1 files changed, 43 insertions, 0 deletions
diff --git a/src/hash/hash.go b/src/hash/hash.go
new file mode 100644
index 000000000..8d138d07f
--- /dev/null
+++ b/src/hash/hash.go
@@ -0,0 +1,43 @@
+// Copyright 2009 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.
+
+// Package hash provides interfaces for hash functions.
+package hash
+
+import "io"
+
+// Hash is the common interface implemented by all hash functions.
+type Hash interface {
+	// Write (via the embedded io.Writer interface) adds more data to the running hash.
+	// It never returns an error.
+	io.Writer
+
+	// Sum appends the current hash to b and returns the resulting slice.
+	// It does not change the underlying hash state.
+	Sum(b []byte) []byte
+
+	// Reset resets the Hash to its initial state.
+	Reset()
+
+	// Size returns the number of bytes Sum will return.
+	Size() int
+
+	// BlockSize returns the hash's underlying block size.
+	// The Write method must be able to accept any amount
+	// of data, but it may operate more efficiently if all writes
+	// are a multiple of the block size.
+	BlockSize() int
+}
+
+// Hash32 is the common interface implemented by all 32-bit hash functions.
+type Hash32 interface {
+	Hash
+	Sum32() uint32
+}
+
+// Hash64 is the common interface implemented by all 64-bit hash functions.
+type Hash64 interface {
+	Hash
+	Sum64() uint64
+}