994 lines
28 KiB
Go
Vendored
994 lines
28 KiB
Go
Vendored
// 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 packet
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import (
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"bytes"
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"crypto"
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"crypto/dsa"
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"crypto/ecdsa"
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"crypto/elliptic"
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"crypto/sha1"
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_ "crypto/sha256"
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_ "crypto/sha512"
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"encoding/binary"
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"fmt"
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"hash"
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"io"
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"math/big"
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"strconv"
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"time"
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"github.com/keybase/go-crypto/brainpool"
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"github.com/keybase/go-crypto/curve25519"
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"github.com/keybase/go-crypto/ed25519"
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"github.com/keybase/go-crypto/openpgp/ecdh"
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"github.com/keybase/go-crypto/openpgp/elgamal"
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"github.com/keybase/go-crypto/openpgp/errors"
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"github.com/keybase/go-crypto/openpgp/s2k"
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"github.com/keybase/go-crypto/rsa"
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)
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var (
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// NIST curve P-224
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oidCurveP224 []byte = []byte{0x2B, 0x81, 0x04, 0x00, 0x21}
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// NIST curve P-256
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oidCurveP256 []byte = []byte{0x2A, 0x86, 0x48, 0xCE, 0x3D, 0x03, 0x01, 0x07}
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// NIST curve P-384
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oidCurveP384 []byte = []byte{0x2B, 0x81, 0x04, 0x00, 0x22}
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// NIST curve P-521
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oidCurveP521 []byte = []byte{0x2B, 0x81, 0x04, 0x00, 0x23}
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// Brainpool curve P-256r1
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oidCurveP256r1 []byte = []byte{0x2B, 0x24, 0x03, 0x03, 0x02, 0x08, 0x01, 0x01, 0x07}
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// Brainpool curve P-384r1
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oidCurveP384r1 []byte = []byte{0x2B, 0x24, 0x03, 0x03, 0x02, 0x08, 0x01, 0x01, 0x0B}
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// Brainpool curve P-512r1
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oidCurveP512r1 []byte = []byte{0x2B, 0x24, 0x03, 0x03, 0x02, 0x08, 0x01, 0x01, 0x0D}
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// EdDSA
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oidEdDSA []byte = []byte{0x2B, 0x06, 0x01, 0x04, 0x01, 0xDA, 0x47, 0x0F, 0x01}
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// cv25519
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oidCurve25519 []byte = []byte{0x2B, 0x06, 0x01, 0x04, 0x01, 0x97, 0x55, 0x01, 0x05, 0x01}
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)
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const maxOIDLength = 10
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// ecdsaKey stores the algorithm-specific fields for ECDSA keys.
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// as defined in RFC 6637, Section 9.
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type ecdsaKey struct {
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// oid contains the OID byte sequence identifying the elliptic curve used
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oid []byte
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// p contains the elliptic curve point that represents the public key
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p parsedMPI
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}
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type edDSAkey struct {
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ecdsaKey
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}
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func copyFrontFill(dst, src []byte, length int) int {
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if srcLen := len(src); srcLen < length {
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return copy(dst[length-srcLen:], src[:])
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} else {
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return copy(dst[:], src[:])
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}
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}
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func (e *edDSAkey) Verify(payload []byte, r parsedMPI, s parsedMPI) bool {
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const halfSigSize = ed25519.SignatureSize / 2
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var sig [ed25519.SignatureSize]byte
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// NOTE: The first byte is 0x40 - MPI header
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// TODO: Maybe clean the code up and use 0x40 as a header when
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// reading and keep only actual number in p field. Find out how
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// other MPIs are stored.
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key := e.p.bytes[1:]
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// Note: it may happen that R + S do not form 64-byte signature buffer that
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// ed25519 expects, but because we copy it over to an array of exact size,
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// we will always pass correctly sized slice to Verify. Slice too short
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// would make ed25519 panic().
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copyFrontFill(sig[:halfSigSize], r.bytes, halfSigSize)
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copyFrontFill(sig[halfSigSize:], s.bytes, halfSigSize)
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return ed25519.Verify(key, payload, sig[:])
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}
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// parseOID reads the OID for the curve as defined in RFC 6637, Section 9.
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func parseOID(r io.Reader) (oid []byte, err error) {
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buf := make([]byte, maxOIDLength)
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if _, err = readFull(r, buf[:1]); err != nil {
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return
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}
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oidLen := buf[0]
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if int(oidLen) > len(buf) {
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err = errors.UnsupportedError("invalid oid length: " + strconv.Itoa(int(oidLen)))
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return
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}
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oid = buf[:oidLen]
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_, err = readFull(r, oid)
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return
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}
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func (f *ecdsaKey) parse(r io.Reader) (err error) {
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if f.oid, err = parseOID(r); err != nil {
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return err
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}
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f.p.bytes, f.p.bitLength, err = readMPI(r)
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return err
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}
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func (f *ecdsaKey) serialize(w io.Writer) (err error) {
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buf := make([]byte, maxOIDLength+1)
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buf[0] = byte(len(f.oid))
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copy(buf[1:], f.oid)
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if _, err = w.Write(buf[:len(f.oid)+1]); err != nil {
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return
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}
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return writeMPIs(w, f.p)
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}
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func getCurveByOid(oid []byte) elliptic.Curve {
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switch {
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case bytes.Equal(oid, oidCurveP224):
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return elliptic.P224()
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case bytes.Equal(oid, oidCurveP256):
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return elliptic.P256()
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case bytes.Equal(oid, oidCurveP384):
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return elliptic.P384()
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case bytes.Equal(oid, oidCurveP521):
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return elliptic.P521()
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case bytes.Equal(oid, oidCurveP256r1):
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return brainpool.P256r1()
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case bytes.Equal(oid, oidCurveP384r1):
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return brainpool.P384r1()
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case bytes.Equal(oid, oidCurveP512r1):
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return brainpool.P512r1()
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case bytes.Equal(oid, oidCurve25519):
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return curve25519.Cv25519()
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default:
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return nil
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}
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}
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func (f *ecdsaKey) newECDSA() (*ecdsa.PublicKey, error) {
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var c = getCurveByOid(f.oid)
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// Curve25519 should not be used in ECDSA.
