First commit of the new bundle format.

.gitignore

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+*~

protos/envelope.proto

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+// https://raw.githubusercontent.com/secure-systems-lab/dsse/9c813476bd36de70a5738c72e784f123ecea16af/envelope.proto
+
+// 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.
+
+syntax = "proto3";
+
+package io.intoto;
+
+option go_package = "github.com/secure-systems-lab/dsse";
+
+// An authenticated message of arbitrary type.
+message Envelope {
+  // Message to be signed. (In JSON, this is encoded as base64.)
+  // REQUIRED.
+  bytes payload = 1;
+
+  // String unambiguously identifying how to interpret payload.
+  // REQUIRED.
+  string payloadType = 2;
+
+  // Signature over:
+  //     PAE(type, body)
+  // Where PAE is defined as:
+  // PAE(type, body) = "DSSEv1" + SP + LEN(type) + SP + type + SP + LEN(body) + SP + body
+  // +               = concatenation
+  // SP              = ASCII space [0x20]
+  // "DSSEv1"        = ASCII [0x44, 0x53, 0x53, 0x45, 0x76, 0x31]
+  // LEN(s)          = ASCII decimal encoding of the byte length of s, with no leading zeros
+  // REQUIRED (length >= 1).
+  repeated Signature signatures = 3;
+}
+
+message Signature {
+  // Signature itself. (In JSON, this is encoded as base64.)
+  // REQUIRED.
+  bytes sig = 1;
+
+  // *Unauthenticated* hint identifying which public key was used.
+  // OPTIONAL.
+  string keyid = 2;
+}

protos/sigstore_bundle.proto

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+// Copyright 2022 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.
+
+syntax = "proto3";
+package dev.sigstore.bundle.v1;
+
+// https://raw.githubusercontent.com/secure-systems-lab/dsse/9c813476bd36de70a5738c72e784f123ecea16af/envelope.proto
+import "envelope.proto";
+import "sigstore_common.proto";
+import "sigstore_rekor.proto";
+
+option go_package = "github.com/sigstore/proto/bundle/v1";
+option java_package = "dev.sigstore.proto.bundle.v1";
+option java_multiple_files = true;
+option java_outer_classname = "BundleProto";
+
+// Notes on versioning.
+// The primary message ('Bundle') MUST be versioned, by populating the
+// 'media_type' field. Semver-ish (only major/minor versions) scheme MUST
+// be used. The current version as specified by this file is:
+// application/vnd.dev.sigstore.bundle+json;version=0.1
+// The semantic version is thus '0.1'.
+
+// Various timestamped counter signatures over the artifacts signature.
+// Currently only RFC3161 signatures are provided. More formats may be added
+// in the future.
+message TimestampVerificationData {
+        // A list of RFC3161 signed timestamps provided by the user.
+        // This can be used when the entry has not been stored on a
+        // transparency log, or in conjuction for a stronger trust model.
+        // Clients MUST verify the hashed message in the message imprint
+        // against the signature in the bundle.
+        repeated dev.sigstore.common.v1.RFC3161SignedTimestamp rfc3161_timestamps = 1;
+}
+
+// VerificationData contains extra data that can be used to verify things
+// such as transparency and timestamp of the signature creation.
+// As this message can be either empty (no inclusion proof or timestamps), or a combination of
+// an arbitrarily number of transparency log entries and signed timestamps,
+// it is the client's responsibility to implement any required verification
+// policies.
+message VerificationData {
+        // This is the inclusion promise and/or proof, where
+        // the timestamp is coming from the transparency log.
+        repeated dev.sigstore.rekor.v1.TransparencyLogEntry tlog_entries = 1;
+        // Timestamp verification data, over the artifact's signature.
+        TimestampVerificationData timestamp_verification_data = 2;
+}
+
+message Bundle {
+        // MUST be application/vnd.dev.sigstore.bundle+json;version=0.1
+        // when encoded as JSON.
+        string media_type = 1;
+        VerificationData verification_data = 2;
+        dev.sigstore.common.v1.VerificationMaterial verification_material = 3;
+        oneof content {
+                dev.sigstore.common.v1.MessageSignature message_signature = 4;
+                // A DSSE envelope can contain arbitrary payloads.
+                // Verifiers must verify that the payload type is a
+                // supported and expected type. This is part of the DSSE
+                // protocol which is defined here https://github.com/secure-systems-lab/dsse/blob/master/protocol.md
+                io.intoto.Envelope dsse_envelope = 5;
+        }
+        // Reserved for future additions of artifact types.
+        reserved 6 to 50;
+}

