ggstd 0.1.0

// // Copyright 2012 The Go Authors. All rights reserved.
// // Use of this source code is governed by a BSD-style
// // license that can be found in the LICENSE file.

// package cipher_test

// import (
// 	"bytes"
// 	"crypto/aes"
// 	"crypto/cipher"
// 	"crypto/rand"
// 	"encoding/hex"
// 	"fmt"
// 	"io"
// 	"os"
// )

// func ExampleNewGCM_encrypt() {
// 	// Load your secret key from a safe place and reuse it across multiple
// 	// Seal/Open calls. (Obviously don't use this example key for anything
// 	// real.) If you want to convert a passphrase to a key, use a suitable
// 	// package like bcrypt or scrypt.
// 	// When decoded the key should be 16 bytes (AES-128) or 32 (AES-256).
// 	key, _ := hex.DecodeString("6368616e676520746869732070617373776f726420746f206120736563726574")
// 	plaintext := []byte("exampleplaintext")

// 	block, err := aes.NewCipher(key)
// 	if err != nil {
// 		panic(err.Error())
// 	}

// 	// Never use more than 2^32 random nonces with a given key because of the risk of a repeat.
// 	nonce := make([]byte, 12)
// 	if _, err := io.ReadFull(rand.Reader, nonce); err != nil {
// 		panic(err.Error())
// 	}

// 	aesgcm, err := cipher.NewGCM(block)
// 	if err != nil {
// 		panic(err.Error())
// 	}

// 	ciphertext := aesgcm.Seal(nil, nonce, plaintext, nil)
// 	fmt.Printf("%x\n", ciphertext)
// }

// func ExampleNewGCM_decrypt() {
// 	// Load your secret key from a safe place and reuse it across multiple
// 	// Seal/Open calls. (Obviously don't use this example key for anything
// 	// real.) If you want to convert a passphrase to a key, use a suitable
// 	// package like bcrypt or scrypt.
// 	// When decoded the key should be 16 bytes (AES-128) or 32 (AES-256).
// 	key, _ := hex.DecodeString("6368616e676520746869732070617373776f726420746f206120736563726574")
// 	ciphertext, _ := hex.DecodeString("c3aaa29f002ca75870806e44086700f62ce4d43e902b3888e23ceff797a7a471")
// 	nonce, _ := hex.DecodeString("64a9433eae7ccceee2fc0eda")

// 	block, err := aes.NewCipher(key)
// 	if err != nil {
// 		panic(err.Error())
// 	}

// 	aesgcm, err := cipher.NewGCM(block)
// 	if err != nil {
// 		panic(err.Error())
// 	}

// 	plaintext, err := aesgcm.Open(nil, nonce, ciphertext, nil)
// 	if err != nil {
// 		panic(err.Error())
// 	}

// 	fmt.Printf("%s\n", plaintext)
// 	// Output: exampleplaintext
// }

// func ExampleNewCBCDecrypter() {
// 	// Load your secret key from a safe place and reuse it across multiple
// 	// NewCipher calls. (Obviously don't use this example key for anything
// 	// real.) If you want to convert a passphrase to a key, use a suitable
// 	// package like bcrypt or scrypt.
// 	key, _ := hex.DecodeString("6368616e676520746869732070617373")
// 	ciphertext, _ := hex.DecodeString("73c86d43a9d700a253a96c85b0f6b03ac9792e0e757f869cca306bd3cba1c62b")

// 	block, err := aes.NewCipher(key)
// 	if err != nil {
// 		panic(err)
// 	}

// 	// The IV needs to be unique, but not secure. Therefore it's common to
// 	// include it at the beginning of the ciphertext.
// 	if len(ciphertext) < aes.block_size {
// 		panic("ciphertext too short")
// 	}
// 	iv := ciphertext[:aes.block_size]
// 	ciphertext = ciphertext[aes.block_size:]

// 	// CBC mode always works in whole blocks.
// 	if len(ciphertext)%aes.block_size != 0 {
// 		panic("ciphertext is not a multiple of the block size")
// 	}

// 	mode := cipher.NewCBCDecrypter(block, iv)

// 	// crypt_blocks can work in-place if the two arguments are the same.
// 	mode.crypt_blocks(ciphertext, ciphertext)

// 	// If the original plaintext lengths are not a multiple of the block
// 	// size, padding would have to be added when encrypting, which would be
// 	// removed at this point. For an example, see
// 	// https://tools.ietf.org/html/rfc5246#section-6.2.3.2. However, it's
// 	// critical to note that ciphertexts must be authenticated (i.e. by
// 	// using crypto/hmac) before being decrypted in order to avoid creating
// 	// a padding oracle.

