103 lines
3.0 KiB
Go
103 lines
3.0 KiB
Go
package connect
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import (
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"bytes"
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"crypto"
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"crypto/rand"
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"crypto/rsa"
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"crypto/x509"
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"crypto/x509/pkix"
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"encoding/asn1"
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"encoding/pem"
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"net"
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"net/url"
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)
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// SigAlgoForKey returns the preferred x509.SignatureAlgorithm for a given key
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// based on it's type. If the key type is not supported we return
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// ECDSAWithSHA256 on the basis that it will fail anyway and we've already type
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// checked keys by the time we call this in general.
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func SigAlgoForKey(key crypto.Signer) x509.SignatureAlgorithm {
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if _, ok := key.(*rsa.PrivateKey); ok {
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return x509.SHA256WithRSA
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}
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// We default to ECDSA but don't bother detecting invalid key types as we do
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// that in lots of other places and it will fail anyway if we try to sign with
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// an incompatible type.
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return x509.ECDSAWithSHA256
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}
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// SigAlgoForKeyType returns the preferred x509.SignatureAlgorithm for a given
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// key type string from configuration or an existing cert. If the key type is
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// not supported we return ECDSAWithSHA256 on the basis that it will fail anyway
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// and we've already type checked config by the time we call this in general.
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func SigAlgoForKeyType(keyType string) x509.SignatureAlgorithm {
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switch keyType {
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case "rsa":
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return x509.SHA256WithRSA
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case "ec":
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fallthrough
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default:
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return x509.ECDSAWithSHA256
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}
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}
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// CreateCSR returns a CSR to sign the given service with SAN entries
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// along with the PEM-encoded private key for this certificate.
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func CreateCSR(uri CertURI, commonName string, privateKey crypto.Signer,
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dnsNames []string, ipAddresses []net.IP, extensions ...pkix.Extension) (string, error) {
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template := &x509.CertificateRequest{
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URIs: []*url.URL{uri.URI()},
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SignatureAlgorithm: SigAlgoForKey(privateKey),
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ExtraExtensions: extensions,
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Subject: pkix.Name{CommonName: commonName},
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DNSNames: dnsNames,
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IPAddresses: ipAddresses,
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}
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// Create the CSR itself
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var csrBuf bytes.Buffer
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bs, err := x509.CreateCertificateRequest(rand.Reader, template, privateKey)
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if err != nil {
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return "", err
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}
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err = pem.Encode(&csrBuf, &pem.Block{Type: "CERTIFICATE REQUEST", Bytes: bs})
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if err != nil {
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return "", err
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}
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return csrBuf.String(), nil
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}
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// CreateCSR returns a CA CSR to sign the given service along with the PEM-encoded
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// private key for this certificate.
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func CreateCACSR(uri CertURI, commonName string, privateKey crypto.Signer) (string, error) {
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ext, err := CreateCAExtension()
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if err != nil {
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return "", err
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}
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return CreateCSR(uri, commonName, privateKey, nil, nil, ext)
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}
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// CreateCAExtension creates a pkix.Extension for the x509 Basic Constraints
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// IsCA field ()
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func CreateCAExtension() (pkix.Extension, error) {
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type basicConstraints struct {
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IsCA bool `asn1:"optional"`
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MaxPathLen int `asn1:"optional"`
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}
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basicCon := basicConstraints{IsCA: true, MaxPathLen: 0}
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bitstr, err := asn1.Marshal(basicCon)
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if err != nil {
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return pkix.Extension{}, err
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}
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return pkix.Extension{
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Id: []int{2, 5, 29, 19}, // from x509 package
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Critical: true,
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Value: bitstr,
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}, nil
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}
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