mirror of
https://github.com/cheat/cheat.git
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390 lines
12 KiB
Go
390 lines
12 KiB
Go
// Copyright 2011 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 openpgp
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import (
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"crypto"
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"crypto/rand"
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"crypto/rsa"
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goerrors "errors"
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"io"
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"math/big"
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"time"
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"github.com/ProtonMail/go-crypto/openpgp/ecdh"
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"github.com/ProtonMail/go-crypto/openpgp/ecdsa"
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"github.com/ProtonMail/go-crypto/openpgp/eddsa"
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"github.com/ProtonMail/go-crypto/openpgp/errors"
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"github.com/ProtonMail/go-crypto/openpgp/internal/algorithm"
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"github.com/ProtonMail/go-crypto/openpgp/internal/ecc"
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"github.com/ProtonMail/go-crypto/openpgp/packet"
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)
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// NewEntity returns an Entity that contains a fresh RSA/RSA keypair with a
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// single identity composed of the given full name, comment and email, any of
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// which may be empty but must not contain any of "()<>\x00".
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// If config is nil, sensible defaults will be used.
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func NewEntity(name, comment, email string, config *packet.Config) (*Entity, error) {
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creationTime := config.Now()
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keyLifetimeSecs := config.KeyLifetime()
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// Generate a primary signing key
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primaryPrivRaw, err := newSigner(config)
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if err != nil {
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return nil, err
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}
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primary := packet.NewSignerPrivateKey(creationTime, primaryPrivRaw)
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if config != nil && config.V5Keys {
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primary.UpgradeToV5()
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}
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e := &Entity{
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PrimaryKey: &primary.PublicKey,
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PrivateKey: primary,
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Identities: make(map[string]*Identity),
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Subkeys: []Subkey{},
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}
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err = e.addUserId(name, comment, email, config, creationTime, keyLifetimeSecs)
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if err != nil {
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return nil, err
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}
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// NOTE: No key expiry here, but we will not return this subkey in EncryptionKey()
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// if the primary/master key has expired.
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err = e.addEncryptionSubkey(config, creationTime, 0)
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if err != nil {
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return nil, err
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}
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return e, nil
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}
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func (t *Entity) AddUserId(name, comment, email string, config *packet.Config) error {
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creationTime := config.Now()
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keyLifetimeSecs := config.KeyLifetime()
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return t.addUserId(name, comment, email, config, creationTime, keyLifetimeSecs)
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}
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func (t *Entity) addUserId(name, comment, email string, config *packet.Config, creationTime time.Time, keyLifetimeSecs uint32) error {
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uid := packet.NewUserId(name, comment, email)
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if uid == nil {
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return errors.InvalidArgumentError("user id field contained invalid characters")
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}
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if _, ok := t.Identities[uid.Id]; ok {
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return errors.InvalidArgumentError("user id exist")
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}
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primary := t.PrivateKey
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isPrimaryId := len(t.Identities) == 0
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selfSignature := createSignaturePacket(&primary.PublicKey, packet.SigTypePositiveCert, config)
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selfSignature.CreationTime = creationTime
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selfSignature.KeyLifetimeSecs = &keyLifetimeSecs
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selfSignature.IsPrimaryId = &isPrimaryId
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selfSignature.FlagsValid = true
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selfSignature.FlagSign = true
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selfSignature.FlagCertify = true
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selfSignature.SEIPDv1 = true // true by default, see 5.8 vs. 5.14
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selfSignature.SEIPDv2 = config.AEAD() != nil
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// Set the PreferredHash for the SelfSignature from the packet.Config.
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// If it is not the must-implement algorithm from rfc4880bis, append that.
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hash, ok := algorithm.HashToHashId(config.Hash())
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if !ok {
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return errors.UnsupportedError("unsupported preferred hash function")
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}
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selfSignature.PreferredHash = []uint8{hash}
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if config.Hash() != crypto.SHA256 {
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selfSignature.PreferredHash = append(selfSignature.PreferredHash, hashToHashId(crypto.SHA256))
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}
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// Likewise for DefaultCipher.
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selfSignature.PreferredSymmetric = []uint8{uint8(config.Cipher())}
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if config.Cipher() != packet.CipherAES128 {
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selfSignature.PreferredSymmetric = append(selfSignature.PreferredSymmetric, uint8(packet.CipherAES128))
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}
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// We set CompressionNone as the preferred compression algorithm because
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// of compression side channel attacks, then append the configured
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// DefaultCompressionAlgo if any is set (to signal support for cases
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// where the application knows that using compression is safe).
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selfSignature.PreferredCompression = []uint8{uint8(packet.CompressionNone)}
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if config.Compression() != packet.CompressionNone {
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selfSignature.PreferredCompression = append(selfSignature.PreferredCompression, uint8(config.Compression()))
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}
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// And for DefaultMode.
