// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package hash provides interfaces for hash functions.
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package hash
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import "io"
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// Hash is the common interface implemented by all hash functions.
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//
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// Hash implementations in the standard library (e.g. hash/crc32 and
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// crypto/sha256) implement the encoding.BinaryMarshaler and
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// encoding.BinaryUnmarshaler interfaces. Marshaling a hash implementation
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// allows its internal state to be saved and used for additional processing
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// later, without having to re-write the data previously written to the hash.
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// The hash state may contain portions of the input in its original form,
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// which users are expected to handle for any possible security implications.
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//
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// Compatibility: Any future changes to hash or crypto packages will endeavor
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// to maintain compatibility with state encoded using previous versions.
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// That is, any released versions of the packages should be able to
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// decode data written with any previously released version,
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// subject to issues such as security fixes.
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// See the Go compatibility document for background: https://golang.org/doc/go1compat
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type Hash interface {
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// Write (via the embedded io.Writer interface) adds more data to the running hash.
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// It never returns an error.
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io.Writer
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// Sum appends the current hash to b and returns the resulting slice.
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// It does not change the underlying hash state.
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Sum(b []byte) []byte
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// Reset resets the Hash to its initial state.
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Reset()
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// Size returns the number of bytes Sum will return.
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Size() int
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// BlockSize returns the hash's underlying block size.
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// The Write method must be able to accept any amount
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// of data, but it may operate more efficiently if all writes
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// are a multiple of the block size.
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BlockSize() int
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}
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// Hash32 is the common interface implemented by all 32-bit hash functions.
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type Hash32 interface {
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Hash
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Sum32() uint32
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}
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// Hash64 is the common interface implemented by all 64-bit hash functions.
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type Hash64 interface {
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Hash
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Sum64() uint64
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}
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