77 lines
1.6 KiB
Go
77 lines
1.6 KiB
Go
package gostdlib
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import (
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"crypto/hmac"
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"errors"
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"github.com/safing/jess/tools"
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)
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func init() {
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tools.Register(&tools.Tool{
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Info: &tools.ToolInfo{
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Name: "HMAC",
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Purpose: tools.PurposeMAC,
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Options: []uint8{
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tools.OptionNeedsDedicatedHasher,
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tools.OptionHasState,
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},
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SecurityLevel: 0, // depends on used hash function
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Comment: "RFC 2104, FIPS 198",
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Author: "Mihir Bellare et al., 1996",
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},
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Factory: func() tools.ToolLogic { return &HMAC{} },
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})
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}
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// HMAC implements the cryptographic interface for HMAC message authentication codes.
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type HMAC struct {
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tools.ToolLogicBase
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key []byte
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}
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// Setup implements the ToolLogic interface.
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func (hm *HMAC) Setup() (err error) {
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// get key
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hm.key, err = hm.Helper().NewSessionKey()
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if err != nil {
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return err
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}
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return nil
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}
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// Reset implements the ToolLogic interface.
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func (hm *HMAC) Reset() error {
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// clean up key
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hm.Helper().Burn(hm.key)
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return nil
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}
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// MAC implements the ToolLogic interface.
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func (hm *HMAC) MAC(data, associatedData []byte) ([]byte, error) {
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// create MAC
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mac := hmac.New(hm.HashTool().New, hm.key)
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// write data
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n, err := mac.Write(data)
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if err != nil {
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return nil, err
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}
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if n != len(data) {
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return nil, errors.New("failed to fully write data to HMAC hasher")
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}
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// write associated data
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if len(associatedData) > 0 {
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n, err := mac.Write(associatedData)
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if err != nil {
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return nil, err
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}
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if n != len(associatedData) {
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return nil, errors.New("failed to fully write associated data to HMAC hasher")
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}
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}
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// return sum
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return mac.Sum(nil), nil
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}
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