
* it is unused and may be set to \c NULL.
* it is used only for blinding and may be set to \c NULL, but
* doing so is DEPRECATED.
* \param p_rng The RNG context to be passed to \p f_rng. This may be
* \c NULL if \p f_rng is \c NULL or doesn't use a context.
*

3
library/ecdsa.c
View file

@ -503,6 +503,8 @@ cleanup:
/*
* Deterministic signature wrappers
*/
#if !defined(MBEDTLS_DEPRECATED_REMOVED)
int mbedtls_ecdsa_sign_det( mbedtls_ecp_group *grp, mbedtls_mpi *r,
mbedtls_mpi *s, const mbedtls_mpi *d,
const unsigned char *buf, size_t blen,
@ -517,6 +519,7 @@ int mbedtls_ecdsa_sign_det( mbedtls_ecp_group *grp, mbedtls_mpi *r,
return( ecdsa_sign_det_restartable( grp, r, s, d, buf, blen, md_alg,
NULL, NULL, NULL ) );
}
#endif /* MBEDTLS_DEPRECATED_REMOVED */
int mbedtls_ecdsa_sign_det_ext( mbedtls_ecp_group *grp, mbedtls_mpi *r,
mbedtls_mpi *s, const mbedtls_mpi *d,