cheat/vendor/github.com/ProtonMail/go-crypto/openpgp/read.go
Christopher Allen Lane 95a4e31b6c chore(deps): upgrade dependencies
Upgrade all dependencies to newest versions.
2023-12-13 08:29:02 -05:00

593 lines
20 KiB
Go

// Copyright 2011 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 openpgp implements high level operations on OpenPGP messages.
package openpgp // import "github.com/ProtonMail/go-crypto/openpgp"
import (
"crypto"
_ "crypto/sha256"
_ "crypto/sha512"
"hash"
"io"
"strconv"
"github.com/ProtonMail/go-crypto/openpgp/armor"
"github.com/ProtonMail/go-crypto/openpgp/errors"
"github.com/ProtonMail/go-crypto/openpgp/internal/algorithm"
"github.com/ProtonMail/go-crypto/openpgp/packet"
_ "golang.org/x/crypto/sha3"
)
// SignatureType is the armor type for a PGP signature.
var SignatureType = "PGP SIGNATURE"
// readArmored reads an armored block with the given type.
func readArmored(r io.Reader, expectedType string) (body io.Reader, err error) {
block, err := armor.Decode(r)
if err != nil {
return
}
if block.Type != expectedType {
return nil, errors.InvalidArgumentError("expected '" + expectedType + "', got: " + block.Type)
}
return block.Body, nil
}
// MessageDetails contains the result of parsing an OpenPGP encrypted and/or
// signed message.
type MessageDetails struct {
IsEncrypted bool // true if the message was encrypted.
EncryptedToKeyIds []uint64 // the list of recipient key ids.
IsSymmetricallyEncrypted bool // true if a passphrase could have decrypted the message.
DecryptedWith Key // the private key used to decrypt the message, if any.
IsSigned bool // true if the message is signed.
SignedByKeyId uint64 // the key id of the signer, if any.
SignedBy *Key // the key of the signer, if available.
LiteralData *packet.LiteralData // the metadata of the contents
UnverifiedBody io.Reader // the contents of the message.
// If IsSigned is true and SignedBy is non-zero then the signature will
// be verified as UnverifiedBody is read. The signature cannot be
// checked until the whole of UnverifiedBody is read so UnverifiedBody
// must be consumed until EOF before the data can be trusted. Even if a
// message isn't signed (or the signer is unknown) the data may contain
// an authentication code that is only checked once UnverifiedBody has
// been consumed. Once EOF has been seen, the following fields are
// valid. (An authentication code failure is reported as a
// SignatureError error when reading from UnverifiedBody.)
Signature *packet.Signature // the signature packet itself.
SignatureError error // nil if the signature is good.
UnverifiedSignatures []*packet.Signature // all other unverified signature packets.
decrypted io.ReadCloser
}
// A PromptFunction is used as a callback by functions that may need to decrypt
// a private key, or prompt for a passphrase. It is called with a list of
// acceptable, encrypted private keys and a boolean that indicates whether a
// passphrase is usable. It should either decrypt a private key or return a
// passphrase to try. If the decrypted private key or given passphrase isn't
// correct, the function will be called again, forever. Any error returned will
// be passed up.
type PromptFunction func(keys []Key, symmetric bool) ([]byte, error)
// A keyEnvelopePair is used to store a private key with the envelope that
// contains a symmetric key, encrypted with that key.
type keyEnvelopePair struct {
key Key
encryptedKey *packet.EncryptedKey
}
// ReadMessage parses an OpenPGP message that may be signed and/or encrypted.
// The given KeyRing should contain both public keys (for signature
// verification) and, possibly encrypted, private keys for decrypting.
// If config is nil, sensible defaults will be used.
func ReadMessage(r io.Reader, keyring KeyRing, prompt PromptFunction, config *packet.Config) (md *MessageDetails, err error) {
var p packet.Packet
var symKeys []*packet.SymmetricKeyEncrypted
var pubKeys []keyEnvelopePair
// Integrity protected encrypted packet: SymmetricallyEncrypted or AEADEncrypted
var edp packet.EncryptedDataPacket
packets := packet.NewReader(r)
md = new(MessageDetails)
md.IsEncrypted = true
// The message, if encrypted, starts with a number of packets
// containing an encrypted decryption key. The decryption key is either
// encrypted to a public key, or with a passphrase. This loop
// collects these packets.
