40 lines
986 B
Go
40 lines
986 B
Go
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package padding
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import "errors"
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var (
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ErrPaddingSize = errors.New("pkcs5 padding size error")
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PKCS5 = &pkcs5{}
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)
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// pkcs5Padding is a pkcs5 padding struct.
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type pkcs5 struct{}
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// Padding is interface used for crypto.
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type Padding interface {
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Padding(src []byte, blockSize int) []byte
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Unpadding(src []byte, blockSize int) ([]byte, error)
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}
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// Padding implements the Padding interface Padding method.
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func (p *pkcs5) Padding(src []byte, blockSize int) []byte {
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srcLen := len(src)
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padLen := byte(blockSize - (srcLen % blockSize))
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pd := make([]byte, srcLen+int(padLen))
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copy(pd, src)
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for i := srcLen; i < len(pd); i++ {
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pd[i] = padLen
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}
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return pd
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}
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// Unpadding implements the Padding interface Unpadding method.
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func (p *pkcs5) Unpadding(src []byte, blockSize int) ([]byte, error) {
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srcLen := len(src)
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paddingLen := int(src[srcLen-1])
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if paddingLen >= srcLen || paddingLen > blockSize {
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return nil, ErrPaddingSize
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}
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return src[:srcLen-paddingLen], nil
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}
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