56 lines
1.1 KiB
Go
56 lines
1.1 KiB
Go
package payload
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import (
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"crypto/cipher"
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"errors"
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"fmt"
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"io"
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)
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type BlockStream func(block cipher.Block, iv []byte) cipher.Stream
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type BlockMode string
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const OFB BlockMode = "ofb"
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func (this BlockMode) GetEncryptorStream() (BlockStream, error) {
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switch this {
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case OFB:
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return cipher.NewOFB, nil
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default:
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err := fmt.Sprintf("BlockMode '%s' is not available", this)
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return nil, errors.New(err)
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}
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}
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func createIV(b cipher.Block, rd io.Reader) ([]byte, error) {
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ret := make([]byte, b.BlockSize())
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if _, err := rd.Read(ret); err != nil {
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return nil, err
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}
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return ret, nil
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}
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func (this BlockMode) GetCipherStream(block cipher.Block, rd io.Reader) (stream cipher.Stream, iv []byte, err error) {
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iv, err = createIV(block, rd)
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if err != nil {
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return nil, nil, err
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}
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streamCreator, err := this.GetEncryptorStream()
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if err != nil {
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return nil, nil, err
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}
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return streamCreator(block, iv), iv, nil
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}
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func GetBlockModeByName(blockModeName string) (BlockMode, error) {
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ret := BlockMode(blockModeName)
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switch ret {
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case OFB:
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return ret, nil
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default:
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return "", errors.New("block mode " + blockModeName + " is not supported")
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}
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}
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