Datasheet

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AES Hardware generates output in DATA register.
Intermediate GHASH is stored in GHASH register and Cipher Text available in DATA register.
Continue 3 to 5 till the input of plain text to get the cipher text and the Hash keys.
At the last input, set CTRLB.EOM.
Write last in-data to DATA reg.
Wait for INTFLAG.ENCCMP to be set.
AES Hardware generates output in DATA register and final Hash key in GHASH register.
Load [LEN(A)]64||[LEN(C)]64 in DATA register and set CTRLB.GFMUL and CTRLB.START as 1.
Wait for INTFLAG.GFMCMP to be set.
AES Hardware generates final GHASH value in GHASH register.
42.6.3.1.5 Tag Generation
Configure CTRLA
1. Set CTRLA.ENABLE to 0
2. Set CTRLA.AESMODE as CTR
3. Set CTRLA.ENABLE to 1
Load J0 value to INITVECTV reg.
Load GHASH value to DATA reg.
Set CTRLB.NEWMSG and CTRLB.START to start the Counter mode operation.
Wait for INTFLAG.ENCCMP to be set.
AES Hardware generates the GCM Tag output in DATA register.
42.6.4 Synchronization
Not applicable.
SAM D5x/E5x Family Data Sheet
AES – Advanced Encryption Standard
© 2019 Microchip Technology Inc.
Datasheet
DS60001507E-page 1423