diff options
Diffstat (limited to 'src/crypto/hmac/hmac.go')
| -rw-r--r-- | src/crypto/hmac/hmac.go | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/src/crypto/hmac/hmac.go b/src/crypto/hmac/hmac.go index a6ba71c275..cdda33c2cb 100644 --- a/src/crypto/hmac/hmac.go +++ b/src/crypto/hmac/hmac.go @@ -120,6 +120,8 @@ func (h *hmac) Reset() { } // New returns a new HMAC hash using the given hash.Hash type and key. +// New functions like sha256.New from crypto/sha256 can be used as h. +// h must return a new Hash every time it is called. // Note that unlike other hash implementations in the standard library, // the returned Hash does not implement encoding.BinaryMarshaler // or encoding.BinaryUnmarshaler. @@ -127,6 +129,19 @@ func New(h func() hash.Hash, key []byte) hash.Hash { hm := new(hmac) hm.outer = h() hm.inner = h() + unique := true + func() { + defer func() { + // The comparison might panic if the underlying types are not comparable. + _ = recover() + }() + if hm.outer == hm.inner { + unique = false + } + }() + if !unique { + panic("crypto/hmac: hash generation function does not produce unique values") + } blocksize := hm.inner.BlockSize() hm.ipad = make([]byte, blocksize) hm.opad = make([]byte, blocksize) |