80 lines
1.6 KiB
Go
80 lines
1.6 KiB
Go
package openssl
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import (
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"bytes"
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"errors"
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)
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var ErrUnPadding = errors.New("UnPadding error")
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const PKCS5_PADDING = "PKCS5"
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const PKCS7_PADDING = "PKCS7"
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const ZEROS_PADDING = "ZEROS"
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func Padding(padding string, src []byte, blockSize int) []byte {
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switch padding {
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case PKCS5_PADDING:
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src = PKCS5Padding(src, blockSize)
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case PKCS7_PADDING:
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src = PKCS7Padding(src, blockSize)
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case ZEROS_PADDING:
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src = ZerosPadding(src, blockSize)
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}
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return src
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}
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func UnPadding(padding string, src []byte) ([]byte, error) {
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switch padding {
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case PKCS5_PADDING:
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return PKCS5Unpadding(src)
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case PKCS7_PADDING:
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return PKCS7UnPadding(src)
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case ZEROS_PADDING:
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return ZerosUnPadding(src)
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}
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return src, nil
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}
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func PKCS5Padding(src []byte, blockSize int) []byte {
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return PKCS7Padding(src, blockSize)
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}
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func PKCS5Unpadding(src []byte) ([]byte, error) {
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return PKCS7UnPadding(src)
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}
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func PKCS7Padding(src []byte, blockSize int) []byte {
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padding := blockSize - len(src)%blockSize
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padtext := bytes.Repeat([]byte{byte(padding)}, padding)
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return append(src, padtext...)
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}
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func PKCS7UnPadding(src []byte) ([]byte, error) {
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length := len(src)
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if length == 0 {
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return src, ErrUnPadding
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}
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unpadding := int(src[length-1])
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if length < unpadding {
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return src, ErrUnPadding
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}
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return src[:(length - unpadding)], nil
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}
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func ZerosPadding(src []byte, blockSize int) []byte {
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paddingCount := blockSize - len(src)%blockSize
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if paddingCount == 0 {
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return src
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} else {
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return append(src, bytes.Repeat([]byte{byte(0)}, paddingCount)...)
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}
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}
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func ZerosUnPadding(src []byte) ([]byte, error) {
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for i := len(src) - 1; ; i-- {
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if src[i] != 0 {
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return src[:i+1], nil
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}
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}
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}
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