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Refactor to prepare for RSA blinding optimisation

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This commit is contained in:
Manuel Pégourié-Gonnard 2013-09-10 13:29:30 +02:00
parent 032c34e206
commit ea53a55c0f
2 changed files with 37 additions and 14 deletions
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5
include/polarssl/rsa.h
View File

@ -89,6 +89,11 @@ typedef struct
mpi RP; /*!< cached R^2 mod P */
mpi RQ; /*!< cached R^2 mod Q */
#if !defined(POLARSSL_RSA_NO_CRT)
mpi Vi; /*!< cached blinding value */
mpi Vf; /*!< cached un-blinding value */
#endif
int padding; /*!< RSA_PKCS_V15 for 1.5 padding and
RSA_PKCS_v21 for OAEP/PSS */
int hash_id; /*!< Hash identifier of md_type_t as

46
library/rsa.c
View File

@ -253,6 +253,27 @@ cleanup:
return( 0 );
}
#if !defined(POLARSSL_RSA_NO_CRT)
/*
* Generate blinding values
*/
static int rsa_prepare_blinding( rsa_context *ctx,
int (*f_rng)(void *, unsigned char *, size_t), void *p_rng )
{
int ret;
/* Unblinding value: Vf = random number */
MPI_CHK( mpi_fill_random( &ctx->Vf, ctx->len - 1, f_rng, p_rng ) );
/* Blinding value: Vi = Vf^(-e) mod N */
MPI_CHK( mpi_inv_mod( &ctx->Vi, &ctx->Vf, &ctx->N ) );
MPI_CHK( mpi_exp_mod( &ctx->Vi, &ctx->Vi, &ctx->E, &ctx->N, &ctx->RN ) );
cleanup:
return( ret );
}
#endif
/*
* Do an RSA private key operation
*/
@ -265,11 +286,8 @@ int rsa_private( rsa_context *ctx,
int ret;
size_t olen;
mpi T, T1, T2;
mpi A, X;
mpi_init( &T ); mpi_init( &T1 ); mpi_init( &T2 );
mpi_init( &A ); mpi_init( &X );
MPI_CHK( mpi_read_binary( &T, input, ctx->len ) );
if( mpi_cmp_mpi( &T, &ctx->N ) >= 0 )
@ -284,14 +302,12 @@ int rsa_private( rsa_context *ctx,
if( f_rng != NULL )
{
/*
* RSA Blinding
* A = rnd MPI
* T = A^E * T mod N
* Blinding
* T = T * Vi mod N
*/
MPI_CHK( mpi_fill_random( &A, ctx->len - 1, f_rng, p_rng ) );
MPI_CHK( mpi_exp_mod( &X, &A, &ctx->E, &ctx->N, NULL ) );
MPI_CHK( mpi_mul_mpi( &X, &X, &T ) );
MPI_CHK( mpi_mod_mpi( &T, &X, &ctx->N ) );
MPI_CHK( rsa_prepare_blinding( ctx, f_rng, p_rng ) );
MPI_CHK( mpi_mul_mpi( &T, &T, &ctx->Vi ) );
MPI_CHK( mpi_mod_mpi( &T, &T, &ctx->N ) );
}
/*
@ -320,10 +336,9 @@ int rsa_private( rsa_context *ctx,
{
/*
* Unblind
* T = T / A mod N
* T = T * Vf mod N
*/
MPI_CHK( mpi_inv_mod( &A, &A, &ctx->N ) );
MPI_CHK( mpi_mul_mpi( &T, &T, &A ) );
MPI_CHK( mpi_mul_mpi( &T, &T, &ctx->Vf ) );
MPI_CHK( mpi_mod_mpi( &T, &T, &ctx->N ) );
}
#endif
@ -334,7 +349,6 @@ int rsa_private( rsa_context *ctx,
cleanup:
mpi_free( &T ); mpi_free( &T1 ); mpi_free( &T2 );
mpi_free( &A ); mpi_free( &X );
if( ret != 0 )
return( POLARSSL_ERR_RSA_PRIVATE_FAILED + ret );
@ -1280,6 +1294,9 @@ int rsa_copy( rsa_context *dst, const rsa_context *src )
MPI_CHK( mpi_copy( &dst->RP, &src->RP ) );
MPI_CHK( mpi_copy( &dst->RQ, &src->RQ ) );
MPI_CHK( mpi_copy( &dst->Vi, &src->Vi ) );
MPI_CHK( mpi_copy( &dst->Vf, &src->Vf ) );
dst->padding = src->padding;
dst->hash_id = src->padding;
@ -1295,6 +1312,7 @@ cleanup:
*/
void rsa_free( rsa_context *ctx )
{
mpi_free( &ctx->Vi ); mpi_free( &ctx->Vf );
mpi_free( &ctx->RQ ); mpi_free( &ctx->RP ); mpi_free( &ctx->RN );
mpi_free( &ctx->QP ); mpi_free( &ctx->DQ ); mpi_free( &ctx->DP );
mpi_free( &ctx->Q ); mpi_free( &ctx->P ); mpi_free( &ctx->D );