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