ceph-csi/vendor/golang.org/x/crypto/poly1305/poly1305.go
Niels de Vos 91774fc936 rebase: vendor dependencies for Vault API
Uses github.com/libopenstorage/secrets to communicate with Vault. This
removes the need for maintaining our own limited Vault APIs.

By adding the new dependency, several other packages got updated in the
process. Unused indirect dependencies have been removed from go.mod.

Signed-off-by: Niels de Vos <ndevos@redhat.com>
2020-11-29 04:03:59 +00:00

100 lines
3.3 KiB
Go

// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package poly1305 implements Poly1305 one-time message authentication code as
// specified in https://cr.yp.to/mac/poly1305-20050329.pdf.
//
// Poly1305 is a fast, one-time authentication function. It is infeasible for an
// attacker to generate an authenticator for a message without the key. However, a
// key must only be used for a single message. Authenticating two different
// messages with the same key allows an attacker to forge authenticators for other
// messages with the same key.
//
// Poly1305 was originally coupled with AES in order to make Poly1305-AES. AES was
// used with a fixed key in order to generate one-time keys from an nonce.
// However, in this package AES isn't used and the one-time key is specified
// directly.
package poly1305 // import "golang.org/x/crypto/poly1305"
import "crypto/subtle"
// TagSize is the size, in bytes, of a poly1305 authenticator.
const TagSize = 16
// Sum generates an authenticator for msg using a one-time key and puts the
// 16-byte result into out. Authenticating two different messages with the same
// key allows an attacker to forge messages at will.
func Sum(out *[16]byte, m []byte, key *[32]byte) {
h := New(key)
h.Write(m)
h.Sum(out[:0])
}
// Verify returns true if mac is a valid authenticator for m with the given key.
func Verify(mac *[16]byte, m []byte, key *[32]byte) bool {
var tmp [16]byte
Sum(&tmp, m, key)
return subtle.ConstantTimeCompare(tmp[:], mac[:]) == 1
}
// New returns a new MAC computing an authentication
// tag of all data written to it with the given key.
// This allows writing the message progressively instead
// of passing it as a single slice. Common users should use
// the Sum function instead.
//
// The key must be unique for each message, as authenticating
// two different messages with the same key allows an attacker
// to forge messages at will.
func New(key *[32]byte) *MAC {
m := &MAC{}
initialize(key, &m.macState)
return m
}
// MAC is an io.Writer computing an authentication tag
// of the data written to it.
//
// MAC cannot be used like common hash.Hash implementations,
// because using a poly1305 key twice breaks its security.
// Therefore writing data to a running MAC after calling
// Sum or Verify causes it to panic.
type MAC struct {
mac // platform-dependent implementation
finalized bool
}
// Size returns the number of bytes Sum will return.
func (h *MAC) Size() int { return TagSize }
// Write adds more data to the running message authentication code.
// It never returns an error.
//
// It must not be called after the first call of Sum or Verify.
func (h *MAC) Write(p []byte) (n int, err error) {
if h.finalized {
panic("poly1305: write to MAC after Sum or Verify")
}
return h.mac.Write(p)
}
// Sum computes the authenticator of all data written to the
// message authentication code.
func (h *MAC) Sum(b []byte) []byte {
var mac [TagSize]byte
h.mac.Sum(&mac)
h.finalized = true
return append(b, mac[:]...)
}
// Verify returns whether the authenticator of all data written to
// the message authentication code matches the expected value.
func (h *MAC) Verify(expected []byte) bool {
var mac [TagSize]byte
h.mac.Sum(&mac)
h.finalized = true
return subtle.ConstantTimeCompare(expected, mac[:]) == 1
}