74 lines
2.0 KiB
Go
74 lines
2.0 KiB
Go
// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package crypto collects common cryptographic constants.
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package crypto
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import (
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"hash"
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)
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// Hash identifies a cryptographic hash function that is implemented in another
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// package.
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type Hash uint
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const (
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MD4 Hash = 1 + iota // in package crypto/md4
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MD5 // in package crypto/md5
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SHA1 // in package crypto/sha1
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SHA224 // in package crypto/sha256
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SHA256 // in package crypto/sha256
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SHA384 // in package crypto/sha512
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SHA512 // in package crypto/sha512
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MD5SHA1 // no implementation; MD5+SHA1 used for TLS RSA
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RIPEMD160 // in package crypto/ripemd160
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maxHash
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)
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var digestSizes = []uint8{
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MD4: 16,
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MD5: 16,
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SHA1: 20,
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SHA224: 28,
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SHA256: 32,
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SHA384: 48,
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SHA512: 64,
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MD5SHA1: 36,
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RIPEMD160: 20,
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}
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// Size returns the length, in bytes, of a digest resulting from the given hash
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// function. It doesn't require that the hash function in question be linked
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// into the program.
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func (h Hash) Size() int {
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if h > 0 && h < maxHash {
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return int(digestSizes[h])
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}
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panic("crypto: Size of unknown hash function")
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}
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var hashes = make([]func() hash.Hash, maxHash)
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// New returns a new hash.Hash calculating the given hash function. If the
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// hash function is not linked into the binary, New returns nil.
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func (h Hash) New() hash.Hash {
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if h > 0 && h < maxHash {
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f := hashes[h]
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if f != nil {
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return f()
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}
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}
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return nil
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}
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// RegisterHash registers a function that returns a new instance of the given
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// hash function. This is intended to be called from the init function in
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// packages that implement hash functions.
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func RegisterHash(h Hash, f func() hash.Hash) {
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if h >= maxHash {
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panic("crypto: RegisterHash of unknown hash function")
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}
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hashes[h] = f
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}
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