libgo/go/crypto/crypto.go

   1 // Copyright 2011 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 crypto collects common cryptographic constants.
   6 package crypto
   7
   8 import (
   9         "hash"
  10 )
  11
  12 // Hash identifies a cryptographic hash function that is implemented in another
  13 // package.
  14 type Hash uint
  15
  16 const (
  17         MD4       Hash = 1 + iota // import code.google.com/p/go.crypto/md4
  18         MD5                       // import crypto/md5
  19         SHA1                      // import crypto/sha1
  20         SHA224                    // import crypto/sha256
  21         SHA256                    // import crypto/sha256
  22         SHA384                    // import crypto/sha512
  23         SHA512                    // import crypto/sha512
  24         MD5SHA1                   // no implementation; MD5+SHA1 used for TLS RSA
  25         RIPEMD160                 // import code.google.com/p/go.crypto/ripemd160
  26         maxHash
  27 )
  28
  29 var digestSizes = []uint8{
  30         MD4:       16,
  31         MD5:       16,
  32         SHA1:      20,
  33         SHA224:    28,
  34         SHA256:    32,
  35         SHA384:    48,
  36         SHA512:    64,
  37         MD5SHA1:   36,
  38         RIPEMD160: 20,
  39 }
  40
  41 // Size returns the length, in bytes, of a digest resulting from the given hash
  42 // function. It doesn't require that the hash function in question be linked
  43 // into the program.
  44 func (h Hash) Size() int {
  45         if h > 0 && h < maxHash {
  46                 return int(digestSizes[h])
  47         }
  48         panic("crypto: Size of unknown hash function")
  49 }
  50
  51 var hashes = make([]func() hash.Hash, maxHash)
  52
  53 // New returns a new hash.Hash calculating the given hash function. New panics
  54 // if the hash function is not linked into the binary.
  55 func (h Hash) New() hash.Hash {
  56         if h > 0 && h < maxHash {
  57                 f := hashes[h]
  58                 if f != nil {
  59                         return f()
  60                 }
  61         }
  62         panic("crypto: requested hash function is unavailable")
  63 }
  64
  65 // Available reports whether the given hash function is linked into the binary.
  66 func (h Hash) Available() bool {
  67         return h < maxHash && hashes[h] != nil
  68 }
  69
  70 // RegisterHash registers a function that returns a new instance of the given
  71 // hash function. This is intended to be called from the init function in
  72 // packages that implement hash functions.
  73 func RegisterHash(h Hash, f func() hash.Hash) {
  74         if h >= maxHash {
  75                 panic("crypto: RegisterHash of unknown hash function")
  76         }
  77         hashes[h] = f
  78 }
  79
  80 // PrivateKey represents a private key using an unspecified algorithm.
  81 type PrivateKey interface{}