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b606c8e440
full diff:88737f569e...69ecbb4d6dIncludes69ecbb4d6d(forward-port of8b5121be2f), which fixes CVE-2020-7919: - Panic in crypto/x509 certificate parsing and golang.org/x/crypto/cryptobyte On 32-bit architectures, a malformed input to crypto/x509 or the ASN.1 parsing functions of golang.org/x/crypto/cryptobyte can lead to a panic. The malformed certificate can be delivered via a crypto/tls connection to a client, or to a server that accepts client certificates. net/http clients can be made to crash by an HTTPS server, while net/http servers that accept client certificates will recover the panic and are unaffected. Thanks to Project Wycheproof for providing the test cases that led to the discovery of this issue. The issue is CVE-2020-7919 and Go issue golang.org/issue/36837. Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
89 lines
3 KiB
Go
89 lines
3 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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// Package poly1305 implements Poly1305 one-time message authentication code as
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// specified in https://cr.yp.to/mac/poly1305-20050329.pdf.
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//
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// Poly1305 is a fast, one-time authentication function. It is infeasible for an
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// attacker to generate an authenticator for a message without the key. However, a
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// key must only be used for a single message. Authenticating two different
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// messages with the same key allows an attacker to forge authenticators for other
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// messages with the same key.
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//
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// Poly1305 was originally coupled with AES in order to make Poly1305-AES. AES was
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// used with a fixed key in order to generate one-time keys from an nonce.
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// However, in this package AES isn't used and the one-time key is specified
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// directly.
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package poly1305 // import "golang.org/x/crypto/poly1305"
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import "crypto/subtle"
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// TagSize is the size, in bytes, of a poly1305 authenticator.
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const TagSize = 16
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// Sum generates an authenticator for msg 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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sum(out, m, key)
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}
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// Verify returns true if mac is a valid authenticator for m with the given key.
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func Verify(mac *[16]byte, m []byte, key *[32]byte) bool {
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var tmp [16]byte
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Sum(&tmp, m, key)
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return subtle.ConstantTimeCompare(tmp[:], mac[:]) == 1
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}
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// New returns a new MAC computing an authentication
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// tag of all data written to it with the given key.
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// This allows writing the message progressively instead
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// of passing it as a single slice. Common users should use
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// the Sum function instead.
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//
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// The key must be unique for each message, as authenticating
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// two different messages with the same key allows an attacker
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// to forge messages at will.
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func New(key *[32]byte) *MAC {
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return &MAC{
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mac: newMAC(key),
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finalized: false,
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}
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}
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// MAC is an io.Writer computing an authentication tag
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// of the data written to it.
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//
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// MAC cannot be used like common hash.Hash implementations,
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// because using a poly1305 key twice breaks its security.
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// Therefore writing data to a running MAC after calling
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// Sum causes it to panic.
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type MAC struct {
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mac // platform-dependent implementation
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finalized bool
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}
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// Size returns the number of bytes Sum will return.
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func (h *MAC) Size() int { return TagSize }
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// Write adds more data to the running message authentication code.
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// It never returns an error.
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//
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// It must not be called after the first call of Sum.
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func (h *MAC) Write(p []byte) (n int, err error) {
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if h.finalized {
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panic("poly1305: write to MAC after Sum")
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}
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return h.mac.Write(p)
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}
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// Sum computes the authenticator of all data written to the
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// message authentication code.
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func (h *MAC) Sum(b []byte) []byte {
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var mac [TagSize]byte
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h.mac.Sum(&mac)
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h.finalized = true
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return append(b, mac[:]...)
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}
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