-
Notifications
You must be signed in to change notification settings - Fork 164
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
Add support for signing with Tink keyset (#2228)
This allows deployers to securely sign in-memory while mitigating key exfiltration, since the key is encrypted at rest and loaded into memory at server startup. Requires providing a path to an encrypted Tink keyset and the Key Encryption Key, a KMS URI for decrypting the keyset. Heavily pulls from Fulcio's Tink implementation. Signed-off-by: Hayden Blauzvern <hblauzvern@google.com>
- Loading branch information
1 parent
2e4be8b
commit 5e341f2
Showing
10 changed files
with
496 additions
and
4 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,87 @@ | ||
| // Copyright 2024 The Sigstore Authors. | ||
| // | ||
| // Licensed under the Apache License, Version 2.0 (the "License"); | ||
| // you may not use this file except in compliance with the License. | ||
| // You may obtain a copy of the License at | ||
| // | ||
| // http://www.apache.org/licenses/LICENSE-2.0 | ||
| // | ||
| // Unless required by applicable law or agreed to in writing, software | ||
| // distributed under the License is distributed on an "AS IS" BASIS, | ||
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| // See the License for the specific language governing permissions and | ||
| // limitations under the License. | ||
|
|
||
| package signer | ||
|
|
||
| import ( | ||
| "context" | ||
| "errors" | ||
| "os" | ||
| "path/filepath" | ||
| "strings" | ||
|
|
||
| tinkUtils "github.com/sigstore/rekor/pkg/signer/tink" | ||
| "github.com/tink-crypto/tink-go-awskms/v2/integration/awskms" | ||
| "github.com/tink-crypto/tink-go-gcpkms/v2/integration/gcpkms" | ||
| "github.com/tink-crypto/tink-go/v2/core/registry" | ||
| "github.com/tink-crypto/tink-go/v2/keyset" | ||
| "github.com/tink-crypto/tink-go/v2/tink" | ||
|
|
||
| "github.com/sigstore/sigstore/pkg/signature" | ||
| ) | ||
|
|
||
| const TinkScheme = "tink" | ||
|
|
||
| // NewTinkSignerWithHandle returns a signature.SignerVerifier that wraps crypto.Signer and a hash function. | ||
| // Provide a path to the encrypted keyset and cloud KMS key URI for decryption | ||
| func NewTinkSigner(ctx context.Context, kekURI, keysetPath string) (signature.Signer, error) { | ||
| kek, err := getKeyEncryptionKey(ctx, kekURI) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| return NewTinkSignerWithHandle(kek, keysetPath) | ||
| } | ||
|
|
||
| // NewTinkSignerWithHandle returns a signature.SignerVerifier that wraps crypto.Signer and a hash function. | ||
| // Provide a path to the encrypted keyset and a key handle for decrypting the keyset | ||
| func NewTinkSignerWithHandle(kek tink.AEAD, keysetPath string) (signature.Signer, error) { | ||
| f, err := os.Open(filepath.Clean(keysetPath)) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| defer f.Close() | ||
|
|
||
| kh, err := keyset.Read(keyset.NewJSONReader(f), kek) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| signer, hash, err := tinkUtils.KeyHandleToSigner(kh) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| return signature.LoadSignerVerifier(signer, hash) | ||
| } | ||
|
|
||
| // getKeyEncryptionKey returns a Tink AEAD encryption key from KMS | ||
| // Supports GCP and AWS | ||
| func getKeyEncryptionKey(ctx context.Context, kmsKey string) (tink.AEAD, error) { | ||
| switch { | ||
| case strings.HasPrefix(kmsKey, "gcp-kms://"): | ||
| gcpClient, err := gcpkms.NewClientWithOptions(ctx, kmsKey) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| registry.RegisterKMSClient(gcpClient) | ||
| return gcpClient.GetAEAD(kmsKey) | ||
| case strings.HasPrefix(kmsKey, "aws-kms://"): | ||
| awsClient, err := awskms.NewClientWithOptions(kmsKey) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| registry.RegisterKMSClient(awsClient) | ||
