telebit/vendor/github.com/jcmturner/gokrb5/v8/crypto/rfc4757/checksum.go

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2020-06-03 06:18:04 +00:00
package rfc4757
import (
"bytes"
"crypto/hmac"
"crypto/md5"
"io"
)
// Checksum returns a hash of the data in accordance with RFC 4757
func Checksum(key []byte, usage uint32, data []byte) ([]byte, error) {
// Create hashing key
s := append([]byte(`signaturekey`), byte(0x00)) //includes zero octet at end
mac := hmac.New(md5.New, key)
mac.Write(s)
Ksign := mac.Sum(nil)
// Format data
tb := UsageToMSMsgType(usage)
p := append(tb, data...)
h := md5.New()
rb := bytes.NewReader(p)
_, err := io.Copy(h, rb)
if err != nil {
return []byte{}, err
}
tmp := h.Sum(nil)
// Generate HMAC
mac = hmac.New(md5.New, Ksign)
mac.Write(tmp)
return mac.Sum(nil), nil
}
// HMAC returns a keyed MD5 checksum of the data
func HMAC(key []byte, data []byte) []byte {
mac := hmac.New(md5.New, key)
mac.Write(data)
return mac.Sum(nil)
}