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Extend blinding to RSA result check

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Signed-off-by: Janos Follath <janos.follath@arm.com>
This commit is contained in:
Janos Follath
2023-11-21 09:46:43 +00:00
parent 10f8366499
commit 2d8624dae2
1 changed files with 8 additions and 8 deletions
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16
library/rsa.c
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@ -1125,8 +1125,6 @@ int mbedtls_rsa_private(mbedtls_rsa_context *ctx,
goto cleanup;
}
MBEDTLS_MPI_CHK(mbedtls_mpi_copy(&I, &T));
/*
* Blinding
* T = T * Vi mod N
@ -1135,6 +1133,8 @@ int mbedtls_rsa_private(mbedtls_rsa_context *ctx,
MBEDTLS_MPI_CHK(mbedtls_mpi_mul_mpi(&T, &T, &ctx->Vi));
MBEDTLS_MPI_CHK(mbedtls_mpi_mod_mpi(&T, &T, &ctx->N));
MBEDTLS_MPI_CHK(mbedtls_mpi_copy(&I, &T));
/*
* Exponent blinding
*/
@ -1203,12 +1203,6 @@ int mbedtls_rsa_private(mbedtls_rsa_context *ctx,
MBEDTLS_MPI_CHK(mbedtls_mpi_add_mpi(&T, &TQ, &TP));
#endif /* MBEDTLS_RSA_NO_CRT */
/*
* Unblind
* T = T * Vf mod N
*/
MBEDTLS_MPI_CHK(rsa_unblind(&T, &ctx->Vf, &ctx->N));
/* Verify the result to prevent glitching attacks. */
MBEDTLS_MPI_CHK(mbedtls_mpi_exp_mod(&C, &T, &ctx->E,
&ctx->N, &ctx->RN));
@ -1217,6 +1211,12 @@ int mbedtls_rsa_private(mbedtls_rsa_context *ctx,
goto cleanup;
}
/*
* Unblind
* T = T * Vf mod N
*/
MBEDTLS_MPI_CHK(rsa_unblind(&T, &ctx->Vf, &ctx->N));
olen = ctx->len;
MBEDTLS_MPI_CHK(mbedtls_mpi_write_binary(&T, output, olen));