protos/sigstore_common.proto

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+// Copyright 2022 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.
+
+syntax = "proto3";
+package dev.sigstore.common.v1;
+
+option go_package = "github.com/sigstore/proto/common/v1";
+option java_package = "dev.sigstore.proto.common.v1";
+option java_multiple_files = true;
+option java_outer_classname = "CommonProto";
+
+// This package defines commonly used message types within the Sigstore
+// community.
+
+// Only a subset of the secure hash standard algorithms are supported.
+// See https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.180-4.pdf for more
+// details.
+// UNSPECIFIED SHOULD not be used, primary reason for inclusion is to force
+// any proto JSON serialization to emit the used hash algorithm, as default
+// option is to *omit* the default value of an emum (which is the first
+// value, represented by '0'.
+enum HashAlgorithm {
+        HASH_ALGORITHM_UNSPECIFIED = 0;
+        SHA2_256 = 1;
+        SHA2_512 = 2;
+}
+
+// HashOutput captures a digest of a 'message' (generic octet sequence)
+// and the corresponding hash algorithm used.
+message HashOutput {
+        HashAlgorithm algorithm = 1;
+        // This is the raw octets of the message digest as computed by
+        // the hash algorithm.
+        bytes digest = 2;
+}
+
+// MessageSignature stores the computed signature over a message.
+message MessageSignature {
+        // Message digest can be used to identify the artifact.
+        HashOutput message_digest = 1;
+        // The raw bytes as returned from the signature algorithm.
+        // The signature algorithm (and so the format of the signature bytes)
+        // are determined by the contents of the 'verification_material',
+        // either a key-pair or a certificate. If using a certificate, the
+        // certificate contains the required information on the signature
+        // algorithm.
+        // When using a key pair, the algorithm MUST be part of the public
+        // key, which MUST be communicated out-of-band.
+        bytes signature = 2;
+}
+
+// This message holds a RFC 3161 timestamp.
+message RFC3161SignedTimestamp {
+        // Signed timestamp is the DER encoded TimeStampResponse.
+        // See https://www.rfc-editor.org/rfc/rfc3161.html#section-2.4.2
+        bytes signed_timestamp = 1;
+}
+
+
+// PublicKeyIdentifier can be used to identify an (out of band) delivered
+// key, to verify a signature.
+message PublicKeyIdentifier {
+        // Optional unauthenticated hint on which key to use.
+        // The format of the hint must be agreed upon out of band by the
+        // signer and the verifiers, and so is not subject to this
+        // specification.
+        // Example use-case is to specify the public key to use, from a
+        // trusted key-ring. Formats may differ depending on implementation,
+        // but a hex encoded digest of the public key is one example.
+        string hint = 1;
+}
+
+message X509Certificate {
+        // DER-encoded X.509 certificate.
+        bytes raw_bytes = 1;
+}
+
+// A chain of X.509 certificates.
+message X509CertificateChain {
+        // The chain of certificates, with indices 0 to n.
+        // The first certificate in the array must be the leaf
+        // certificate used for signing. Any intermediate certificates
+        // must be stored as offset 1 to n-1, and the root certificate at
+        // position n.
+        repeated X509Certificate certificates = 1;
+}
+
+// VerificationMaterial captures details on the materials used to verify
+// signatures.
+message VerificationMaterial {
+        oneof content {
+                PublicKeyIdentifier public_key = 1;
+                X509CertificateChain x509_certificate_chain = 2;
+        }
+}

