72 lines
1.8 KiB
Go
72 lines
1.8 KiB
Go
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package KFEncryption
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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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"io"
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)
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// Encrypt takes a plaintext byte array and encrypts it using the provided key.
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// it returns the ciphertext and an error if one occurs.
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// it generates the cipher text using AES-CGM and a nonce.
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// a nonce is a number that can only be used once and will be unique for each encryption, but it is not a secret..
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// it is safe to store the nonce along the cipher text.
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// the nonce is prepended to the cipher text.
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func Encrypt(plaintext []byte, key string) ([]byte, error) {
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block, err := aes.NewCipher(validateKey([]byte(key), 32))
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if err != nil {
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return nil, err
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}
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nonce := make([]byte, 12)
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if _, err := io.ReadFull(rand.Reader, nonce); err != nil {
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return nil, err
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}
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newCGM, err := cipher.NewGCM(block)
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if err != nil {
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return nil, err
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}
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cipherText := newCGM.Seal(nonce, nonce, plaintext, nil)
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return cipherText, nil
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}
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// Decrypt takes a cipher text byte array and decrypts it using the provided key
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func Decrypt(cipherText []byte, key string) ([]byte, error) {
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block, err := aes.NewCipher(validateKey([]byte(key), 32))
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if err != nil {
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return nil, err
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}
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newCGM, err := cipher.NewGCM(block)
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if err != nil {
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return nil, err
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}
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nonceSize := newCGM.NonceSize()
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if len(cipherText) < nonceSize {
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return nil, err
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}
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nonce, cipherText := cipherText[:nonceSize], cipherText[nonceSize:]
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plainText, err := newCGM.Open(nil, nonce, cipherText, nil)
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if err != nil {
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return nil, err
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}
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return plainText, nil
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}
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// validateKey takes a key and a length and returns a key of the correct length by truncating or padding it
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func validateKey(key []byte, length int) []byte {
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if len(key) == length {
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return key
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}
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newKey := make([]byte, length)
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copy(newKey, key)
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return newKey
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}
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