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if c == nil || bytes.Equal(f.oid, oidCurve25519) {
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return nil, errors.UnsupportedError(fmt.Sprintf("unsupported oid: %x", f.oid))
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}
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// Note: Unmarshal already checks if point is on curve.
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x, y := elliptic.Unmarshal(c, f.p.bytes)
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if x == nil {
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return nil, errors.UnsupportedError("failed to parse EC point")
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}
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return &ecdsa.PublicKey{Curve: c, X: x, Y: y}, nil
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}
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func (f *ecdsaKey) newECDH() (*ecdh.PublicKey, error) {
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var c = getCurveByOid(f.oid)
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if c == nil {
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return nil, errors.UnsupportedError(fmt.Sprintf("unsupported oid: %x", f.oid))
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}
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// ecdh.Unmarshal handles unmarshaling for all curve types. It
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// also checks if point is on curve.
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x, y := ecdh.Unmarshal(c, f.p.bytes)
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if x == nil {
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return nil, errors.UnsupportedError("failed to parse EC point")
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}
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return &ecdh.PublicKey{Curve: c, X: x, Y: y}, nil
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}
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func (f *ecdsaKey) byteLen() int {
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return 1 + len(f.oid) + 2 + len(f.p.bytes)
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}
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type kdfHashFunction byte
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type kdfAlgorithm byte
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// ecdhKdf stores key derivation function parameters
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// used for ECDH encryption. See RFC 6637, Section 9.
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type ecdhKdf struct {
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KdfHash kdfHashFunction
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KdfAlgo kdfAlgorithm
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}
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func (f *ecdhKdf) parse(r io.Reader) (err error) {
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buf := make([]byte, 1)
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if _, err = readFull(r, buf); err != nil {
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return
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}
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kdfLen := int(buf[0])
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if kdfLen < 3 {
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return errors.UnsupportedError("Unsupported ECDH KDF length: " + strconv.Itoa(kdfLen))
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}
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buf = make([]byte, kdfLen)
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if _, err = readFull(r, buf); err != nil {
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return
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}
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reserved := int(buf[0])
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f.KdfHash = kdfHashFunction(buf[1])
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f.KdfAlgo = kdfAlgorithm(buf[2])
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if reserved != 0x01 {
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return errors.UnsupportedError("Unsupported KDF reserved field: " + strconv.Itoa(reserved))
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}
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return
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}
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func (f *ecdhKdf) serialize(w io.Writer) (err error) {
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buf := make([]byte, 4)
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// See RFC 6637, Section 9, Algorithm-Specific Fields for ECDH keys.
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buf[0] = byte(0x03) // Length of the following fields
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buf[1] = byte(0x01) // Reserved for future extensions, must be 1 for now
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buf[2] = byte(f.KdfHash)
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buf[3] = byte(f.KdfAlgo)
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_, err = w.Write(buf[:])
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return
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}
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func (f *ecdhKdf) byteLen() int {
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return 4
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}
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// PublicKey represents an OpenPGP public key. See RFC 4880, section 5.5.2.
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type PublicKey struct {
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CreationTime time.Time
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PubKeyAlgo PublicKeyAlgorithm
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PublicKey interface{} // *rsa.PublicKey, *dsa.PublicKey or *ecdsa.PublicKey
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Fingerprint [20]byte
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KeyId uint64
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IsSubkey bool
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n, e, p, q, g, y parsedMPI
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// RFC 6637 fields
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ec *ecdsaKey
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ecdh *ecdhKdf
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// EdDSA fields (no RFC available), uses ecdsa scaffolding
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edk *edDSAkey
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}
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// signingKey provides a convenient abstraction over signature verification
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// for v3 and v4 public keys.
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type signingKey interface {
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SerializeSignaturePrefix(io.Writer)
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serializeWithoutHeaders(io.Writer) error
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}
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func FromBig(n *big.Int) parsedMPI {
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return parsedMPI{
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bytes: n.Bytes(),
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bitLength: uint16(n.BitLen()),
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}
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}
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func FromBytes(bytes []byte) parsedMPI {
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return parsedMPI{
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bytes: bytes,
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bitLength: uint16(8 * len(bytes)),
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}
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}
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// NewRSAPublicKey returns a PublicKey that wraps the given rsa.PublicKey.
