Switch to keybase go-crypto (for some elliptic curve key) + test (#1925)

* Switch to keybase go-crypto (for some elliptic curve key) + test

* Use assert.NoError 

and add a little more context to failing test description

* Use assert.(No)Error everywhere 🌈

and assert.Error in place of .Nil/.NotNil

vendor/github.com/keybase/go-crypto/openpgp/packet/reader.go

@@ -0,0 +1,76 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package packet
+
+import (
+	"io"
+
+	"github.com/keybase/go-crypto/openpgp/errors"
+)
+
+// Reader reads packets from an io.Reader and allows packets to be 'unread' so
+// that they result from the next call to Next.
+type Reader struct {
+	q       []Packet
+	readers []io.Reader
+}
+
+// New io.Readers are pushed when a compressed or encrypted packet is processed
+// and recursively treated as a new source of packets. However, a carefully
+// crafted packet can trigger an infinite recursive sequence of packets. See
+// http://mumble.net/~campbell/misc/pgp-quine
+// https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2013-4402
+// This constant limits the number of recursive packets that may be pushed.
+const maxReaders = 32
+
+// Next returns the most recently unread Packet, or reads another packet from
+// the top-most io.Reader. Unknown packet types are skipped.
+func (r *Reader) Next() (p Packet, err error) {
+	if len(r.q) > 0 {
+		p = r.q[len(r.q)-1]
+		r.q = r.q[:len(r.q)-1]
+		return
+	}
+
+	for len(r.readers) > 0 {
+		p, err = Read(r.readers[len(r.readers)-1])
+		if err == nil {
+			return
+		}
+		if err == io.EOF {
+			r.readers = r.readers[:len(r.readers)-1]
+			continue
+		}
+		if _, ok := err.(errors.UnknownPacketTypeError); !ok {
+			return nil, err
+		}
+	}
+	return nil, io.EOF
+}
+
+// Push causes the Reader to start reading from a new io.Reader. When an EOF
+// error is seen from the new io.Reader, it is popped and the Reader continues
+// to read from the next most recent io.Reader. Push returns a StructuralError
+// if pushing the reader would exceed the maximum recursion level, otherwise it
+// returns nil.
+func (r *Reader) Push(reader io.Reader) (err error) {
+	if len(r.readers) >= maxReaders {
+		return errors.StructuralError("too many layers of packets")
+	}
+	r.readers = append(r.readers, reader)
+	return nil
+}
+
+// Unread causes the given Packet to be returned from the next call to Next.
+func (r *Reader) Unread(p Packet) {
+	r.q = append(r.q, p)
+}
+
+func NewReader(r io.Reader) *Reader {
+	return &Reader{
+		q:       nil,
+		readers: []io.Reader{r},
+	}
+}