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Improve INFO field building.
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@gareth-palmer
gareth-palmer committed Jul 12, 2024
1 parent 3d7516c commit f4cad85
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Showing 3 changed files with 50 additions and 50 deletions.
58 changes: 28 additions & 30 deletions enccnf
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Original file line number Diff line number Diff line change
Expand Up @@ -94,7 +94,6 @@ def parse_enc_file(enc_file, tftp_certificate_file):
print(f'Header Length: {header_length} bytes')

hash_algorithm = None

signature_index = 0
signature_length = 0

Expand Down Expand Up @@ -274,7 +273,6 @@ def remove_enc_file(enc_file, private_key_file):
if tlv_tag != HEADER_VERSION:
raise ProgramError(f'Tag is not HEADER_VERSION: {tlv_tag}')

# Skip version
tlv_index += tlv_length

(tlv_tag, tlv_length) = struct.unpack_from('> B H', tlv_data, tlv_index)
Expand Down Expand Up @@ -477,17 +475,17 @@ def build_enc_file(cnf_file, tftp_certificate_file, certificate_file, hash_algor
serial_number = certificate.serial_number
serial_number = serial_number.to_bytes((serial_number.bit_length() + 7) // 8, byteorder = 'big')

signer_info = 3 + len(signer_name) + 3 + len(serial_number) + 3 + len(issuer_name)
tlv_data += struct.pack('> B H', HEADER_SIGNER_INFO, signer_info)
signer_info = struct.pack('> B H', HEADER_SIGNER_NAME, len(signer_name))
signer_info += signer_name

tlv_data += struct.pack('> B H', HEADER_SIGNER_NAME, len(signer_name))
tlv_data += signer_name
signer_info += struct.pack('> B H', HEADER_SERIAL_NUMBER, len(serial_number))
signer_info += serial_number

tlv_data += struct.pack('> B H', HEADER_SERIAL_NUMBER, len(serial_number))
tlv_data += serial_number
signer_info += struct.pack('> B H', HEADER_ISSUER_NAME, len(issuer_name))
signer_info += issuer_name

tlv_data += struct.pack('> B H', HEADER_ISSUER_NAME, len(issuer_name))
tlv_data += issuer_name
tlv_data += struct.pack('> B H', HEADER_SIGNER_INFO, len(signer_info))
tlv_data += signer_info

tlv_data += struct.pack('> B H', HEADER_SIGNATURE_INFO, 15)
tlv_data += struct.pack('> B H B', HEADER_HASH_ALGORITHM, 1, HASH_SHA512 if hash_algorithm == 'sha512' else HASH_SHA1)
Expand All @@ -496,7 +494,9 @@ def build_enc_file(cnf_file, tftp_certificate_file, certificate_file, hash_algor
tlv_data += struct.pack('> B H B', HEADER_SIGNATURE_ALGORITHM, 1, 0)
tlv_data += struct.pack('> B H B', HEADER_SIGNATURE_MODULUS, 1, [64, 128, 256, 512].index(signature_length))

# Index where the signature will be inserted
signature_index = len(tlv_data)

filename = os.path.basename(enc_file).encode('utf-8') + b'\x00'

tlv_data += struct.pack('> B H', HEADER_FILENAME, len(filename))
Expand All @@ -522,37 +522,34 @@ def build_enc_file(cnf_file, tftp_certificate_file, certificate_file, hash_algor
xml = encryptor.update(xml) + encryptor.finalize()
encryption_key = device_public_key.encrypt(encryption_key, padding.PKCS1v15())

encryption_info_index = len(tlv_data)
tlv_data += struct.pack('> B H', HEADER_ENCRYPTION_INFO, 0)
encryption_iv_info = struct.pack('> B H B', HEADER_ENCRYPTION_UNKNOWN1, 1, 0)

# Combined length of the next 3 fields
encryption_iv_info = 3 + 1 + 3 + len(encryption_iv) + 3 + 2
tlv_data += struct.pack('> B H', HEADER_ENCRYPTION_IV_INFO, encryption_iv_info)
encryption_iv_info += struct.pack('> B H', HEADER_ENCRYPTION_IV, len(encryption_iv))
encryption_iv_info += encryption_iv

tlv_data += struct.pack('> B H B', HEADER_ENCRYPTION_UNKNOWN1, 1, 0)
encryption_iv_info += struct.pack('> B H H', HEADER_ENCRYPTION_PADDING, 2, encryption_padding)

tlv_data += struct.pack('> B H', HEADER_ENCRYPTION_IV, len(encryption_iv))
tlv_data += encryption_iv
encryption_key_info = struct.pack('> B H B', HEADER_ENCRYPTION_UNKNOWN2, 1, 0)
encryption_key_info += struct.pack('> B H H', HEADER_ENCRYPTION_KEY_SIZE, 2, len(encryption_key) * 8)
encryption_key_info += struct.pack('> B H B', HEADER_ENCRYPTION_KEY_ALGORITHM, 1, 1) # AES?

tlv_data += struct.pack('> B H H', HEADER_ENCRYPTION_PADDING, 2, encryption_padding)
encryption_key_info += struct.pack('> B H', HEADER_ENCRYPTION_KEY, len(encryption_key))
encryption_key_info += encryption_key