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func NewRSAPublicKey(creationTime time.Time, pub *rsa.PublicKey) *PublicKey {
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pk := &PublicKey{
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CreationTime: creationTime,
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PubKeyAlgo: PubKeyAlgoRSA,
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PublicKey: pub,
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n: FromBig(pub.N),
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e: FromBig(big.NewInt(int64(pub.E))),
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}
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pk.setFingerPrintAndKeyId()
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return pk
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}
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// NewDSAPublicKey returns a PublicKey that wraps the given dsa.PublicKey.
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func NewDSAPublicKey(creationTime time.Time, pub *dsa.PublicKey) *PublicKey {
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pk := &PublicKey{
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CreationTime: creationTime,
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PubKeyAlgo: PubKeyAlgoDSA,
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PublicKey: pub,
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p: FromBig(pub.P),
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q: FromBig(pub.Q),
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g: FromBig(pub.G),
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y: FromBig(pub.Y),
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}
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pk.setFingerPrintAndKeyId()
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return pk
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}
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// check EdDSA public key material.
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// There is currently no RFC for it, but it doesn't mean it's not
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// implemented or in use.
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func (e *edDSAkey) check() error {
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if !bytes.Equal(e.oid, oidEdDSA) {
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return errors.UnsupportedError(fmt.Sprintf("Bad OID for EdDSA key: %v", e.oid))
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}
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if bLen := len(e.p.bytes); bLen != 33 { // 32 bytes for ed25519 key and 1 byte for 0x40 header
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return errors.UnsupportedError(fmt.Sprintf("Unexpected EdDSA public key length: %d", bLen))
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}
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return nil
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}
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// NewElGamalPublicKey returns a PublicKey that wraps the given elgamal.PublicKey.
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func NewElGamalPublicKey(creationTime time.Time, pub *elgamal.PublicKey) *PublicKey {
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pk := &PublicKey{
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CreationTime: creationTime,
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PubKeyAlgo: PubKeyAlgoElGamal,
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PublicKey: pub,
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p: FromBig(pub.P),
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g: FromBig(pub.G),
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y: FromBig(pub.Y),
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}
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pk.setFingerPrintAndKeyId()
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return pk
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}
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func getCurveOid(curve elliptic.Curve) (res []byte, err error) {
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switch curve {
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case elliptic.P224():
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res = oidCurveP224
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case elliptic.P256():
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res = oidCurveP256
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case elliptic.P384():
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res = oidCurveP384
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case elliptic.P521():
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res = oidCurveP521
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case brainpool.P256r1():
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res = oidCurveP256r1
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case brainpool.P384r1():
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res = oidCurveP384r1
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case brainpool.P512r1():
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res = oidCurveP512r1
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case curve25519.Cv25519():
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res = oidCurve25519
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default:
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err = errors.UnsupportedError("unknown curve")
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}
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return
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}
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func NewECDSAPublicKey(creationTime time.Time, pub *ecdsa.PublicKey) *PublicKey {
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pk := &PublicKey{
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CreationTime: creationTime,
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PubKeyAlgo: PubKeyAlgoECDSA,
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PublicKey: pub,
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ec: new(ecdsaKey),
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}
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oid, _ := getCurveOid(pub.Curve)
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pk.ec.oid = oid
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bs, bitLen := ecdh.Marshal(pub.Curve, pub.X, pub.Y)
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pk.ec.p.bytes = bs
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pk.ec.p.bitLength = uint16(bitLen)
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pk.setFingerPrintAndKeyId()
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return pk
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}
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func NewECDHPublicKey(creationTime time.Time, pub *ecdh.PublicKey) *PublicKey {
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pk := &PublicKey{
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CreationTime: creationTime,
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PubKeyAlgo: PubKeyAlgoECDH,
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PublicKey: pub,
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ec: new(ecdsaKey),
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}
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oid, _ := getCurveOid(pub.Curve)
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pk.ec.oid = oid
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bs, bitLen := ecdh.Marshal(pub.Curve, pub.X, pub.Y)
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pk.ec.p.bytes = bs
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pk.ec.p.bitLength = uint16(bitLen)
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hashbyte, _ := s2k.HashToHashId(crypto.SHA512)
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pk.ecdh = &ecdhKdf{
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KdfHash: kdfHashFunction(hashbyte),
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KdfAlgo: kdfAlgorithm(CipherAES256),
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}
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pk.setFingerPrintAndKeyId()
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return pk
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}
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func (pk *PublicKey) parse(r io.Reader) (err error) {
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// RFC 4880, section 5.5.2
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var buf [6]byte
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_, err = readFull(r, buf[:])
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if err != nil {
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return
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}
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if buf[0] != 4 {
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return errors.UnsupportedError("public key version")
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}
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pk.CreationTime = time.Unix(int64(uint32(buf[1])<<24|uint32(buf[2])<<16|uint32(buf[3])<<8|uint32(buf[4])), 0)
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pk.PubKeyAlgo = PublicKeyAlgorithm(buf[5])
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switch pk.PubKeyAlgo {
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case PubKeyAlgoRSA, PubKeyAlgoRSAEncryptOnly, PubKeyAlgoRSASignOnly:
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err = pk.parseRSA(r)
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case PubKeyAlgoDSA:
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err = pk.parseDSA(r)
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case PubKeyAlgoElGamal:
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err = pk.parseElGamal(r)
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case PubKeyAlgoEdDSA:
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pk.edk = new(edDSAkey)
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if err = pk.edk.parse(r); err != nil {
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return err
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}
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err = pk.edk.check()
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if err == nil {
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pk.PublicKey = ed25519.PublicKey(pk.edk.p.bytes[1:])
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}
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case PubKeyAlgoECDSA:
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pk.ec = new(ecdsaKey)
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if err = pk.ec.parse(r); err != nil {
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return err
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}
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pk.PublicKey, err = pk.ec.newECDSA()
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case PubKeyAlgoECDH:
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pk.ec = new(ecdsaKey)
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if err = pk.ec.parse(r); err != nil {
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return
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}
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pk.ecdh = new(ecdhKdf)
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if err = pk.ecdh.parse(r); err != nil {
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return
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}
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pk.PublicKey, err = pk.ec.newECDH()
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case PubKeyAlgoBadElGamal:
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// Key has ElGamal format but nil-implementation - it will
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// load but it's not possible to do any operations using this
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// key.
