Fix Failure in Cryptocell tests on Montgomrery curve #11512
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Change the order of the input keys and output secret given and returned from the CC API, to address correct endianity.
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@RonEld, thank you for your changes. |
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@ARMmbed/mbed-os-crypto Please review |
bump |
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It looks like the general algorithm has been maintained, but I don't understand one of the conversions' direction. @RonEld could you please clarify that for me?
| ecdhParams->privKey, CURVE_25519_KEY_SIZE , | ||
| ecdhParams->pubKey, CURVE_25519_KEY_SIZE , | ||
| &ecdhParams->kgTempData ) ); | ||
| if ( ret != 0 ) | ||
| { | ||
| goto cleanup; | ||
| } | ||
| ret = convert_CrysError_to_mbedtls_err( | ||
| CRYS_COMMON_ConvertLswMswWordsToMsbLsbBytes( secret, |
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Shouldn't this conversion go the other way? We have converted the private and public key to the MsbLsbBytes so that CRYS_ECMONT_Scalarmult() can operate on them, but I would expect the output temp_buf to still be in that encoding. If we now want to operate on it further, outside the Cryptocell world, I'd expect the temp_buf to be converted to the LswMswWords again here.
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But this is what mbedtls_mpi_read_binary() does in line 282.
Note that this operation was added after the test vector in our tests failed, so the output of this function is now as expected outside the Cryptocell world
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Thanks for the clarification 👍
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Test run: FAILEDSummary: 1 of 11 test jobs failed Failed test jobs:
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Looks like a CI license issue so restarting |
Test run: FAILEDSummary: 2 of 11 test jobs failed Failed test jobs:
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Test run: FAILEDSummary: 1 of 11 test jobs failed Failed test jobs:
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Exporters restarted |
Description
After the addition of ECDH tests for curve 25519, they failed for Cryptocell, because of different endianity of the input keys and outpu calulated secret. This fix changes the input and output to correct endianity as expected by Mbed TLS and Cryptocell.
This was tested with test_suite_ecdh on target NRF52840_DK
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@ARMmbed/mbed-os-crypto
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