87 lines
2.1 KiB
Go
87 lines
2.1 KiB
Go
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package cipher
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import (
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"bytes"
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"crypto/aes"
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"crypto/cipher"
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"encoding/base64"
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"strings"
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)
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type Crypto interface {
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Encrypt(plainText string) (string, error)
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Decrypt(cipherIvKey string) (string, error)
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}
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type niceCrypto struct {
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cipherKey string
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cipherIvKey string
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}
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func (c niceCrypto) Encrypt(plainText string) (string, error) {
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if strings.TrimSpace(plainText) == "" {
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return plainText, nil
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}
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block, err := aes.NewCipher([]byte(c.cipherKey))
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if err != nil {
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return "", err
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}
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encrypter := cipher.NewCBCEncrypter(block, []byte(c.cipherIvKey))
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paddedPlainText := padPKCS7([]byte(plainText), encrypter.BlockSize())
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cipherText := make([]byte, len(paddedPlainText))
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// CryptBlocks 함수에 데이터(paddedPlainText)와 암호화 될 데이터를 저장할 슬라이스(cipherText)를 넣으면 암호화가 된다.
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encrypter.CryptBlocks(cipherText, paddedPlainText)
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return base64.StdEncoding.EncodeToString(cipherText), nil
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}
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func (c niceCrypto) Decrypt(cipherText string) (string, error) {
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if strings.TrimSpace(cipherText) == "" {
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return cipherText, nil
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}
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decodedCipherText, err := base64.StdEncoding.DecodeString(cipherText)
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if err != nil {
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return "", err
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}
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block, err := aes.NewCipher([]byte(c.cipherKey))
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if err != nil {
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return "", err
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}
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decrypter := cipher.NewCBCDecrypter(block, []byte(c.cipherIvKey))
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plainText := make([]byte, len(decodedCipherText))
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decrypter.CryptBlocks(plainText, decodedCipherText)
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trimmedPlainText := trimPKCS5(plainText)
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return string(trimmedPlainText), nil
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}
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func NewNiceCrypto(cipherKey, cipherIvKey string) (Crypto, error) {
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if ck := len(cipherKey); ck != 32 {
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return nil, aes.KeySizeError(ck)
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}
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if cik := len(cipherIvKey); cik != 16 {
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return nil, aes.KeySizeError(cik)
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}
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return &niceCrypto{cipherKey, cipherIvKey}, nil
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}
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func padPKCS7(plainText []byte, blockSize int) []byte {
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padding := blockSize - len(plainText)%blockSize
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padText := bytes.Repeat([]byte{byte(padding)}, padding)
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return append(plainText, padText...)
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}
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func trimPKCS5(text []byte) []byte {
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padding := text[len(text)-1]
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return text[:len(text)-int(padding)]
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}
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