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         "strconv"
  11 )
  12
  13 // Hash identifies a cryptographic hash function that is implemented in another
  14 // package.
  15 type Hash uint
  16
  17 const (
  18         MD4       Hash = 1 + iota // import code.google.com/p/go.crypto/md4
  19         MD5                       // import crypto/md5
  20         SHA1                      // import crypto/sha1
  21         SHA224                    // import crypto/sha256
  22         SHA256                    // import crypto/sha256
  23         SHA384                    // import crypto/sha512
  24         SHA512                    // import crypto/sha512
  25         MD5SHA1                   // no implementation; MD5+SHA1 used for TLS RSA
  26         RIPEMD160                 // import code.google.com/p/go.crypto/ripemd160
  27         maxHash
  28 )
  29
  30 var digestSizes = []uint8{
  31         MD4:       16,
  32         MD5:       16,
  33         SHA1:      20,
  34         SHA224:    28,
  35         SHA256:    32,
  36         SHA384:    48,
  37         SHA512:    64,
  38         MD5SHA1:   36,
  39         RIPEMD160: 20,
  40 }
  41
  42 // Size returns the length, in bytes, of a digest resulting from the given hash
  43 // function. It doesn't require that the hash function in question be linked
  44 // into the program.
  45 func (h Hash) Size() int {
  46         if h > 0 && h < maxHash {
  47                 return int(digestSizes[h])
  48         }
  49         panic("crypto: Size of unknown hash function")
  50 }
  51
  52 var hashes = make([]func() hash.Hash, maxHash)
  53
  54 // New returns a new hash.Hash calculating the given hash function. New panics
  55 // if the hash function is not linked into the binary.
  56 func (h Hash) New() hash.Hash {
  57         if h > 0 && h < maxHash {
  58                 f := hashes[h]
  59                 if f != nil {
  60                         return f()
  61                 }
  62         }
  63         panic("crypto: requested hash function #" + strconv.Itoa(int(h)) + " is unavailable")
  64 }
  65
  66 // Available reports whether the given hash function is linked into the binary.
  67 func (h Hash) Available() bool {
  68         return h < maxHash && hashes[h] != nil
  69 }
  70
  71 // RegisterHash registers a function that returns a new instance of the given
  72 // hash function. This is intended to be called from the init function in
  73 // packages that implement hash functions.
  74 func RegisterHash(h Hash, f func() hash.Hash) {
  75         if h >= maxHash {
  76                 panic("crypto: RegisterHash of unknown hash function")
  77         }
  78         hashes[h] = f
  79 }
  80
  81 // PublicKey represents a public key using an unspecified algorithm.
  82 type PublicKey interface{}
  83
  84 // PrivateKey represents a private key using an unspecified algorithm.
  85 type PrivateKey interface{}