gitea/vendor/github.com/miekg/dns/dnssec_keygen.go
2021-02-28 18:08:33 -05:00

141 lines
3.1 KiB
Go
Vendored

package dns
import (
"crypto"
"crypto/ecdsa"
"crypto/elliptic"
"crypto/rand"
"crypto/rsa"
"math/big"
"golang.org/x/crypto/ed25519"
)
// Generate generates a DNSKEY of the given bit size.
// The public part is put inside the DNSKEY record.
// The Algorithm in the key must be set as this will define
// what kind of DNSKEY will be generated.
// The ECDSA algorithms imply a fixed keysize, in that case
// bits should be set to the size of the algorithm.
func (k *DNSKEY) Generate(bits int) (crypto.PrivateKey, error) {
switch k.Algorithm {
case RSASHA1, RSASHA256, RSASHA1NSEC3SHA1:
if bits < 512 || bits > 4096 {
return nil, ErrKeySize
}
case RSASHA512:
if bits < 1024 || bits > 4096 {
return nil, ErrKeySize
}
case ECDSAP256SHA256:
if bits != 256 {
return nil, ErrKeySize
}
case ECDSAP384SHA384:
if bits != 384 {
return nil, ErrKeySize
}
case ED25519:
if bits != 256 {
return nil, ErrKeySize
}
default:
return nil, ErrAlg
}
switch k.Algorithm {
case RSASHA1, RSASHA256, RSASHA512, RSASHA1NSEC3SHA1:
priv, err := rsa.GenerateKey(rand.Reader, bits)
if err != nil {
return nil, err
}
k.setPublicKeyRSA(priv.PublicKey.E, priv.PublicKey.N)
return priv, nil
case ECDSAP256SHA256, ECDSAP384SHA384:
var c elliptic.Curve
switch k.Algorithm {
case ECDSAP256SHA256:
c = elliptic.P256()
case ECDSAP384SHA384:
c = elliptic.P384()
}
priv, err := ecdsa.GenerateKey(c, rand.Reader)
if err != nil {
return nil, err
}
k.setPublicKeyECDSA(priv.PublicKey.X, priv.PublicKey.Y)
return priv, nil
case ED25519:
pub, priv, err := ed25519.GenerateKey(rand.Reader)
if err != nil {
return nil, err
}
k.setPublicKeyED25519(pub)
return priv, nil
default:
return nil, ErrAlg
}
}
// Set the public key (the value E and N)
func (k *DNSKEY) setPublicKeyRSA(_E int, _N *big.Int) bool {
if _E == 0 || _N == nil {
return false
}
buf := exponentToBuf(_E)
buf = append(buf, _N.Bytes()...)
k.PublicKey = toBase64(buf)
return true
}
// Set the public key for Elliptic Curves
func (k *DNSKEY) setPublicKeyECDSA(_X, _Y *big.Int) bool {
if _X == nil || _Y == nil {
return false
}
var intlen int
switch k.Algorithm {
case ECDSAP256SHA256:
intlen = 32
case ECDSAP384SHA384:
intlen = 48
}
k.PublicKey = toBase64(curveToBuf(_X, _Y, intlen))
return true
}
// Set the public key for Ed25519
func (k *DNSKEY) setPublicKeyED25519(_K ed25519.PublicKey) bool {
if _K == nil {
return false
}
k.PublicKey = toBase64(_K)
return true
}
// Set the public key (the values E and N) for RSA
// RFC 3110: Section 2. RSA Public KEY Resource Records
func exponentToBuf(_E int) []byte {
var buf []byte
i := big.NewInt(int64(_E)).Bytes()
if len(i) < 256 {
buf = make([]byte, 1, 1+len(i))
buf[0] = uint8(len(i))
} else {
buf = make([]byte, 3, 3+len(i))
buf[0] = 0
buf[1] = uint8(len(i) >> 8)
buf[2] = uint8(len(i))
}
buf = append(buf, i...)
return buf
}
// Set the public key for X and Y for Curve. The two
// values are just concatenated.
func curveToBuf(_X, _Y *big.Int, intlen int) []byte {
buf := intToBytes(_X, intlen)
buf = append(buf, intToBytes(_Y, intlen)...)
return buf
}