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69 lines
1.5 KiB
Go
69 lines
1.5 KiB
Go
// Copyright 2012 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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// +build amd64,!gccgo,!appengine
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package poly1305
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//go:noescape
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func initialize(state *[7]uint64, key *[32]byte)
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//go:noescape
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func update(state *[7]uint64, msg []byte)
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//go:noescape
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func finalize(tag *[TagSize]byte, state *[7]uint64)
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// Sum generates an authenticator for m using a one-time key and puts the
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// 16-byte result into out. Authenticating two different messages with the same
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// key allows an attacker to forge messages at will.
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func Sum(out *[16]byte, m []byte, key *[32]byte) {
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h := newMAC(key)
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h.Write(m)
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h.Sum(out)
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}
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func newMAC(key *[32]byte) (h mac) {
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initialize(&h.state, key)
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return
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}
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type mac struct {
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state [7]uint64 // := uint64{ h0, h1, h2, r0, r1, pad0, pad1 }
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buffer [TagSize]byte
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offset int
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}
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func (h *mac) Write(p []byte) (n int, err error) {
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n = len(p)
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if h.offset > 0 {
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remaining := TagSize - h.offset
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if n < remaining {
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h.offset += copy(h.buffer[h.offset:], p)
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return n, nil
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}
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copy(h.buffer[h.offset:], p[:remaining])
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p = p[remaining:]
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h.offset = 0
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update(&h.state, h.buffer[:])
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}
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if nn := len(p) - (len(p) % TagSize); nn > 0 {
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update(&h.state, p[:nn])
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p = p[nn:]
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}
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if len(p) > 0 {
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h.offset += copy(h.buffer[h.offset:], p)
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}
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return n, nil
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}
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func (h *mac) Sum(out *[16]byte) {
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state := h.state
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if h.offset > 0 {
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update(&state, h.buffer[:h.offset])
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}
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finalize(out, &state)
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}
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