Methods, systems, and devices for wireless communications are described. In some examples, a first device may combine, for each of a set of sub-blocks of a block of data, a set of unencoded bits associated with a respective sub-block with a matrix to generate a set of encoded bits. The first device may transmit a first message including the block to a second device. The second device may determine respective probabilities of successful decoding of respective selected candidate codewords for the set of sub-blocks of the block based on receiving the first message and may transmit one or more indicators associated with one or more sub-blocks based on the respective probabilities of successful decoding of the respective selected candidate codewords. The first device may transmit a second message including redundancy information for the one or more sub-blocks based on transmitting the one or more indicators.