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err = pk.parseElGamal(r)
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if err != nil {
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pk.PublicKey = nil
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}
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default:
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err = errors.UnsupportedError("public key type: " + strconv.Itoa(int(pk.PubKeyAlgo)))
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}
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if err != nil {
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return
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}
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pk.setFingerPrintAndKeyId()
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return
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}
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func (pk *PublicKey) setFingerPrintAndKeyId() {
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// RFC 4880, section 12.2
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fingerPrint := sha1.New()
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pk.SerializeSignaturePrefix(fingerPrint)
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pk.serializeWithoutHeaders(fingerPrint)
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copy(pk.Fingerprint[:], fingerPrint.Sum(nil))
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pk.KeyId = binary.BigEndian.Uint64(pk.Fingerprint[12:20])
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}
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// parseRSA parses RSA public key material from the given Reader. See RFC 4880,
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// section 5.5.2.
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func (pk *PublicKey) parseRSA(r io.Reader) (err error) {
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pk.n.bytes, pk.n.bitLength, err = readMPI(r)
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if err != nil {
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return
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}
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pk.e.bytes, pk.e.bitLength, err = readMPI(r)
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if err != nil {
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return
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}
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|
|
if len(pk.e.bytes) > 7 {
|
|
err = errors.UnsupportedError("large public exponent")
|
|
return
|
|
}
|
|
rsa := &rsa.PublicKey{
|
|
N: new(big.Int).SetBytes(pk.n.bytes),
|
|
E: 0,
|
|
}
|
|
// Warning: incompatibility with crypto/rsa: keybase fork uses
|
|
// int64 public exponents instead of int32.
|
|
for i := 0; i < len(pk.e.bytes); i++ {
|
|
rsa.E <<= 8
|
|
rsa.E |= int64(pk.e.bytes[i])
|
|
}
|
|
pk.PublicKey = rsa
|
|
return
|
|
}
|
|
|
|
// parseDSA parses DSA public key material from the given Reader. See RFC 4880,
|
|
// section 5.5.2.
|
|
func (pk *PublicKey) parseDSA(r io.Reader) (err error) {
|
|
pk.p.bytes, pk.p.bitLength, err = readMPI(r)
|
|
if err != nil {
|
|
return
|
|
}
|
|
pk.q.bytes, pk.q.bitLength, err = readMPI(r)
|
|
if err != nil {
|
|
return
|
|
}
|
|
pk.g.bytes, pk.g.bitLength, err = readMPI(r)
|
|
if err != nil {
|
|
return
|
|
}
|
|
pk.y.bytes, pk.y.bitLength, err = readMPI(r)
|
|
if err != nil {
|
|
return
|
|
}
|
|
|
|
dsa := new(dsa.PublicKey)
|
|
dsa.P = new(big.Int).SetBytes(pk.p.bytes)
|
|
dsa.Q = new(big.Int).SetBytes(pk.q.bytes)
|
|
dsa.G = new(big.Int).SetBytes(pk.g.bytes)
|
|
dsa.Y = new(big.Int).SetBytes(pk.y.bytes)
|
|
pk.PublicKey = dsa
|
|
return
|
|
}
|
|
|
|
// parseElGamal parses ElGamal public key material from the given Reader. See
|
|
// RFC 4880, section 5.5.2.
|
|
func (pk *PublicKey) parseElGamal(r io.Reader) (err error) {
|
|
pk.p.bytes, pk.p.bitLength, err = readMPI(r)
|
|
if err != nil {
|
|
return
|
|
}
|
|
pk.g.bytes, pk.g.bitLength, err = readMPI(r)
|
|
if err != nil {
|
|
return
|
|
}
|
|
pk.y.bytes, pk.y.bitLength, err = readMPI(r)
|
|
if err != nil {
|
|
return
|
|
}
|
|
|
|
elgamal := new(elgamal.PublicKey)
|
|
elgamal.P = new(big.Int).SetBytes(pk.p.bytes)
|
|
elgamal.G = new(big.Int).SetBytes(pk.g.bytes)
|
|
elgamal.Y = new(big.Int).SetBytes(pk.y.bytes)
|
|
pk.PublicKey = elgamal
|
|
return
|
|
}
|
|
|
|
// SerializeSignaturePrefix writes the prefix for this public key to the given Writer.
|
|
// The prefix is used when calculating a signature over this public key. See
|
|
// RFC 4880, section 5.2.4.
