import "crypto/des"

func ExampleNewTripleDESCipher() {
	// NewTripleDESCipher can also be used when EDE2 is required by
	// duplicating the first 8 bytes of the 16-byte key.
	ede2Key := []byte("example key 1234")

	var tripleDESKey []byte
	tripleDESKey = append(tripleDESKey, ede2Key[:16]...)
	tripleDESKey = append(tripleDESKey, ede2Key[:8]...)

	_, err := des.NewTripleDESCipher(tripleDESKey)
	if err != nil {
		panic(err)
	}

}

// A tripleDESCipher is an instance of TripleDES encryption.
type tripleDESCipher struct {
	cipher1, cipher2, cipher3 desCipher
}

// NewTripleDESCipher creates and returns a new [cipher.Block].
func NewTripleDESCipher(key []byte) (cipher.Block, error) {
	if len(key) != 24 {
		return nil, KeySizeError(len(key))
	}

	c := new(tripleDESCipher)
	c.cipher1.generateSubkeys(key[:8])

	cipher:     PEMCipherDES,
	name:       "DES-CBC",
	cipherFunc: des.NewCipher,
	keySize:    8,
	blockSize:  des.BlockSize,
}, {
	cipher:     PEMCipher3DES,
	name:       "DES-EDE3-CBC",
	cipherFunc: des.NewTripleDESCipher,
	keySize:    24,
	blockSize:  des.BlockSize,
}, {
	cipher:     PEMCipherAES128,
	name:       "AES-128-CBC",
	cipherFunc: aes.NewCipher,
	keySize:    16,
	blockSize:  aes.BlockSize,
}, {