ParsePackets:
for {
p, err = packets.Next()
if err != nil {
return nil, err
}
switch p := p.(type) {
case *packet.SymmetricKeyEncrypted:
// This packet contains the decryption key encrypted with a passphrase.
md.IsSymmetricallyEncrypted = true
symKeys = append(symKeys, p)
case *packet.EncryptedKey:
// This packet contains the decryption key encrypted to a public key.
md.EncryptedToKeyIds = append(md.EncryptedToKeyIds, p.KeyId)
switch p.Algo {
case packet.PubKeyAlgoRSA, packet.PubKeyAlgoRSAEncryptOnly, packet.PubKeyAlgoElGamal, packet.PubKeyAlgoECDH:
break
default:
continue
}
if keyring != nil {
var keys []Key
if p.KeyId == 0 {
keys = keyring.DecryptionKeys()
} else {
keys = keyring.KeysById(p.KeyId)
}
for _, k := range keys {
pubKeys = append(pubKeys, keyEnvelopePair{k, p})
}
}
case *packet.SymmetricallyEncrypted:
if !p.IntegrityProtected && !config.AllowUnauthenticatedMessages() {
return nil, errors.UnsupportedError("message is not integrity protected")
}
edp = p
break ParsePackets
case *packet.AEADEncrypted:
edp = p
break ParsePackets
case *packet.Compressed, *packet.LiteralData, *packet.OnePassSignature:
// This message isn't encrypted.
if len(symKeys) != 0 || len(pubKeys) != 0 {
return nil, errors.StructuralError("key material not followed by encrypted message")
}
packets.Unread(p)
return readSignedMessage(packets, nil, keyring, config)
}
}
var candidates []Key
var decrypted io.ReadCloser
// Now that we have the list of encrypted keys we need to decrypt at
// least one of them or, if we cannot, we need to call the prompt
// function so that it can decrypt a key or give us a passphrase.
FindKey:
for {
// See if any of the keys already have a private key available
candidates = candidates[:0]
candidateFingerprints := make(map[string]bool)
for _, pk := range pubKeys {
if pk.key.PrivateKey == nil {
continue
}
if !pk.key.PrivateKey.Encrypted {
if len(pk.encryptedKey.Key) == 0 {
errDec := pk.encryptedKey.Decrypt(pk.key.PrivateKey, config)
if errDec != nil {
continue
}
}
// Try to decrypt symmetrically encrypted
decrypted, err = edp.Decrypt(pk.encryptedKey.CipherFunc, pk.encryptedKey.Key)
if err != nil && err != errors.ErrKeyIncorrect {
return nil, err
}
if decrypted != nil {
md.DecryptedWith = pk.key
break FindKey
}
} else {
fpr := string(pk.key.PublicKey.Fingerprint[:])
if v := candidateFingerprints[fpr]; v {
continue
}
candidates = append(candidates, pk.key)
candidateFingerprints[fpr] = true
}
}
if len(candidates) == 0 && len(symKeys) == 0 {
return nil, errors.ErrKeyIncorrect
}
if prompt == nil {
return nil, errors.ErrKeyIncorrect
}
passphrase, err := prompt(candidates, len(symKeys) != 0)
if err != nil {
return nil, err
}
// Try the symmetric passphrase first
if len(symKeys) != 0 && passphrase != nil {
for _, s := range symKeys {
key, cipherFunc, err := s.Decrypt(passphrase)
// In v4, on wrong passphrase, session key decryption is very likely to result in an invalid cipherFunc:
// only for < 5% of cases we will proceed to decrypt the data
if err == nil {
decrypted, err = edp.Decrypt(cipherFunc, key)
if err != nil {
return nil, err
}
if decrypted != nil {
break FindKey
}
}
}
}
}
md.decrypted = decrypted
if err := packets.Push(decrypted); err != nil {
return nil, err
}
mdFinal, sensitiveParsingErr := readSignedMessage(packets, md, keyring, config)
if sensitiveParsingErr != nil {
return nil, errors.StructuralError("parsing error")
}
return mdFinal, nil
}
// readSignedMessage reads a possibly signed message if mdin is non-zero then
// that structure is updated and returned. Otherwise a fresh MessageDetails is
// used.
