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crypto/ed25519: implement ed25519 on s390x using KDSA instruction

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This CL allows the usage of KDSA instruction when it is available.  The
instruction is designed to be resistant to side channel attacks and
offers performance improvement for ed25519.

Benchmarks:
name              old time/op    new time/op    delta
Signing-8            120µs ±20%      62µs ±12%   -48.40%  (p=0.000 n=10+10)
Verification-8       325µs ±17%      69µs ±10%   -78.80%  (p=0.000 n=10+10)

name              old alloc/op   new alloc/op   delta
Signing-8             448B ± 0%        0B       -100.00%  (p=0.000 n=10+10)
Verification-8        288B ± 0%        0B       -100.00%  (p=0.000 n=10+10)

name              old allocs/op  new allocs/op  delta
Signing-8             5.00 ± 0%      0.00       -100.00%  (p=0.000 n=10+10)
Verification-8        2.00 ± 0%      0.00       -100.00%  (p=0.000 n=10+10)

Change-Id: I0330ce83d807370b419ce638bc2cae4cb3c250dc
Reviewed-on: https://go-review.googlesource.com/c/go/+/202578
Run-TryBot: Michael Munday <mike.munday@ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Munday <mike.munday@ibm.com>
This commit is contained in:
Ruixin(Peter) Bao 2019-10-21 13:18:31 -04:00 committed by Michael Munday
parent 6a4441d6fe
commit d646c035f9
5 changed files with 273 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
src/crypto/ed25519/ed25519.go
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@ -142,7 +142,7 @@ func Sign(privateKey PrivateKey, message []byte) []byte {
return signature
}
func sign(signature, privateKey, message []byte) {
func signGeneric(signature, privateKey, message []byte) {
if l := len(privateKey); l != PrivateKeySize {
panic("ed25519: bad private key length: " + strconv.Itoa(l))
}
@ -189,6 +189,10 @@ func sign(signature, privateKey, message []byte) {
// Verify reports whether sig is a valid signature of message by publicKey. It
// will panic if len(publicKey) is not PublicKeySize.
func Verify(publicKey PublicKey, message, sig []byte) bool {
return verify(publicKey, message, sig)
}
func verifyGeneric(publicKey PublicKey, message, sig []byte) bool {
if l := len(publicKey); l != PublicKeySize {
panic("ed25519: bad public key length: " + strconv.Itoa(l))
}

15
src/crypto/ed25519/ed25519_noasm.go Normal file
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@ -0,0 +1,15 @@
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build !s390x purego
package ed25519
func sign(signature, privateKey, message []byte) {
signGeneric(signature, privateKey, message)
}
func verify(publicKey PublicKey, message, sig []byte) bool {
return verifyGeneric(publicKey, message, sig)
}

53
src/crypto/ed25519/ed25519_s390x.go Normal file
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@ -0,0 +1,53 @@
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build !purego
package ed25519
import (
"internal/cpu"
"strconv"
)
//go:noescape
func kdsaSign(message, signature, privateKey []byte) bool
//go:noescape
func kdsaVerify(message, signature, publicKey []byte) bool
// sign does a check to see if hardware has Edwards Curve instruction available.
// If it does, use the hardware implementation. Otherwise, use the generic version.
func sign(signature, privateKey, message []byte) {
if cpu.S390X.HasEDDSA {
if l := len(privateKey); l != PrivateKeySize {
panic("ed25519: bad private key length: " + strconv.Itoa(l))
}
ret := kdsaSign(message, signature, privateKey[:32])
if !ret {
panic("ed25519: kdsa sign has a failure")
}
return
}
signGeneric(signature, privateKey, message)
}
// verify does a check to see if hardware has Edwards Curve instruction available.
// If it does, use the hardware implementation for eddsa verfication. Otherwise, the generic
// version is used
func verify(publicKey PublicKey, message, sig []byte) bool {
if cpu.S390X.HasEDDSA {
if l := len(publicKey); l != PublicKeySize {
panic("ed25519: bad public key length: " + strconv.Itoa(l))
}
if len(sig) != SignatureSize || sig[63]&224 != 0 {
return false
}
return kdsaVerify(message, sig, publicKey)
}
return verifyGeneric(publicKey, message, sig)
}

