Reduced-latency packet ciphering

A hardware cipher module to cipher a packet, comprising:

• a key scheduling engine comprising circuitry configured to:
• receive a compact key and generate a first portion of a set of round keys, the portion including a first round key, based on the compact key;
• determine which of a forward cipher algorithm and a backward cipher algorithm is indicated by an indication of a cipher mode to be applied to the packet, and base on the indication of the cipher mode whether to generate a key-scheduling-done indication prior to completion of calculation of an entire set of round keys;
• generate a key-scheduling-done indication after the first round key is generated and before a last round key of the set of round keys is generated, wherein the generating the key-scheduling-done indication is based on the indication of the cipher mode signifying that a forward cipher algorithm is to be applied to the packet;
• and
• generate a remaining portion of the set of round keys, including the last round key;
• and
• a ciphering engine comprising circuitry configured to begin to cipher the packet with one of the set of round keys as a result of receiving the key schedule done indication.

A method for ciphering a packet, comprising:

• receiving, by a cipher circuit, compact key and beginning to generate a set of round keys, including a first round key, based on the compact key;
• receiving, by the cipher circuit, an indication of a cipher mode to be applied to the packet,
• determining, by the cipher circuit, which of a forward cipher algorithm and a backward cipher algorithm is indicated by the indication of the cipher mode, and based on the indication of the cipher mode whether to begin to cipher the packet before all of a set of round keys is generated;
• in a case in which determining the finds that the packet is to be ciphered with a forward cipher algorithm, beginning, by a cipher circuit, to cipher the packet with one of the set of round keys after the first round key is generated and before all of the set of round keys is generated;
• and
• in a case in which the determining finds that the packet is to be ciphered with a backward cipher algorithm, beginning, by a cipher circuit, to cipher the packet with one of the set of round keys after all of the set of round keys is generated.