From 47ee7708123347a925aac44709e53a13d1c486e8 Mon Sep 17 00:00:00 2001 From: Janos Follath Date: Wed, 27 Dec 2023 10:33:00 +0000 Subject: [PATCH] RSA: remove unneeded temporaries Signed-off-by: Janos Follath --- library/rsa.c | 21 +++------------------ 1 file changed, 3 insertions(+), 18 deletions(-) diff --git a/library/rsa.c b/library/rsa.c index f57909b71..111af680f 100644 --- a/library/rsa.c +++ b/library/rsa.c @@ -1056,18 +1056,9 @@ int mbedtls_rsa_private(mbedtls_rsa_context *ctx, /* Temporaries holding the blinded exponents for * the mod p resp. mod q computation (if used). */ mbedtls_mpi DP_blind, DQ_blind; - - /* Pointers to actual exponents to be used - either the unblinded - * or the blinded ones, depending on the presence of a PRNG. */ - mbedtls_mpi *DP = &ctx->DP; - mbedtls_mpi *DQ = &ctx->DQ; #else /* Temporary holding the blinded exponent (if used). */ mbedtls_mpi D_blind; - - /* Pointer to actual exponent to be used - either the unblinded - * or the blinded one, depending on the presence of a PRNG. */ - mbedtls_mpi *D = &ctx->D; #endif /* MBEDTLS_RSA_NO_CRT */ /* Temporaries holding the initial input and the double @@ -1143,8 +1134,6 @@ int mbedtls_rsa_private(mbedtls_rsa_context *ctx, MBEDTLS_MPI_CHK(mbedtls_mpi_mul_mpi(&D_blind, &P1, &Q1)); MBEDTLS_MPI_CHK(mbedtls_mpi_mul_mpi(&D_blind, &D_blind, &R)); MBEDTLS_MPI_CHK(mbedtls_mpi_add_mpi(&D_blind, &D_blind, &ctx->D)); - - D = &D_blind; #else /* * DP_blind = ( P - 1 ) * R + DP @@ -1155,8 +1144,6 @@ int mbedtls_rsa_private(mbedtls_rsa_context *ctx, MBEDTLS_MPI_CHK(mbedtls_mpi_add_mpi(&DP_blind, &DP_blind, &ctx->DP)); - DP = &DP_blind; - /* * DQ_blind = ( Q - 1 ) * R + DQ */ @@ -1165,12 +1152,10 @@ int mbedtls_rsa_private(mbedtls_rsa_context *ctx, MBEDTLS_MPI_CHK(mbedtls_mpi_mul_mpi(&DQ_blind, &Q1, &R)); MBEDTLS_MPI_CHK(mbedtls_mpi_add_mpi(&DQ_blind, &DQ_blind, &ctx->DQ)); - - DQ = &DQ_blind; #endif /* MBEDTLS_RSA_NO_CRT */ #if defined(MBEDTLS_RSA_NO_CRT) - MBEDTLS_MPI_CHK(mbedtls_mpi_exp_mod(&T, &T, D, &ctx->N, &ctx->RN)); + MBEDTLS_MPI_CHK(mbedtls_mpi_exp_mod(&T, &T, &D_blind, &ctx->N, &ctx->RN)); #else /* * Faster decryption using the CRT @@ -1179,8 +1164,8 @@ int mbedtls_rsa_private(mbedtls_rsa_context *ctx, * TQ = input ^ dQ mod Q */ - MBEDTLS_MPI_CHK(mbedtls_mpi_exp_mod(&TP, &T, DP, &ctx->P, &ctx->RP)); - MBEDTLS_MPI_CHK(mbedtls_mpi_exp_mod(&TQ, &T, DQ, &ctx->Q, &ctx->RQ)); + MBEDTLS_MPI_CHK(mbedtls_mpi_exp_mod(&TP, &T, &DP_blind, &ctx->P, &ctx->RP)); + MBEDTLS_MPI_CHK(mbedtls_mpi_exp_mod(&TQ, &T, &DQ_blind, &ctx->Q, &ctx->RQ)); /* * T = (TP - TQ) * (Q^-1 mod P) mod P