// 	fmt.Printf("%s\n", ciphertext)
// 	// Output: exampleplaintext
// }

// func ExampleNewCBCEncrypter() {
// 	// Load your secret key from a safe place and reuse it across multiple
// 	// NewCipher calls. (Obviously don't use this example key for anything
// 	// real.) If you want to convert a passphrase to a key, use a suitable
// 	// package like bcrypt or scrypt.
// 	key, _ := hex.DecodeString("6368616e676520746869732070617373")
// 	plaintext := []byte("exampleplaintext")

// 	// CBC mode works on blocks so plaintexts may need to be padded to the
// 	// next whole block. For an example of such padding, see
// 	// https://tools.ietf.org/html/rfc5246#section-6.2.3.2. Here we'll
// 	// assume that the plaintext is already of the correct length.
// 	if len(plaintext)%aes.block_size != 0 {
// 		panic("plaintext is not a multiple of the block size")
// 	}

// 	block, err := aes.NewCipher(key)
// 	if err != nil {
// 		panic(err)
// 	}

// 	// The IV needs to be unique, but not secure. Therefore it's common to
// 	// include it at the beginning of the ciphertext.
// 	ciphertext := make([]byte, aes.block_size+len(plaintext))
// 	iv := ciphertext[:aes.block_size]
// 	if _, err := io.ReadFull(rand.Reader, iv); err != nil {
// 		panic(err)
// 	}

// 	mode := cipher.NewCBCEncrypter(block, iv)
// 	mode.crypt_blocks(ciphertext[aes.block_size:], plaintext)

// 	// It's important to remember that ciphertexts must be authenticated
// 	// (i.e. by using crypto/hmac) as well as being encrypted in order to
// 	// be secure.

// 	fmt.Printf("%x\n", ciphertext)
// }

// func ExampleNewCFBDecrypter() {
// 	// Load your secret key from a safe place and reuse it across multiple
// 	// NewCipher calls. (Obviously don't use this example key for anything
// 	// real.) If you want to convert a passphrase to a key, use a suitable
// 	// package like bcrypt or scrypt.
// 	key, _ := hex.DecodeString("6368616e676520746869732070617373")
// 	ciphertext, _ := hex.DecodeString("7dd015f06bec7f1b8f6559dad89f4131da62261786845100056b353194ad")

// 	block, err := aes.NewCipher(key)
// 	if err != nil {
// 		panic(err)
// 	}

// 	// The IV needs to be unique, but not secure. Therefore it's common to
// 	// include it at the beginning of the ciphertext.
// 	if len(ciphertext) < aes.block_size {
// 		panic("ciphertext too short")
// 	}
// 	iv := ciphertext[:aes.block_size]
// 	ciphertext = ciphertext[aes.block_size:]

// 	stream := cipher.NewCFBDecrypter(block, iv)

// 	// xor_key_stream can work in-place if the two arguments are the same.
// 	stream.xor_key_stream(ciphertext, ciphertext)
// 	fmt.Printf("%s", ciphertext)
// 	// Output: some plaintext
// }

// func ExampleNewCFBEncrypter() {
// 	// Load your secret key from a safe place and reuse it across multiple
// 	// NewCipher calls. (Obviously don't use this example key for anything
// 	// real.) If you want to convert a passphrase to a key, use a suitable
// 	// package like bcrypt or scrypt.
// 	key, _ := hex.DecodeString("6368616e676520746869732070617373")
// 	plaintext := []byte("some plaintext")

// 	block, err := aes.NewCipher(key)
// 	if err != nil {
// 		panic(err)
// 	}

// 	// The IV needs to be unique, but not secure. Therefore it's common to
// 	// include it at the beginning of the ciphertext.
// 	ciphertext := make([]byte, aes.block_size+len(plaintext))
// 	iv := ciphertext[:aes.block_size]
// 	if _, err := io.ReadFull(rand.Reader, iv); err != nil {
// 		panic(err)
// 	}

// 	stream := cipher.NewCFBEncrypter(block, iv)
// 	stream.xor_key_stream(ciphertext[aes.block_size:], plaintext)

// 	// It's important to remember that ciphertexts must be authenticated
// 	// (i.e. by using crypto/hmac) as well as being encrypted in order to
// 	// be secure.
// 	fmt.Printf("%x\n", ciphertext)
// }

// func ExampleNewCTR() {
// 	// Load your secret key from a safe place and reuse it across multiple
// 	// NewCipher calls. (Obviously don't use this example key for anything
// 	// real.) If you want to convert a passphrase to a key, use a suitable
// 	// package like bcrypt or scrypt.
// 	key, _ := hex.DecodeString("6368616e676520746869732070617373")
// 	plaintext := []byte("some plaintext")

// 	block, err := aes.NewCipher(key)
// 	if err != nil {
// 		panic(err)
// 	}

// 	// The IV needs to be unique, but not secure. Therefore it's common to
// 	// include it at the beginning of the ciphertext.
// 	ciphertext := make([]byte, aes.block_size+len(plaintext))
// 	iv := ciphertext[:aes.block_size]
// 	if _, err := io.ReadFull(rand.Reader, iv); err != nil {
// 		panic(err)
// 	}

// 	stream := cipher.NewCTR(block, iv)
// 	stream.xor_key_stream(ciphertext[aes.block_size:], plaintext)

// 	// It's important to remember that ciphertexts must be authenticated
// 	// (i.e. by using crypto/hmac) as well as being encrypted in order to
// 	// be secure.

