Reduce the size of mbedtls_mpi
Reduce the size of mbedtls_mpi from 3 words to 2 on most architectures. This also reduces the code size significantly in bignum.o and ecp_curves.o, with negligible variations in other modules. This removes the ability to set MBEDTLS_MPI_MAX_LIMBS to a value >=65536, but we don't support customizing this value anyway (it's always 10000). Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
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053022fe24
3 changed files with 16 additions and 8 deletions
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@ -214,10 +214,13 @@ typedef struct mbedtls_mpi {
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* Note that this implies that calloc() or `... = {0}` does not create
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* a valid MPI representation. You must call mbedtls_mpi_init().
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*/
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int MBEDTLS_PRIVATE(s);
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signed short MBEDTLS_PRIVATE(s);
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/** Total number of limbs in \c p. */
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size_t MBEDTLS_PRIVATE(n);
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unsigned short MBEDTLS_PRIVATE(n);
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#if MBEDTLS_MPI_MAX_LIMBS > 65535
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#error "MBEDTLS_MPI_MAX_LIMBS > 65535 is not supported"
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#endif
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/** Pointer to limbs.
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*
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@ -114,7 +114,9 @@ int mbedtls_mpi_grow(mbedtls_mpi *X, size_t nblimbs)
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mbedtls_free(X->p);
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}
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X->n = nblimbs;
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/* nblimbs fits in n because we ensure that MBEDTLS_MPI_MAX_LIMBS
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* fits, and we've checked that nblimbs <= MBEDTLS_MPI_MAX_LIMBS. */
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X->n = (unsigned short) nblimbs;
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X->p = p;
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}
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@ -162,7 +164,9 @@ int mbedtls_mpi_shrink(mbedtls_mpi *X, size_t nblimbs)
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mbedtls_free(X->p);
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}
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X->n = i;
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/* i fits in n because we ensure that MBEDTLS_MPI_MAX_LIMBS
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* fits, and we've checked that i <= nblimbs <= MBEDTLS_MPI_MAX_LIMBS. */
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X->n = (unsigned short) i;
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X->p = p;
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return 0;
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@ -1574,8 +1578,8 @@ static void mpi_montred(mbedtls_mpi *A, const mbedtls_mpi *N,
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{
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mbedtls_mpi_uint z = 1;
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mbedtls_mpi U;
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U.n = U.s = (int) z;
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U.n = 1;
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U.s = 1;
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U.p = &z;
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mpi_montmul(A, &U, N, mm, T);
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@ -4512,12 +4512,13 @@ static const mbedtls_ecp_point brainpoolP512r1_T[32] = {
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defined(MBEDTLS_ECP_DP_CURVE448_ENABLED)
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/*
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* Create an MPI from embedded constants
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* (assumes len is an exact multiple of sizeof(mbedtls_mpi_uint))
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* (assumes len is an exact multiple of sizeof(mbedtls_mpi_uint) and
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* len < 1048576)
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*/
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static inline void ecp_mpi_load(mbedtls_mpi *X, const mbedtls_mpi_uint *p, size_t len)
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{
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X->s = 1;
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X->n = len / sizeof(mbedtls_mpi_uint);
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X->n = (unsigned short) (len / sizeof(mbedtls_mpi_uint));
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X->p = (mbedtls_mpi_uint *) p;
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}
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#endif
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