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Adjust mpi_montmul() to new signature of mpi_mul_hlp()

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A previous commit has changed the signature of mpi_mul_hlp, making the length
of the output explicit. This commit adjusts mpi_montmul() accordingly.

It also fixes a comment on the required size of the temporary value
passed to mpi_montmul() (but does not change the call-sites).

Signed-off-by: Hanno Becker <hanno.becker@arm.com>
This commit is contained in:
Hanno Becker 2022-04-06 06:45:45 +01:00
parent 74a11a31cb
commit e141702551
1 changed files with 9 additions and 6 deletions
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15
library/bignum.c
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@ -1907,8 +1907,8 @@ static void mpi_montg_init( mbedtls_mpi_uint *mm, const mbedtls_mpi *N )
* \param mm The value calculated by `mpi_montg_init(&mm, N)`. * \param mm The value calculated by `mpi_montg_init(&mm, N)`.
* This is -N^-1 mod 2^ciL. * This is -N^-1 mod 2^ciL.
* \param[in,out] T A bignum for temporary storage. * \param[in,out] T A bignum for temporary storage.
* It must be at least twice the limb size of N plus 2 * It must be at least twice the limb size of N plus 1
* (T->n >= 2 * (N->n + 1)). * (T->n >= 2 * N->n + 1).
* Its initial content is unused and * Its initial content is unused and
* its final content is indeterminate. * its final content is indeterminate.
* Note that unlike the usual convention in the library * Note that unlike the usual convention in the library
@ -1934,10 +1934,13 @@ static void mpi_montmul( mbedtls_mpi *A, const mbedtls_mpi *B, const mbedtls_mpi
u0 = A->p[i]; u0 = A->p[i];
u1 = ( d[0] + u0 * B->p[0] ) * mm; u1 = ( d[0] + u0 * B->p[0] ) * mm;
mpi_mul_hlp( m, B->p, d, u0 ); (void) mpi_mul_hlp( d, n + 2,
mpi_mul_hlp( n, N->p, d, u1 ); B->p, m,
u0 );
d++; d[n + 1] = 0; (void) mpi_mul_hlp( d, n + 2,
N->p, n,
u1 );
d++;
} }
/* At this point, d is either the desired result or the desired result /* At this point, d is either the desired result or the desired result