github.com/elfadel/cilium@v1.6.12/pkg/crypto/sha1/sha1.go (about)

     1  // Copyright 2019 Authors of Cilium
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package sha1
    16  
    17  import (
    18  	"crypto/sha1"
    19  	"encoding"
    20  	"encoding/hex"
    21  	"fmt"
    22  	"hash"
    23  )
    24  
    25  // ResumableHash is the intefrace for a hash that can be stored and copied.
    26  //
    27  // Unlike hash implementations in the standard library, it does not implement
    28  // the encoding.BinaryMarshaler and encoding.BinaryUnmarshaler interfaces;
    29  // however, it does provide a method for creating a copy of the underlying
    30  // hash. This allows the hash to be stored, duplicated, and resumed at a later
    31  // time. For convenience, it also provides a standard method for converting
    32  // the hash into a string.
    33  type ResumableHash interface {
    34  	hash.Hash
    35  	fmt.Stringer
    36  	Copy() (ResumableHash, error)
    37  }
    38  
    39  // digest is a wrapper for the standard sha1 library which implements
    40  // ResumableHash.
    41  type digest struct {
    42  	hash.Hash
    43  }
    44  
    45  // New returns a new ResumableHash computing the SHA1 checksum.
    46  func New() ResumableHash {
    47  	return &digest{
    48  		sha1.New(),
    49  	}
    50  }
    51  
    52  // Copy duplicates the hash and returns the copy.
    53  func (d *digest) Copy() (ResumableHash, error) {
    54  	newHash := hash.Hash(sha1.New())
    55  	state, err := d.Hash.(encoding.BinaryMarshaler).MarshalBinary()
    56  	if err != nil {
    57  		return nil, err
    58  	}
    59  	if err := newHash.(encoding.BinaryUnmarshaler).UnmarshalBinary(state); err != nil {
    60  		return nil, err
    61  	}
    62  	return &digest{
    63  		newHash,
    64  	}, nil
    65  }
    66  
    67  // String returns a string representation of the underlying hash.
    68  func (d *digest) String() string {
    69  	return hex.EncodeToString(d.Sum(nil))
    70  }