protos/sigstore_rekor.proto

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+// Copyright 2022 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.
+
+syntax = "proto3";
+package dev.sigstore.rekor.v1;
+
+option go_package = "github.com/sigstore/proto/rekor/v1";
+option java_package = "dev.sigstore.proto.rekor.v1";
+option java_multiple_files = true;
+option java_outer_classname = "RekorProto";
+
+// KindVersion contains the entry's kind and api version.
+message KindVersion {
+        // Kind is the type of entry being stored in the log.
+        // See here for a list: https://github.com/sigstore/rekor/tree/main/pkg/types
+        string kind = 1;
+        // The specific api version of the type.
+        string version = 2;
+}
+
+// The checkpoint contains a signature of the tree head (root hash),
+// size of the tree, the transparency log's unique identifier (log ID),
+// hostname and the current time.
+// The result is a string, the format is described here
+// https://github.com/transparency-dev/formats/blob/main/log/README.md
+// The details are here https://github.com/sigstore/rekor/blob/a6e58f72b6b18cc06cefe61808efd562b9726330/pkg/util/signed_note.go#L114
+// The signature has the same format as
+// TransparencyLogEntry.inclusion_proof. See below for more details.
+message Checkpoint {
+        string envelope = 1;
+}
+
+// InclusionProof is the proof returned from the transparency log. Can
+// be used for on line verification against the log.
+message InclusionProof {
+        // The index of the entry in the log.
+        int64 log_index = 1;
+        // The hash digest stored at the root of the merkle tree at the time
+        // the proof was generated.
+        bytes root_hash = 2;
+        // The size of the merkle tree at the time the proof was generated.
+        int64 tree_size = 3;
+        // A list of hashes required to compute the inclusion proof, sorted
+        // in order from leaf to root.
+        repeated bytes hashes = 4;
+        // Signature of the tree head, as of the time of this proof was
+        // generated. See above info on 'Checkpoint' for more details.
+        Checkpoint checkpoint = 5;
+}
+
+// The inclusion promise is calculated by Rekor. It's calculated as a
+// signature over a canonical JSON serialization of the persisted entry, the
+// log ID, log index and the integration timestamp.
+// See https://github.com/sigstore/rekor/blob/a6e58f72b6b18cc06cefe61808efd562b9726330/pkg/api/entries.go#L54
+// The format of the signature depends on the transparency log's public key.
+// If the signature algorithm requires a hash function and/or a signature
+// scheme (e.g. RSA) those has to be retrieved out-of-band from the log's
+// operators, together with the public key.
+// This is used to verify the integration timestamp's value and that the log has promised to include the entry.
+message InclusionPromise {
+        bytes signed_entry_timestamp = 1;
+}
+
+// LogId captures the identity of a transparency log.
+message LogId {
+        // The unique id of the log, represented as the SHA-256 hash
+        // of the log's public key, computed over the DER encoding.
+        // This is similar to how it works for certificate transparency logs:
+        // https://www.rfc-editor.org/rfc/rfc6962#section-3.2
+        bytes key_id = 1;
+}
+
+// TransparencyLogEntry captures all the details required from Rekor to
+// reconstruct an entry, given that the payload is provided via other means.
+// This type can easily be created from the existing response from Rekor.
+// Future iterations could rely on Rekor returning the minimal set of
+// attributes (excluding the payload) that are required for verifying the
+// inclusion promise. The inclusion promise (called SignedEntryTimestamp in
+// the response from Rekor) is similar to a Signed Certificate Timestamp
+// as described here https://www.rfc-editor.org/rfc/rfc9162#name-signed-certificate-timestam.
+message TransparencyLogEntry {
+        // The index of the entry in the log.
+        int64 log_index = 1;
+        // The unique identifier of the log.
+        LogId log_id = 2;
+        // The kind (type) and version of the object associated with this
+        // entry. These values are required to construct the entry during
+        // verification.
+        KindVersion kind_version = 3;
+        // The UNIX timestamp from the log when the entry was persisted.
+        int64 integrated_time = 4;
+        // The inclusion promise/signed entry timestamp from the log.
+        InclusionPromise inclusion_promise = 5;
+        // The inclusion proof can be used for online verification that the
+        // entry was appended to the log, and that the log has not been
+        // altered.
+       InclusionProof inclusion_proof = 6;
+}