hash.go

     1  // Copyright 2024 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 fips140hash
     6  
     7  import (
     8  	fsha3 "crypto/internal/fips140/sha3"
     9  	"crypto/sha3"
    10  	"hash"
    11  	_ "unsafe"
    12  )
    13  
    14  //go:linkname sha3Unwrap
    15  func sha3Unwrap(*sha3.SHA3) *fsha3.Digest
    16  
    17  // Unwrap returns h, or a crypto/internal/fips140 inner implementation of h.
    18  //
    19  // The return value can be type asserted to one of
    20  // [crypto/internal/fips140/sha256.Digest],
    21  // [crypto/internal/fips140/sha512.Digest], or
    22  // [crypto/internal/fips140/sha3.Digest] if it is a FIPS 140-3 approved hash.
    23  func Unwrap(h hash.Hash) hash.Hash {
    24  	if sha3, ok := h.(*sha3.SHA3); ok {
    25  		return sha3Unwrap(sha3)
    26  	}
    27  	return h
    28  }
    29  
    30  // UnwrapNew returns a function that calls newHash and applies [Unwrap] to the
    31  // return value.
    32  func UnwrapNew[Hash hash.Hash](newHash func() Hash) func() hash.Hash {
    33  	return func() hash.Hash { return Unwrap(newHash()) }
    34  }
    35
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