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package cryptoutil
import (
"crypto/aes"
"crypto/cipher"
"crypto/rand"
)
// Performs an encryption using AES/CBC/PKCS7
// with a random IV prepended using AES/ECB/None.
func SymmetricEncrypt(ciph cipher.Block, src []byte) []byte {
// get a random IV and ECB encrypt it
iv := make([]byte, aes.BlockSize, aes.BlockSize)
_, err := rand.Read(iv)
if err != nil {
panic(err)
}
encryptedIv := make([]byte, aes.BlockSize, aes.BlockSize)
newECBEncrypter(ciph).CryptBlocks(encryptedIv, iv)
// pad it, copy the IV to the first 16 bytes and encrypt the rest with CBC
encrypted := padPKCS7WithIV(src)
copy(encrypted, encryptedIv)
cipher.NewCBCEncrypter(ciph, iv).CryptBlocks(encrypted[aes.BlockSize:], encrypted[aes.BlockSize:])
return encrypted
}
// Decrypts data from the reader using AES/CBC/PKCS7 with an IV
// prepended using AES/ECB/None. The src slice may not be used anymore.
func SymmetricDecrypt(ciph cipher.Block, src []byte) []byte {
iv := src[:aes.BlockSize]
newECBDecrypter(ciph).CryptBlocks(iv, iv)
data := src[aes.BlockSize:]
cipher.NewCBCDecrypter(ciph, iv).CryptBlocks(data, data)
return unpadPKCS7(data)
}
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