IAPM (mode)

Integrity Aware Parallelizable Mode (IAPM) is a mode of operation for cryptographic block ciphers. As its name implies, it allows for a parallel mode of operation for higher throughput.

IAPM was the first cipher mode created to provide both authentication and privacy in a single pass. Previously, two passes would be required to achieve both benefits: for example the first pass using DES in CBC mode and the second pass authenticating with HMAC-MD5. IAPM allows for a single pass achieving both authentication and privacy.

OCB mode also provides authentication and privacy in a single pass, but both have been supplanted by Galois/Counter Mode.

IAPM mode was designed by Charanjit Jutla. The OCB inventor, Phillip Rogaway, gives credit to Jutla for inventing the single-pass technique.

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