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
56 lines
1.3 KiB
Go
56 lines
1.3 KiB
Go
package crypto
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import (
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"bytes"
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"crypto/sha1" // #nosec
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"io"
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)
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// GuessDataWithHash guesses data from data_with_hash.
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func GuessDataWithHash(dataWithHash []byte) []byte {
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// data_with_hash := SHA1(data) + data + (0-15 random bytes);
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// such that length be divisible by 16;
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if len(dataWithHash) <= sha1.Size {
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// Data length too small.
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return nil
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}
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v := dataWithHash[:sha1.Size]
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for i := 0; i < 16; i++ {
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if len(dataWithHash)-i < sha1.Size {
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// End of slice reached.
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return nil
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}
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data := dataWithHash[sha1.Size : len(dataWithHash)-i]
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h := sha1.Sum(data) // #nosec
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if bytes.Equal(h[:], v) {
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// Found.
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return data
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}
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}
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return nil
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}
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func paddedLen16(l int) int {
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n := 16 * (l / 16)
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if n < l {
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n += 16
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}
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return n
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}
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// DataWithHash prepends data with SHA1(data) and 0..15 random bytes so result
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// length is divisible by 16.
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//
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// Use GuessDataWithHash(result) to obtain data.
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func DataWithHash(data []byte, randomSource io.Reader) ([]byte, error) {
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dataWithHash := make([]byte, paddedLen16(len(data)+sha1.Size))
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h := sha1.Sum(data) // #nosec
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copy(dataWithHash, h[:])
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copy(dataWithHash[sha1.Size:], data)
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if _, err := io.ReadFull(randomSource, dataWithHash[sha1.Size+len(data):]); err != nil {
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return nil, err
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}
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return dataWithHash, nil
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}
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