The PSA Crypto API uses 0 as the initial counter value, but the test vector
in RFC 7539 uses 1. So the unit tests here include an extra leading block.
The expected data for this leading block was calculated with Cryptodome.
#!/usr/bin/env python3
import re
from Cryptodome.Cipher import ChaCha20
key = bytes.fromhex('000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f')
nonce = bytes.fromhex('000000000000004a00000000')
encrypt = lambda pt: ChaCha20.new(key=key, nonce=nonce).encrypt(pt)
# Cryptodome uses counter=0, like PSA Crypto. Prepend a 64-byte input block #0
# so that the plaintext from RFC 7539 starts exactly at block #1.
header = b'The RFC 7539 test vector uses counter=1, but PSA uses counter=0.'
assert(len(header) == 64)
sunscreen = b"Ladies and Gentlemen of the class of '99: If I could offer you only one tip for the future, sunscreen would be it."
plaintext = header + sunscreen
zeros = b'\x00' * len(plaintext)
keystream = encrypt(zeros)
ciphertext = encrypt(plaintext)
print('RFC 7539 §2.4.2')
print('Keystream:')
print(re.sub(r'(..)', r'\1:', keystream[64:].hex()))
print('Ciphertext Subscreen:')
print(re.sub(r'(..)', r'\1 ', ciphertext[64:].hex()))
print('')
print(f"""\
PSA symmetric decrypt: ChaCha20, RFC7539 keystream
depends_on:PSA_WANT_ALG_STREAM_CIPHER:PSA_WANT_KEY_TYPE_CHACHA20
# Keystream from RFC 7539 §2.4.2, with an extra 64-byte output block prepended
# because the test vector starts at counter=1 but our API starts at counter=0.
cipher_decrypt:PSA_ALG_STREAM_CIPHER:PSA_KEY_TYPE_CHACHA20:"{key.hex()}":"{nonce.hex()}":"{zeros.hex()}":"{keystream.hex()}"
PSA symmetric decrypt: ChaCha20, RFC7539 sunscreen
depends_on:PSA_WANT_ALG_STREAM_CIPHER:PSA_WANT_KEY_TYPE_CHACHA20
# Test vector from RFC 7539 §2.4.2, with an extra 64-byte block prepended
# because the test vector starts at counter=1 but our API starts at counter=0.
cipher_decrypt:PSA_ALG_STREAM_CIPHER:PSA_KEY_TYPE_CHACHA20:"{key.hex()}":"{nonce.hex()}":"{ciphertext.hex()}":"{plaintext.hex()}"
""")
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Send data (call to mbedtls_ssl_flush_output()) only from
the loop over the handshake steps. That way, we do not
have to take care of the partial writings (MBEDTLS_ERR_SSL_WANT_WRITE
error code) on the network in handshake step handlers.
Signed-off-by: Ronald Cron <ronald.cron@arm.com>
Even if certificate authentication is disabled at build
time, go through the MBEDTLS_SSL_CLIENT_CERTIFICATE state.
It simplifies overall the code for a small code size
cost when certificate authentication is disabled at build
time. Furthermore that way we have only one point in the
code where we switch to the handshake keys for record
encryption.
Signed-off-by: Ronald Cron <ronald.cron@arm.com>
* Remove expected_output_data: since asymmetric encryption is randomized,
it can't be useful.
* The decryption check needs the private exponent, not the public exponent.
* Use PSA macro for the expected ciphertext buffer size.
* Move RSA sanity checks to their own function for clarity.
* For RSAES-PKCS1-v1_5, check that the result of the private key operation
has the form 0x00 0x02 ... 0x00 M where M is the plaintext.
* For OAEP, check that the result of the private key operation starts with
0x00. The rest is the result of masking which it would be possible to
check here, but not worth the trouble of implementing.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
This is automatic in CPython but not guaranteed by the language. Be friendly
to other Python implementations.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
