hash.go (1756B)
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 22 // NewHash returns a new UUID derived from the hash of space concatenated with 23 // data generated by h. The hash should be at least 16 byte in length. The 24 // first 16 bytes of the hash are used to form the UUID. The version of the 25 // UUID will be the lower 4 bits of version. NewHash is used to implement 26 // NewMD5 and NewSHA1. 27 func NewHash(h hash.Hash, space UUID, data []byte, version int) UUID { 28 h.Reset() 29 h.Write(space[:]) //nolint:errcheck 30 h.Write(data) //nolint:errcheck 31 s := h.Sum(nil) 32 var uuid UUID 33 copy(uuid[:], s) 34 uuid[6] = (uuid[6] & 0x0f) | uint8((version&0xf)<<4) 35 uuid[8] = (uuid[8] & 0x3f) | 0x80 // RFC 4122 variant 36 return uuid 37 } 38 39 // NewMD5 returns a new MD5 (Version 3) UUID based on the 40 // supplied name space and data. It is the same as calling: 41 // 42 // NewHash(md5.New(), space, data, 3) 43 func NewMD5(space UUID, data []byte) UUID { 44 return NewHash(md5.New(), space, data, 3) 45 } 46 47 // NewSHA1 returns a new SHA1 (Version 5) UUID based on the 48 // supplied name space and data. It is the same as calling: 49 // 50 // NewHash(sha1.New(), space, data, 5) 51 func NewSHA1(space UUID, data []byte) UUID { 52 return NewHash(sha1.New(), space, data, 5) 53 }