|
|
func (pk *PublicKey) SerializeSignaturePrefix(h io.Writer) {
|
|
var pLength uint16
|
|
switch pk.PubKeyAlgo {
|
|
case PubKeyAlgoRSA, PubKeyAlgoRSAEncryptOnly, PubKeyAlgoRSASignOnly:
|
|
pLength += 2 + uint16(len(pk.n.bytes))
|
|
pLength += 2 + uint16(len(pk.e.bytes))
|
|
case PubKeyAlgoDSA:
|
|
pLength += 2 + uint16(len(pk.p.bytes))
|
|
pLength += 2 + uint16(len(pk.q.bytes))
|
|
pLength += 2 + uint16(len(pk.g.bytes))
|
|
pLength += 2 + uint16(len(pk.y.bytes))
|
|
case PubKeyAlgoElGamal, PubKeyAlgoBadElGamal:
|
|
pLength += 2 + uint16(len(pk.p.bytes))
|
|
pLength += 2 + uint16(len(pk.g.bytes))
|
|
pLength += 2 + uint16(len(pk.y.bytes))
|
|
case PubKeyAlgoECDSA:
|
|
pLength += uint16(pk.ec.byteLen())
|
|
case PubKeyAlgoECDH:
|
|
pLength += uint16(pk.ec.byteLen())
|
|
pLength += uint16(pk.ecdh.byteLen())
|
|
case PubKeyAlgoEdDSA:
|
|
pLength += uint16(pk.edk.byteLen())
|
|
default:
|
|
panic("unknown public key algorithm")
|
|
}
|
|
pLength += 6
|
|
h.Write([]byte{0x99, byte(pLength >> 8), byte(pLength)})
|
|
return
|
|
}
|
|
|
|
func (pk *PublicKey) Serialize(w io.Writer) (err error) {
|
|
length := 6 // 6 byte header
|
|
|
|
switch pk.PubKeyAlgo {
|
|
case PubKeyAlgoRSA, PubKeyAlgoRSAEncryptOnly, PubKeyAlgoRSASignOnly:
|
|
length += 2 + len(pk.n.bytes)
|
|
length += 2 + len(pk.e.bytes)
|
|
case PubKeyAlgoDSA:
|
|
length += 2 + len(pk.p.bytes)
|
|
length += 2 + len(pk.q.bytes)
|
|
length += 2 + len(pk.g.bytes)
|
|
length += 2 + len(pk.y.bytes)
|
|
case PubKeyAlgoElGamal, PubKeyAlgoBadElGamal:
|
|
length += 2 + len(pk.p.bytes)
|
|
length += 2 + len(pk.g.bytes)
|
|
length += 2 + len(pk.y.bytes)
|
|
case PubKeyAlgoECDSA:
|
|
length += pk.ec.byteLen()
|
|
case PubKeyAlgoECDH:
|
|
length += pk.ec.byteLen()
|
|
length += pk.ecdh.byteLen()
|
|
case PubKeyAlgoEdDSA:
|
|
length += pk.edk.byteLen()
|
|
default:
|
|
panic("unknown public key algorithm")
|
|
}
|
|
|
|
packetType := packetTypePublicKey
|
|
if pk.IsSubkey {
|
|
packetType = packetTypePublicSubkey
|
|
}
|
|
err = serializeHeader(w, packetType, length)
|
|
if err != nil {
|
|
return
|
|
}
|
|
return pk.serializeWithoutHeaders(w)
|
|
}
|
|
|
|
// serializeWithoutHeaders marshals the PublicKey to w in the form of an
|
|
// OpenPGP public key packet, not including the packet header.
|
|
func (pk *PublicKey) serializeWithoutHeaders(w io.Writer) (err error) {
|
|
var buf [6]byte
|
|
buf[0] = 4
|
|
t := uint32(pk.CreationTime.Unix())
|
|
buf[1] = byte(t >> 24)
|
|
buf[2] = byte(t >> 16)
|
|
buf[3] = byte(t >> 8)
|
|
buf[4] = byte(t)
|
|
buf[5] = byte(pk.PubKeyAlgo)
|
|
|
|
_, err = w.Write(buf[:])
|
|
if err != nil {
|
|
return
|
|
}
|
|
|
|
switch pk.PubKeyAlgo {
|
|
case PubKeyAlgoRSA, PubKeyAlgoRSAEncryptOnly, PubKeyAlgoRSASignOnly:
|
|
return writeMPIs(w, pk.n, pk.e)
|
|
case PubKeyAlgoDSA:
|
|
return writeMPIs(w, pk.p, pk.q, pk.g, pk.y)
|
|
case PubKeyAlgoElGamal, PubKeyAlgoBadElGamal:
|
|
return writeMPIs(w, pk.p, pk.g, pk.y)
|
|
case PubKeyAlgoECDSA:
|
|
return pk.ec.serialize(w)
|
|
case PubKeyAlgoEdDSA:
|
|
return pk.edk.serialize(w)
|
|
case PubKeyAlgoECDH:
|
|
if err = pk.ec.serialize(w); err != nil {
|
|
return
|
|
}
|
|
return pk.ecdh.serialize(w)
|
|
}
|
|
return errors.InvalidArgumentError("bad public-key algorithm")
|
|
}
|
|
|
|
// CanSign returns true iff this public key can generate signatures
|
|
func (pk *PublicKey) CanSign() bool {
|
|
return pk.PubKeyAlgo != PubKeyAlgoRSAEncryptOnly && pk.PubKeyAlgo != PubKeyAlgoElGamal
|
|
}
|
|
|
|
// VerifySignature returns nil iff sig is a valid signature, made by this
|
|
// public key, of the data hashed into signed. signed is mutated by this call.