| return awsClient.GetAEAD(kmsKey) | ||
| default: | ||
| return nil, errors.New("unsupported KMS key type") | ||
| } | ||
| } |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,157 @@ | ||
| // Copyright 2024 The Sigstore Authors. | ||
| // | ||
| // Licensed under the Apache License, Version 2.0 (the "License"); | ||
| // you may not use this file except in compliance with the License. | ||
| // You may obtain a copy of the License at | ||
| // | ||
| // http://www.apache.org/licenses/LICENSE-2.0 | ||
| // | ||
| // Unless required by applicable law or agreed to in writing, software | ||
| // distributed under the License is distributed on an "AS IS" BASIS, | ||
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| // See the License for the specific language governing permissions and | ||
| // limitations under the License. | ||
|
|
||
| package tink | ||
|
|
||
| // Copy of https://github.com/sigstore/fulcio/blob/a781da9903c63a2cd2c0f0c1c2bfc763196db44f/pkg/ca/tinkca/signer.go | ||
| // with a modification for including the hash function when creating the signer | ||
|
|
||
| import ( | ||
| "crypto" | ||
| "crypto/ecdsa" | ||
| "crypto/ed25519" | ||
| "errors" | ||
| "fmt" | ||
| "math/big" | ||
|
|
||
| "github.com/tink-crypto/tink-go/v2/insecurecleartextkeyset" | ||
| "github.com/tink-crypto/tink-go/v2/keyset" | ||
| commonpb "github.com/tink-crypto/tink-go/v2/proto/common_go_proto" | ||
| ecdsapb "github.com/tink-crypto/tink-go/v2/proto/ecdsa_go_proto" | ||
| ed25519pb "github.com/tink-crypto/tink-go/v2/proto/ed25519_go_proto" | ||
| tinkpb "github.com/tink-crypto/tink-go/v2/proto/tink_go_proto" | ||
| signatureSubtle "github.com/tink-crypto/tink-go/v2/signature/subtle" | ||
| "github.com/tink-crypto/tink-go/v2/subtle" | ||
| "google.golang.org/protobuf/proto" | ||
| ) | ||
|
|
||
| var ( | ||
| ecdsaSignerKeyVersion = 0 | ||
| ecdsaSignerTypeURL = "type.googleapis.com/google.crypto.tink.EcdsaPrivateKey" | ||
| ed25519SignerKeyVersion = 0 | ||
| ed25519SignerTypeURL = "type.googleapis.com/google.crypto.tink.Ed25519PrivateKey" | ||
| ) | ||
|
|
||
| // KeyHandleToSigner converts a key handle to the crypto.Signer interface. | ||
| // Heavily pulls from Tink's signature and subtle packages. | ||
| func KeyHandleToSigner(kh *keyset.Handle) (crypto.Signer, crypto.Hash, error) { | ||
| // extract the key material from the key handle | ||
| ks := insecurecleartextkeyset.KeysetMaterial(kh) | ||
|
|
||
| k := getPrimaryKey(ks) | ||
| if k == nil { | ||
| return nil, 0, errors.New("no enabled key found in keyset") | ||
| } | ||
|
|
||
| switch k.GetTypeUrl() { | ||
| case ecdsaSignerTypeURL: | ||
| // https://github.com/tink-crypto/tink-go/blob/0aadc94a816408c4bdf95885b3c9860ecfd55fc0/signature/ecdsa/signer_key_manager.go#L48 | ||
| privKey := new(ecdsapb.EcdsaPrivateKey) | ||
| if err := proto.Unmarshal(k.GetValue(), privKey); err != nil { | ||
| return nil, 0, fmt.Errorf("error unmarshalling ecdsa private key: %w", err) | ||
| } | ||
| if err := validateEcdsaPrivKey(privKey); err != nil { | ||
| return nil, 0, fmt.Errorf("error validating ecdsa private key: %w", err) | ||
| } | ||
| // https://github.com/tink-crypto/tink-go/blob/0aadc94a816408c4bdf95885b3c9860ecfd55fc0/signature/subtle/ecdsa_signer.go#L37 | ||
| hashAlg, curve, _ := getECDSAParamNames(privKey.PublicKey.Params) | ||
| p := new(ecdsa.PrivateKey) | ||
| c := subtle.GetCurve(curve) | ||
| if c == nil { | ||
| return nil, 0, errors.New("tink ecdsa signer: invalid curve") | ||
| } | ||
| p.PublicKey.Curve = c | ||
| p.D = new(big.Int).SetBytes(privKey.GetKeyValue()) | ||
| p.PublicKey.X, p.PublicKey.Y = c.ScalarBaseMult(privKey.GetKeyValue()) | ||
| hash := getHashFunc(hashAlg) | ||
| return p, hash, nil | ||
