yaole
102 lines
2.1 KiB
Go
102 lines
2.1 KiB
Go
package sm
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import (
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"crypto"
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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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// I try to keep it consistent with the standard library
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type Hash struct {
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crypto.Hash
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}
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// HashFunc simply returns the value of h so that Hash implements SignerOpts.
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func (h Hash) HashFunc() crypto.Hash {
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return h.Hash
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}
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func (h Hash) String() string {
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switch h {
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case SM3:
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return "SM3"
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case SM3WithID:
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return "SM3WithID"
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default:
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// return ""
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return h.Hash.String()
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}
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}
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var (
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SM3 Hash
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SM3WithID Hash
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maxHash Hash
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)
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var SHA1 = Hash{crypto.SHA1}
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var SHA256 = Hash{crypto.SHA256}
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func init() {
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// A hack to get the maxHash in crypto.
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i := new(crypto.Hash)
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*i = 1
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defer func() {
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_ = recover()
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SM3 = Hash{Hash: *i}
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SM3WithID = Hash{Hash: *i + 1}
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maxHash = Hash{Hash: *i + 2}
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}()
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for {
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(*i).Size()
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*i++
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}
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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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switch h {
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case SM3, SM3WithID:
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return 32
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default:
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return h.Hash.Size()
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}
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}
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var hashes = make(map[Hash]func() hash.Hash)
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// New returns a new hash.Hash calculating the given hash function. New panics
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// if the hash function is not linked into the binary.
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func (h Hash) New() hash.Hash {
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if h.Hash >= SM3.Hash && h.Hash < maxHash.Hash {
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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 h.Hash.New()
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}
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// Available reports whether the given hash function is linked into the binary.
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func (h Hash) Available() bool {
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if h.Hash >= SM3.Hash && h.Hash < maxHash.Hash {
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return true
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}
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return h.Hash.Available()
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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.Hash >= maxHash.Hash {
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panic("crypto: RegisterHash of unknown hash function")
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}
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// if h.Hash < SM3.Hash {
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// crypto.RegisterHash(h.Hash, f)
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// }
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hashes[h] = f
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}
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