func readSignedMessage(packets *packet.Reader, mdin *MessageDetails, keyring KeyRing, config *packet.Config) (md *MessageDetails, err error) {
if mdin == nil {
mdin = new(MessageDetails)
}
md = mdin
var p packet.Packet
var h hash.Hash
var wrappedHash hash.Hash
var prevLast bool
FindLiteralData:
for {
p, err = packets.Next()
if err != nil {
return nil, err
}
switch p := p.(type) {
case *packet.Compressed:
if err := packets.Push(p.Body); err != nil {
return nil, err
}
case *packet.OnePassSignature:
if prevLast {
return nil, errors.UnsupportedError("nested signature packets")
}
if p.IsLast {
prevLast = true
}
h, wrappedHash, err = hashForSignature(p.Hash, p.SigType)
if err != nil {
md.SignatureError = err
}
md.IsSigned = true
md.SignedByKeyId = p.KeyId
if keyring != nil {
keys := keyring.KeysByIdUsage(p.KeyId, packet.KeyFlagSign)
if len(keys) > 0 {
md.SignedBy = &keys[0]
}
}
case *packet.LiteralData:
md.LiteralData = p
break FindLiteralData
}
}
if md.IsSigned && md.SignatureError == nil {
md.UnverifiedBody = &signatureCheckReader{packets, h, wrappedHash, md, config}
} else if md.decrypted != nil {
md.UnverifiedBody = checkReader{md}
} else {
md.UnverifiedBody = md.LiteralData.Body
}
return md, nil
}
// hashForSignature returns a pair of hashes that can be used to verify a
// signature. The signature may specify that the contents of the signed message
// should be preprocessed (i.e. to normalize line endings). Thus this function
// returns two hashes. The second should be used to hash the message itself and
// performs any needed preprocessing.
func hashForSignature(hashFunc crypto.Hash, sigType packet.SignatureType) (hash.Hash, hash.Hash, error) {
if _, ok := algorithm.HashToHashIdWithSha1(hashFunc); !ok {
return nil, nil, errors.UnsupportedError("unsupported hash function")
}
if !hashFunc.Available() {
return nil, nil, errors.UnsupportedError("hash not available: " + strconv.Itoa(int(hashFunc)))
}
h := hashFunc.New()
switch sigType {
case packet.SigTypeBinary:
return h, h, nil
case packet.SigTypeText:
return h, NewCanonicalTextHash(h), nil
}
return nil, nil, errors.UnsupportedError("unsupported signature type: " + strconv.Itoa(int(sigType)))
}
// checkReader wraps an io.Reader from a LiteralData packet. When it sees EOF
// it closes the ReadCloser from any SymmetricallyEncrypted packet to trigger
// MDC checks.
type checkReader struct {
md *MessageDetails
}
func (cr checkReader) Read(buf []byte) (int, error) {
n, sensitiveParsingError := cr.md.LiteralData.Body.Read(buf)
if sensitiveParsingError == io.EOF {
mdcErr := cr.md.decrypted.Close()
if mdcErr != nil {
return n, mdcErr
}
return n, io.EOF
}
if sensitiveParsingError != nil {
return n, errors.StructuralError("parsing error")
}
return n, nil
}
// signatureCheckReader wraps an io.Reader from a LiteralData packet and hashes
// the data as it is read. When it sees an EOF from the underlying io.Reader
// it parses and checks a trailing Signature packet and triggers any MDC checks.