| case ed25519SignerTypeURL: | ||
| // https://github.com/tink-crypto/tink-go/blob/0aadc94a816408c4bdf95885b3c9860ecfd55fc0/signature/ed25519/signer_key_manager.go#L47 | ||
| privKey := new(ed25519pb.Ed25519PrivateKey) | ||
| if err := proto.Unmarshal(k.GetValue(), privKey); err != nil { | ||
| return nil, 0, fmt.Errorf("error unmarshalling ed25519 private key: %w", err) | ||
| } | ||
| if err := validateEd25519PrivKey(privKey); err != nil { | ||
| return nil, 0, fmt.Errorf("error validating ed25519 private key: %w", err) | ||
| } | ||
| // https://github.com/tink-crypto/tink-go/blob/0aadc94a816408c4bdf95885b3c9860ecfd55fc0/signature/subtle/ed25519_signer.go#L27 | ||
| p := ed25519.NewKeyFromSeed(privKey.GetKeyValue()) | ||
| return p, crypto.SHA512, nil | ||
| default: | ||
| return nil, 0, fmt.Errorf("unsupported key type: %s", k.GetTypeUrl()) | ||
| } | ||
| } | ||
|
|
||
| // getPrimaryKey returns the first enabled key from a keyset. | ||
| func getPrimaryKey(ks *tinkpb.Keyset) *tinkpb.KeyData { | ||
| for _, k := range ks.GetKey() { | ||
| if k.GetKeyId() == ks.GetPrimaryKeyId() && k.GetStatus() == tinkpb.KeyStatusType_ENABLED { | ||
| return k.GetKeyData() | ||
| } | ||
| } | ||
| return nil | ||
| } | ||
|
|
||
| // validateEcdsaPrivKey validates the given ECDSAPrivateKey. | ||
| // https://github.com/tink-crypto/tink-go/blob/0aadc94a816408c4bdf95885b3c9860ecfd55fc0/signature/ecdsa/signer_key_manager.go#L151 | ||
| func validateEcdsaPrivKey(key *ecdsapb.EcdsaPrivateKey) error { | ||
| if err := keyset.ValidateKeyVersion(key.Version, uint32(ecdsaSignerKeyVersion)); err != nil { | ||
| return fmt.Errorf("ecdsa: invalid key version in key: %s", err) | ||
| } | ||
| if err := keyset.ValidateKeyVersion(key.GetPublicKey().GetVersion(), uint32(ecdsaSignerKeyVersion)); err != nil { | ||
| return fmt.Errorf("ecdsa: invalid public version in key: %s", err) | ||
| } | ||
| hash, curve, encoding := getECDSAParamNames(key.PublicKey.Params) | ||
| return signatureSubtle.ValidateECDSAParams(hash, curve, encoding) | ||
| } | ||
|
|
||
| // getECDSAParamNames returns the string representations of each parameter in | ||
| // the given ECDSAParams. | ||
| // https://github.com/tink-crypto/tink-go/blob/0aadc94a816408c4bdf95885b3c9860ecfd55fc0/signature/ecdsa/proto.go#L24 | ||
| func getECDSAParamNames(params *ecdsapb.EcdsaParams) (string, string, string) { | ||
| hashName := commonpb.HashType_name[int32(params.GetHashType())] | ||
| curveName := commonpb.EllipticCurveType_name[int32(params.GetCurve())] | ||
| encodingName := ecdsapb.EcdsaSignatureEncoding_name[int32(params.GetEncoding())] | ||
| return hashName, curveName, encodingName | ||
| } | ||
|
|
||
| // validateEd25519PrivKey validates the given ED25519PrivateKey. | ||
| // https://github.com/tink-crypto/tink-go/blob/0aadc94a816408c4bdf95885b3c9860ecfd55fc0/signature/ed25519/signer_key_manager.go#L157 | ||
| func validateEd25519PrivKey(key *ed25519pb.Ed25519PrivateKey) error { | ||
| if err := keyset.ValidateKeyVersion(key.Version, uint32(ed25519SignerKeyVersion)); err != nil { | ||
| return fmt.Errorf("ed25519: invalid key: %w", err) | ||
| } | ||
| if len(key.KeyValue) != ed25519.SeedSize { | ||
| return fmt.Errorf("ed25519: invalid key length, got %d", len(key.KeyValue)) | ||
| } | ||
| return nil | ||
| } | ||
|
|
||
| // getHashFunc returns the hash function for a given hash name | ||
| func getHashFunc(hash string) crypto.Hash { | ||
| switch hash { | ||
| case "SHA1": | ||
| return crypto.SHA1 | ||
| case "SHA224": | ||
| return crypto.SHA224 | ||
| case "SHA256": | ||
| return crypto.SHA256 | ||
| case "SHA384": | ||
| return crypto.SHA384 | ||
| case "SHA512": | ||
| return crypto.SHA512 | ||
| default: | ||
| return crypto.SHA256 | ||
| } | ||
| } |
Oops, something went wrong.