163
src/crypto/ed25519/ed25519_s390x.s Normal file
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@ -0,0 +1,163 @@
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build !purego
#include "textflag.h"
// func kdsaSign(message, signature, privateKey []byte) bool
TEXT ·kdsaSign(SB), $4096-73
// The kdsa instruction takes function code,
// buffer's location, message's location and message len
// as parameters. Out of those, the function code and buffer's location
// should be placed in R0 and R1 respectively. The message's location
// and message length should be placed in an even-odd register pair. (e.g: R2 and R3)
// The content of parameter block(buffer) looks like the following:
// Signature R, Signature S and Private Key all take 32 bytes.
// In the signing case, the signatures(R and S) will be generated by
// the signing instruction and get placed in the locations shown in the parameter block.
// 0 +---------------+
// | Signature(R) |
// 32 +---------------+
// | Signature(S) |
// 64 +---------------+
// | Private Key |
// 96 +---------------+
// | Reserved |
// 112+---------------+
// | |
// | ... |
// | |
// 4088 +---------------+
// The following code section setups the buffer from stack:
// Get the address of the buffer stack variable.
MOVD $buffer-4096(SP), R1
// Zero the buffer.
MOVD R1, R2
MOVD $(4096/256), R0 // number of 256 byte chunks to clear
clear:
XC $256, (R2), (R2)
MOVD $256(R2), R2
BRCTG R0, clear
MOVD $40, R0 // EDDSA-25519 sign has a function code of 40
LMG message+0(FP), R2, R3 // R2=base R3=len
LMG signature+24(FP), R4, R5 // R4=base R5=len
LMG privateKey+48(FP), R6, R7 // R6=base R7=len
// Checks the length of signature and private key
CMPBNE R5, $64, panic
CMPBNE R7, $32, panic
// The instruction uses RFC 8032's private key, which is the first 32 bytes
// of the private key in this package. So we copy that into the buffer.
MVC $32, (R6), 64(R1)
loop:
WORD $0xB93A0002 // The KDSA instruction
BVS loop // The instruction is exectued by hardware and can be interrupted. This does a retry when that happens.
BNE error
success:
// The signatures generated are in big-endian form, so we
// need to reverse the bytes of Signature(R) and Signature(S) in the buffers to transform
// them from big-endian to little-endian.
// Transform Signature(R) from big endian to little endian and copy into the signature
MVCIN $32, 31(R1), (R4)
// Transform Signature(S) from big endian to little endian and copy into the signature
MVCIN $32, 63(R1), 32(R4)
MOVB $1, ret+72(FP)
RET
error:
// return false
MOVB $0, ret+72(FP)
RET
panic:
UNDEF
// func kdsaVerify(message, signature, publicKey []byte) bool
TEXT ·kdsaVerify(SB), $4096-73
// The kdsa instruction takes function code,
// buffer's location, message's location and message len
// as parameters. Out of those, the function code and buffer's location
// should be placed in R0 and R1 respectively. The message's location
// and message length should be placed in an even-odd register pair. (e.g: R2 and R3)
// The parameter block(buffer) is similar to that of signing, except that
// we use public key for verification, and Signatures(R and S) are provided
// as input parameters to the parameter block.
// 0 +---------------+
// | Signature(R) |
// 32 +---------------+
// | Signature(S) |
// 64 +---------------+
// | Public Key |
// 96 +---------------+
// | Reserved |
// 112+---------------+
// | |
// | ... |
// | |
// 4088 +---------------+
// The following code section setups the buffer from stack:
// Get the address of the buffer stack variable.
MOVD $buffer-4096(SP), R1
// Zero the buffer.
MOVD R1, R2
MOVD $(4096/256), R0 // number of 256 byte chunks to clear
clear:
XC $256, (R2), (R2)
MOVD $256(R2), R2
BRCTG R0, clear
MOVD $32, R0 // EDDSA-25519 verify has a function code of 32
LMG message+0(FP), R2, R3 // R2=base R3=len
LMG signature+24(FP), R4, R5 // R4=base R5=len
LMG publicKey+48(FP), R6, R7 // R6=base R7=len
// Checks the length of public key and signature
CMPBNE R5, $64, panic
CMPBNE R7, $32, panic
verify:
// The instruction needs Signature(R), Signature(S) and public key
// to be in big-endian form during computation. Therefore,
// we do the transformation (from little endian to big endian) and copy those into the buffer.
// Transform Signature(R) from little endian to big endian and copy into the buffer
MVCIN $32, 31(R4), (R1)
// Transform Signature(S) from little endian to big endian and copy into the buffer
MVCIN $32, 63(R4), 32(R1)
// Transform Public Key from little endian to big endian and copy into the buffer
MVCIN $32, 31(R6), 64(R1)
verifyLoop:
WORD $0xB93A0002 // KDSA instruction
BVS verifyLoop // Retry upon hardware interrupt
BNE error
success:
MOVB $1, ret+72(FP)
RET
error:
MOVB $0, ret+72(FP)
RET
panic:
UNDEF