type signatureCheckReader struct {
packets *packet.Reader
h, wrappedHash hash.Hash
md *MessageDetails
config *packet.Config
}
func (scr *signatureCheckReader) Read(buf []byte) (int, error) {
n, sensitiveParsingError := scr.md.LiteralData.Body.Read(buf)
// Hash only if required
if scr.md.SignedBy != nil {
scr.wrappedHash.Write(buf[:n])
}
if sensitiveParsingError == io.EOF {
var p packet.Packet
var readError error
var sig *packet.Signature
p, readError = scr.packets.Next()
for readError == nil {
var ok bool
if sig, ok = p.(*packet.Signature); ok {
if sig.Version == 5 && (sig.SigType == 0x00 || sig.SigType == 0x01) {
sig.Metadata = scr.md.LiteralData
}
// If signature KeyID matches
if scr.md.SignedBy != nil && *sig.IssuerKeyId == scr.md.SignedByKeyId {
key := scr.md.SignedBy
signatureError := key.PublicKey.VerifySignature(scr.h, sig)
if signatureError == nil {
signatureError = checkSignatureDetails(key, sig, scr.config)
}
scr.md.Signature = sig
scr.md.SignatureError = signatureError
} else {
scr.md.UnverifiedSignatures = append(scr.md.UnverifiedSignatures, sig)
}
}
p, readError = scr.packets.Next()
}
if scr.md.SignedBy != nil && scr.md.Signature == nil {
if scr.md.UnverifiedSignatures == nil {
scr.md.SignatureError = errors.StructuralError("LiteralData not followed by signature")
} else {
scr.md.SignatureError = errors.StructuralError("No matching signature found")
}
}
// The SymmetricallyEncrypted packet, if any, might have an
// unsigned hash of its own. In order to check this we need to
// close that Reader.
if scr.md.decrypted != nil {
mdcErr := scr.md.decrypted.Close()
if mdcErr != nil {
return n, mdcErr
}
}
return n, io.EOF
}
if sensitiveParsingError != nil {
return n, errors.StructuralError("parsing error")
}
return n, nil
}
// VerifyDetachedSignature takes a signed file and a detached signature and
// returns the signature packet and the entity the signature was signed by,
// if any, and a possible signature verification error.
// If the signer isn't known, ErrUnknownIssuer is returned.
func VerifyDetachedSignature(keyring KeyRing, signed, signature io.Reader, config *packet.Config) (sig *packet.Signature, signer *Entity, err error) {
var expectedHashes []crypto.Hash
return verifyDetachedSignature(keyring, signed, signature, expectedHashes, config)
}
// VerifyDetachedSignatureAndHash performs the same actions as
// VerifyDetachedSignature and checks that the expected hash functions were used.
func VerifyDetachedSignatureAndHash(keyring KeyRing, signed, signature io.Reader, expectedHashes []crypto.Hash, config *packet.Config) (sig *packet.Signature, signer *Entity, err error) {
return verifyDetachedSignature(keyring, signed, signature, expectedHashes, config)
}
// CheckDetachedSignature takes a signed file and a detached signature and
// returns the entity the signature was signed by, if any, and a possible
// signature verification error. If the signer isn't known,
// ErrUnknownIssuer is returned.
func CheckDetachedSignature(keyring KeyRing, signed, signature io.Reader, config *packet.Config) (signer *Entity, err error) {
var expectedHashes []crypto.Hash
return CheckDetachedSignatureAndHash(keyring, signed, signature, expectedHashes, config)
}
// CheckDetachedSignatureAndHash performs the same actions as
// CheckDetachedSignature and checks that the expected hash functions were used.