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modes := []uint8{uint8(config.AEAD().Mode())}
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if config.AEAD().Mode() != packet.AEADModeOCB {
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modes = append(modes, uint8(packet.AEADModeOCB))
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}
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// For preferred (AES256, GCM), we'll generate (AES256, GCM), (AES256, OCB), (AES128, GCM), (AES128, OCB)
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for _, cipher := range selfSignature.PreferredSymmetric {
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for _, mode := range modes {
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selfSignature.PreferredCipherSuites = append(selfSignature.PreferredCipherSuites, [2]uint8{cipher, mode})
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}
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}
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// User ID binding signature
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err := selfSignature.SignUserId(uid.Id, &primary.PublicKey, primary, config)
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if err != nil {
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return err
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}
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t.Identities[uid.Id] = &Identity{
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Name: uid.Id,
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UserId: uid,
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SelfSignature: selfSignature,
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Signatures: []*packet.Signature{selfSignature},
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}
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return nil
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}
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// AddSigningSubkey adds a signing keypair as a subkey to the Entity.
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// If config is nil, sensible defaults will be used.
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func (e *Entity) AddSigningSubkey(config *packet.Config) error {
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creationTime := config.Now()
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keyLifetimeSecs := config.KeyLifetime()
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subPrivRaw, err := newSigner(config)
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if err != nil {
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return err
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}
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sub := packet.NewSignerPrivateKey(creationTime, subPrivRaw)
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sub.IsSubkey = true
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if config != nil && config.V5Keys {
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sub.UpgradeToV5()
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}
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subkey := Subkey{
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PublicKey: &sub.PublicKey,
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PrivateKey: sub,
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}
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subkey.Sig = createSignaturePacket(e.PrimaryKey, packet.SigTypeSubkeyBinding, config)
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subkey.Sig.CreationTime = creationTime
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subkey.Sig.KeyLifetimeSecs = &keyLifetimeSecs
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subkey.Sig.FlagsValid = true
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subkey.Sig.FlagSign = true
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subkey.Sig.EmbeddedSignature = createSignaturePacket(subkey.PublicKey, packet.SigTypePrimaryKeyBinding, config)
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subkey.Sig.EmbeddedSignature.CreationTime = creationTime
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err = subkey.Sig.EmbeddedSignature.CrossSignKey(subkey.PublicKey, e.PrimaryKey, subkey.PrivateKey, config)
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if err != nil {
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return err
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}
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err = subkey.Sig.SignKey(subkey.PublicKey, e.PrivateKey, config)
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if err != nil {
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return err
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}
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e.Subkeys = append(e.Subkeys, subkey)
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return nil
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}
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// AddEncryptionSubkey adds an encryption keypair as a subkey to the Entity.
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// If config is nil, sensible defaults will be used.
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func (e *Entity) AddEncryptionSubkey(config *packet.Config) error {
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creationTime := config.Now()
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keyLifetimeSecs := config.KeyLifetime()
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return e.addEncryptionSubkey(config, creationTime, keyLifetimeSecs)
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}
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func (e *Entity) addEncryptionSubkey(config *packet.Config, creationTime time.Time, keyLifetimeSecs uint32) error {
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subPrivRaw, err := newDecrypter(config)
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if err != nil {
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return err
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}
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sub := packet.NewDecrypterPrivateKey(creationTime, subPrivRaw)
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sub.IsSubkey = true
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if config != nil && config.V5Keys {
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sub.UpgradeToV5()
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}
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subkey := Subkey{
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PublicKey: &sub.PublicKey,
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PrivateKey: sub,
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}
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subkey.Sig = createSignaturePacket(e.PrimaryKey, packet.SigTypeSubkeyBinding, config)
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subkey.Sig.CreationTime = creationTime
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subkey.Sig.KeyLifetimeSecs = &keyLifetimeSecs
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subkey.Sig.FlagsValid = true
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subkey.Sig.FlagEncryptStorage = true
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subkey.Sig.FlagEncryptCommunications = true
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err = subkey.Sig.SignKey(subkey.PublicKey, e.PrivateKey, config)
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if err != nil {
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return err
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}
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e.Subkeys = append(e.Subkeys, subkey)
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return nil
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}
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// Generates a signing key
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func newSigner(config *packet.Config) (signer interface{}, err error) {
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switch config.PublicKeyAlgorithm() {
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case packet.PubKeyAlgoRSA:
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bits := config.RSAModulusBits()
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if bits < 1024 {
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return nil, errors.InvalidArgumentError("bits must be >= 1024")
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}
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if config != nil && len(config.RSAPrimes) >= 2 {
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primes := config.RSAPrimes[0:2]
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config.RSAPrimes = config.RSAPrimes[2:]
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return generateRSAKeyWithPrimes(config.Random(), 2, bits, primes)
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}
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return rsa.GenerateKey(config.Random(), bits)
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case packet.PubKeyAlgoEdDSA:
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curve := ecc.FindEdDSAByGenName(string(config.CurveName()))
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if curve == nil {
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return nil, errors.InvalidArgumentError("unsupported curve")
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}
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priv, err := eddsa.GenerateKey(config.Random(), curve)
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if err != nil {
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return nil, err
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}
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return priv, nil
