dnssec_privkey.go raw

   1  package dns
   2  
   3  import (
   4  	"crypto"
   5  	"crypto/ecdsa"
   6  	"crypto/ed25519"
   7  	"crypto/rsa"
   8  	"math/big"
   9  	"strconv"
  10  )
  11  
  12  const format = "Private-key-format: v1.3\n"
  13  
  14  var bigIntOne = big.NewInt(1)
  15  
  16  // PrivateKeyString converts a PrivateKey to a string. This string has the same
  17  // format as the private-key-file of BIND9 (Private-key-format: v1.3).
  18  // It needs some info from the key (the algorithm), so its a method of the DNSKEY.
  19  // It supports *rsa.PrivateKey, *ecdsa.PrivateKey and ed25519.PrivateKey.
  20  func (r *DNSKEY) PrivateKeyString(p crypto.PrivateKey) string {
  21  	algorithm := strconv.Itoa(int(r.Algorithm))
  22  	algorithm += " (" + AlgorithmToString[r.Algorithm] + ")"
  23  
  24  	switch p := p.(type) {
  25  	case *rsa.PrivateKey:
  26  		modulus := toBase64(p.PublicKey.N.Bytes())
  27  		e := big.NewInt(int64(p.PublicKey.E))
  28  		publicExponent := toBase64(e.Bytes())
  29  		privateExponent := toBase64(p.D.Bytes())
  30  		prime1 := toBase64(p.Primes[0].Bytes())
  31  		prime2 := toBase64(p.Primes[1].Bytes())
  32  		// Calculate Exponent1/2 and Coefficient as per: http://en.wikipedia.org/wiki/RSA#Using_the_Chinese_remainder_algorithm
  33  		// and from: http://code.google.com/p/go/issues/detail?id=987
  34  		p1 := new(big.Int).Sub(p.Primes[0], bigIntOne)
  35  		q1 := new(big.Int).Sub(p.Primes[1], bigIntOne)
  36  		exp1 := new(big.Int).Mod(p.D, p1)
  37  		exp2 := new(big.Int).Mod(p.D, q1)
  38  		coeff := new(big.Int).ModInverse(p.Primes[1], p.Primes[0])
  39  
  40  		exponent1 := toBase64(exp1.Bytes())
  41  		exponent2 := toBase64(exp2.Bytes())
  42  		coefficient := toBase64(coeff.Bytes())
  43  
  44  		return format +
  45  			"Algorithm: " + algorithm + "\n" +
  46  			"Modulus: " + modulus + "\n" +
  47  			"PublicExponent: " + publicExponent + "\n" +
  48  			"PrivateExponent: " + privateExponent + "\n" +
  49  			"Prime1: " + prime1 + "\n" +
  50  			"Prime2: " + prime2 + "\n" +
  51  			"Exponent1: " + exponent1 + "\n" +
  52  			"Exponent2: " + exponent2 + "\n" +
  53  			"Coefficient: " + coefficient + "\n"
  54  
  55  	case *ecdsa.PrivateKey:
  56  		var intlen int
  57  		switch r.Algorithm {
  58  		case ECDSAP256SHA256:
  59  			intlen = 32
  60  		case ECDSAP384SHA384:
  61  			intlen = 48
  62  		}
  63  		private := toBase64(intToBytes(p.D, intlen))
  64  		return format +
  65  			"Algorithm: " + algorithm + "\n" +
  66  			"PrivateKey: " + private + "\n"
  67  
  68  	case ed25519.PrivateKey:
  69  		private := toBase64(p.Seed())
  70  		return format +
  71  			"Algorithm: " + algorithm + "\n" +
  72  			"PrivateKey: " + private + "\n"
  73  
  74  	default:
  75  		return ""
  76  	}
  77  }
  78