|
|
func (pk *PublicKey) VerifySignature(signed hash.Hash, sig *Signature) (err error) {
|
|
if !pk.CanSign() {
|
|
return errors.InvalidArgumentError("public key cannot generate signatures")
|
|
}
|
|
|
|
signed.Write(sig.HashSuffix)
|
|
hashBytes := signed.Sum(nil)
|
|
|
|
// NOTE(maxtaco) 2016-08-22
|
|
//
|
|
// We used to do this:
|
|
//
|
|
// if hashBytes[0] != sig.HashTag[0] || hashBytes[1] != sig.HashTag[1] {
|
|
// return errors.SignatureError("hash tag doesn't match")
|
|
// }
|
|
//
|
|
// But don't do anything in this case. Some GPGs generate bad
|
|
// 2-byte hash prefixes, but GPG also doesn't seem to care on
|
|
// import. See BrentMaxwell's key. I think it's safe to disable
|
|
// this check!
|
|
|
|
if pk.PubKeyAlgo != sig.PubKeyAlgo {
|
|
return errors.InvalidArgumentError("public key and signature use different algorithms")
|
|
}
|
|
|
|
switch pk.PubKeyAlgo {
|
|
case PubKeyAlgoRSA, PubKeyAlgoRSASignOnly:
|
|
rsaPublicKey, _ := pk.PublicKey.(*rsa.PublicKey)
|
|
err = rsa.VerifyPKCS1v15(rsaPublicKey, sig.Hash, hashBytes, padToKeySize(rsaPublicKey, sig.RSASignature.bytes))
|
|
if err != nil {
|
|
return errors.SignatureError("RSA verification failure")
|
|
}
|
|
return nil
|
|
case PubKeyAlgoDSA:
|
|
dsaPublicKey, _ := pk.PublicKey.(*dsa.PublicKey)
|
|
// Need to truncate hashBytes to match FIPS 186-3 section 4.6.
|
|
subgroupSize := (dsaPublicKey.Q.BitLen() + 7) / 8
|
|
if len(hashBytes) > subgroupSize {
|
|
hashBytes = hashBytes[:subgroupSize]
|
|
}
|
|
if !dsa.Verify(dsaPublicKey, hashBytes, new(big.Int).SetBytes(sig.DSASigR.bytes), new(big.Int).SetBytes(sig.DSASigS.bytes)) {
|
|
return errors.SignatureError("DSA verification failure")
|
|
}
|
|
return nil
|
|
case PubKeyAlgoECDSA:
|
|
ecdsaPublicKey := pk.PublicKey.(*ecdsa.PublicKey)
|
|
if !ecdsa.Verify(ecdsaPublicKey, hashBytes, new(big.Int).SetBytes(sig.ECDSASigR.bytes), new(big.Int).SetBytes(sig.ECDSASigS.bytes)) {
|
|
return errors.SignatureError("ECDSA verification failure")
|
|
}
|
|
return nil
|
|
case PubKeyAlgoEdDSA:
|
|
if !pk.edk.Verify(hashBytes, sig.EdDSASigR, sig.EdDSASigS) {
|
|
return errors.SignatureError("EdDSA verification failure")
|
|
}
|
|
return nil
|
|
default:
|
|
return errors.SignatureError("Unsupported public key algorithm used in signature")
|
|
}
|
|
panic("unreachable")
|
|
}
|
|
|
|
// VerifySignatureV3 returns nil iff sig is a valid signature, made by this
|
|
// public key, of the data hashed into signed. signed is mutated by this call.
|
|
func (pk *PublicKey) VerifySignatureV3(signed hash.Hash, sig *SignatureV3) (err error) {
|
|
if !pk.CanSign() {
|
|
return errors.InvalidArgumentError("public key cannot generate signatures")
|
|
}
|
|
|
|
suffix := make([]byte, 5)
|
|
suffix[0] = byte(sig.SigType)
|
|
binary.BigEndian.PutUint32(suffix[1:], uint32(sig.CreationTime.Unix()))
|
|
signed.Write(suffix)
|
|
hashBytes := signed.Sum(nil)
|
|
|
|
if hashBytes[0] != sig.HashTag[0] || hashBytes[1] != sig.HashTag[1] {
|
|
return errors.SignatureError("hash tag doesn't match")
|
|
}
|
|
|
|
if pk.PubKeyAlgo != sig.PubKeyAlgo {
|
|
return errors.InvalidArgumentError("public key and signature use different algorithms")
|
|
}
|
|
|
|
switch pk.PubKeyAlgo {
|
|
case PubKeyAlgoRSA, PubKeyAlgoRSASignOnly:
|
|
rsaPublicKey := pk.PublicKey.(*rsa.PublicKey)
|
|
if err = rsa.VerifyPKCS1v15(rsaPublicKey, sig.Hash, hashBytes, padToKeySize(rsaPublicKey, sig.RSASignature.bytes)); err != nil {
|
|
return errors.SignatureError("RSA verification failure")
|
|
}
|
|
return
|
|
case PubKeyAlgoDSA:
|
|
dsaPublicKey := pk.PublicKey.(*dsa.PublicKey)
|
|
// Need to truncate hashBytes to match FIPS 186-3 section 4.6.
