github.com/ethereumproject/go-ethereum@v5.5.2+incompatible/crypto/sha3/shake.go (about)

     1  // Copyright 2014 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package sha3
     6  
     7  // This file defines the ShakeHash interface, and provides
     8  // functions for creating SHAKE instances, as well as utility
     9  // functions for hashing bytes to arbitrary-length output.
    10  
    11  import (
    12  	"io"
    13  )
    14  
    15  // ShakeHash defines the interface to hash functions that
    16  // support arbitrary-length output.
    17  type ShakeHash interface {
    18  	// Write absorbs more data into the hash's state. It panics if input is
    19  	// written to it after output has been read from it.
    20  	io.Writer
    21  
    22  	// Read reads more output from the hash; reading affects the hash's
    23  	// state. (ShakeHash.Read is thus very different from Hash.Sum)
    24  	// It never returns an error.
    25  	io.Reader
    26  
    27  	// Clone returns a copy of the ShakeHash in its current state.
    28  	Clone() ShakeHash
    29  
    30  	// Reset resets the ShakeHash to its initial state.
    31  	Reset()
    32  }
    33  
    34  func (d *state) Clone() ShakeHash {
    35  	return d.clone()
    36  }
    37  
    38  // NewShake128 creates a new SHAKE128 variable-output-length ShakeHash.
    39  // Its generic security strength is 128 bits against all attacks if at
    40  // least 32 bytes of its output are used.
    41  func NewShake128() ShakeHash { return &state{rate: 168, dsbyte: 0x1f} }
    42  
    43  // NewShake256 creates a new SHAKE128 variable-output-length ShakeHash.
    44  // Its generic security strength is 256 bits against all attacks if
    45  // at least 64 bytes of its output are used.
    46  func NewShake256() ShakeHash { return &state{rate: 136, dsbyte: 0x1f} }
    47  
    48  // ShakeSum128 writes an arbitrary-length digest of data into hash.
    49  func ShakeSum128(hash, data []byte) {
    50  	h := NewShake128()
    51  	h.Write(data)
    52  	h.Read(hash)
    53  }
    54  
    55  // ShakeSum256 writes an arbitrary-length digest of data into hash.
    56  func ShakeSum256(hash, data []byte) {
    57  	h := NewShake256()
    58  	h.Write(data)
    59  	h.Read(hash)
    60  }