Skip to content

Commit

Permalink
Move the AES-GCM key manager into aesgcm
Browse files Browse the repository at this point in the history 
This is a safe change because key managers aren't exported from `aead`.
The key manager is registered by `aesgcm.init()`; `aesgcm` is "force-included" by `aead` to make sure key managers get registered.

PiperOrigin-RevId: 668897500
Change-Id: Ifc11160a162ba81c0af8e1f0678fa1da6507c035
  • Loading branch information
@morambro @copybara-github
morambro authored and copybara-github committed Aug 29, 2024
1 parent 01edfcf commit 97cbe32
Show file tree
Hide file tree
Showing 9 changed files with 264 additions and 216 deletions.
3 changes: 1 addition & 2 deletions aead/BUILD.bazel
View file
Original file line number Diff line number Diff line change
Expand Up @@ -11,7 +11,6 @@ go_library(
"aead_factory.go",
"aead_key_templates.go",
"aes_ctr_hmac_aead_key_manager.go",
"aes_gcm_key_manager.go",
"aes_gcm_siv_key_manager.go",
"chacha20poly1305_key_manager.go",
"kms_envelope_aead.go",
Expand All @@ -21,6 +20,7 @@ go_library(
importpath = "github.com/tink-crypto/tink-go/v2/aead",
visibility = ["//visibility:public"],
deps = [
"//aead/aesgcm",
"//aead/subtle",
"//core/cryptofmt",
"//core/primitiveset",
Expand Down Expand Up @@ -57,7 +57,6 @@ go_test(
"aead_key_templates_test.go",
"aead_test.go",
"aes_ctr_hmac_aead_key_manager_test.go",
"aes_gcm_key_manager_test.go",
"aes_gcm_siv_key_manager_test.go",
"chacha20poly1305_key_manager_test.go",
"kms_envelope_aead_example_test.go",
Expand Down
8 changes: 1 addition & 7 deletions aead/aead.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,7 @@ package aead
import (
"fmt"

_ "github.com/tink-crypto/tink-go/v2/aead/aesgcm" // To register the AES-GCM key manager.
"github.com/tink-crypto/tink-go/v2/core/registry"
"github.com/tink-crypto/tink-go/v2/internal/internalregistry"
)
Expand All @@ -29,13 +30,6 @@ func init() {
panic(fmt.Sprintf("aead.init() failed: %v", err))
}

if err := registry.RegisterKeyManager(new(aesGCMKeyManager)); err != nil {
panic(fmt.Sprintf("aead.init() failed: %v", err))
}
if err := internalregistry.AllowKeyDerivation(aesGCMTypeURL); err != nil {
panic(fmt.Sprintf("aead.init() failed: %v", err))
}

if err := registry.RegisterKeyManager(new(chaCha20Poly1305KeyManager)); err != nil {
panic(fmt.Sprintf("aead.init() failed: %v", err))
}
Expand Down
4 changes: 4 additions & 0 deletions aead/aead_key_templates.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,10 @@ import (
tinkpb "github.com/tink-crypto/tink-go/v2/proto/tink_go_proto"
)

const (
aesGCMTypeURL = "type.googleapis.com/google.crypto.tink.AesGcmKey"
)

// This file contains pre-generated KeyTemplates for AEAD keys. One can use these templates
// to generate new Keysets.

Expand Down
28 changes: 26 additions & 2 deletions aead/aesgcm/BUILD.bazel
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2,13 +2,25 @@ load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")

go_library(
name = "aesgcm",
srcs = ["aesgcm.go"],
srcs = [
"aesgcm.go",
"key.go",
"key_manager.go",
],
importpath = "github.com/tink-crypto/tink-go/v2/aead/aesgcm",
visibility = ["//visibility:public"],
deps = [
"//aead/subtle",
"//core/registry",
"//internal/internalregistry",
"//internal/outputprefix",
"//key",
"//keyset",
"//proto/aes_gcm_go_proto",
"//proto/tink_go_proto",
"//secretdata",
"//subtle/random",
"@org_golang_google_protobuf//proto",
],
)