|
|
subgroupSize := (dsaPublicKey.Q.BitLen() + 7) / 8
|
|
if len(hashBytes) > subgroupSize {
|
|
hashBytes = hashBytes[:subgroupSize]
|
|
}
|
|
if !dsa.Verify(dsaPublicKey, hashBytes, new(big.Int).SetBytes(sig.DSASigR.bytes), new(big.Int).SetBytes(sig.DSASigS.bytes)) {
|
|
return errors.SignatureError("DSA verification failure")
|
|
}
|
|
return nil
|
|
default:
|
|
panic("shouldn't happen")
|
|
}
|
|
panic("unreachable")
|
|
}
|
|
|
|
// keySignatureHash returns a Hash of the message that needs to be signed for
|
|
// pk to assert a subkey relationship to signed.
|
|
func keySignatureHash(pk, signed signingKey, hashFunc crypto.Hash) (h hash.Hash, err error) {
|
|
if !hashFunc.Available() {
|
|
return nil, errors.UnsupportedError("hash function")
|
|
}
|
|
h = hashFunc.New()
|
|
|
|
updateKeySignatureHash(pk, signed, h)
|
|
|
|
return
|
|
}
|
|
|
|
// updateKeySignatureHash does the actual hash updates for keySignatureHash.
|
|
func updateKeySignatureHash(pk, signed signingKey, h hash.Hash) {
|
|
// RFC 4880, section 5.2.4
|
|
pk.SerializeSignaturePrefix(h)
|
|
pk.serializeWithoutHeaders(h)
|
|
signed.SerializeSignaturePrefix(h)
|
|
signed.serializeWithoutHeaders(h)
|
|
}
|
|
|
|
// VerifyKeySignature returns nil iff sig is a valid signature, made by this
|
|
// public key, of signed.
|
|
func (pk *PublicKey) VerifyKeySignature(signed *PublicKey, sig *Signature) error {
|
|
h, err := keySignatureHash(pk, signed, sig.Hash)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
if err = pk.VerifySignature(h, sig); err != nil {
|
|
return err
|
|
}
|
|
|
|
if sig.FlagSign {
|
|
|
|
// BUG(maxtaco)
|
|
//
|
|
// We should check for more than FlagsSign here, because if
|
|
// you read keys.go, we can sometimes use signing subkeys even if they're
|
|
// not explicitly flagged as such. However, so doing fails lots of currently
|
|
// working tests, so I'm not going to do much here.
|
|
//
|
|
// In other words, we should have this disjunction in the condition above:
|
|
//
|
|
// || (!sig.FlagsValid && pk.PubKeyAlgo.CanSign()) {
|
|
//
|
|
|
|
// Signing subkeys must be cross-signed. See
|
|
// https://www.gnupg.org/faq/subkey-cross-certify.html.
|
|
if sig.EmbeddedSignature == nil {
|
|
return errors.StructuralError("signing subkey is missing cross-signature")
|
|
}
|
|
// Verify the cross-signature. This is calculated over the same
|
|
// data as the main signature, so we cannot just recursively
|
|
// call signed.VerifyKeySignature(...)
|
|
if h, err = keySignatureHash(pk, signed, sig.EmbeddedSignature.Hash); err != nil {
|
|
return errors.StructuralError("error while hashing for cross-signature: " + err.Error())
|
|
}
|
|
if err := signed.VerifySignature(h, sig.EmbeddedSignature); err != nil {
|
|
return errors.StructuralError("error while verifying cross-signature: " + err.Error())
|
|
}
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
func keyRevocationHash(pk signingKey, hashFunc crypto.Hash) (h hash.Hash, err error) {
|
|
if !hashFunc.Available() {
|
|
return nil, errors.UnsupportedError("hash function")
|
|
}
|
|
h = hashFunc.New()
|
|
|
|
// RFC 4880, section 5.2.4
|
|
pk.SerializeSignaturePrefix(h)
|
|
pk.serializeWithoutHeaders(h)
|
|
|
|
return
|
|
}
|
|
|
|
// VerifyRevocationSignature returns nil iff sig is a valid signature, made by this
|
|
// public key.
|
|
func (pk *PublicKey) VerifyRevocationSignature(revokedKey *PublicKey, sig *Signature) (err error) {
|
|
h, err := keyRevocationHash(revokedKey, sig.Hash)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
return pk.VerifySignature(h, sig)
|
|
}
|
|
|
|
type teeHash struct {
|
|
h hash.Hash
|
|
}
|
|
|
|
func (t teeHash) Write(b []byte) (n int, err error) {
|
|
fmt.Printf("hash -> %s %+v\n", string(b), b)
|
|
return t.h.Write(b)
|
|
}
|
|
func (t teeHash) Sum(b []byte) []byte { return t.h.Sum(b) }
|
|
func (t teeHash) Reset() { t.h.Reset() }
|
|
func (t teeHash) Size() int { return t.h.Size() }
|
|
func (t teeHash) BlockSize() int { return t.h.BlockSize() }
|
|
|
|
// userIdSignatureHash returns a Hash of the message that needs to be signed
|
|
// to assert that pk is a valid key for id.
