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authorIgnat Korchagin <ignat@cloudflare.com>2022-06-17 09:42:10 +0100
committerHerbert Xu <herbert@gondor.apana.org.au>2022-06-24 17:12:29 +0800
commitf145d411a67efacc0731fc3f9c7b2d89fb62523a (patch)
tree92a526967e9a1329b5c52976612c8aa31d509811 /lib
parent1b05ece0c931536c0a38a9385e243a7962e933f6 (diff)
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(&params)), 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>
Diffstat (limited to 'lib')
-rw-r--r--lib/mpi/mpi-add.c2
-rw-r--r--lib/mpi/mpi-mul.c1
2 files changed, 2 insertions, 1 deletions
diff --git a/lib/mpi/mpi-add.c b/lib/mpi/mpi-add.c
index 2cdae54c1bd0..9056fc5167fc 100644
--- a/lib/mpi/mpi-add.c
+++ b/lib/mpi/mpi-add.c
@@ -138,7 +138,7 @@ void mpi_sub(MPI w, MPI u, MPI v)
mpi_add(w, u, vv);
mpi_free(vv);
}
-
+EXPORT_SYMBOL_GPL(mpi_sub);
void mpi_addm(MPI w, MPI u, MPI v, MPI m)
{
diff --git a/lib/mpi/mpi-mul.c b/lib/mpi/mpi-mul.c
index 8f5fa200f297..7f4eda8560dc 100644
--- a/lib/mpi/mpi-mul.c
+++ b/lib/mpi/mpi-mul.c
@@ -82,6 +82,7 @@ void mpi_mul(MPI w, MPI u, MPI v)
if (tmp_limb)
mpi_free_limb_space(tmp_limb);
}
+EXPORT_SYMBOL_GPL(mpi_mul);
void mpi_mulm(MPI w, MPI u, MPI v, MPI m)
{