44
src/crypto/ed25519/ed25519_test.go
View File

@ -26,6 +26,14 @@ func (zeroReader) Read(buf []byte) (int, error) {
return len(buf), nil
}
// signGenericWrapper is identical to Sign except that it unconditionally calls signGeneric directly
// rather than going through the sign function that might call assembly code.
func signGenericWrapper(privateKey PrivateKey, msg []byte) []byte {
sig := make([]byte, SignatureSize)
signGeneric(sig, privateKey, msg)
return sig
}
func TestUnmarshalMarshal(t *testing.T) {
pub, _, _ := GenerateKey(rand.Reader)
@ -45,22 +53,33 @@ func TestUnmarshalMarshal(t *testing.T) {
}
func TestSignVerify(t *testing.T) {
t.Run("Generic", func(t *testing.T) { testSignVerify(t, signGenericWrapper, verifyGeneric) })
t.Run("Native", func(t *testing.T) { testSignVerify(t, Sign, Verify) })
}
func testSignVerify(t *testing.T, signImpl func(privateKey PrivateKey, message []byte) []byte,
verifyImpl func(publicKey PublicKey, message, sig []byte) bool) {
var zero zeroReader
public, private, _ := GenerateKey(zero)
message := []byte("test message")
sig := Sign(private, message)
if !Verify(public, message, sig) {
sig := signImpl(private, message)
if !verifyImpl(public, message, sig) {
t.Errorf("valid signature rejected")
}
wrongMessage := []byte("wrong message")
if Verify(public, wrongMessage, sig) {
if verifyImpl(public, wrongMessage, sig) {
t.Errorf("signature of different message accepted")
}
}
func TestCryptoSigner(t *testing.T) {
t.Run("Generic", func(t *testing.T) { testCryptoSigner(t, verifyGeneric) })
t.Run("Native", func(t *testing.T) { testCryptoSigner(t, Verify) })
}
func testCryptoSigner(t *testing.T, verifyImpl func(publicKey PublicKey, message, sig []byte) bool) {
var zero zeroReader
public, private, _ := GenerateKey(zero)
@ -83,7 +102,7 @@ func TestCryptoSigner(t *testing.T) {
t.Fatalf("error from Sign(): %s", err)
}
if !Verify(public, message, signature) {
if !verifyImpl(public, message, signature) {
t.Errorf("Verify failed on signature from Sign()")
}
}
@ -105,6 +124,12 @@ func TestEqual(t *testing.T) {
}
func TestGolden(t *testing.T) {
t.Run("Generic", func(t *testing.T) { testGolden(t, signGenericWrapper, verifyGeneric) })
t.Run("Native", func(t *testing.T) { testGolden(t, Sign, Verify) })
}
func testGolden(t *testing.T, signImpl func(privateKey PrivateKey, message []byte) []byte,
verifyImpl func(publicKey PublicKey, message, sig []byte) bool) {
// sign.input.gz is a selection of test cases from
// https://ed25519.cr.yp.to/python/sign.input
testDataZ, err := os.Open("testdata/sign.input.gz")
@ -146,12 +171,12 @@ func TestGolden(t *testing.T) {
copy(priv[:], privBytes)
copy(priv[32:], pubKey)
sig2 := Sign(priv[:], msg)
sig2 := signImpl(priv[:], msg)
if !bytes.Equal(sig, sig2[:]) {
t.Errorf("different signature result on line %d: %x vs %x", lineNo, sig, sig2)
}
if !Verify(pubKey, msg, sig2) {
if !verifyImpl(pubKey, msg, sig2) {
t.Errorf("signature failed to verify on line %d", lineNo)
}
@ -175,6 +200,11 @@ func TestGolden(t *testing.T) {
}
func TestMalleability(t *testing.T) {
t.Run("Generic", func(t *testing.T) { testMalleability(t, verifyGeneric) })
t.Run("Native", func(t *testing.T) { testMalleability(t, Verify) })
}
func testMalleability(t *testing.T, verifyImpl func(publicKey PublicKey, message, sig []byte) bool) {
// https://tools.ietf.org/html/rfc8032#section-5.1.7 adds an additional test
// that s be in [0, order). This prevents someone from adding a multiple of
// order to s and obtaining a second valid signature for the same message.
@ -193,7 +223,7 @@ func TestMalleability(t *testing.T) {
0xb1, 0x08, 0xc3, 0xbd, 0xae, 0x36, 0x9e, 0xf5, 0x49, 0xfa,
}
if Verify(publicKey, msg, sig) {
if verifyImpl(publicKey, msg, sig) {
t.Fatal("non-canonical signature accepted")
}
}