Filippo Valsorda
8c9ba31836
Fixes golang/go#65250 Change-Id: I6a6a6964a2c87e529be50dd67fec462483b07b75 Reviewed-on: https://go-review.googlesource.com/c/crypto/+/701535 Reviewed-by: Mark Freeman <markfreeman@google.com> Auto-Submit: Filippo Valsorda <filippo@golang.org> Reviewed-by: Daniel McCarney <daniel@binaryparadox.net> LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Michael Pratt <mpratt@google.com>
50 lines
1.4 KiB
Go
50 lines
1.4 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 auth authenticates a message using a secret key.
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//
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// This package is interoperable with [NaCl].
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//
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// The auth package is essentially a wrapper for HMAC-SHA-512 (implemented by
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// crypto/hmac and crypto/sha512), truncated to 32 bytes. It is [frozen] and is
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// not accepting new features.
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//
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// [NaCl]: https://nacl.cr.yp.to/auth.html
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// [frozen]: https://go.dev/wiki/Frozen
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package auth
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import (
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"crypto/hmac"
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"crypto/sha512"
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)
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const (
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// Size is the size, in bytes, of an authenticated digest.
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Size = 32
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// KeySize is the size, in bytes, of an authentication key.
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KeySize = 32
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)
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// Sum generates an authenticator for m using a secret key and returns the
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// 32-byte digest.
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func Sum(m []byte, key *[KeySize]byte) *[Size]byte {
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mac := hmac.New(sha512.New, key[:])
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mac.Write(m)
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out := new([Size]byte)
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copy(out[:], mac.Sum(nil)[:Size])
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return out
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}
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// Verify checks that digest is a valid authenticator of message m under the
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// given secret key. Verify does not leak timing information.
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func Verify(digest []byte, m []byte, key *[KeySize]byte) bool {
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if len(digest) != Size {
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return false
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}
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mac := hmac.New(sha512.New, key[:])
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mac.Write(m)
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expectedMAC := mac.Sum(nil) // first 256 bits of 512-bit sum
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return hmac.Equal(digest, expectedMAC[:Size])
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}
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