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hpke: set the scheme on hybrid KEM keys #706

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20 changes: 12 additions & 8 deletions hpke/hybridkem.go
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Original file line number Diff line number Diff line change
Expand Up @@ -190,12 +190,14 @@ func (h hybridKEM) DeriveKeyPair(seed []byte) (kem.PublicKey, kem.PrivateKey) {
pubB, privB := h.kemB.DeriveKeyPair(seedB)

privKey := &hybridKEMPrivKey{
privA: privA,
privB: privB,
scheme: h,
privA: privA,
privB: privB,
}
pubKey := &hybridKEMPubKey{
pubA: pubA,
pubB: pubB,
scheme: h,
pubA: pubA,
pubB: pubB,
}

return pubKey, privKey
Expand Down Expand Up @@ -225,8 +227,9 @@ func (h hybridKEM) UnmarshalBinaryPrivateKey(data []byte) (kem.PrivateKey, error
}

return &hybridKEMPrivKey{
privA: skA,
privB: skB,
scheme: h,
privA: skA,
privB: skB,
}, nil
}

Expand All @@ -244,7 +247,8 @@ func (h hybridKEM) UnmarshalBinaryPublicKey(data []byte) (kem.PublicKey, error)
}

return &hybridKEMPubKey{
pubA: pkA,
pubB: pkB,
scheme: h,
pubA: pkA,
pubB: pkB,
}, nil
}
55 changes: 46 additions & 9 deletions hpke/kem_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -6,27 +6,42 @@ import (

"github.com/cloudflare/circl/hpke"
"github.com/cloudflare/circl/internal/test"
"github.com/cloudflare/circl/kem"
)

var kemIDs = []hpke.KEM{
hpke.KEM_P256_HKDF_SHA256,
hpke.KEM_P384_HKDF_SHA384,
hpke.KEM_P521_HKDF_SHA512,
hpke.KEM_X25519_HKDF_SHA256,
hpke.KEM_X448_HKDF_SHA512,
hpke.KEM_X25519_KYBER768_DRAFT00,
}

func TestKemKeysExactLength(t *testing.T) {
for _, kemID := range []hpke.KEM{
hpke.KEM_P256_HKDF_SHA256,
hpke.KEM_P384_HKDF_SHA384,
hpke.KEM_P521_HKDF_SHA512,
hpke.KEM_X25519_HKDF_SHA256,
hpke.KEM_X448_HKDF_SHA512,
hpke.KEM_X25519_KYBER768_DRAFT00,
} {
for _, kemID := range kemIDs {
checkExactLengthUnmarshal(t, kemID)
}
}

func checkExactLengthUnmarshal(t *testing.T, kemID hpke.KEM) {
func TestKemKeysScheme(t *testing.T) {
for _, kemID := range kemIDs {
checkKeysScheme(t, kemID)
}
}

func genKeyPair(t *testing.T, kemID hpke.KEM) (kem.Scheme, kem.PublicKey, kem.PrivateKey) {
t.Helper()
scheme := kemID.Scheme()
pk, sk, err := scheme.GenerateKeyPair()
if err != nil {
t.Fatal(err)
}
return scheme, pk, sk
}

func checkExactLengthUnmarshal(t *testing.T, kemID hpke.KEM) {
scheme, pk, sk := genKeyPair(t, kemID)
skBytes, err := sk.MarshalBinary()
test.CheckNoErr(t, err, "marshal private key")
pkBytes, err := pk.MarshalBinary()
Expand Down Expand Up @@ -58,3 +73,25 @@ func checkExactLengthUnmarshal(t *testing.T, kemID hpke.KEM) {
test.CheckOk(pk.Equal(gotPk), "public keys must match", t)
})
}

func checkKeysScheme(t *testing.T, kemID hpke.KEM) {
scheme, pk, sk := genKeyPair(t, kemID)

t.Run(scheme.Name(), func(t *testing.T) {
test.CheckOk(sk.Scheme().Name() == scheme.Name(), "private key scheme must match", t)
test.CheckOk(pk.Scheme().Name() == scheme.Name(), "public key scheme must match", t)
test.CheckOk(sk.Public().Scheme().Name() == scheme.Name(), "derived public key scheme must match", t)

skBytes, err := sk.MarshalBinary()
test.CheckNoErr(t, err, "marshal private key")
gotSk, err := scheme.UnmarshalBinaryPrivateKey(skBytes)
test.CheckNoErr(t, err, "unmarshal private key")
test.CheckOk(gotSk.Scheme().Name() == scheme.Name(), "unmarshaled private key scheme must match", t)

pkBytes, err := pk.MarshalBinary()
test.CheckNoErr(t, err, "marshal public key")
gotPk, err := scheme.UnmarshalBinaryPublicKey(pkBytes)
test.CheckNoErr(t, err, "unmarshal public key")
test.CheckOk(gotPk.Scheme().Name() == scheme.Name(), "unmarshaled public key scheme must match", t)
})
}