A data packet transmission method between a transmitter and a receiver through a radio-electric channel, said method comprising a first transmission of a packet, said first transmission comprising the steps implemented in the transmitter: - performing a first linear ciphering of said packet through a first sequence of ciphering keys so as to obtain a first packet; - performing a linear error detecting coding of the first packet through an error detecting code so as to obtain a first intermediate packet; and - performing a linear error correcting coding of the first intermediate packet through a first error correcting code so as to obtain a first coded packet; wherein, when the first coded packet is received and that it is detected by said method that it is erroneous, the method comprises at least a second transmission of said packet, the second transmission comprising the steps implemented in the transmitter: - performing a second linear ciphering of said packet through a second sequence of ciphering keys being different from the first sequence of ciphering keys of said first ciphering so as to obtain a second packet different from the first packet; - performing a linear error detecting coding of the second packet through said error detecting code so as to obtain a second intermediate packet; and - performing a linear error correcting coding of the second intermediate packet through a second error correcting code so as to obtain a second coded packet; and the steps implemented in the receiver: - performing a modification of the first coded packet and/or of the second coded packet so as to obtain two packets in which the difference due to the first and second processings is compensated for; - performing a combination (110; 128; 142; 172) of both packets according to a hybrid automatic repeat request, HARQ, procedure; and - performing a decoding (112; 130; 144; 174) of the combined packet through a third error correcting code depending on the first and second error correcting codes; characterized in that the modification step comprises the sub-steps of: - coding the difference between the first and second key sequences through the error detecting code and the first or respectively the second error correcting code; and - using (124; 140) the coded difference to modify the first coded packet or respectively the second coded packet. - performing a first linear ciphering of said packet through a first sequence of ciphering keys so as to obtain a first packet; - performing a linear error detecting coding of the first packet through an error detecting code so as to obtain a first intermediate packet; and - performing a linear error correcting coding of the first intermediate packet through a first error correcting code so as to obtain a first coded packet; - performing a second linear ciphering of said packet through a second sequence of ciphering keys being different from the first sequence of ciphering keys of said first ciphering so as to obtain a second packet different from the first packet; - performing a linear error detecting coding of the second packet through said error detecting code so as to obtain a second intermediate packet; and - performing a linear error correcting coding of the second intermediate packet through a second error correcting code so as to obtain a second coded packet; - performing a modification of the first coded packet and/or of the second coded packet so as to obtain two packets in which the difference due to the first and second processings is compensated for; - performing a combination (110; 128; 142; 172) of both packets according to a hybrid automatic repeat request, HARQ, procedure; and - performing a decoding (112; 130; 144; 174) of the combined packet through a third error correcting code depending on the first and second error correcting codes; characterized in that the modification step comprises the sub-steps of: - coding the difference between the first and second key sequences through the error detecting code and the first or respectively the second error correcting code; and - using (124; 140) the coded difference to modify the first coded packet or respectively the second coded packet. - coding the difference between the first and second key sequences through the error detecting code and the first or respectively the second error correcting code; and - using (124; 140) the coded difference to modify the first coded packet or respectively the second coded packet.