Table 141. Processing Time (In Clock Cycle); Table 142. Processing Time (In Clock Cycle) For Ecb, Cbc And Ctr; Table 143. Processing Time (In Clock Cycle) For Gcm And Cmac - ST STM32L4x6 Reference Manual

Advanced encryption standard hardware accelerator (AES)
25.12 Processing time
The following tables summarize the time required to process a 128-bit block for each mode
of operation.
Mode 1: Encryption
Mode 2: Key derivation
Mode 3: Decryption
Mode 4: Key derivation + decryption

Table 142. Processing time (in clock cycle) for ECB, CBC and CTR

Key size Mode of operation
Mode 1: Encryption
Mode 2: Key derivation
128-bit
Mode 3: Decryption
Mode 4: Key derivation + decryption ECB, CBC
Mode 1: Encryption
Mode 2: Key derivation
256-bit
Mode 3: Decryption
Mode 4: Key derivation + decryption ECB, CBC
Key size
128-bit
256-bit
Note: Mode 2 and mode 4 has no meaning when GCM is selected.
Mode operation (mode 1 to mode 4) has no meaning when GMAC/CMAC is used.
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Table 141. Processing time (in clock cycle)

Mode of operation

Table 143. Processing time (in clock cycle) for GCM and CMAC

Mode of operation
Mode 1: Encryption/
Mode 3: Decryption
-
-
Mode 1: Encryption/
Mode 3: Decryption
-
-
DocID024597 Rev 3
Computation
Input phase
8
-
8
8
Input
Algorithm
phase
ECB, CBC, CTR 8
-
ECB, CBC, CTR 8
8
ECB, CBC, CTR 8
-
ECB, CBC, CTR 8
8
Algorithm
Phase
GCM 215
GMAC 215
CMAC
GCM 299
GMAC 299
CMAC
Output
phase phase
202 4
80 -
202 4
276 4
Computation Output
phase
202
- 80
202
276
286
- 109
286
380
Init Header Payload
phase phase
67 202
67
- 206
67 286
67
- 290
RM0351
Total
214
80
214
288
Total
phase
4 214
- 80
4 214
4 288
4 298
- 109
4 298
4 392
Tag
phase
202
- 202
- 202
286
- 286
- 286