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//go:build !windows
// Copyright (c) 2018, Ian Haken. 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 main
import (
"crypto/rsa"
"crypto/x509"
"flag"
"fmt"
"io"
"os"
)
func verifyAction() {
var pubKeyPath = flag.String("public-key", "publickey", "Input path of public key file")
var hashAlgArg = flag.String("hash", "SHA256", "Hash algorithm to use when verifying the signature")
var signaturePath = flag.String("signature", "sig.data", "Input path of previously generated signature")
var dataPath = flag.String("data", "", "Path to the data that was signed. If empty or omitted, the data will be read from stdin.")
flag.CommandLine.Parse(os.Args[2:])
hashAlg, ok := hashNames[*hashAlgArg]
if !ok {
fmt.Fprintf(os.Stderr, "Invalid hash algorithm: %s\n", *hashAlgArg)
return
}
var err error
var data []byte
if *dataPath == "" {
data, err = io.ReadAll(os.Stdin)
} else {
data, err = os.ReadFile(*dataPath)
}
if err != nil {
fmt.Fprintf(os.Stderr, "Error reading input data: %s\n", err)
return
}
signature, err := os.ReadFile(*signaturePath)
if err != nil {
fmt.Fprintf(os.Stderr, "Error reading signature file: %s\n", err)
return
}
pubKeyBytes, err := os.ReadFile(*pubKeyPath)
if err != nil {
fmt.Fprintf(os.Stderr, "Error reading public key file: %s\n", err)
return
}
pubKey, err := x509.ParsePKIXPublicKey(pubKeyBytes)
if err != nil {
fmt.Fprintf(os.Stderr, "Error parsing public key: %s\n", err)
return
}
rsaPubKey, ok := pubKey.(*rsa.PublicKey)
if !ok {
fmt.Fprintf(os.Stderr, "Expected public key to be an RSA key, but was %T\n", pubKey)
return
}
hash := hashAlg.New()
if _, err = hash.Write(data); err != nil {
fmt.Fprintf(os.Stderr, "Error building hash of data: %s\n", err)
return
}
hashed := hash.Sum(nil)
if err = rsa.VerifyPKCS1v15(rsaPubKey, hashAlg, hashed[:], signature); err != nil {
fmt.Fprintf(os.Stderr, "Error from verification: %s\n", err)
return
}
fmt.Printf("Signature valid.\n")
}
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