[dev.boringcrypto] crypto/internal/boring: avoid allocation in big.Int conversion
The conversion via byte slices is inefficient; we can convert via word slices
and avoid the copy entirely.
For #51940.
Change-Id: I06f747e0acffffae427d9706d43bdacf146c027d
Reviewed-on: https://go-review.googlesource.com/c/go/+/395875
Reviewed-by: Roland Shoemaker <roland@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
diff --git a/src/crypto/internal/boring/boring.go b/src/crypto/internal/boring/boring.go
index 29e0baa..7c6a730 100644
--- a/src/crypto/internal/boring/boring.go
+++ b/src/crypto/internal/boring/boring.go
@@ -18,6 +18,8 @@
"crypto/internal/boring/sig"
_ "crypto/internal/boring/syso"
"math/big"
+ "math/bits"
+ "unsafe"
)
const available = true
@@ -58,15 +60,26 @@
func (e fail) Error() string { return "boringcrypto: " + string(e) + " failed" }
+func wbase(b []big.Word) *C.uint8_t {
+ if len(b) == 0 {
+ return nil
+ }
+ return (*C.uint8_t)(unsafe.Pointer(&b[0]))
+}
+
+const wordBytes = bits.UintSize / 8
+
func bigToBN(x *big.Int) *C.GO_BIGNUM {
- raw := x.Bytes()
- return C._goboringcrypto_BN_bin2bn(base(raw), C.size_t(len(raw)), nil)
+ raw := x.Bits()
+ return C._goboringcrypto_BN_le2bn(wbase(raw), C.size_t(len(raw)*wordBytes), nil)
}
func bnToBig(bn *C.GO_BIGNUM) *big.Int {
- raw := make([]byte, C._goboringcrypto_BN_num_bytes(bn))
- n := C._goboringcrypto_BN_bn2bin(bn, base(raw))
- return new(big.Int).SetBytes(raw[:n])
+ raw := make([]big.Word, (C._goboringcrypto_BN_num_bytes(bn)+wordBytes-1)/wordBytes)
+ if C._goboringcrypto_BN_bn2le_padded(wbase(raw), C.size_t(len(raw)*wordBytes), bn) == 0 {
+ panic("boringcrypto: bignum conversion failed")
+ }
+ return new(big.Int).SetBits(raw)
}
func bigToBn(bnp **C.GO_BIGNUM, b *big.Int) bool {
@@ -77,8 +90,7 @@
if b == nil {
return true
}
- raw := b.Bytes()
- bn := C._goboringcrypto_BN_bin2bn(base(raw), C.size_t(len(raw)), nil)
+ bn := bigToBN(b)
if bn == nil {
return false
}
diff --git a/src/crypto/internal/boring/goboringcrypto.h b/src/crypto/internal/boring/goboringcrypto.h
index 37b7917..d6d99b1 100644
--- a/src/crypto/internal/boring/goboringcrypto.h
+++ b/src/crypto/internal/boring/goboringcrypto.h
@@ -141,7 +141,9 @@
unsigned _goboringcrypto_BN_num_bytes(const GO_BIGNUM*);
int _goboringcrypto_BN_is_negative(const GO_BIGNUM*);
GO_BIGNUM* _goboringcrypto_BN_bin2bn(const uint8_t*, size_t, GO_BIGNUM*);
+GO_BIGNUM* _goboringcrypto_BN_le2bn(const uint8_t*, size_t, GO_BIGNUM*);
size_t _goboringcrypto_BN_bn2bin(const GO_BIGNUM*, uint8_t*);
+int _goboringcrypto_BN_bn2le_padded(uint8_t*, size_t, const GO_BIGNUM*);
// #include <openssl/ec.h>
/*unchecked (opaque)*/ typedef struct GO_EC_GROUP { char data[1]; } GO_EC_GROUP;
diff --git a/src/crypto/internal/boring/syso/goboringcrypto_linux_amd64.syso b/src/crypto/internal/boring/syso/goboringcrypto_linux_amd64.syso
index 2459dd7..72e6c17 100644
--- a/src/crypto/internal/boring/syso/goboringcrypto_linux_amd64.syso
+++ b/src/crypto/internal/boring/syso/goboringcrypto_linux_amd64.syso
Binary files differ
