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Create sample key material for symmetric keys

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Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
This commit is contained in:
Gilles Peskine 2021-01-26 21:26:26 +01:00
parent df63968c0c
commit 397b0287b1
1 changed files with 26 additions and 0 deletions
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26
scripts/mbedtls_dev/crypto_knowledge.py
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@ -85,3 +85,29 @@ class KeyType:
assert self.params is not None
return self.ECC_KEY_SIZES[self.params[0]]
return self.KEY_TYPE_SIZES[self.private_type]
# "48657265006973206b6579a064617461"
DATA_BLOCK = b'Here\000is key\240data'
def key_material(self, bits: int) -> bytes:
"""Return a byte string containing suitable key material with the given bit length.
Use the PSA export representation. The resulting byte string is one that
can be obtained with the following code:
```
psa_set_key_type(&attributes, `self.expression`);
psa_set_key_bits(&attributes, `bits`);
psa_set_key_usage_flags(&attributes, PSA_KEY_USAGE_EXPORT);
psa_generate_key(&attributes, &id);
psa_export_key(id, `material`, ...);
```
"""
if bits % 8 != 0:
raise ValueError('Non-integer number of bytes: {} bits'.format(bits))
length = bits // 8
if self.name == 'PSA_KEY_TYPE_DES':
# "644573206b457901644573206b457902644573206b457904"
des3 = b'dEs kEy\001dEs kEy\002dEs kEy\004'
return des3[:length]
# TODO: ECC, RSA
return b''.join([self.DATA_BLOCK] * (length // len(self.DATA_BLOCK)) +
[self.DATA_BLOCK[:length % len(self.DATA_BLOCK)]])