get_consistency_proof.go

Documentation: github.com/google/certificate-transparency-go/client/ctclient/cmd

     1  // Copyright 2022 Google LLC. All Rights Reserved.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package cmd
    16  
    17  import (
    18  	"context"
    19  	"crypto/sha256"
    20  	"encoding/base64"
    21  	"encoding/hex"
    22  	"fmt"
    23  
    24  	"github.com/google/certificate-transparency-go/client"
    25  	"github.com/spf13/cobra"
    26  	"github.com/transparency-dev/merkle/proof"
    27  	"github.com/transparency-dev/merkle/rfc6962"
    28  	"k8s.io/klog/v2"
    29  )
    30  
    31  var (
    32  	treeHash string
    33  	prevSize uint64
    34  	prevHash string
    35  )
    36  
    37  func init() {
    38  	cmd := cobra.Command{
    39  		Use:     fmt.Sprintf("get-consistency-proof %s --size=N --tree_hash=hash --prev_size=N --prev_hash=hash", connectionFlags),
    40  		Aliases: []string{"getconsistencyproof", "consistency-proof", "consistency"},
    41  		Short:   "Fetch and verify a consistency proof between two tree states",
    42  		Args:    cobra.MaximumNArgs(0),
    43  		Run: func(cmd *cobra.Command, _ []string) {
    44  			runGetConsistencyProof(cmd.Context())
    45  		},
    46  	}
    47  	// TODO(pavelkalinnikov): Don't share this parameter with get-inclusion-proof.
    48  	cmd.Flags().Uint64Var(&treeSize, "size", 0, "Tree size to query at")
    49  	cmd.Flags().StringVar(&treeHash, "tree_hash", "", "Tree hash to check against (as hex string or base64)")
    50  	cmd.Flags().Uint64Var(&prevSize, "prev_size", 0, "Previous tree size to get consistency against")
    51  	cmd.Flags().StringVar(&prevHash, "prev_hash", "", "Previous tree hash to check against (as hex string or base64)")
    52  	rootCmd.AddCommand(&cmd)
    53  }
    54  
    55  // runGetConsistencyProof runs the get-consistency-proof command.
    56  func runGetConsistencyProof(ctx context.Context) {
    57  	logClient := connect(ctx)
    58  	if treeSize <= 0 {
    59  		klog.Exit("No valid --size supplied")
    60  	}
    61  	if prevSize <= 0 {
    62  		klog.Exit("No valid --prev_size supplied")
    63  	}
    64  	var hash1, hash2 []byte
    65  	if prevHash != "" {
    66  		var err error
    67  		hash1, err = hashFromString(prevHash)
    68  		if err != nil {
    69  			klog.Exitf("Invalid --prev_hash: %v", err)
    70  		}
    71  	}
    72  	if treeHash != "" {
    73  		var err error
    74  		hash2, err = hashFromString(treeHash)
    75  		if err != nil {
    76  			klog.Exitf("Invalid --tree_hash: %v", err)
    77  		}
    78  	}
    79  	if (hash1 != nil) != (hash2 != nil) {
    80  		klog.Exitf("Need both --prev_hash and --tree_hash or neither")
    81  	}
    82  	getConsistencyProofBetween(ctx, logClient, prevSize, treeSize, hash1, hash2)
    83  }
    84  
    85  func getConsistencyProofBetween(ctx context.Context, logClient client.CheckLogClient, first, second uint64, prevHash, treeHash []byte) {
    86  	pf, err := logClient.GetSTHConsistency(ctx, uint64(first), uint64(second))
    87  	if err != nil {
    88  		exitWithDetails(err)
    89  	}
    90  	fmt.Printf("Consistency proof from size %d to size %d:\n", first, second)
    91  	for _, e := range pf {
    92  		fmt.Printf("  %x\n", e)
    93  	}
    94  	if prevHash == nil || treeHash == nil {
    95  		return
    96  	}
    97  	// We have tree hashes so we can verify the proof.
    98  	if err := proof.VerifyConsistency(rfc6962.DefaultHasher, first, second, pf, prevHash, treeHash); err != nil {
    99  		klog.Exitf("Failed to VerifyConsistency(%x @size=%d, %x @size=%d): %v", prevHash, first, treeHash, second, err)
   100  	}
   101  	fmt.Printf("Verified that hash %x @%d + proof = hash %x @%d\n", prevHash, first, treeHash, second)
   102  }
   103  
   104  func hashFromString(input string) ([]byte, error) {
   105  	hash, err := hex.DecodeString(input)
   106  	if err == nil && len(hash) == sha256.Size {
   107  		return hash, nil
   108  	}
   109  	hash, err = base64.StdEncoding.DecodeString(input)
   110  	if err == nil && len(hash) == sha256.Size {
   111  		return hash, nil
   112  	}
   113  	return nil, fmt.Errorf("hash value %q failed to parse as 32-byte hex or base64", input)
   114  }
   115
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