Aes Galois/Counter Mode (Gcm); Figure 92. Message Construction In Gcm - ST STM32G0 1 Series Reference Manual

AES hardware accelerator (AES)
Suspend/resume operations in CTR mode
Like for the CBC mode, it is possible to interrupt a message to send a higher priority
message, and resume the message that was interrupted. Detailed CBC suspend/resume
sequence is described in
Note: Like for CBC mode, the AES_IVRx registers must be reloaded during the resume operation.
20.4.10

AES Galois/counter mode (GCM)

Overview
The AES Galois/counter mode (GCM) allows encrypting and authenticating a plaintext
message into the corresponding ciphertext and tag (also known as message authentication
code). To ensure confidentiality, GCM algorithm is based on AES counter mode. It uses a
multiplier over a fixed finite field to generate the tag.
GCM chaining is defined in NIST Special Publication 800-38D, Recommendation for Block
Cipher Modes of Operation - Galois/Counter Mode (GCM) and GMAC. A typical message
construction in GCM mode is given in
16-byte
boundaries
Additional authenticated data
ICB
4-byte boundaries
Initialization vector (IV)
Zero padding / zeroed bits
492/1390
Section 20.4.8: AES basic chaining modes (ECB,

Figure 92. Message construction in GCM

Len(A)
0
(AAD)
Counter
RM0444 Rev 5
Figure 92.
Len(P) = Len(C)
Plaintext (P)
Authenticated & encrypted ciphertext (C)
Authentication tag (T)
RM0444
CBC).
[Len(A)] [Len(C)]
64 64
Last
0
block
0
MSv42157V1