80 lines
1.7 KiB
Go
80 lines
1.7 KiB
Go
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package main
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import (
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"bytes"
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"crypto/rand"
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"crypto/rsa"
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"crypto/x509"
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"encoding/pem"
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"fmt"
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"io"
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"log"
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"os"
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)
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func generateOrRetrieveRSAKeys(name string, size int) (io.Reader, []byte, error) {
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var pemprvkey bytes.Buffer
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var prvKey *rsa.PrivateKey
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fd, err := os.Open(name + ".pem")
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if os.IsNotExist(err) {
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log.Println("Private RSA key not found, generating a new one")
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fd, err = os.Create(name + ".pem")
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if err != nil {
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return nil, nil, fmt.Errorf("unable to open the file for writing: %w", err)
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}
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defer fd.Close()
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prvKey, err = rsa.GenerateKey(rand.Reader, size)
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if err != nil {
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return nil, nil, err
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}
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pkcs1prvkey := x509.MarshalPKCS1PrivateKey(prvKey)
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var tmpprvkey bytes.Buffer
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w := io.MultiWriter(&tmpprvkey, &pemprvkey)
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err = pem.Encode(w, &pem.Block{Type: "RSA PRIVATE KEY", Bytes: pkcs1prvkey})
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if err != nil {
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return nil, nil, err
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}
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// Save it!
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_, err = tmpprvkey.WriteTo(fd)
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if err != nil {
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return nil, nil, err
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}
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} else if err != nil {
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return nil, nil, err
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} else {
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defer fd.Close()
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var tmpprvkey bytes.Buffer
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io.Copy(io.MultiWriter(&tmpprvkey, &pemprvkey), fd)
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decodedpem, _ := pem.Decode(tmpprvkey.Bytes())
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if decodedpem == nil {
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return nil, nil, fmt.Errorf("unable to decode PEM data")
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} else if decodedpem.Type != "RSA PRIVATE KEY" {
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return nil, nil, fmt.Errorf("not the expected PEM type: %s intead of RSA PRIVATE KEY", decodedpem.Type)
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}
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prvKey, err = x509.ParsePKCS1PrivateKey(decodedpem.Bytes)
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}
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pubkey := prvKey.Public()
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pkixpub, err := x509.MarshalPKIXPublicKey(pubkey.(*rsa.PublicKey))
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if err != nil {
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return nil, nil, err
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}
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pempubkey := pem.EncodeToMemory(
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&pem.Block{
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Type: "PUBLIC KEY",
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Bytes: pkixpub,
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},
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)
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return &pemprvkey, pempubkey, nil
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}
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