DateKeys/capsule/signature_test.go

package capsule_test

import (
	"bytes"
	"strings"
	"testing"

	"g.activething.com/go/DateKeys/authorkey"
	"g.activething.com/go/DateKeys/capsule"
)

// Spec v0.11 §29.8: AUTHOR_MESSAGE is ASCII text of 99 bytes with its code,
// and control_commit does not depend on L.
func TestAuthorMessage(t *testing.T) {
	var cc, hd [32]byte
	cc[0], hd[0] = 1, 2
	m := capsule.AuthorMessage(cc, hd, capsule.SignersDigest(capsule.AlgEd25519, nil))
	if capsule.AuthorMessageSize != 99 || len(m) != 99 || !bytes.HasPrefix(m, []byte(capsule.AuthorMessagePrefix+"\n")) || m[98] != '\n' {
		t.Fatalf("AUTHOR_MESSAGE %q", m)
	}
	if code := capsule.AuthorCode(m); len(code) != 9 || code[4] != '-' || code[:4] != string(m[34:38]) {
		t.Errorf("code %q", code)
	}
	if capsule.SignersDigest(capsule.AlgEd25519, nil) == capsule.SignersDigest(capsule.AlgCMS, nil) {
		t.Error("signers_digest does not bind alg")
	}
	c := &capsule.Control{PayloadLength: 100, Padding: capsule.Reforzado}
	c.PayloadIdentity[0] = 7
	a, err := capsule.ControlCommit(c, capsule.Format3)
	if err != nil {
		t.Fatal(err)
	}
	c.PayloadLength = 1 << 40
	if b, _ := capsule.ControlCommit(c, capsule.Format3); b != a {
		t.Error("control_commit depends on L")
	}
	c.PayloadIdentity[0] = 8
	if b, _ := capsule.ControlCommit(c, capsule.Format3); b == a {
		t.Error("control_commit does not depend on I_PAYLOAD")
	}
	if capsule.SigPart(nil)[0] != 0 || len(capsule.SigPart([]byte{1})) != 33 {
		t.Error("SIG_PART")
	}
}

// Spec v0.11 §29.7, §29.9: a signature of alg 1 gives F4, or F3 with a saved
// key; F2 when it does not verify; F1 without the capsule around it, as in
// v0.10, and for what this reader does not implement.
func TestEvaluateSecurityIn(t *testing.T) {
	key, _ := authorkey.Generate()
	ctx := &capsule.SecurityContext{}
	ctx.ControlCommit[0], ctx.HeadDigest[0] = 1, 2
	msg := capsule.AuthorMessage(ctx.ControlCommit, ctx.HeadDigest, capsule.SignersDigest(capsule.AlgEd25519, nil))
	security := func(alg uint64, pub, sig []byte) []byte {
		content, err := capsule.EncodeAuthorSignature(alg, pub, sig)
		if err != nil {
			t.Fatal(err)
		}
		b, err := capsule.EncodeSecurityWith(content, nil)
		if err != nil {
			t.Fatal(err)
		}
		return b
	}
	signed := security(capsule.AlgEd25519, key.Public(), key.Sign(msg))
	v := capsule.EvaluateSecurityIn(signed, ctx)
	if v.Signature != capsule.VerdictSignedOther || !bytes.Equal(v.AuthorKey[:], key.Public()) {
		t.Fatalf("verdicts %+v", v)
	}
	pub, _ := authorkey.PublicString(key.Public())
	if line := v.Lines()[0]; !strings.Contains(line, pub) || !strings.HasSuffix(line, "No prueba quién la tiene.") {
		t.Errorf("F4 line %q", line)
	}
	ctx.AuthorKeys = map[string]string{pub: "Ana"}
	if v := capsule.EvaluateSecurityIn(signed, ctx); v.Signature != capsule.VerdictSignedSaved || v.Lines()[0] != "Firmado con la clave que guardaste como Ana." {
		t.Errorf("F3: %+v %q", v, v.Lines())
	}
	other := *ctx
	other.HeadDigest[0] = 3
	if v := capsule.EvaluateSecurityIn(signed, &other); v.Signature != capsule.VerdictSignatureInvalid {
		t.Errorf("another head: %s", v.Signature)
	}
	for name, b := range map[string][]byte{
		"no context":       signed,
		"a key of 31":      security(capsule.AlgEd25519, key.Public()[:31], key.Sign(msg)),
		"alg 2, not yet":   security(capsule.AlgCMS, []byte{1}, []byte{1}),
		"an unknown alg 9": security(9, key.Public(), key.Sign(msg)),
	} {
		c := ctx
		if name == "no context" {
			c = nil
		}
		if v := capsule.EvaluateSecurityIn(b, c); v.Signature != capsule.VerdictSignatureUnchecked {
			t.Errorf("%s: %s", name, v.Signature)
		}
	}
}