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config.go
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config.go
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// 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 packet
import (
"crypto"
"crypto/rand"
"io"
"math/big"
"time"
"github.com/ProtonMail/go-crypto/openpgp/s2k"
)
var (
defaultRejectPublicKeyAlgorithms = map[PublicKeyAlgorithm]bool{
PubKeyAlgoElGamal: true,
PubKeyAlgoDSA: true,
}
defaultRejectMessageHashAlgorithms = map[crypto.Hash]bool{
crypto.SHA1: true,
crypto.MD5: true,
crypto.RIPEMD160: true,
}
defaultRejectCurves = map[Curve]bool{
CurveSecP256k1: true,
}
)
// Config collects a number of parameters along with sensible defaults.
// A nil *Config is valid and results in all default values.
type Config struct {
// Rand provides the source of entropy.
// If nil, the crypto/rand Reader is used.
Rand io.Reader
// DefaultHash is the default hash function to be used.
// If zero, SHA-256 is used.
DefaultHash crypto.Hash
// DefaultCipher is the cipher to be used.
// If zero, AES-128 is used.
DefaultCipher CipherFunction
// Time returns the current time as the number of seconds since the
// epoch. If Time is nil, time.Now is used.
Time func() time.Time
// DefaultCompressionAlgo is the compression algorithm to be
// applied to the plaintext before encryption. If zero, no
// compression is done.
DefaultCompressionAlgo CompressionAlgo
// CompressionConfig configures the compression settings.
CompressionConfig *CompressionConfig
// S2K (String to Key) config, used for key derivation in the context of secret key encryption
// and password-encrypted data.
// If nil, the default configuration is used
S2KConfig *s2k.Config
// Iteration count for Iterated S2K (String to Key).
// Only used if sk2.Mode is nil.
// This value is duplicated here from s2k.Config for backwards compatibility.
// It determines the strength of the passphrase stretching when
// the said passphrase is hashed to produce a key. S2KCount
// should be between 65536 and 65011712, inclusive. If Config
// is nil or S2KCount is 0, the value 16777216 used. Not all
// values in the above range can be represented. S2KCount will
// be rounded up to the next representable value if it cannot
// be encoded exactly. When set, it is strongly encrouraged to
// use a value that is at least 65536. See RFC 4880 Section
// 3.7.1.3.
//
// Deprecated: SK2Count should be configured in S2KConfig instead.
S2KCount int
// RSABits is the number of bits in new RSA keys made with NewEntity.
// If zero, then 2048 bit keys are created.
RSABits int
// The public key algorithm to use - will always create a signing primary
// key and encryption subkey.
Algorithm PublicKeyAlgorithm
// Some known primes that are optionally prepopulated by the caller
RSAPrimes []*big.Int
// Curve configures the desired packet.Curve if the Algorithm is PubKeyAlgoECDSA,
// PubKeyAlgoEdDSA, or PubKeyAlgoECDH. If empty Curve25519 is used.
Curve Curve
// AEADConfig configures the use of the new AEAD Encrypted Data Packet,
// defined in the draft of the next version of the OpenPGP specification.
// If a non-nil AEADConfig is passed, usage of this packet is enabled. By
// default, it is disabled. See the documentation of AEADConfig for more
// configuration options related to AEAD.
// **Note: using this option may break compatibility with other OpenPGP
// implementations, as well as future versions of this library.**
AEADConfig *AEADConfig
// V6Keys configures version 6 key generation. If false, this package still
// supports version 6 keys, but produces version 4 keys.
V6Keys bool
// Minimum RSA key size allowed for key generation and message signing, verification and encryption.
MinRSABits uint16
// Reject insecure algorithms, only works with v2 api
RejectPublicKeyAlgorithms map[PublicKeyAlgorithm]bool
RejectMessageHashAlgorithms map[crypto.Hash]bool
RejectCurves map[Curve]bool
// "The validity period of the key. This is the number of seconds after
// the key creation time that the key expires. If this is not present
// or has a value of zero, the key never expires. This is found only on
// a self-signature.""
// https://tools.ietf.org/html/rfc4880#section-5.2.3.6
KeyLifetimeSecs uint32
// "The validity period of the signature. This is the number of seconds
// after the signature creation time that the signature expires. If
// this is not present or has a value of zero, it never expires."
// https://tools.ietf.org/html/rfc4880#section-5.2.3.10
SigLifetimeSecs uint32
// SigningKeyId is used to specify the signing key to use (by Key ID).
// By default, the signing key is selected automatically, preferring
// signing subkeys if available.
SigningKeyId uint64
// SigningIdentity is used to specify a user ID (packet Signer's User ID, type 28)
// when producing a generic certification signature onto an existing user ID.
// The identity must be present in the signer Entity.
SigningIdentity string
// InsecureAllowUnauthenticatedMessages controls, whether it is tolerated to read
// encrypted messages without Modification Detection Code (MDC).
// MDC is mandated by the IETF OpenPGP Crypto Refresh draft and has long been implemented
// in most OpenPGP implementations. Messages without MDC are considered unnecessarily
// insecure and should be prevented whenever possible.
// In case one needs to deal with messages from very old OpenPGP implementations, there
// might be no other way than to tolerate the missing MDC. Setting this flag, allows this
// mode of operation. It should be considered a measure of last resort.
InsecureAllowUnauthenticatedMessages bool
// KnownNotations is a map of Notation Data names to bools, which controls
// the notation names that are allowed to be present in critical Notation Data
// signature subpackets.
KnownNotations map[string]bool
// SignatureNotations is a list of Notations to be added to any signatures.
SignatureNotations []*Notation
// CheckIntendedRecipients controls, whether the OpenPGP Intended Recipient Fingerprint feature
// should be enabled for encryption and decryption.
