2020-09-21 00:20:55 +08:00
/* mpi-mul.c - MPI functions
* Copyright ( C ) 1994 , 1996 , 1998 , 2001 , 2002 ,
* 2003 Free Software Foundation , Inc .
*
* This file is part of Libgcrypt .
*
* Note : This code is heavily based on the GNU MP Library .
* Actually it ' s the same code with only minor changes in the
* way the data is stored ; this is to support the abstraction
* of an optional secure memory allocation which may be used
* to avoid revealing of sensitive data due to paging etc .
*/
# include "mpi-internal.h"
void mpi_mul ( MPI w , MPI u , MPI v )
{
mpi_size_t usize , vsize , wsize ;
mpi_ptr_t up , vp , wp ;
mpi_limb_t cy ;
int usign , vsign , sign_product ;
int assign_wp = 0 ;
mpi_ptr_t tmp_limb = NULL ;
if ( u - > nlimbs < v - > nlimbs ) {
/* Swap U and V. */
usize = v - > nlimbs ;
usign = v - > sign ;
up = v - > d ;
vsize = u - > nlimbs ;
vsign = u - > sign ;
vp = u - > d ;
} else {
usize = u - > nlimbs ;
usign = u - > sign ;
up = u - > d ;
vsize = v - > nlimbs ;
vsign = v - > sign ;
vp = v - > d ;
}
sign_product = usign ^ vsign ;
wp = w - > d ;
/* Ensure W has space enough to store the result. */
wsize = usize + vsize ;
if ( w - > alloced < wsize ) {
if ( wp = = up | | wp = = vp ) {
wp = mpi_alloc_limb_space ( wsize ) ;
assign_wp = 1 ;
} else {
mpi_resize ( w , wsize ) ;
wp = w - > d ;
}
} else { /* Make U and V not overlap with W. */
if ( wp = = up ) {
/* W and U are identical. Allocate temporary space for U. */
up = tmp_limb = mpi_alloc_limb_space ( usize ) ;
/* Is V identical too? Keep it identical with U. */
if ( wp = = vp )
vp = up ;
/* Copy to the temporary space. */
MPN_COPY ( up , wp , usize ) ;
} else if ( wp = = vp ) {
/* W and V are identical. Allocate temporary space for V. */
vp = tmp_limb = mpi_alloc_limb_space ( vsize ) ;
/* Copy to the temporary space. */
MPN_COPY ( vp , wp , vsize ) ;
}
}
if ( ! vsize )
wsize = 0 ;
else {
mpihelp_mul ( wp , up , usize , vp , vsize , & cy ) ;
wsize - = cy ? 0 : 1 ;
}
if ( assign_wp )
mpi_assign_limb_space ( w , wp , wsize ) ;
w - > nlimbs = wsize ;
w - > sign = sign_product ;
if ( tmp_limb )
mpi_free_limb_space ( tmp_limb ) ;
}
crypto: rsa - implement Chinese Remainder Theorem for faster private key operations
Changes from v1:
* exported mpi_sub and mpi_mul, otherwise the build fails when RSA is a module
The kernel RSA ASN.1 private key parser already supports only private keys with
additional values to be used with the Chinese Remainder Theorem [1], but these
values are currently not used.
This rudimentary CRT implementation speeds up RSA private key operations for the
following Go benchmark up to ~3x.
This implementation also tries to minimise the allocation of additional MPIs,
so existing MPIs are reused as much as possible (hence the variable names are a
bit weird).
The benchmark used:
```
package keyring_test
import (
"crypto"
"crypto/rand"
"crypto/rsa"
"crypto/x509"
"io"
"syscall"
"testing"
"unsafe"
)
type KeySerial int32
type Keyring int32
const (
KEY_SPEC_PROCESS_KEYRING Keyring = -2
KEYCTL_PKEY_SIGN = 27
)
var (
keyTypeAsym = []byte("asymmetric\x00")
sha256pkcs1 = []byte("enc=pkcs1 hash=sha256\x00")
)
func (keyring Keyring) LoadAsym(desc string, payload []byte) (KeySerial, error) {
cdesc := []byte(desc + "\x00")
serial, _, errno := syscall.Syscall6(syscall.SYS_ADD_KEY, uintptr(unsafe.Pointer(&keyTypeAsym[0])), uintptr(unsafe.Pointer(&cdesc[0])), uintptr(unsafe.Pointer(&payload[0])), uintptr(len(payload)), uintptr(keyring), uintptr(0))
if errno == 0 {
return KeySerial(serial), nil
}
return KeySerial(serial), errno
}
type pkeyParams struct {
key_id KeySerial
in_len uint32
out_or_in2_len uint32
__spare [7]uint32
}
// the output signature buffer is an input parameter here, because we want to
// avoid Go buffer allocation leaking into our benchmarks
func (key KeySerial) Sign(info, digest, out []byte) error {
var params pkeyParams
params.key_id = key
params.in_len = uint32(len(digest))
params.out_or_in2_len = uint32(len(out))
_, _, errno := syscall.Syscall6(syscall.SYS_KEYCTL, KEYCTL_PKEY_SIGN, uintptr(unsafe.Pointer(¶ms)), uintptr(unsafe.Pointer(&info[0])), uintptr(unsafe.Pointer(&digest[0])), uintptr(unsafe.Pointer(&out[0])), uintptr(0))
if errno == 0 {
return nil
}
return errno
}
func BenchmarkSign(b *testing.B) {
priv, err := rsa.GenerateKey(rand.Reader, 2048)
if err != nil {
b.Fatalf("failed to generate private key: %v", err)
}
pkcs8, err := x509.MarshalPKCS8PrivateKey(priv)
if err != nil {
b.Fatalf("failed to serialize the private key to PKCS8 blob: %v", err)
}
serial, err := KEY_SPEC_PROCESS_KEYRING.LoadAsym("test rsa key", pkcs8)
if err != nil {
b.Fatalf("failed to load the private key into the keyring: %v", err)
}
b.Logf("loaded test rsa key: %v", serial)
digest := make([]byte, 32)
_, err = io.ReadFull(rand.Reader, digest)
if err != nil {
b.Fatalf("failed to generate a random digest: %v", err)
}
sig := make([]byte, 256)
for n := 0; n < b.N; n++ {
err = serial.Sign(sha256pkcs1, digest, sig)
if err != nil {
b.Fatalf("failed to sign the digest: %v", err)
}
}
err = rsa.VerifyPKCS1v15(&priv.PublicKey, crypto.SHA256, digest, sig)
if err != nil {
b.Fatalf("failed to verify the signature: %v", err)
}
}
```
[1]: https://en.wikipedia.org/wiki/RSA_(cryptosystem)#Using_the_Chinese_remainder_algorithm
Signed-off-by: Ignat Korchagin <ignat@cloudflare.com>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-06-17 09:42:10 +01:00
EXPORT_SYMBOL_GPL ( mpi_mul ) ;
2020-09-21 00:20:55 +08:00
void mpi_mulm ( MPI w , MPI u , MPI v , MPI m )
{
mpi_mul ( w , u , v ) ;
mpi_tdiv_r ( w , w , m ) ;
}
EXPORT_SYMBOL_GPL ( mpi_mulm ) ;
