hash.go

Documentation: github.com/google/uuid

     1  // Copyright 2016 Google Inc.  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 uuid
     6  
     7  import (
     8  	"crypto/md5"
     9  	"crypto/sha1"
    10  	"hash"
    11  )
    12  
    13  // Well known namespace IDs and UUIDs
    14  var (
    15  	NameSpaceDNS  = Must(Parse("6ba7b810-9dad-11d1-80b4-00c04fd430c8"))
    16  	NameSpaceURL  = Must(Parse("6ba7b811-9dad-11d1-80b4-00c04fd430c8"))
    17  	NameSpaceOID  = Must(Parse("6ba7b812-9dad-11d1-80b4-00c04fd430c8"))
    18  	NameSpaceX500 = Must(Parse("6ba7b814-9dad-11d1-80b4-00c04fd430c8"))
    19  	Nil           UUID // empty UUID, all zeros
    20  
    21  	// The Max UUID is special form of UUID that is specified to have all 128 bits set to 1.
    22  	Max = UUID{
    23  		0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
    24  		0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
    25  	}
    26  )
    27  
    28  // NewHash returns a new UUID derived from the hash of space concatenated with
    29  // data generated by h.  The hash should be at least 16 byte in length.  The
    30  // first 16 bytes of the hash are used to form the UUID.  The version of the
    31  // UUID will be the lower 4 bits of version.  NewHash is used to implement
    32  // NewMD5 and NewSHA1.
    33  func NewHash(h hash.Hash, space UUID, data []byte, version int) UUID {
    34  	h.Reset()
    35  	h.Write(space[:]) //nolint:errcheck
    36  	h.Write(data)     //nolint:errcheck
    37  	s := h.Sum(nil)
    38  	var uuid UUID
    39  	copy(uuid[:], s)
    40  	uuid[6] = (uuid[6] & 0x0f) | uint8((version&0xf)<<4)
    41  	uuid[8] = (uuid[8] & 0x3f) | 0x80 // RFC 4122 variant
    42  	return uuid
    43  }
    44  
    45  // NewMD5 returns a new MD5 (Version 3) UUID based on the
    46  // supplied name space and data.  It is the same as calling:
    47  //
    48  //  NewHash(md5.New(), space, data, 3)
    49  func NewMD5(space UUID, data []byte) UUID {
    50  	return NewHash(md5.New(), space, data, 3)
    51  }
    52  
    53  // NewSHA1 returns a new SHA1 (Version 5) UUID based on the
    54  // supplied name space and data.  It is the same as calling:
    55  //
    56  //  NewHash(sha1.New(), space, data, 5)
    57  func NewSHA1(space UUID, data []byte) UUID {
    58  	return NewHash(sha1.New(), space, data, 5)
    59  }
    60
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