chore: vendor

vendor/github.com/ProtonMail/go-crypto/openpgp/internal/encoding/mpi.go

@@ -0,0 +1,91 @@
+// Copyright 2017 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 encoding
+
+import (
+	"io"
+	"math/big"
+	"math/bits"
+)
+
+// An MPI 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 MPI struct {
+	bytes     []byte
+	bitLength uint16
+}
+
+// NewMPI returns a MPI initialized with bytes.
+func NewMPI(bytes []byte) *MPI {
+	for len(bytes) != 0 && bytes[0] == 0 {
+		bytes = bytes[1:]
+	}
+	if len(bytes) == 0 {
+		bitLength := uint16(0)
+		return &MPI{bytes, bitLength}
+	}
+	bitLength := 8*uint16(len(bytes)-1) + uint16(bits.Len8(bytes[0]))
+	return &MPI{bytes, bitLength}
+}
+
+// Bytes returns the decoded data.
+func (m *MPI) Bytes() []byte {
+	return m.bytes
+}
+
+// BitLength is the size in bits of the decoded data.
+func (m *MPI) BitLength() uint16 {
+	return m.bitLength
+}
+
+// EncodedBytes returns the encoded data.
+func (m *MPI) EncodedBytes() []byte {
+	return append([]byte{byte(m.bitLength >> 8), byte(m.bitLength)}, m.bytes...)
+}
+
+// EncodedLength is the size in bytes of the encoded data.
+func (m *MPI) EncodedLength() uint16 {
+	return uint16(2 + len(m.bytes))
+}
+
+// ReadFrom reads into m the next MPI from r.
+func (m *MPI) ReadFrom(r io.Reader) (int64, error) {
+	var buf [2]byte
+	n, err := io.ReadFull(r, buf[0:])
+	if err != nil {
+		if err == io.EOF {
+			err = io.ErrUnexpectedEOF
+		}
+		return int64(n), err
+	}
+
+	m.bitLength = uint16(buf[0])<<8 | uint16(buf[1])
+	m.bytes = make([]byte, (int(m.bitLength)+7)/8)
+
+	nn, err := io.ReadFull(r, m.bytes)
+	if err == io.EOF {
+		err = io.ErrUnexpectedEOF
+	}
+
+	// remove leading zero bytes from malformed GnuPG encoded MPIs:
+	// https://bugs.gnupg.org/gnupg/issue1853
+	// for _, b := range m.bytes {
+	// 	if b != 0 {
+	// 		break
+	// 	}
+	// 	m.bytes = m.bytes[1:]
+	// 	m.bitLength -= 8
+	// }
+
+	return int64(n) + int64(nn), err
+}
+
+// SetBig initializes m with the bits from n.
+func (m *MPI) SetBig(n *big.Int) *MPI {
+	m.bytes = n.Bytes()
+	m.bitLength = uint16(n.BitLen())
+	return m
+}