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Golang PKCS7 Padding/Unpadding
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| // pkcs7strip remove pkcs7 padding | |
| func pkcs7strip(data []byte, blockSize int) ([]byte, error) { | |
| length := len(data) | |
| if length == 0 { | |
| return nil, errors.New("pkcs7: Data is empty") | |
| } | |
| if length%blockSize != 0 { | |
| return nil, errors.New("pkcs7: Data is not block-aligned") | |
| } | |
| padLen := int(data[length-1]) | |
| ref := bytes.Repeat([]byte{byte(padLen)}, padLen) | |
| if padLen > blockSize || padLen == 0 || !bytes.HasSuffix(data, ref) { | |
| return nil, errors.New("pkcs7: Invalid padding") | |
| } | |
| return data[:length-padLen], nil | |
| } | |
| // pkcs7pad add pkcs7 padding | |
| func pkcs7pad(data []byte, blockSize int) ([]byte, error) { | |
| if blockSize <= 1 || blockSize >= 256 { | |
| return nil, fmt.Errorf("pkcs7: Invalid block size %d", blockSize) | |
| } else { | |
| padLen := blockSize - len(data) % blockSize | |
| padding := bytes.Repeat([]byte{byte(padLen)}, padLen) | |
| return append(data, padding...), nil | |
| } | |
| } |
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