scrypt: use math.bits rotate functions instead of ad-hoc implementation
This makes code more readable and idiomatic. No change in benchmarks.
Updates golang/go#31456
Change-Id: I010bbff33580350019ce2b0ff13847261905d32f
Reviewed-on: https://go-review.googlesource.com/c/crypto/+/174137
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
diff --git a/scrypt/scrypt.go b/scrypt/scrypt.go
index 3362afd..2f81fe4 100644
--- a/scrypt/scrypt.go
+++ b/scrypt/scrypt.go
@@ -10,6 +10,7 @@
import (
"crypto/sha256"
"errors"
+ "math/bits"
"golang.org/x/crypto/pbkdf2"
)
@@ -52,77 +53,45 @@
x9, x10, x11, x12, x13, x14, x15 := w9, w10, w11, w12, w13, w14, w15
for i := 0; i < 8; i += 2 {
- u := x0 + x12
- x4 ^= u<<7 | u>>(32-7)
- u = x4 + x0
- x8 ^= u<<9 | u>>(32-9)
- u = x8 + x4
- x12 ^= u<<13 | u>>(32-13)
- u = x12 + x8
- x0 ^= u<<18 | u>>(32-18)
+ x4 ^= bits.RotateLeft32(x0+x12, 7)
+ x8 ^= bits.RotateLeft32(x4+x0, 9)
+ x12 ^= bits.RotateLeft32(x8+x4, 13)
+ x0 ^= bits.RotateLeft32(x12+x8, 18)
- u = x5 + x1
- x9 ^= u<<7 | u>>(32-7)
- u = x9 + x5
- x13 ^= u<<9 | u>>(32-9)
- u = x13 + x9
- x1 ^= u<<13 | u>>(32-13)
- u = x1 + x13
- x5 ^= u<<18 | u>>(32-18)
+ x9 ^= bits.RotateLeft32(x5+x1, 7)
+ x13 ^= bits.RotateLeft32(x9+x5, 9)
+ x1 ^= bits.RotateLeft32(x13+x9, 13)
+ x5 ^= bits.RotateLeft32(x1+x13, 18)
- u = x10 + x6
- x14 ^= u<<7 | u>>(32-7)
- u = x14 + x10
- x2 ^= u<<9 | u>>(32-9)
- u = x2 + x14
- x6 ^= u<<13 | u>>(32-13)
- u = x6 + x2
- x10 ^= u<<18 | u>>(32-18)
+ x14 ^= bits.RotateLeft32(x10+x6, 7)
+ x2 ^= bits.RotateLeft32(x14+x10, 9)
+ x6 ^= bits.RotateLeft32(x2+x14, 13)
+ x10 ^= bits.RotateLeft32(x6+x2, 18)
- u = x15 + x11
- x3 ^= u<<7 | u>>(32-7)
- u = x3 + x15
- x7 ^= u<<9 | u>>(32-9)
- u = x7 + x3
- x11 ^= u<<13 | u>>(32-13)
- u = x11 + x7
- x15 ^= u<<18 | u>>(32-18)
+ x3 ^= bits.RotateLeft32(x15+x11, 7)
+ x7 ^= bits.RotateLeft32(x3+x15, 9)
+ x11 ^= bits.RotateLeft32(x7+x3, 13)
+ x15 ^= bits.RotateLeft32(x11+x7, 18)
- u = x0 + x3
- x1 ^= u<<7 | u>>(32-7)
- u = x1 + x0
- x2 ^= u<<9 | u>>(32-9)
- u = x2 + x1
- x3 ^= u<<13 | u>>(32-13)
- u = x3 + x2
- x0 ^= u<<18 | u>>(32-18)
+ x1 ^= bits.RotateLeft32(x0+x3, 7)
+ x2 ^= bits.RotateLeft32(x1+x0, 9)
+ x3 ^= bits.RotateLeft32(x2+x1, 13)
+ x0 ^= bits.RotateLeft32(x3+x2, 18)
- u = x5 + x4
- x6 ^= u<<7 | u>>(32-7)
- u = x6 + x5
- x7 ^= u<<9 | u>>(32-9)
- u = x7 + x6
- x4 ^= u<<13 | u>>(32-13)
- u = x4 + x7
- x5 ^= u<<18 | u>>(32-18)
+ x6 ^= bits.RotateLeft32(x5+x4, 7)
+ x7 ^= bits.RotateLeft32(x6+x5, 9)
+ x4 ^= bits.RotateLeft32(x7+x6, 13)
+ x5 ^= bits.RotateLeft32(x4+x7, 18)
- u = x10 + x9
- x11 ^= u<<7 | u>>(32-7)
- u = x11 + x10
- x8 ^= u<<9 | u>>(32-9)
- u = x8 + x11
- x9 ^= u<<13 | u>>(32-13)
- u = x9 + x8
- x10 ^= u<<18 | u>>(32-18)
+ x11 ^= bits.RotateLeft32(x10+x9, 7)
+ x8 ^= bits.RotateLeft32(x11+x10, 9)
+ x9 ^= bits.RotateLeft32(x8+x11, 13)
+ x10 ^= bits.RotateLeft32(x9+x8, 18)
- u = x15 + x14
- x12 ^= u<<7 | u>>(32-7)
- u = x12 + x15
- x13 ^= u<<9 | u>>(32-9)
- u = x13 + x12
- x14 ^= u<<13 | u>>(32-13)
- u = x14 + x13
- x15 ^= u<<18 | u>>(32-18)
+ x12 ^= bits.RotateLeft32(x15+x14, 7)
+ x13 ^= bits.RotateLeft32(x12+x15, 9)
+ x14 ^= bits.RotateLeft32(x13+x12, 13)
+ x15 ^= bits.RotateLeft32(x14+x13, 18)
}
x0 += w0
x1 += w1
