mirror of https://github.com/cheat/cheat.git
144 lines
3.7 KiB
Go
144 lines
3.7 KiB
Go
// Copyright 2017 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 algorithm
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import (
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"crypto"
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"fmt"
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"hash"
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)
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// Hash is an official hash function algorithm. See RFC 4880, section 9.4.
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type Hash interface {
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// Id returns the algorithm ID, as a byte, of Hash.
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Id() uint8
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// Available reports whether the given hash function is linked into the binary.
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Available() bool
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// HashFunc simply returns the value of h so that Hash implements SignerOpts.
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HashFunc() crypto.Hash
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// New returns a new hash.Hash calculating the given hash function. New
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// panics if the hash function is not linked into the binary.
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New() hash.Hash
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// Size returns the length, in bytes, of a digest resulting from the given
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// hash function. It doesn't require that the hash function in question be
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// linked into the program.
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Size() int
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// String is the name of the hash function corresponding to the given
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// OpenPGP hash id.
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String() string
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}
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// The following vars mirror the crypto/Hash supported hash functions.
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var (
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SHA1 Hash = cryptoHash{2, crypto.SHA1}
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SHA256 Hash = cryptoHash{8, crypto.SHA256}
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SHA384 Hash = cryptoHash{9, crypto.SHA384}
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SHA512 Hash = cryptoHash{10, crypto.SHA512}
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SHA224 Hash = cryptoHash{11, crypto.SHA224}
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SHA3_256 Hash = cryptoHash{12, crypto.SHA3_256}
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SHA3_512 Hash = cryptoHash{14, crypto.SHA3_512}
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)
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// HashById represents the different hash functions specified for OpenPGP. See
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// http://www.iana.org/assignments/pgp-parameters/pgp-parameters.xhtml#pgp-parameters-14
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var (
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HashById = map[uint8]Hash{
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SHA256.Id(): SHA256,
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SHA384.Id(): SHA384,
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SHA512.Id(): SHA512,
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SHA224.Id(): SHA224,
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SHA3_256.Id(): SHA3_256,
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SHA3_512.Id(): SHA3_512,
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}
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)
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// cryptoHash contains pairs relating OpenPGP's hash identifier with
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// Go's crypto.Hash type. See RFC 4880, section 9.4.
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type cryptoHash struct {
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id uint8
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crypto.Hash
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}
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// Id returns the algorithm ID, as a byte, of cryptoHash.
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func (h cryptoHash) Id() uint8 {
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return h.id
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}
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var hashNames = map[uint8]string{
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SHA256.Id(): "SHA256",
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SHA384.Id(): "SHA384",
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SHA512.Id(): "SHA512",
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SHA224.Id(): "SHA224",
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SHA3_256.Id(): "SHA3-256",
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SHA3_512.Id(): "SHA3-512",
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}
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func (h cryptoHash) String() string {
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s, ok := hashNames[h.id]
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if !ok {
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panic(fmt.Sprintf("Unsupported hash function %d", h.id))
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}
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return s
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}
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// HashIdToHash returns a crypto.Hash which corresponds to the given OpenPGP
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// hash id.
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func HashIdToHash(id byte) (h crypto.Hash, ok bool) {
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if hash, ok := HashById[id]; ok {
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return hash.HashFunc(), true
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}
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return 0, false
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}
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// HashIdToHashWithSha1 returns a crypto.Hash which corresponds to the given OpenPGP
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// hash id, allowing sha1.
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func HashIdToHashWithSha1(id byte) (h crypto.Hash, ok bool) {
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if hash, ok := HashById[id]; ok {
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return hash.HashFunc(), true
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}
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if id == SHA1.Id() {
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return SHA1.HashFunc(), true
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}
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return 0, false
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}
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// HashIdToString returns the name of the hash function corresponding to the
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// given OpenPGP hash id.
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func HashIdToString(id byte) (name string, ok bool) {
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if hash, ok := HashById[id]; ok {
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return hash.String(), true
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}
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return "", false
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}
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// HashToHashId returns an OpenPGP hash id which corresponds the given Hash.
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func HashToHashId(h crypto.Hash) (id byte, ok bool) {
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for id, hash := range HashById {
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if hash.HashFunc() == h {
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return id, true
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}
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}
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return 0, false
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}
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// HashToHashIdWithSha1 returns an OpenPGP hash id which corresponds the given Hash,
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// allowing instances of SHA1
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func HashToHashIdWithSha1(h crypto.Hash) (id byte, ok bool) {
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for id, hash := range HashById {
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if hash.HashFunc() == h {
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return id, true
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}
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}
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if h == SHA1.HashFunc() {
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return SHA1.Id(), true
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}
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return 0, false
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}
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