From ff3fe2ea8c5d5f495bad676275e20f1df70c2a41 Mon Sep 17 00:00:00 2001
From: armfazh <armfazh@cloudflare.com>
Date: Fri, 19 Jan 2024 15:54:46 -0800
Subject: [PATCH] Updating documentation for OPRF package.

OPRF is compatible with RFC-9497. https://www.rfc-editor.org/info/rfc9497
---
 oprf/keys.go                                  |  5 +++-
 oprf/oprf.go                                  | 23 ++++++++++---------
 .../{allVectors.json => rfc9497.json}         |  0
 oprf/vectors_test.go                          |  6 ++---
 zk/dleq/dleq.go                               |  2 +-
 5 files changed, 20 insertions(+), 16 deletions(-)
 rename oprf/testdata/{allVectors.json => rfc9497.json} (100%)

diff --git a/oprf/keys.go b/oprf/keys.go
index c4859ba4e..151f77849 100644
--- a/oprf/keys.go
+++ b/oprf/keys.go
@@ -66,7 +66,7 @@ func GenerateKey(s Suite, rnd io.Reader) (*PrivateKey, error) {
 	return &PrivateKey{p, privateKey, nil}, nil
 }
 
-// DeriveKey generates a private key from a given seed and optional info string.
+// DeriveKey generates a private key from a 32-byte seed and an optional info string.
 func DeriveKey(s Suite, mode Mode, seed, info []byte) (*PrivateKey, error) {
 	const maxTries = 255
 	p, ok := s.(params)
@@ -76,6 +76,9 @@ func DeriveKey(s Suite, mode Mode, seed, info []byte) (*PrivateKey, error) {
 	if !isValidMode(mode) {
 		return nil, ErrInvalidMode
 	}
+	if len(seed) != 32 {
+		return nil, ErrInvalidSeed
+	}
 	p.m = mode
 
 	lenInfo := []byte{0, 0}
diff --git a/oprf/oprf.go b/oprf/oprf.go
index febe5b1e1..c8a8774c0 100644
--- a/oprf/oprf.go
+++ b/oprf/oprf.go
@@ -4,7 +4,7 @@
 // computing the output of a PRF. One party (the server) holds the PRF secret
 // key, and the other (the client) holds the PRF input.
 //
-// This package is compatible with the OPRF specification at draft-irtf-cfrg-voprf [1].
+// This package is compatible with the OPRF specification at RFC-9497 [1].
 //
 // # Protocol Overview
 //
@@ -43,7 +43,7 @@
 //
 // # References
 //
-// [1] draft-irtf-cfrg-voprf: https://datatracker.ietf.org/doc/draft-irtf-cfrg-voprf
+// [1] RFC-9497: https://www.rfc-editor.org/info/rfc9497
 package oprf
 
 import (
@@ -237,19 +237,20 @@ func mustWrite(h io.Writer, bytes []byte) {
 		panic(err)
 	}
 	if len(bytes) != bytesLen {
-		panic("failed to write")
+		panic("oprf: failed to write")
 	}
 }
 
 var (
-	ErrInvalidSuite       = errors.New("invalid suite")
-	ErrInvalidMode        = errors.New("invalid mode")
-	ErrDeriveKeyPairError = errors.New("key pair derivation failed")
-	ErrInvalidInput       = errors.New("invalid input")
-	ErrInvalidInfo        = errors.New("invalid info")
-	ErrInvalidProof       = errors.New("proof verification failed")
-	ErrInverseZero        = errors.New("inverting a zero value")
-	ErrNoKey              = errors.New("must provide a key")
+	ErrInvalidSuite       = errors.New("oprf: invalid suite")
+	ErrInvalidMode        = errors.New("oprf: invalid mode")
+	ErrDeriveKeyPairError = errors.New("oprf: key pair derivation failed")
+	ErrInvalidInput       = errors.New("oprf: invalid input")
+	ErrInvalidSeed        = errors.New("oprf: invalid seed size")
+	ErrInvalidInfo        = errors.New("oprf: invalid info")
+	ErrInvalidProof       = errors.New("oprf: proof verification failed")
+	ErrInverseZero        = errors.New("oprf: inverting a zero value")
+	ErrNoKey              = errors.New("oprf: must provide a key")
 )
 
 type (
diff --git a/oprf/testdata/allVectors.json b/oprf/testdata/rfc9497.json
similarity index 100%
rename from oprf/testdata/allVectors.json
rename to oprf/testdata/rfc9497.json
diff --git a/oprf/vectors_test.go b/oprf/vectors_test.go
index f21703b86..774dc50fa 100644
--- a/oprf/vectors_test.go
+++ b/oprf/vectors_test.go
@@ -107,6 +107,7 @@ func (v *vector) SetUpParties(t *testing.T) (id params, s commonServer, c common
 	suite, err := GetSuite(v.Identifier)
 	test.CheckNoErr(t, err, "suite id")
 	seed := toBytes(t, v.Seed, "seed for key derivation")
+	test.CheckOk(len(seed) == 32, ErrInvalidSeed.Error(), t)
 	keyInfo := toBytes(t, v.KeyInfo, "info for key derivation")
 	privateKey, err := DeriveKey(suite, v.Mode, seed, keyInfo)
 	test.CheckNoErr(t, err, "deriving key")
@@ -237,10 +238,9 @@ func (v *vector) test(t *testing.T) {
 }
 
 func TestVectors(t *testing.T) {
-	// Draft published at https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-voprf-10
+	// RFC-9497 published at https://www.rfc-editor.org/info/rfc9497
 	// Test vectors at https://github.com/cfrg/draft-irtf-cfrg-voprf
-	// Version supported: v10
-	v := readFile(t, "testdata/allVectors.json")
+	v := readFile(t, "testdata/rfc9497.json")
 
 	for i := range v {
 		suite, err := GetSuite(v[i].Identifier)
diff --git a/zk/dleq/dleq.go b/zk/dleq/dleq.go
index 6527b0c3a..1e7cce84a 100644
--- a/zk/dleq/dleq.go
+++ b/zk/dleq/dleq.go
@@ -6,7 +6,7 @@
 //
 // References:
 //
-//	[1] draft-irtf-cfrg-voprf: https://datatracker.ietf.org/doc/draft-irtf-cfrg-voprf
+//	[1] RFC-9497: https://www.rfc-editor.org/info/rfc9497
 package dleq
 
 import (