2020-09-20 16:20:55 +00:00
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/* mpi-mul.c - MPI functions
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* Copyright (C) 1994, 1996, 1998, 2001, 2002,
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* 2003 Free Software Foundation, Inc.
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*
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* This file is part of Libgcrypt.
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*
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* Note: This code is heavily based on the GNU MP Library.
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* Actually it's the same code with only minor changes in the
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* way the data is stored; this is to support the abstraction
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* of an optional secure memory allocation which may be used
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* to avoid revealing of sensitive data due to paging etc.
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*/
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#include "mpi-internal.h"
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void mpi_mul(MPI w, MPI u, MPI v)
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{
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mpi_size_t usize, vsize, wsize;
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mpi_ptr_t up, vp, wp;
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mpi_limb_t cy;
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int usign, vsign, sign_product;
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int assign_wp = 0;
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mpi_ptr_t tmp_limb = NULL;
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if (u->nlimbs < v->nlimbs) {
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/* Swap U and V. */
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usize = v->nlimbs;
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usign = v->sign;
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up = v->d;
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vsize = u->nlimbs;
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vsign = u->sign;
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vp = u->d;
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} else {
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usize = u->nlimbs;
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usign = u->sign;
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up = u->d;
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vsize = v->nlimbs;
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vsign = v->sign;
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vp = v->d;
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}
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sign_product = usign ^ vsign;
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wp = w->d;
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/* Ensure W has space enough to store the result. */
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wsize = usize + vsize;
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if (w->alloced < wsize) {
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if (wp == up || wp == vp) {
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wp = mpi_alloc_limb_space(wsize);
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assign_wp = 1;
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} else {
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mpi_resize(w, wsize);
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wp = w->d;
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}
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} else { /* Make U and V not overlap with W. */
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if (wp == up) {
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/* W and U are identical. Allocate temporary space for U. */
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up = tmp_limb = mpi_alloc_limb_space(usize);
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/* Is V identical too? Keep it identical with U. */
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if (wp == vp)
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vp = up;
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/* Copy to the temporary space. */
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MPN_COPY(up, wp, usize);
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} else if (wp == vp) {
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/* W and V are identical. Allocate temporary space for V. */
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vp = tmp_limb = mpi_alloc_limb_space(vsize);
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/* Copy to the temporary space. */
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MPN_COPY(vp, wp, vsize);
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}
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}
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if (!vsize)
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wsize = 0;
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else {
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mpihelp_mul(wp, up, usize, vp, vsize, &cy);
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wsize -= cy ? 0:1;
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}
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if (assign_wp)
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mpi_assign_limb_space(w, wp, wsize);
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w->nlimbs = wsize;
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w->sign = sign_product;
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if (tmp_limb)
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mpi_free_limb_space(tmp_limb);
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}
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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 08:42:10 +00:00
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EXPORT_SYMBOL_GPL(mpi_mul);
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2020-09-20 16:20:55 +00:00
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void mpi_mulm(MPI w, MPI u, MPI v, MPI m)
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{
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mpi_mul(w, u, v);
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mpi_tdiv_r(w, w, m);
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}
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EXPORT_SYMBOL_GPL(mpi_mulm);
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