1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
|
package cryptoutil
import (
"crypto"
"crypto/ecdsa"
"crypto/elliptic"
"crypto/rsa"
"crypto/sha256"
"encoding/asn1"
"errors"
)
// GenerateSubjectKeyID generates Subject Key Identifier (SKI) using SHA-256
// hash of the public key bytes according to RFC 7093 section 2.
func GenerateSubjectKeyID(pub crypto.PublicKey) ([]byte, error) {
var pubBytes []byte
var err error
switch pub := pub.(type) {
case *rsa.PublicKey:
pubBytes, err = asn1.Marshal(*pub)
if err != nil {
return nil, err
}
case *ecdsa.PublicKey:
pubBytes = elliptic.Marshal(pub.Curve, pub.X, pub.Y)
default:
return nil, errors.New("only ECDSA and RSA public keys are supported")
}
hash := sha256.Sum256(pubBytes)
// According to RFC 7093, The keyIdentifier is composed of the leftmost
// 160-bits of the SHA-256 hash of the value of the BIT STRING
// subjectPublicKey (excluding the tag, length, and number of unused bits).
return hash[:20], nil
}
|