// (See https://www.ietf.org/archive/id/draft-ietf-openpgp-crypto-refresh-12.html#name-intended-recipient-fingerpr).
// When the flag is set, encryption produces Intended Recipient Fingerprint signature sub-packets and decryption
// checks whether the key it was encrypted to is one of the included fingerprints in the signature.
// If the flag is disabled, no Intended Recipient Fingerprint sub-packets are created or checked.
// The default behavior, when the config or flag is nil, is to enable the feature.
CheckIntendedRecipients *bool
// CacheSessionKey controls if decryption should return the session key used for decryption.
// If the flag is set, the session key is cached in the message details struct.
CacheSessionKey bool
// CheckPacketSequence is a flag that controls if the pgp message reader should strictly check
// that the packet sequence conforms with the grammar mandated by rfc4880.
// The default behavior, when the config or flag is nil, is to check the packet sequence.
CheckPacketSequence *bool
}
func (c *Config) Random() io.Reader {
if c == nil || c.Rand == nil {
return rand.Reader
}
return c.Rand
}
func (c *Config) Hash() crypto.Hash {
if c == nil || uint(c.DefaultHash) == 0 {
return crypto.SHA256
}
return c.DefaultHash
}
func (c *Config) Cipher() CipherFunction {
if c == nil || uint8(c.DefaultCipher) == 0 {
return CipherAES128
}
return c.DefaultCipher
}
func (c *Config) Now() time.Time {
if c == nil || c.Time == nil {
return time.Now().Truncate(time.Second)
}
return c.Time().Truncate(time.Second)
}
// KeyLifetime returns the validity period of the key.
func (c *Config) KeyLifetime() uint32 {
if c == nil {
return 0
}
return c.KeyLifetimeSecs
}
// SigLifetime returns the validity period of the signature.
func (c *Config) SigLifetime() uint32 {
if c == nil {
return 0
}
return c.SigLifetimeSecs
}
func (c *Config) Compression() CompressionAlgo {
if c == nil {
return CompressionNone
}
return c.DefaultCompressionAlgo
}
func (c *Config) RSAModulusBits() int {
if c == nil || c.RSABits == 0 {
return 2048
}
return c.RSABits
}
func (c *Config) PublicKeyAlgorithm() PublicKeyAlgorithm {
if c == nil || c.Algorithm == 0 {
return PubKeyAlgoRSA
}
return c.Algorithm
}
func (c *Config) CurveName() Curve {
if c == nil || c.Curve == "" {
return Curve25519
}
return c.Curve
}
// Deprecated: The hash iterations should now be queried via the S2K() method.
func (c *Config) PasswordHashIterations() int {
if c == nil || c.S2KCount == 0 {
return 0
}
return c.S2KCount
}
func (c *Config) S2K() *s2k.Config {
if c == nil {
return nil
}
// for backwards compatibility
if c != nil && c.S2KCount > 0 && c.S2KConfig == nil {
return &s2k.Config{
S2KCount: c.S2KCount,
}
}
return c.S2KConfig
}
func (c *Config) AEAD() *AEADConfig {
if c == nil {
return nil
}
return c.AEADConfig
}
func (c *Config) SigningKey() uint64 {
if c == nil {
return 0
}
return c.SigningKeyId
}
func (c *Config) SigningUserId() string {
if c == nil {
return ""
}
return c.SigningIdentity
}
func (c *Config) AllowUnauthenticatedMessages() bool {
if c == nil {
return false
}
return c.InsecureAllowUnauthenticatedMessages
}
func (c *Config) KnownNotation(notationName string) bool {
if c == nil {
return false
}
return c.KnownNotations[notationName]
}
func (c *Config) Notations() []*Notation {
if c == nil {
return nil
}
return c.SignatureNotations
}
func (c *Config) V6() bool {
if c == nil {
return false
}
return c.V6Keys
}
func (c *Config) IntendedRecipients() bool {
if c == nil || c.CheckIntendedRecipients == nil {
return true
}
return *c.CheckIntendedRecipients
}
func (c *Config) RetrieveSessionKey() bool {
if c == nil {
return false
}
return c.CacheSessionKey
}
func (c *Config) MinimumRSABits() uint16 {
if c == nil || c.MinRSABits == 0 {
return 2047
}
return c.MinRSABits
}
func (c *Config) RejectPublicKeyAlgorithm(alg PublicKeyAlgorithm) bool {
var rejectedAlgorithms map[PublicKeyAlgorithm]bool
if c == nil || c.RejectPublicKeyAlgorithms == nil {
// Default
rejectedAlgorithms = defaultRejectPublicKeyAlgorithms
} else {
rejectedAlgorithms = c.RejectPublicKeyAlgorithms
}
return rejectedAlgorithms[alg]
}
func (c *Config) RejectMessageHashAlgorithm(hash crypto.Hash) bool {
var rejectedAlgorithms map[crypto.Hash]bool
if c == nil || c.RejectMessageHashAlgorithms == nil {
// Default
rejectedAlgorithms = defaultRejectMessageHashAlgorithms
} else {
rejectedAlgorithms = c.RejectMessageHashAlgorithms
}
return rejectedAlgorithms[hash]
}
func (c *Config) RejectCurve(curve Curve) bool {
var rejectedCurve map[Curve]bool
if c == nil || c.RejectCurves == nil {
// Default
rejectedCurve = defaultRejectCurves
} else {
rejectedCurve = c.RejectCurves
}
return rejectedCurve[curve]
}
func (c *Config) StrictPacketSequence() bool {
if c == nil || c.CheckPacketSequence == nil {
return true
}
return *c.CheckPacketSequence
}