45 lines
1.3 KiB
Go
45 lines
1.3 KiB
Go
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package dns
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import (
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"crypto/sha256"
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"crypto/x509"
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"encoding/hex"
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)
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// Sign creates a SMIMEA record from an SSL certificate.
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func (r *SMIMEA) Sign(usage, selector, matchingType int, cert *x509.Certificate) (err error) {
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r.Hdr.Rrtype = TypeSMIMEA
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r.Usage = uint8(usage)
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r.Selector = uint8(selector)
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r.MatchingType = uint8(matchingType)
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r.Certificate, err = CertificateToDANE(r.Selector, r.MatchingType, cert)
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return err
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}
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// Verify verifies a SMIMEA record against an SSL certificate. If it is OK
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// a nil error is returned.
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func (r *SMIMEA) Verify(cert *x509.Certificate) error {
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c, err := CertificateToDANE(r.Selector, r.MatchingType, cert)
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if err != nil {
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return err // Not also ErrSig?
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}
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if r.Certificate == c {
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return nil
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}
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return ErrSig // ErrSig, really?
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}
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// SMIMEAName returns the ownername of a SMIMEA resource record as per the
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// format specified in RFC 'draft-ietf-dane-smime-12' Section 2 and 3
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func SMIMEAName(email, domain string) (string, error) {
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hasher := sha256.New()
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hasher.Write([]byte(email))
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// RFC Section 3: "The local-part is hashed using the SHA2-256
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// algorithm with the hash truncated to 28 octets and
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// represented in its hexadecimal representation to become the
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// left-most label in the prepared domain name"
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return hex.EncodeToString(hasher.Sum(nil)[:28]) + "." + "_smimecert." + domain, nil
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}
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