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56 lines
1.3 KiB
56 lines
1.3 KiB
3 years ago
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package crypto
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import (
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"crypto/aes"
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"io"
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"github.com/gotd/ige"
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"github.com/gotd/td/bin"
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)
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func countPadding(l int) int { return 16 + (16 - (l % 16)) }
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// encryptMessage encrypts plaintext using AES-IGE.
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func (c Cipher) encryptMessage(k AuthKey, plaintext *bin.Buffer) (EncryptedMessage, error) {
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offset := len(plaintext.Buf)
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plaintext.Buf = append(plaintext.Buf, make([]byte, countPadding(offset))...)
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if _, err := io.ReadFull(c.rand, plaintext.Buf[offset:]); err != nil {
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return EncryptedMessage{}, err
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}
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messageKey := MessageKey(k.Value, plaintext.Buf, c.encryptSide)
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key, iv := Keys(k.Value, messageKey, c.encryptSide)
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aesBlock, err := aes.NewCipher(key[:])
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if err != nil {
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return EncryptedMessage{}, err
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}
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msg := EncryptedMessage{
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AuthKeyID: k.ID,
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MsgKey: messageKey,
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EncryptedData: make([]byte, len(plaintext.Buf)),
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}
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ige.EncryptBlocks(aesBlock, iv[:], msg.EncryptedData, plaintext.Buf)
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return msg, nil
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}
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// Encrypt encrypts EncryptedMessageData using AES-IGE to given buffer.
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func (c Cipher) Encrypt(key AuthKey, data EncryptedMessageData, b *bin.Buffer) error {
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b.Reset()
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if err := data.EncodeWithoutCopy(b); err != nil {
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return err
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}
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msg, err := c.encryptMessage(key, b)
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if err != nil {
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return err
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}
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b.Reset()
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if err := msg.Encode(b); err != nil {
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return err
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}
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return nil
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}
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