Expand All @@ -20,11 +32,23 @@ alias(

go_test(
name = "aesgcm_test",
srcs = ["aesgcm_test.go"],
srcs = [
"key_manager_test.go",
"key_test.go",
],
deps = [
":aesgcm",
"//aead/subtle",
"//core/cryptofmt",
"//core/registry",
"//insecuresecretdataaccess",
"//internal/internalregistry",
"//proto/aes_gcm_go_proto",
"//proto/tink_go_proto",
"//secretdata",
"//subtle/random",
"//testutil",
"@com_github_google_go_cmp//cmp",
"@org_golang_google_protobuf//proto",
],
)
179 changes: 8 additions & 171 deletions aead/aesgcm/aesgcm.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -12,184 +12,21 @@
// See the License for the specific language governing permissions and
// limitations under the License.

// Package aesgcm implements AES-GCM parameters and key.
// Package aesgcm implements AES-GCM parameters and key, as well as key manager.
package aesgcm

import (
"bytes"
"fmt"

"github.com/tink-crypto/tink-go/v2/internal/outputprefix"
"github.com/tink-crypto/tink-go/v2/key"
"github.com/tink-crypto/tink-go/v2/secretdata"
"github.com/tink-crypto/tink-go/v2/core/registry"
"github.com/tink-crypto/tink-go/v2/internal/internalregistry"
)

// Variant is the prefix variant of AES-GCM keys.
//
// It describes how the prefix of the ciphertext is constructed. For AEAD there
// are three options:
//
// * TINK: prepends '0x01<big endian key id>' to the ciphertext.
// * CRUNCHY: prepends '0x00<big endian key id>' to the ciphertext.
// * NO_PREFIX: adds no prefix to the ciphertext.
type Variant int

const (
// VariantUnknown is the default and invalid value of Variant.
VariantUnknown Variant = iota
// VariantTink prefixes '0x01<big endian key id>' to the ciphertext.
VariantTink
// VariantCrunchy prefixes '0x00<big endian key id>' to the ciphertext.
VariantCrunchy
// VariantNoPrefix adds no prefix to the ciphertext.
VariantNoPrefix
)

func (variant Variant) String() string {
switch variant {
case VariantTink:
return "TINK"
case VariantCrunchy:
return "CRUNCHY"
case VariantNoPrefix:
return "NO_PREFIX"
default:
return "UNKNOWN"
}
}

// calculateOutputPrefix calculates the output prefix from keyID.
func calculateOutputPrefix(variant Variant, keyID uint32) ([]byte, error) {
switch variant {
case VariantTink:
return outputprefix.Tink(keyID), nil
case VariantCrunchy:
return outputprefix.Legacy(keyID), nil
case VariantNoPrefix:
return nil, nil
default:
return nil, fmt.Errorf("invalid output prefix variant: %v", variant)
}
}

// Parameters specifies an AES-GCM key.
type Parameters struct {
keySizeInBytes int
ivSizeInBytes int
tagSizeInBytes int
variant Variant
}

var _ key.Parameters = (*Parameters)(nil)

// KeySizeInBytes returns the size of the key in bytes.
func (p *Parameters) KeySizeInBytes() int { return p.keySizeInBytes }

// IVSizeInBytes returns the size of the IV in bytes.
func (p *Parameters) IVSizeInBytes() int { return p.ivSizeInBytes }

// TagSizeInBytes returns the size of the tag in bytes.
func (p *Parameters) TagSizeInBytes() int { return p.tagSizeInBytes }

// Variant returns the variant of the key.
func (p *Parameters) Variant() Variant { return p.variant }

// ParametersOpts specifies options for creating AES-GCM parameters.
type ParametersOpts struct {
KeySizeInBytes int
IVSizeInBytes int
TagSizeInBytes int
Variant Variant
}