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case packet.PubKeyAlgoECDSA:
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curve := ecc.FindECDSAByGenName(string(config.CurveName()))
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if curve == nil {
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return nil, errors.InvalidArgumentError("unsupported curve")
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}
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priv, err := ecdsa.GenerateKey(config.Random(), curve)
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if err != nil {
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return nil, err
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}
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return priv, nil
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default:
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return nil, errors.InvalidArgumentError("unsupported public key algorithm")
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}
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}
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// Generates an encryption/decryption key
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func newDecrypter(config *packet.Config) (decrypter interface{}, err error) {
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switch config.PublicKeyAlgorithm() {
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case packet.PubKeyAlgoRSA:
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bits := config.RSAModulusBits()
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if bits < 1024 {
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return nil, errors.InvalidArgumentError("bits must be >= 1024")
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}
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if config != nil && len(config.RSAPrimes) >= 2 {
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primes := config.RSAPrimes[0:2]
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config.RSAPrimes = config.RSAPrimes[2:]
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return generateRSAKeyWithPrimes(config.Random(), 2, bits, primes)
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}
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return rsa.GenerateKey(config.Random(), bits)
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case packet.PubKeyAlgoEdDSA, packet.PubKeyAlgoECDSA:
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fallthrough // When passing EdDSA or ECDSA, we generate an ECDH subkey
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case packet.PubKeyAlgoECDH:
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var kdf = ecdh.KDF{
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Hash: algorithm.SHA512,
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Cipher: algorithm.AES256,
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}
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curve := ecc.FindECDHByGenName(string(config.CurveName()))
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if curve == nil {
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return nil, errors.InvalidArgumentError("unsupported curve")
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}
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return ecdh.GenerateKey(config.Random(), curve, kdf)
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default:
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return nil, errors.InvalidArgumentError("unsupported public key algorithm")
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}
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}
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var bigOne = big.NewInt(1)
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// generateRSAKeyWithPrimes generates a multi-prime RSA keypair of the
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// given bit size, using the given random source and prepopulated primes.
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func generateRSAKeyWithPrimes(random io.Reader, nprimes int, bits int, prepopulatedPrimes []*big.Int) (*rsa.PrivateKey, error) {
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priv := new(rsa.PrivateKey)
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priv.E = 65537
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if nprimes < 2 {
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return nil, goerrors.New("generateRSAKeyWithPrimes: nprimes must be >= 2")
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}
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if bits < 1024 {
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return nil, goerrors.New("generateRSAKeyWithPrimes: bits must be >= 1024")
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}
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primes := make([]*big.Int, nprimes)
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NextSetOfPrimes:
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for {
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todo := bits
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// crypto/rand should set the top two bits in each prime.
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// Thus each prime has the form
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// p_i = 2^bitlen(p_i) × 0.11... (in base 2).
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// And the product is:
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// P = 2^todo × α
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// where α is the product of nprimes numbers of the form 0.11...
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//
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// If α < 1/2 (which can happen for nprimes > 2), we need to
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// shift todo to compensate for lost bits: the mean value of 0.11...
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// is 7/8, so todo + shift - nprimes * log2(7/8) ~= bits - 1/2
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// will give good results.
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if nprimes >= 7 {
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todo += (nprimes - 2) / 5
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}
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for i := 0; i < nprimes; i++ {
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var err error
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if len(prepopulatedPrimes) == 0 {
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primes[i], err = rand.Prime(random, todo/(nprimes-i))
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if err != nil {
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return nil, err
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}
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} else {
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primes[i] = prepopulatedPrimes[0]
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prepopulatedPrimes = prepopulatedPrimes[1:]
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}
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todo -= primes[i].BitLen()
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}
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// Make sure that primes is pairwise unequal.
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for i, prime := range primes {
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for j := 0; j < i; j++ {
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if prime.Cmp(primes[j]) == 0 {
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continue NextSetOfPrimes
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}
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}
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}
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n := new(big.Int).Set(bigOne)
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totient := new(big.Int).Set(bigOne)
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pminus1 := new(big.Int)
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for _, prime := range primes {
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n.Mul(n, prime)
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pminus1.Sub(prime, bigOne)
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totient.Mul(totient, pminus1)
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}
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if n.BitLen() != bits {
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// This should never happen for nprimes == 2 because
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// crypto/rand should set the top two bits in each prime.
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// For nprimes > 2 we hope it does not happen often.
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continue NextSetOfPrimes
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}
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priv.D = new(big.Int)
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e := big.NewInt(int64(priv.E))
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ok := priv.D.ModInverse(e, totient)
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if ok != nil {
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priv.Primes = primes
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priv.N = n
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break
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}
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}
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priv.Precompute()
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return priv, nil
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}
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