yuzu-emu/mbedtls
1
0
Fork 0
mirror of https://github.com/yuzu-emu/mbedtls.git synced 2024-11-25 18:45:46 +01:00
Code Issues Packages Projects Releases Wiki Activity

Merge pull request #665 from ARMmbed/dev/yanesca/iotcrypt-958-ecdsa-side-channel-fix-2.16

Browse Source 
Backport 2.16: ECDSA side channel fix
This commit is contained in:
Jaeden Amero 2019-11-12 10:37:22 +00:00 committed by GitHub
commit 3f1c68a1e2
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 8 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
ChangeLog
View File

@ -2,6 +2,13 @@ mbed TLS ChangeLog (Sorted per branch, date)
= mbed TLS 2.16.x branch released xxxx-xx-xx
Security
* Fix side channel vulnerability in ECDSA. Our bignum implementation is not
constant time/constant trace, so side channel attacks can retrieve the
blinded value, factor it (as it is smaller than RSA keys and not guaranteed
to have only large prime factors), and then, by brute force, recover the
key. Reported by Alejandro Cabrera Aldaya and Billy Brumley.
Bugfix
* Remove redundant line for getting the bitlen of a bignum, since the variable
holding the returned value is overwritten a line after.

1
library/ecdsa.c
View File

@ -363,6 +363,7 @@ modn:
MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( &e, &e, s ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &e, &e, &t ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( pk, pk, &t ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( pk, pk, &grp->N ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( s, pk, &grp->N ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( s, s, &e ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( s, s, &grp->N ) );