// NewParameters creates a new AES-GCM Parameters object.
func NewParameters(opts ParametersOpts) (*Parameters, error) {
if opts.KeySizeInBytes != 16 && opts.KeySizeInBytes != 24 && opts.KeySizeInBytes != 32 {
return nil, fmt.Errorf("aesgcm.Parameters: unsupported key size; want 16, 24, or 32, got: %v", opts.KeySizeInBytes)
}
if opts.IVSizeInBytes <= 0 {
return nil, fmt.Errorf("aesgcm.Parameters: unsupported IV size; want > 0, got: %v", opts.IVSizeInBytes)
func init() {
if err := registry.RegisterKeyManager(new(keyManager)); err != nil {
panic(fmt.Sprintf("aesgcm.init() failed: %v", err))
}
if opts.TagSizeInBytes < 12 || opts.TagSizeInBytes > 16 {
return nil, fmt.Errorf("aesgcm.Parameters: unsupported tag size; want >= 12 and <= 16, got: %v", opts.TagSizeInBytes)
if err := internalregistry.AllowKeyDerivation(typeURL); err != nil {
panic(fmt.Sprintf("aesgcm.init() failed: %v", err))
}
if opts.Variant == VariantUnknown {
return nil, fmt.Errorf("aesgcm.Parameters: unsupported variant: %v", opts.Variant)
}
return &Parameters{
keySizeInBytes: opts.KeySizeInBytes,
ivSizeInBytes: opts.IVSizeInBytes,
tagSizeInBytes: opts.TagSizeInBytes,
variant: opts.Variant,
}, nil
}

// HasIDRequirement returns whether the key has an ID requirement.
func (p *Parameters) HasIDRequirement() bool { return p.variant != VariantNoPrefix }

// Equals returns whether this Parameters object is equal to other.
func (p *Parameters) Equals(other key.Parameters) bool {
actualParams, ok := other.(*Parameters)
return ok && p.HasIDRequirement() == actualParams.HasIDRequirement() &&
p.keySizeInBytes == actualParams.keySizeInBytes &&
p.ivSizeInBytes == actualParams.ivSizeInBytes &&
p.tagSizeInBytes == actualParams.tagSizeInBytes &&
p.variant == actualParams.variant
}

// Key represents an AES-GCM key.
type Key struct {
keyBytes secretdata.Bytes
id uint32
outputPrefix []byte
parameters *Parameters
}

var _ key.Key = (*Key)(nil)

// NewKey creates a new AES-GCM key with key, keyID and parameters.
func NewKey(keyBytes secretdata.Bytes, keyID uint32, parameters *Parameters) (*Key, error) {
if parameters == nil {
return nil, fmt.Errorf("aesgcm.NewKey: parameters is nil")
}
if keyBytes.Len() != int(parameters.KeySizeInBytes()) {
return nil, fmt.Errorf("aesgcm.NewKey: key.Len() = %v, want %v", keyBytes.Len(), parameters.KeySizeInBytes())
}
outputPrefix, err := calculateOutputPrefix(parameters.Variant(), keyID)
if err != nil {
return nil, fmt.Errorf("aesgcm.NewKey: %v", err)
}
return &Key{
keyBytes: keyBytes,
id: keyID,
outputPrefix: outputPrefix,
parameters: parameters,
}, nil
}

// KeyBytes returns the key material.
//
// This function provides access to partial key material. See
// https://developers.google.com/tink/design/access_control#access_of_parts_of_a_key
// for more information.
func (k *Key) KeyBytes() secretdata.Bytes { return k.keyBytes }

// Parameters returns the parameters of this key.
func (k *Key) Parameters() key.Parameters { return k.parameters }

// IDRequirement returns whether the key ID and whether it is required
//
// If not required, the returned key ID is not usable.
func (k *Key) IDRequirement() (uint32, bool) { return k.id, k.Parameters().HasIDRequirement() }

// OutputPrefix returns the output prefix.
func (k *Key) OutputPrefix() []byte { return bytes.Clone(k.outputPrefix) }

// Equals returns whether this key object is equal to other.
func (k *Key) Equals(other key.Key) bool {
that, ok := other.(*Key)
return ok && k.Parameters().Equals(that.Parameters()) &&
k.id == that.id &&
k.keyBytes.Equals(&that.keyBytes) &&
bytes.Equal(k.outputPrefix, that.outputPrefix)
}
Loading

0 comments on commit 97cbe32

Please sign in to comment.