blob: 7484f25b8056bc702befa550a81616edc2a56eee [file] [log] [blame] [edit]
// Copyright 2024 The BoringSSL 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
//
// https://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.
//go:build ignore
// This trivial program is used to corrupt the FIPS module. This is done as
// part of FIPS testing to show that the integrity check is effective.
//
// It finds the (sole) occurance of a given hex pattern in a file and flips the
// first bit. The hex pattern is intended to be the output of running
// `BORINGSSL_FIPS_SHOW_HASH=1 ninja bcm.o`, i.e. the integrity hash value of
// the module. By flipping the first bit we ensure that the check will
// mismatch.
//
// This is a simplier version of `break-hash.go` for when we're building with
// BORINGSSL_FIPS_SHOW_HASH. (But we don't do that in all cases.)
package main
import (
"bytes"
"encoding/hex"
"fmt"
"io/ioutil"
"os"
)
func main() {
if len(os.Args) != 3 {
fmt.Fprintln(os.Stderr, "Usage: program <hex_string> <file_path>")
os.Exit(1)
}
hexString := os.Args[1]
filePath := os.Args[2]
// Decode hex string
searchBytes, err := hex.DecodeString(hexString)
if err != nil {
fmt.Fprintln(os.Stderr, "Error decoding hex string:", err)
os.Exit(1)
}
// Read file contents
content, err := ioutil.ReadFile(filePath)
if err != nil {
fmt.Fprintln(os.Stderr, "Error reading file:", err)
os.Exit(1)
}
// Search for the occurrence of the hex string
index := bytes.Index(content, searchBytes)
if index == -1 {
fmt.Fprintln(os.Stderr, "Hex string not found in the file")
os.Exit(1)
}
// Check for other occurrences
if bytes.Index(content[index+len(searchBytes):], searchBytes) != -1 {
fmt.Fprintln(os.Stderr, "Multiple occurrences of the hex string found")
os.Exit(1)
}
// Flip the first bit
content[index] ^= 0x80
// Write updated contents to stdout
os.Stdout.Write(content)
}