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Source file src/hash/hash.go

Documentation: hash

  // 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.
  //
  // Hash implementations in the standard library (e.g. hash/crc32 and
  // crypto/sha256) implement the encoding.BinaryMarshaler and
  // encoding.BinaryUnmarshaler interfaces. Marshaling a hash implementation
  // allows its internal state to be saved and used for additional processing
  // later, without having to re-write the data previously written to the hash.
  // The hash state may contain portions of the input in its original form,
  // which users are expected to handle for any possible security implications.
  //
  // Compatibility: Any future changes to hash or crypto packages will endeavor
  // to maintain compatibility with state encoded using previous versions.
  // That is, any released versions of the packages should be able to
  // decode data written with any previously released version,
  // subject to issues such as security fixes.
  // See the Go compatibility document for background: https://golang.org/doc/go1compat
  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
  }
  

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