github.com/goreleaser/nfpm/v2@v2.44.0/internal/sign/rsa.go (about)

     1  package sign
     2  
     3  import (
     4  	"crypto"
     5  	"crypto/rand"
     6  	"crypto/rsa"
     7  	"crypto/sha1" // nolint:gosec
     8  	"crypto/x509"
     9  	"encoding/pem"
    10  	"errors"
    11  	"fmt"
    12  	"io"
    13  	"os"
    14  )
    15  
    16  var (
    17  	errNoPemBlock   = errors.New("no PEM block found")
    18  	errDigestNotSH1 = errors.New("digest is not a SHA1 hash")
    19  	errNoPassphrase = errors.New("key is encrypted but no passphrase was provided")
    20  	errNoRSAKey     = errors.New("key is not an RSA key")
    21  )
    22  
    23  const (
    24  	PKCS1PrivkeyPreamble = "RSA PRIVATE KEY"
    25  	PKCS8PrivkeyPreamble = "PRIVATE KEY"
    26  )
    27  
    28  // RSASignSHA1Digest signs the provided SHA1 message digest. The key file
    29  // must be in the PEM format and can either be encrypted or not.
    30  func RSASignSHA1Digest(sha1Digest []byte, keyFile, passphrase string) ([]byte, error) {
    31  	if len(sha1Digest) != sha1.Size {
    32  		return nil, errDigestNotSH1
    33  	}
    34  
    35  	keyFileContent, err := os.ReadFile(keyFile)
    36  	if err != nil {
    37  		return nil, fmt.Errorf("reading key file: %w", err)
    38  	}
    39  
    40  	block, _ := pem.Decode(keyFileContent)
    41  	if block == nil {
    42  		return nil, errNoPemBlock
    43  	}
    44  
    45  	blockData := block.Bytes
    46  	if x509.IsEncryptedPEMBlock(block) { //nolint:staticcheck
    47  		if passphrase == "" {
    48  			return nil, errNoPassphrase
    49  		}
    50  
    51  		var decryptedBlockData []byte
    52  
    53  		decryptedBlockData, err = x509.DecryptPEMBlock(block, []byte(passphrase)) //nolint:staticcheck
    54  		if err != nil {
    55  			return nil, fmt.Errorf("decrypt private key PEM block: %w", err)
    56  		}
    57  
    58  		blockData = decryptedBlockData
    59  	}
    60  
    61  	var priv crypto.Signer
    62  
    63  	switch block.Type {
    64  	case PKCS1PrivkeyPreamble:
    65  		priv, err = x509.ParsePKCS1PrivateKey(blockData)
    66  		if err != nil {
    67  			return nil, fmt.Errorf("parse PKCS#1 private key: %w", err)
    68  		}
    69  	case PKCS8PrivkeyPreamble:
    70  		privAny, err := x509.ParsePKCS8PrivateKey(blockData)
    71  		if err != nil {
    72  			return nil, fmt.Errorf("parse PKCS#8 private key: %w", err)
    73  		}
    74  		privTmp, ok := privAny.(crypto.Signer)
    75  		if !ok {
    76  			return nil, fmt.Errorf("cannot sign with given private key")
    77  		}
    78  		priv = privTmp
    79  	default:
    80  		return nil, fmt.Errorf(`key type "%v" is not supported`, block.Type)
    81  	}
    82  
    83  	signature, err := priv.Sign(rand.Reader, sha1Digest, crypto.SHA1)
    84  	if err != nil {
    85  		return nil, fmt.Errorf("signing: %w", err)
    86  	}
    87  
    88  	return signature, nil
    89  }
    90  
    91  func rsaSign(message io.Reader, keyFile, passphrase string) ([]byte, error) {
    92  	sha1Hash := sha1.New() // nolint:gosec
    93  	_, err := io.Copy(sha1Hash, message)
    94  	if err != nil {
    95  		return nil, fmt.Errorf("create SHA1 message digest: %w", err)
    96  	}
    97  
    98  	return RSASignSHA1Digest(sha1Hash.Sum(nil), keyFile, passphrase)
    99  }
   100  
   101  // RSAVerifySHA1Digest is exported for use in tests and verifies a signature over the
   102  // provided SHA1 hash of a message. The key file must be in the PEM format.
   103  func RSAVerifySHA1Digest(sha1Digest, signature []byte, publicKeyFile string) error {
   104  	if len(sha1Digest) != sha1.Size {
   105  		return errDigestNotSH1
   106  	}
   107  
   108  	keyFileContent, err := os.ReadFile(publicKeyFile)
   109  	if err != nil {
   110  		return fmt.Errorf("reading key file: %w", err)
   111  	}
   112  
   113  	block, _ := pem.Decode(keyFileContent)
   114  	if block == nil {
   115  		return errNoPemBlock
   116  	}
   117  
   118  	pub, err := x509.ParsePKIXPublicKey(block.Bytes)
   119  	if err != nil {
   120  		return fmt.Errorf("parse PKIX public key: %w", err)
   121  	}
   122  
   123  	rsaPub, ok := pub.(*rsa.PublicKey)
   124  	if !ok {
   125  		return errNoRSAKey
   126  	}
   127  
   128  	err = rsa.VerifyPKCS1v15(rsaPub, crypto.SHA1, sha1Digest, signature)
   129  	if err != nil {
   130  		return fmt.Errorf("verify PKCS1v15 signature: %w", err)
   131  	}
   132  
   133  	return nil
   134  }
   135  
   136  func rsaVerify(message io.Reader, signature []byte, publicKeyFile string) error {
   137  	sha1Hash := sha1.New() // nolint:gosec
   138  	_, err := io.Copy(sha1Hash, message)
   139  	if err != nil {
   140  		return fmt.Errorf("create SHA1 message digest: %w", err)
   141  	}
   142  
   143  	return RSAVerifySHA1Digest(sha1Hash.Sum(nil), signature, publicKeyFile)
   144  }