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