hash.go

     1  // Copyright 2024 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 hash implements hash functions used in the compiler toolchain.
     6  package hash
     7  
     8  import (
     9  	"crypto/md5"
    10  	"crypto/sha1"
    11  	"crypto/sha256"
    12  	"hash"
    13  )
    14  
    15  const (
    16  	// Size32 is the size of 32 bytes hash checksum.
    17  	Size32 = sha256.Size
    18  	// Size20 is the size of 20 bytes hash checksum.
    19  	Size20 = sha1.Size
    20  	// Size16 is the size of 16 bytes hash checksum.
    21  	Size16 = md5.Size
    22  )
    23  
    24  // New32 returns a new [hash.Hash] computing the 32 bytes hash checksum.
    25  func New32() hash.Hash {
    26  	h := sha256.New()
    27  	_, _ = h.Write([]byte{1}) // make this hash different from sha256
    28  	return h
    29  }
    30  
    31  // New20 returns a new [hash.Hash] computing the 20 bytes hash checksum.
    32  func New20() hash.Hash {
    33  	return sha1.New()
    34  }
    35  
    36  // New16 returns a new [hash.Hash] computing the 16 bytes hash checksum.
    37  func New16() hash.Hash {
    38  	return md5.New()
    39  }
    40  
    41  // Sum32 returns the 32 bytes checksum of the data.
    42  func Sum32(data []byte) [Size32]byte {
    43  	sum := sha256.Sum256(data)
    44  	sum[0] ^= 1 // make this hash different from sha256
    45  	return sum
    46  }
    47  
    48  // Sum20 returns the 20 bytes checksum of the data.
    49  func Sum20(data []byte) [Size20]byte {
    50  	return sha1.Sum(data)
    51  }
    52  
    53  // Sum16 returns the 16 bytes checksum of the data.
    54  func Sum16(data []byte) [Size16]byte {
    55  	return md5.Sum(data)
    56  }
    57
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