|
|
func userIdSignatureHash(id string, pk *PublicKey, hashFunc crypto.Hash) (h hash.Hash, err error) {
|
|
if !hashFunc.Available() {
|
|
return nil, errors.UnsupportedError("hash function")
|
|
}
|
|
h = hashFunc.New()
|
|
|
|
updateUserIdSignatureHash(id, pk, h)
|
|
|
|
return
|
|
}
|
|
|
|
// updateUserIdSignatureHash does the actual hash updates for
|
|
// userIdSignatureHash.
|
|
func updateUserIdSignatureHash(id string, pk *PublicKey, h hash.Hash) {
|
|
// RFC 4880, section 5.2.4
|
|
pk.SerializeSignaturePrefix(h)
|
|
pk.serializeWithoutHeaders(h)
|
|
|
|
var buf [5]byte
|
|
buf[0] = 0xb4
|
|
buf[1] = byte(len(id) >> 24)
|
|
buf[2] = byte(len(id) >> 16)
|
|
buf[3] = byte(len(id) >> 8)
|
|
buf[4] = byte(len(id))
|
|
h.Write(buf[:])
|
|
h.Write([]byte(id))
|
|
|
|
return
|
|
}
|
|
|
|
// VerifyUserIdSignature returns nil iff sig is a valid signature, made by this
|
|
// public key, that id is the identity of pub.
|
|
func (pk *PublicKey) VerifyUserIdSignature(id string, pub *PublicKey, sig *Signature) (err error) {
|
|
h, err := userIdSignatureHash(id, pub, sig.Hash)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
return pk.VerifySignature(h, sig)
|
|
}
|
|
|
|
// VerifyUserIdSignatureV3 returns nil iff sig is a valid signature, made by this
|
|
// public key, that id is the identity of pub.
|
|
func (pk *PublicKey) VerifyUserIdSignatureV3(id string, pub *PublicKey, sig *SignatureV3) (err error) {
|
|
h, err := userIdSignatureV3Hash(id, pub, sig.Hash)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
return pk.VerifySignatureV3(h, sig)
|
|
}
|
|
|
|
// KeyIdString returns the public key's fingerprint in capital hex
|
|
// (e.g. "6C7EE1B8621CC013").
|
|
func (pk *PublicKey) KeyIdString() string {
|
|
return fmt.Sprintf("%X", pk.Fingerprint[12:20])
|
|
}
|
|
|
|
// KeyIdShortString returns the short form of public key's fingerprint
|
|
// in capital hex, as shown by gpg --list-keys (e.g. "621CC013").
|
|
func (pk *PublicKey) KeyIdShortString() string {
|
|
return fmt.Sprintf("%X", pk.Fingerprint[16:20])
|
|
}
|
|
|
|
// A parsedMPI is used to store the contents of a big integer, along with the
|
|
// bit length that was specified in the original input. This allows the MPI to
|
|
// be reserialized exactly.
|
|
type parsedMPI struct {
|
|
bytes []byte
|
|
bitLength uint16
|
|
}
|
|
|
|
// writeMPIs is a utility function for serializing several big integers to the
|
|
// given Writer.
|
|
func writeMPIs(w io.Writer, mpis ...parsedMPI) (err error) {
|
|
for _, mpi := range mpis {
|
|
err = writeMPI(w, mpi.bitLength, mpi.bytes)
|
|
if err != nil {
|
|
return
|
|
}
|
|
}
|
|
return
|
|
}
|
|
|
|
// BitLength returns the bit length for the given public key. Used for
|
|
// displaying key information, actual buffers and BigInts inside may
|
|
// have non-matching different size if the key is invalid.
|
|
func (pk *PublicKey) BitLength() (bitLength uint16, err error) {
|
|
switch pk.PubKeyAlgo {
|
|
case PubKeyAlgoRSA, PubKeyAlgoRSAEncryptOnly, PubKeyAlgoRSASignOnly:
|
|
bitLength = pk.n.bitLength
|
|
case PubKeyAlgoDSA:
|
|
bitLength = pk.p.bitLength
|
|
case PubKeyAlgoElGamal, PubKeyAlgoBadElGamal:
|
|
bitLength = pk.p.bitLength
|
|
case PubKeyAlgoECDH:
|
|
ecdhPublicKey := pk.PublicKey.(*ecdh.PublicKey)
|
|
bitLength = uint16(ecdhPublicKey.Curve.Params().BitSize)
|
|
case PubKeyAlgoECDSA:
|
|
ecdsaPublicKey := pk.PublicKey.(*ecdsa.PublicKey)
|
|
bitLength = uint16(ecdsaPublicKey.Curve.Params().BitSize)
|
|
case PubKeyAlgoEdDSA:
|
|
// EdDSA only support ed25519 curves right now, just return
|
|
// the length. Also, we don't have any PublicKey.Curve object
|
|
// to look the size up from.
|
|
bitLength = 256
|
|
default:
|
|
err = errors.InvalidArgumentError("bad public-key algorithm")
|
|
}
|
|
return
|
|
}
|
|
|
|
func (pk *PublicKey) ErrorIfDeprecated() error {
|
|
switch pk.PubKeyAlgo {
|
|
case PubKeyAlgoBadElGamal:
|
|
return errors.DeprecatedKeyError("ElGamal Encrypt or Sign (algo 20) is deprecated")
|
|
default:
|
|
return nil
|
|
}
|
|
}
|