Adam Van Ymeren
7a04f298d2
- update to latest telegram layer - remove some references to fields in tg.Entities that don't exist in the schema - originally added here: https://github.com/beeper/td/commit/820929062a2ba0104397bc01235ab58a9cff780e - referenced here - https://github.com/mautrix/telegramgo/commit/124f0967ed195b5a380c9bd02e170ada9710dde3 - https://github.com/mautrix/telegramgo/commit/4205047aab2e0639217148b5d125bfaab668bd8e
73 lines
2.0 KiB
Go
73 lines
2.0 KiB
Go
package crypto
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import (
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"crypto/aes"
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"crypto/sha1" // #nosec
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"io"
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"github.com/go-faster/errors"
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"github.com/gotd/ige"
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"go.mau.fi/mautrix-telegram/pkg/gotd/bin"
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)
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// DecryptExchangeAnswer decrypts messages created during key exchange.
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func DecryptExchangeAnswer(data, key, iv []byte) (dst []byte, err error) {
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// Decrypting inner data.
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cipher, err := aes.NewCipher(key)
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if err != nil {
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return nil, errors.Wrap(err, "create aes cipher")
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}
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dataWithHash := make([]byte, len(data))
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// Checking length. Invalid length will lead to panic in CryptBlocks.
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if len(dataWithHash)%cipher.BlockSize() != 0 {
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return nil, errors.Errorf("invalid len of data_with_hash (%d %% 16 != 0)", len(dataWithHash))
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}
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ige.DecryptBlocks(cipher, iv, dataWithHash, data)
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dst = GuessDataWithHash(dataWithHash)
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if data == nil {
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// Most common cause of this error is invalid crypto implementation,
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// i.e. invalid keys are used to decrypt payload which lead to
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// decrypt failure, so data does not match sha1 with any padding.
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return nil, errors.New("guess data from data_with_hash")
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}
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return
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}
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// EncryptExchangeAnswer encrypts messages created during key exchange.
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func EncryptExchangeAnswer(rand io.Reader, answer, key, iv []byte) (dst []byte, err error) {
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cipher, err := aes.NewCipher(key)
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if err != nil {
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return nil, errors.Wrap(err, "create aes cipher")
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}
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answerWithHash, err := DataWithHash(answer, rand)
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if err != nil {
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return nil, errors.Wrap(err, "get answer with hash")
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}
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dst = make([]byte, len(answerWithHash))
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ige.EncryptBlocks(cipher, iv, dst, answerWithHash)
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return
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}
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// NonceHash1 computes nonce_hash_1.
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// See https://core.telegram.org/mtproto/auth_key#dh-key-exchange-complete.
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func NonceHash1(newNonce bin.Int256, key Key) (r bin.Int128) {
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var buf []byte
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buf = append(buf, newNonce[:]...)
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buf = append(buf, 1)
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buf = append(buf, sha(key[:])[0:8]...)
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buf = sha(buf)[4:20]
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copy(r[:], buf)
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return
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}
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func sha(v []byte) []byte {
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h := sha1.Sum(v) // #nosec
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return h[:]
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}
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