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RSA blinding added for CRT operations

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This commit is contained in:
Paul Bakker 2013-08-30 11:00:25 +02:00
parent 548957dd49
commit aab30c130c
2 changed files with 31 additions and 6 deletions
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4
ChangeLog
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@ -46,6 +46,10 @@ Bugfix
* zlib compression/decompression skipped on empty blocks
* Support for AIX header locations in net.c module
Security
* RSA blinding on CRT operations to counter timing attacks
(found by Cyril Arnaud and Pierre-Alain Fouque)
= Version 1.2.8 released 2013-06-19
Features
* Parsing of PKCS#8 encrypted private key files

33
library/rsa.c
View file

@ -265,13 +265,15 @@ int rsa_private( rsa_context *ctx,
int ret;
size_t olen;
mpi T, T1, T2;
((void) f_rng);
((void) p_rng);
mpi A, X;
if( f_rng == NULL )
return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
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 )
{
mpi_free( &T );
@ -281,6 +283,16 @@ int rsa_private( rsa_context *ctx,
#if defined(POLARSSL_RSA_NO_CRT)
MPI_CHK( mpi_exp_mod( &T, &T, &ctx->D, &ctx->N, &ctx->RN ) );
#else
/*
* RSA Blinding
* A = rnd MPI
* T = A^E * T 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 ) );
/*
* faster decryption using the CRT
*
@ -298,10 +310,18 @@ int rsa_private( rsa_context *ctx,
MPI_CHK( mpi_mod_mpi( &T, &T1, &ctx->P ) );
/*
* output = T2 + T * Q
* X = T2 + T * Q
*/
MPI_CHK( mpi_mul_mpi( &T1, &T, &ctx->Q ) );
MPI_CHK( mpi_add_mpi( &T, &T2, &T1 ) );
MPI_CHK( mpi_add_mpi( &X, &T2, &T1 ) );
/*
* Unblind
* T = X / A mod N
*/
MPI_CHK( mpi_inv_mod( &A, &A, &ctx->N ) );
MPI_CHK( mpi_mul_mpi( &T, &X, &A ) );
MPI_CHK( mpi_mod_mpi( &T, &T, &ctx->N ) );
#endif
olen = ctx->len;
@ -310,6 +330,7 @@ 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 );
@ -1410,7 +1431,7 @@ int rsa_self_test( int verbose )
sha1( rsa_plaintext, PT_LEN, sha1sum );
if( rsa_pkcs1_sign( &rsa, NULL, NULL, RSA_PRIVATE, POLARSSL_MD_SHA1, 0,
if( rsa_pkcs1_sign( &rsa, myrand, NULL, RSA_PRIVATE, POLARSSL_MD_SHA1, 0,
sha1sum, rsa_ciphertext ) != 0 )
{
if( verbose != 0 )