func CheckDetachedSignatureAndHash(keyring KeyRing, signed, signature io.Reader, expectedHashes []crypto.Hash, config *packet.Config) (signer *Entity, err error) {
_, signer, err = verifyDetachedSignature(keyring, signed, signature, expectedHashes, config)
return
}
func verifyDetachedSignature(keyring KeyRing, signed, signature io.Reader, expectedHashes []crypto.Hash, config *packet.Config) (sig *packet.Signature, signer *Entity, err error) {
var issuerKeyId uint64
var hashFunc crypto.Hash
var sigType packet.SignatureType
var keys []Key
var p packet.Packet
expectedHashesLen := len(expectedHashes)
packets := packet.NewReader(signature)
for {
p, err = packets.Next()
if err == io.EOF {
return nil, nil, errors.ErrUnknownIssuer
}
if err != nil {
return nil, nil, err
}
var ok bool
sig, ok = p.(*packet.Signature)
if !ok {
return nil, nil, errors.StructuralError("non signature packet found")
}
if sig.IssuerKeyId == nil {
return nil, nil, errors.StructuralError("signature doesn't have an issuer")
}
issuerKeyId = *sig.IssuerKeyId
hashFunc = sig.Hash
sigType = sig.SigType
for i, expectedHash := range expectedHashes {
if hashFunc == expectedHash {
break
}
if i+1 == expectedHashesLen {
return nil, nil, errors.StructuralError("hash algorithm mismatch with cleartext message headers")
}
}
keys = keyring.KeysByIdUsage(issuerKeyId, packet.KeyFlagSign)
if len(keys) > 0 {
break
}
}
if len(keys) == 0 {
panic("unreachable")
}
h, wrappedHash, err := hashForSignature(hashFunc, sigType)
if err != nil {
return nil, nil, err
}
if _, err := io.Copy(wrappedHash, signed); err != nil && err != io.EOF {
return nil, nil, err
}
for _, key := range keys {
err = key.PublicKey.VerifySignature(h, sig)
if err == nil {
return sig, key.Entity, checkSignatureDetails(&key, sig, config)
}
}
return nil, nil, err
}
// CheckArmoredDetachedSignature performs the same actions as
// CheckDetachedSignature but expects the signature to be armored.
func CheckArmoredDetachedSignature(keyring KeyRing, signed, signature io.Reader, config *packet.Config) (signer *Entity, err error) {
body, err := readArmored(signature, SignatureType)
if err != nil {
return
}
return CheckDetachedSignature(keyring, signed, body, config)
}
// checkSignatureDetails returns an error if:
// - The signature (or one of the binding signatures mentioned below)
// has a unknown critical notation data subpacket
// - The primary key of the signing entity is revoked
// - The primary identity is revoked
// - The signature is expired
// - The primary key of the signing entity is expired according to the
// primary identity binding signature
//
// ... or, if the signature was signed by a subkey and:
// - The signing subkey is revoked
// - The signing subkey is expired according to the subkey binding signature
// - The signing subkey binding signature is expired
// - The signing subkey cross-signature is expired
//
// NOTE: The order of these checks is important, as the caller may choose to
// ignore ErrSignatureExpired or ErrKeyExpired errors, but should never
// ignore any other errors.
//
// TODO: Also return an error if:
// - The primary key is expired according to a direct-key signature
// - (For V5 keys only:) The direct-key signature (exists and) is expired
func checkSignatureDetails(key *Key, signature *packet.Signature, config *packet.Config) error {
now := config.Now()
primaryIdentity := key.Entity.PrimaryIdentity()
signedBySubKey := key.PublicKey != key.Entity.PrimaryKey
sigsToCheck := []*packet.Signature{signature, primaryIdentity.SelfSignature}
if signedBySubKey {
sigsToCheck = append(sigsToCheck, key.SelfSignature, key.SelfSignature.EmbeddedSignature)
}
for _, sig := range sigsToCheck {
for _, notation := range sig.Notations {
if notation.IsCritical && !config.KnownNotation(notation.Name) {
return errors.SignatureError("unknown critical notation: " + notation.Name)
}
}
}
if key.Entity.Revoked(now) || // primary key is revoked
(signedBySubKey && key.Revoked(now)) || // subkey is revoked
primaryIdentity.Revoked(now) { // primary identity is revoked
return errors.ErrKeyRevoked
}
if key.Entity.PrimaryKey.KeyExpired(primaryIdentity.SelfSignature, now) { // primary key is expired
return errors.ErrKeyExpired
}
if signedBySubKey {
if key.PublicKey.KeyExpired(key.SelfSignature, now) { // subkey is expired
return errors.ErrKeyExpired
}
}
for _, sig := range sigsToCheck {
if sig.SigExpired(now) { // any of the relevant signatures are expired
return errors.ErrSignatureExpired
}
}
return nil
}