forked from fbsobreira/gotron-sdk
/
crypto.go
54 lines (48 loc) · 1.19 KB
/
crypto.go
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package keystore
import (
"crypto/aes"
"crypto/cipher"
)
func aesCTRXOR(key, inText, iv []byte) ([]byte, error) {
// AES-128 is selected due to size of encryptKey.
aesBlock, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
stream := cipher.NewCTR(aesBlock, iv)
outText := make([]byte, len(inText))
stream.XORKeyStream(outText, inText)
return outText, err
}
func aesCBCDecrypt(key, cipherText, iv []byte) ([]byte, error) {
aesBlock, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
decrypter := cipher.NewCBCDecrypter(aesBlock, iv)
paddedPlaintext := make([]byte, len(cipherText))
decrypter.CryptBlocks(paddedPlaintext, cipherText)
plaintext := pkcs7Unpad(paddedPlaintext)
if plaintext == nil {
return nil, ErrDecrypt
}
return plaintext, err
}
// From https://leanpub.com/gocrypto/read#leanpub-auto-block-cipher-modes
func pkcs7Unpad(in []byte) []byte {
if len(in) == 0 {
return nil
}
padding := in[len(in)-1]
if int(padding) > len(in) || padding > aes.BlockSize {
return nil
} else if padding == 0 {
return nil
}
for i := len(in) - 1; i > len(in)-int(padding)-1; i-- {
if in[i] != padding {
return nil
}
}
return in[:len(in)-int(padding)]
}