some problems about AES CCM

[LeeRJ]

1st problem:

There are some failed case when i run  \v2.9.1\modules\bsim_hw_models\nrf_hw_models\tests\zephyr_apps\54_aar_ccm_ecb\src\test_ccm.c

2nd problem:

If I reduce the amount of encrypted data in test_ccm_12b_encr_ble_255b_w_adata_nomac, the encryption process gets stuck.

[LeeRJ]

ZTEST(nrf_ccm_tests, test_ccm_12c_encr_ble_0_255b_w_adata_nomac)
{
	printk("Encrypt 0-255 byte payload with adata and no MAC in BLE mode\n");

	uint8_t K[16] = {0x99, 0xAD, 0x1B, 0x52, 0x26, 0xA3, 0x7E, 0x3E, 0x05, 0x8E, 0x3B, 0x8E, 0x27, 0xC2, 0xC6, 0x66};
	uint8_t N[16] = {0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x80, 0x24, 0xAB, 0xDC, 0xBA, 0xBE, 0xBA, 0xAF, 0xDE};
	uint8_t A[] = {0x0E};
	uint8_t P[] = {0x0,  0x1,  0x2,  0x3,  0x4,  0x5,  0x6,  0x7,  0x8,  0x9, 0xa, 0xb,  0xc,  0xd,  0xe,  0xf,  0x10,
			0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, 0x20, 0x21,
			0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, 0x30, 0x31, 0x32,
			0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f, 0x40, 0x41, 0x42, 0x43,
			0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f, 0x50, 0x51, 0x52, 0x53, 0x54,
			0x55, 0x56, 0x57, 0x58, 0x59, 0x5a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f, 0x60, 0x61, 0x62, 0x63, 0x64, 0x65,
			0x66, 0x67, 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76,
			0x77, 0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f, 0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
			0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f, 0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98,
			0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f, 0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7, 0xa8, 0xa9,
			0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf, 0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7, 0xb8, 0xb9, 0xba,
			0xbb, 0xbc, 0xbd, 0xbe, 0xbf, 0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xcb,
			0xcc, 0xcd, 0xce, 0xcf, 0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda, 0xdb, 0xdc,
			0xdd, 0xde, 0xdf, 0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed,
			0xee, 0xef, 0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8, 0xf9, 0xfa};
	uint8_t C[] = {
			0x6D, 0x71, 0xB7, 0x03, 0x74, 0x41, 0x0C, 0x9D, 0x0A, 0x74, 0xE2, 0xFD, 0x67, 0x67, 0x64, 0x26, 0x0A, 0xF6, 0x76,
			0x6F, 0x59, 0x4B, 0x7B, 0xBC, 0xC6, 0xDF, 0x18, 0x5B, 0x50, 0x2D, 0x3D, 0x5E, 0xD9, 0xAF, 0xF6, 0xB8, 0xFE, 0x86,
			0xC5, 0x23, 0x3A, 0xA8, 0x35, 0xE4, 0xE6, 0xA0, 0xB6, 0xC9, 0x48, 0xFF, 0xFF, 0xF5, 0xA0, 0xC0, 0x19, 0x32, 0x71,
			0x60, 0x61, 0x0C, 0x1B, 0xE5, 0x43, 0xCE, 0xB5, 0xBC, 0x9E, 0x3A, 0x3D, 0x85, 0xB7, 0xAA, 0x65, 0x64, 0x2E, 0x38,
			0x82, 0x27, 0x3D, 0xA4, 0x13, 0xFE, 0xE5, 0x89, 0x1F, 0x2F, 0x0E, 0x9B, 0x02, 0x0B, 0x10, 0xCD, 0xA8, 0xCD, 0xBA,
			0xA6, 0xD0, 0x40, 0x44, 0xD0, 0x75, 0x37, 0xBB, 0x06, 0x16, 0x54, 0x04, 0x7F, 0x8A, 0x0C, 0x2E, 0x7E, 0xB8, 0x06,
			0x06, 0x63, 0x3F, 0x4A, 0x08, 0xFF, 0x21, 0x28, 0x6C, 0x8F, 0x65, 0xB6, 0x29, 0xE5, 0xFC, 0x58, 0x29, 0x7D, 0x55,
			0xFE, 0xA8, 0x24, 0xDE, 0xE5, 0xB1, 0x8C, 0x9B, 0xAF, 0xD3, 0x78, 0xCE, 0x87, 0x92, 0x07, 0x4F, 0x40, 0x75, 0xE6,
			0xA7, 0x61, 0x09, 0x73, 0xBE, 0x0A, 0x29, 0x05, 0x3F, 0xF7, 0xBD, 0xD8, 0x9C, 0xC7, 0xDA, 0x4B, 0xAC, 0xE9, 0xC2,
			0xE4, 0xD7, 0x4C, 0x2C, 0x26, 0x8C, 0x00, 0xE4, 0xE6, 0xBE, 0x05, 0x0E, 0xC2, 0xDA, 0x1E, 0xA7, 0xAE, 0xD7, 0x35,
			0xA8, 0x26, 0xCD, 0xF8, 0x93, 0x93, 0x26, 0x0C, 0xD5, 0x47, 0x9B, 0x7C, 0x35, 0x62, 0x7D, 0xFB, 0xCF, 0xAD, 0x78,
			0x91, 0xA6, 0x0C, 0xC8, 0x5C, 0xBF, 0x05, 0xBF, 0x7E, 0xE4, 0x0C, 0x4A, 0x9E, 0xC9, 0xD2, 0x9F, 0x75, 0x7A, 0x58,
			0x84, 0x9B, 0xD4, 0x9A, 0x2B, 0x51, 0xB2, 0x4A, 0x3A, 0x45, 0xEB, 0x58, 0x33, 0x86, 0x53, 0xC5, 0xBA, 0x63, 0x73,
			0xB6, 0x89, 0x25, 0xD7,
	};
	unsigned mac_len = 0;
	uint8_t adata_mask = 0xE3;

	for (uint8_t len = 0; len <= 255; len++)
	{
		build_ccm_test_case_and_run(K, N, P, len, len, A, sizeof(A), C, len, mac_len, adata_mask, false,
				false, ENCRYPT, BLE_MODE, NULL, false);
	}
}

I wrote an example of encrypting data of different lengths according to test_ccm_12b, but it got stuck when len=36.

[Sigurd Hellesvik]

Could this be Errata [1] CCM: MAC error is returned if MDATA size is slightly larger than MLEN?

Try to set MLEN (len) to a lot higher than sizeof(P), as suggested in the workaround

[Sigurd Hellesvik]

Did you test the sample I uploaded? Does it work for you?

LeeRJ said:

I need to encrypt packets on-the-fly in radio transmit mode later, so I need to know why it freezes when use CCM.

It freezes in  here in the sample code.

If the freeze is an issue for you, you can make this loop time out, and then handle it as an error.

[LeeRJ]

The solution is not very reliable since it's unclear when issues may arise. Could it be a chip design problem similar to Errata [1] CCM: MAC error is returned if MDATA size is slightly larger than MLEN? I want to identify the root cause and resolve it.

[Sigurd Hellesvik]

We will look into this to see if we can find a root cause.

In the meantime, if you need a workaround, you can use the timeout I suggested before.

[LeeRJ]

OK, thanks a lot!

[Sigurd Hellesvik]

Unfortunally, I have not found anything yet, but know that I am still looking into this.