dnssec_privkey.go

Documentation: github.com/miekg/dns

     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
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