hash.go (1963B)
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 }