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// Copyright 2018 Google LLC. All Rights Reserved.
//
// 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 util
import (
"crypto/sha256"
ct "github.com/google/certificate-transparency-go"
"github.com/google/certificate-transparency-go/tls"
"github.com/google/trillian"
"k8s.io/klog/v2"
)
// BuildLogLeaf returns a Trillian LogLeaf structure for a (pre-)cert and the
// chain of certificates leading it up to a known root.
func BuildLogLeaf(logPrefix string,
merkleLeaf ct.MerkleTreeLeaf, leafIndex int64,
cert ct.ASN1Cert, chain []ct.ASN1Cert, isPrecert bool,
) (*trillian.LogLeaf, error) {
return buildLogLeaf(logPrefix, merkleLeaf, leafIndex, cert, chain, nil, isPrecert)
}
// ExtraDataForChain creates the extra data associated with a log entry as
// described in RFC6962 section 4.6.
func ExtraDataForChain(cert ct.ASN1Cert, chain []ct.ASN1Cert, isPrecert bool) ([]byte, error) {
var extra interface{}
if isPrecert {
// For a pre-cert, the extra data is a TLS-encoded PrecertChainEntry.
extra = ct.PrecertChainEntry{
PreCertificate: cert,
CertificateChain: chain,
}
} else {
// For a certificate, the extra data is a TLS-encoded:
// ASN.1Cert certificate_chain<0..2^24-1>;
// containing the chain after the leaf.
extra = ct.CertificateChain{Entries: chain}
}
return tls.Marshal(extra)
}
// BuildLogLeafWithChainHash returns a Trillian LogLeaf structure for a
// (pre-)cert and the chain of certificates leading it up to a known root.
func BuildLogLeafWithChainHash(logPrefix string, merkleLeaf ct.MerkleTreeLeaf, leafIndex int64, cert ct.ASN1Cert, chainHash []byte, isPrecert bool) (*trillian.LogLeaf, error) {
return buildLogLeaf(logPrefix, merkleLeaf, leafIndex, cert, nil, chainHash, isPrecert)
}
// ExtraDataForChainHash creates the extra data associated with a log entry as
// described in RFC6962 section 4.6 except the chain being replaced with its hash.
func ExtraDataForChainHash(cert ct.ASN1Cert, chainHash []byte, isPrecert bool) ([]byte, error) {
var extra any
if isPrecert {
// For a pre-cert, the extra data is a TLS-encoded PrecertChainEntry.
extra = ct.PrecertChainEntryHash{
PreCertificate: cert,
IssuanceChainHash: chainHash,
}
} else {
// For a certificate, the extra data is a TLS-encoded:
// ASN.1Cert certificate_chain<0..2^24-1>;
// containing the chain after the leaf.
extra = ct.CertificateChainHash{
IssuanceChainHash: chainHash,
}
}
return tls.Marshal(extra)
}
// buildLogLeaf builds the trillian.LogLeaf. The chainHash argument controls
// whether ExtraDataForChain or ExtraDataForChainHash method will be called.
// If chainHash is not nil, but neither is chain, then chain will be ignored.
func buildLogLeaf(logPrefix string, merkleLeaf ct.MerkleTreeLeaf, leafIndex int64, cert ct.ASN1Cert, chain []ct.ASN1Cert, chainHash []byte, isPrecert bool) (*trillian.LogLeaf, error) {
leafData, err := tls.Marshal(merkleLeaf)
if err != nil {
klog.Warningf("%s: Failed to serialize Merkle leaf: %v", logPrefix, err)
return nil, err
}
var extraData []byte
if chainHash == nil {
extraData, err = ExtraDataForChain(cert, chain, isPrecert)
} else {
extraData, err = ExtraDataForChainHash(cert, chainHash, isPrecert)
}
if err != nil {
klog.Warningf("%s: Failed to serialize chain for ExtraData: %v", logPrefix, err)
return nil, err
}
// leafIDHash allows Trillian to detect duplicate entries, so this should be
// a hash over the cert data.
leafIDHash := sha256.Sum256(cert.Data)
return &trillian.LogLeaf{
LeafValue: leafData,
ExtraData: extraData,
LeafIndex: leafIndex,
LeafIdentityHash: leafIDHash[:],
}, nil
}
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