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ArduinoLibs
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ArduinoLibs
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All cryptographic algorithms have been optimized for 8-bit Arduino platforms like the Uno. Memory usage is also reduced, particularly for SHA1, SHA256, and SHA512 which save 256, 192, and 512 bytes respectively over traditional implementations. For all algorithms, static sbox tables and the like are placed into program memory to further reduce data memory usage.
ChaCha with 20 rounds and 256-bit keys is the recommended symmetric encryption algorithm because it is twice as fast as AES128, constant-time, and much more secure. AES128, AES192, and AES256 are provided for use in applications where compatibility with other systems is desirable.
BLAKE2s and BLAKE2b are variations on the ChaCha stream cipher, designed for hashing, with 256-bit and 512-bit hash outputs respectively. They are intended as high performance replacements for SHA256 and SHA512 for when speed is critical but exact bit-compatibility of hash values is not.
All figures are for the Arduino Uno running at 16 MHz. Figures for the Ardunino Mega 2560 running at 16 MHz are similar:
| Encryption Algorithm | Encryption (per byte) | Decryption (per byte) | Key Setup | State Size (bytes) |
| AES128 (ECB mode) | 36.90us | 66.48us | 160.00us | 213 |
| AES192 (ECB mode) | 44.20us | 80.35us | 166.54us | 245 |
| AES256 (ECB mode) | 51.50us | 94.22us | 227.97us | 277 |
| ChaCha (20 rounds) | 14.87us | 14.88us | 43.74us | 132 |
| ChaCha (12 rounds) | 10.38us | 10.38us | 43.74us | 132 |
| ChaCha (8 rounds) | 8.13us | 8.14us | 43.74us | 132 |
| AEAD Algorithm | Encryption (per byte) | Decryption (per byte) | Key Setup | State Size (bytes) |
| ChaChaPoly | 41.23us | 41.23us | 902.55us | 255 |
| GCM<AES128> | 186.47us | 186.42us | 1388.43us | 316 |
| GCM<AES192> | 194.17us | 193.72us | 1628.67us | 348 |
| GCM<AES256> | 201.47us | 201.02us | 1923.78us | 380 |
| Hash Algorithm | Hashing (per byte) | Finalization | Key Setup | State Size (bytes) |
| SHA1 | 21.90us | 95 | ||
| SHA256 | 43.85us | 107 | ||
| SHA512 | 123.24us | 211 | ||
| SHA3_256 | 121.69us | 405 | ||
| SHA3_512 | 229.12us | 405 | ||
| BLAKE2s | 18.54us | 171 | ||
| BLAKE2b | 50.58us | 339 | ||
| Poly1305 | 26.29us | 87 | ||
| GHASH | 148.14us | 33 | ||
Where a cipher supports more than one key size (such as ChaCha), the values are typically almost identical for 128-bit and 256-bit keys so only the maximum is shown above.
Public key algorithms have the following results on an Arduino Uno:
| Algorithm | Operation | Time | Comment |
| Curve25519 | eval() | 3738 ms | Raw curve evaluation |
| Curve25519 | dh1() | 3740 ms | First half of Diffie-Hellman key agreement |
| Curve25519 | dh2() | 3738 ms | Second half of Diffie-Hellman key agreement |
1.8.6
