diff options
Diffstat (limited to 'src/pkg/crypto/subtle/constant_time.go')
| -rw-r--r-- | src/pkg/crypto/subtle/constant_time.go | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/src/pkg/crypto/subtle/constant_time.go b/src/pkg/crypto/subtle/constant_time.go index de1a4e8c5..9c4b14a65 100644 --- a/src/pkg/crypto/subtle/constant_time.go +++ b/src/pkg/crypto/subtle/constant_time.go @@ -49,9 +49,14 @@ func ConstantTimeEq(x, y int32) int { return int(z & 1) } -// ConstantTimeCopy copies the contents of y into x iff v == 1. If v == 0, x is left unchanged. -// Its behavior is undefined if v takes any other value. +// ConstantTimeCopy copies the contents of y into x (a slice of equal length) +// if v == 1. If v == 0, x is left unchanged. Its behavior is undefined if v +// takes any other value. func ConstantTimeCopy(v int, x, y []byte) { + if len(x) != len(y) { + panic("subtle: slices have different lengths") + } + xmask := byte(v - 1) ymask := byte(^(v - 1)) for i := 0; i < len(x); i++ { |