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