// 	// CTR mode is the same for both encryption and decryption, so we can
// 	// also decrypt that ciphertext with NewCTR.

// 	plaintext2 := make([]byte, len(plaintext))
// 	stream = cipher.NewCTR(block, iv)
// 	stream.xor_key_stream(plaintext2, ciphertext[aes.block_size:])

// 	fmt.Printf("%s\n", plaintext2)
// 	// Output: some plaintext
// }

// func ExampleNewOFB() {
// 	// Load your secret key from a safe place and reuse it across multiple
// 	// NewCipher calls. (Obviously don't use this example key for anything
// 	// real.) If you want to convert a passphrase to a key, use a suitable
// 	// package like bcrypt or scrypt.
// 	key, _ := hex.DecodeString("6368616e676520746869732070617373")
// 	plaintext := []byte("some plaintext")

// 	block, err := aes.NewCipher(key)
// 	if err != nil {
// 		panic(err)
// 	}

// 	// The IV needs to be unique, but not secure. Therefore it's common to
// 	// include it at the beginning of the ciphertext.
// 	ciphertext := make([]byte, aes.block_size+len(plaintext))
// 	iv := ciphertext[:aes.block_size]
// 	if _, err := io.ReadFull(rand.Reader, iv); err != nil {
// 		panic(err)
// 	}

// 	stream := cipher.NewOFB(block, iv)
// 	stream.xor_key_stream(ciphertext[aes.block_size:], plaintext)

// 	// It's important to remember that ciphertexts must be authenticated
// 	// (i.e. by using crypto/hmac) as well as being encrypted in order to
// 	// be secure.

// 	// OFB mode is the same for both encryption and decryption, so we can
// 	// also decrypt that ciphertext with NewOFB.

// 	plaintext2 := make([]byte, len(plaintext))
// 	stream = cipher.NewOFB(block, iv)
// 	stream.xor_key_stream(plaintext2, ciphertext[aes.block_size:])

// 	fmt.Printf("%s\n", plaintext2)
// 	// Output: some plaintext
// }

// func ExampleStreamReader() {
// 	// Load your secret key from a safe place and reuse it across multiple
// 	// NewCipher calls. (Obviously don't use this example key for anything
// 	// real.) If you want to convert a passphrase to a key, use a suitable
// 	// package like bcrypt or scrypt.
// 	key, _ := hex.DecodeString("6368616e676520746869732070617373")

// 	encrypted, _ := hex.DecodeString("cf0495cc6f75dafc23948538e79904a9")
// 	bReader := bytes.NewReader(encrypted)

// 	block, err := aes.NewCipher(key)
// 	if err != nil {
// 		panic(err)
// 	}

// 	// If the key is unique for each ciphertext, then it's ok to use a zero
// 	// IV.
// 	var iv [aes.block_size]byte
// 	stream := cipher.NewOFB(block, iv[:])

// 	reader := &cipher.StreamReader{S: stream, R: bReader}
// 	// Copy the input to the output stream, decrypting as we go.
// 	if _, err := io.Copy(os.Stdout, reader); err != nil {
// 		panic(err)
// 	}

// 	// Note that this example is simplistic in that it omits any
// 	// authentication of the encrypted data. If you were actually to use
// 	// StreamReader in this manner, an attacker could flip arbitrary bits in
// 	// the output.

// 	// Output: some secret text
// }

// func ExampleStreamWriter() {
// 	// Load your secret key from a safe place and reuse it across multiple
// 	// NewCipher calls. (Obviously don't use this example key for anything
// 	// real.) If you want to convert a passphrase to a key, use a suitable
// 	// package like bcrypt or scrypt.
// 	key, _ := hex.DecodeString("6368616e676520746869732070617373")

// 	bReader := bytes.NewReader([]byte("some secret text"))

// 	block, err := aes.NewCipher(key)
// 	if err != nil {
// 		panic(err)
// 	}

// 	// If the key is unique for each ciphertext, then it's ok to use a zero
// 	// IV.
// 	var iv [aes.block_size]byte
// 	stream := cipher.NewOFB(block, iv[:])

// 	var out bytes.Buffer

// 	writer := &cipher.StreamWriter{S: stream, W: &out}
// 	// Copy the input to the output buffer, encrypting as we go.
// 	if _, err := io.Copy(writer, bReader); err != nil {
// 		panic(err)
// 	}

// 	// Note that this example is simplistic in that it omits any
// 	// authentication of the encrypted data. If you were actually to use
// 	// StreamReader in this manner, an attacker could flip arbitrary bits in
// 	// the decrypted result.

// 	fmt.Printf("%x\n", out.Bytes())
// 	// Output: cf0495cc6f75dafc23948538e79904a9
// }