153 lines
4.3 KiB
Go
153 lines
4.3 KiB
Go
package dns
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import (
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"os"
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"io"
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"big"
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"fmt"
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"strconv"
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"crypto/rsa"
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"crypto/rand"
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"encoding/line"
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)
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// Empty interface that is used as a wrapper around all possible
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// private key implementations from the crypto package.
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type PrivateKey interface{}
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// Generate a key 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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func (r *RR_DNSKEY) Generate(bits int) (PrivateKey, os.Error) {
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switch r.Algorithm {
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case AlgRSAMD5, AlgRSASHA1, AlgRSASHA256:
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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 AlgRSASHA512:
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if bits < 1024 || bits > 4096 {
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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 r.Algorithm {
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case AlgRSAMD5, AlgRSASHA1, AlgRSASHA256, AlgRSASHA512:
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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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keybuf := exponentToBuf(priv.PublicKey.E)
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keybuf = append(keybuf, priv.PublicKey.N.Bytes()...)
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r.PublicKey = unpackBase64(keybuf)
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return priv, nil
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}
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return nil, nil // Dummy return
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}
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// Convert a PrivateKey to a string. This
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// string has the same format as the private-key-file of BIND9 (Private-key-format: v1.3).
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// It needs some info from the key (hashing, keytag), so its a method of the RR_DNSKEY.
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func (r *RR_DNSKEY) PrivateKeyString(p PrivateKey) (s string) {
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switch t := p.(type) {
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case *rsa.PrivateKey:
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algorithm := strconv.Itoa(int(r.Algorithm)) + " (" + alg_str[r.Algorithm] + ")"
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modulus := unpackBase64(t.PublicKey.N.Bytes())
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e := big.NewInt(int64(t.PublicKey.E))
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publicExponent := unpackBase64(e.Bytes())
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privateExponent := unpackBase64(t.D.Bytes())
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prime1 := unpackBase64(t.P.Bytes())
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prime2 := unpackBase64(t.Q.Bytes())
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// Calculate Exponent1/2 and Coefficient as per: http://en.wikipedia.org/wiki/RSA#Using_the_Chinese_remainder_algorithm
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// and from: http://code.google.com/p/go/issues/detail?id=987
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one := big.NewInt(1)
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minusone := big.NewInt(-1)
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p_1 := big.NewInt(0).Sub(t.P, one)
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q_1 := big.NewInt(0).Sub(t.Q, one)
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exp1 := big.NewInt(0).Mod(t.D, p_1)
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exp2 := big.NewInt(0).Mod(t.D, q_1)
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coeff := big.NewInt(0).Exp(t.Q, minusone, t.P)
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exponent1 := unpackBase64(exp1.Bytes())
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exponent2 := unpackBase64(exp2.Bytes())
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coefficient := unpackBase64(coeff.Bytes())
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s = "Private-key-format: v1.3\n" +
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"Algorithm: " + algorithm + "\n" +
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"Modules: " + modulus + "\n" +
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"PublicExponent: " + publicExponent + "\n" +
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"PrivateExponent: " + privateExponent + "\n" +
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"Prime1: " + prime1 + "\n" +
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"Prime2: " + prime2 + "\n" +
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"Exponent1: " + exponent1 + "\n" +
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"Exponent2: " + exponent2 + "\n" +
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"Coefficient: " + coefficient + "\n"
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}
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return
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}
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// Read a private key (file) string and create a public key. Return the private key.
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func (k *RR_DNSKEY) ReadPrivateKey(q io.Reader) (PrivateKey, os.Error) {
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p := new(rsa.PrivateKey)
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var left, right string
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r := line.NewReader(q, 300)
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line, _, err := r.ReadLine()
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for err == nil {
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n, _ := fmt.Sscanf(string(line), "%s %s+\n", &left, &right)
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if n > 0 {
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switch left {
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case "Private-key-format:":
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if right != "v1.3" {
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return nil, ErrPrivKey
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}
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case "Algorithm:":
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a, _ := strconv.Atoi(right)
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if a == 0 {
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return nil, ErrAlg
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}
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k.Algorithm = uint8(a)
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case "Modulus:", "PublicExponent:", "PrivateExponent:", "Prime1:", "Prime2:":
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v, err := packBase64([]byte(right))
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if err != nil {
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return nil, err
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}
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if left == "Modulus:" {
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p.PublicKey.N = big.NewInt(0)
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p.PublicKey.N.SetBytes(v)
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}
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if left == "PublicExponent:" {
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i := big.NewInt(0)
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i.SetBytes(v)
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// Int64 should be large enough
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p.PublicKey.E = int(i.Int64())
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}
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if left == "PrivateExponent:" {
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p.D = big.NewInt(0)
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p.D.SetBytes(v)
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}
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if left == "Prime1:" {
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p.P = big.NewInt(0)
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p.P.SetBytes(v)
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}
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if left == "Prime2:" {
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p.Q = big.NewInt(0)
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p.Q.SetBytes(v)
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}
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case "Exponent1:", "Exponent2:", "Coefficient:":
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/* not used in Go (yet) */
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case "Created:", "Publish:", "Activate:":
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/* not used in Go (yet) */
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default:
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return nil, ErrKey
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}
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}
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line, _, err = r.ReadLine()
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}
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if ! k.setPublicKeyRSA(p.PublicKey.E, p.PublicKey.N) {
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return nil, ErrKey
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}
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return p, nil
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}
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