# Combined length of the next 4 fields
encryption_key_info = 3 + 1 + 3 + 2 + 3 + 1 + 3 + len(encryption_key)
tlv_data += struct.pack('> B H', HEADER_ENCRYPTION_KEY_INFO, encryption_key_info)
encryption_info = struct.pack('> B H', HEADER_ENCRYPTION_IV_INFO, len(encryption_iv_info))
encryption_info += encryption_iv_info

tlv_data += struct.pack('> B H B', HEADER_ENCRYPTION_UNKNOWN2, 1, 0)
tlv_data += struct.pack('> B H H', HEADER_ENCRYPTION_KEY_SIZE, 2, len(encryption_key) * 8)
tlv_data += struct.pack('> B H B', HEADER_ENCRYPTION_KEY_ALGORITHM, 1, 1) # AES?
encryption_info += struct.pack('> B H', HEADER_ENCRYPTION_KEY_INFO, len(encryption_key_info))
encryption_info += encryption_key_info

tlv_data += struct.pack('> B H', HEADER_ENCRYPTION_KEY, len(encryption_key))
tlv_data += encryption_key
tlv_data += struct.pack('> B H', HEADER_ENCRYPTION_INFO, len(encryption_info))
tlv_data += encryption_info

tlv_data += struct.pack('> B H B', HEADER_ENCRYPTION_HASH_ALGORITHM, 1, HASH_SHA512 if hash_algorithm == 'sha512' else HASH_SHA1)

tlv_data += struct.pack('> B H', HEADER_ENCRYPTION_HASH, len(encryption_hash))
tlv_data += encryption_hash

struct.pack_into('> H', tlv_data, encryption_info_index + 1, len(tlv_data) - (encryption_info_index + 3))

# Pad to 4 byte boundary
while (len(tlv_data) + 3 + signature_length) % 4:
tlv_data.append(HEADER_PADDING)
Expand All @@ -568,7 +565,8 @@ def build_enc_file(cnf_file, tftp_certificate_file, certificate_file, hash_algor
try:
with open(enc_file, 'wb') as file:
file.write(tlv_data[:signature_index])
file.write(struct.pack('> B H', HEADER_SIGNATURE, len(signature)) + signature)
file.write(struct.pack('> B H', HEADER_SIGNATURE, len(signature)))
file.write(signature)
file.write(tlv_data[signature_index:])

except (PermissionError, IsADirectoryError) as error:
Expand Down
22 changes: 12 additions & 10 deletions sgnfile
View file
Original file line number Diff line number Diff line change
Expand Up @@ -80,7 +80,6 @@ def parse_sgn_file(sgn_file, tftp_certificate_file):
print(f'Header Length: {header_length} bytes')

hash_algorithm = None

signature_index = 0
signature_length = 0

Expand Down Expand Up @@ -295,17 +294,17 @@ def build_sgn_file(input_file, tftp_certificate_file, hash_algorithm, filename):
serial_number = certificate.serial_number
serial_number = serial_number.to_bytes((serial_number.bit_length() + 7) // 8, byteorder = 'big')

signer_info = 3 + len(signer_name) + 3 + len(serial_number) + 3 + len(issuer_name)
tlv_data += struct.pack('> B H', HEADER_SIGNER_INFO, signer_info)
signer_info = struct.pack('> B H', HEADER_SIGNER_NAME, len(signer_name))
signer_info += signer_name

tlv_data += struct.pack('> B H', HEADER_SIGNER_NAME, len(signer_name))
tlv_data += signer_name
signer_info += struct.pack('> B H', HEADER_SERIAL_NUMBER, len(serial_number))
signer_info += serial_number

tlv_data += struct.pack('> B H', HEADER_SERIAL_NUMBER, len(serial_number))
tlv_data += serial_number
signer_info += struct.pack('> B H', HEADER_ISSUER_NAME, len(issuer_name))
signer_info += issuer_name

tlv_data += struct.pack('> B H', HEADER_ISSUER_NAME, len(issuer_name))
tlv_data += issuer_name
tlv_data += struct.pack('> B H', HEADER_SIGNER_INFO, len(signer_info))
tlv_data += signer_info

tlv_data += struct.pack('> B H', HEADER_SIGNATURE_INFO, 15)
tlv_data += struct.pack('> B H B', HEADER_HASH_ALGORITHM, 1, HASH_SHA512 if hash_algorithm == 'sha512' else HASH_SHA1)
Expand All @@ -314,7 +313,9 @@ def build_sgn_file(input_file, tftp_certificate_file, hash_algorithm, filename):
tlv_data += struct.pack('> B H B', HEADER_SIGNATURE_ALGORITHM, 1, 0)
tlv_data += struct.pack('> B H B', HEADER_SIGNATURE_MODULUS, 1, [64, 128, 256, 512].index(signature_length))

# Index where the signature will be inserted
signature_index = len(tlv_data)

filename = filename.encode('utf-8') + b'\x00'

tlv_data += struct.pack('> B H', HEADER_FILENAME, len(filename))
Expand All @@ -337,7 +338,8 @@ def build_sgn_file(input_file, tftp_certificate_file, hash_algorithm, filename):
try:
with open(sgn_file, 'wb') as file:
file.write(tlv_data[:signature_index])
file.write(struct.pack('> B H', HEADER_SIGNATURE, len(signature)) + signature)
file.write(struct.pack('> B H', HEADER_SIGNATURE, len(signature)))
file.write(signature)
file.write(tlv_data[signature_index:])

except (PermissionError, IsADirectoryError) as error:
Expand Down
20 changes: 10 additions & 10 deletions tlvfile
View file
Original file line number Diff line number Diff line change
Expand Up @@ -103,7 +103,6 @@ def parse_tlv_file(tlv_file):

sast_serial_number = None
hash_algorithm = None

signature_index = 0
signature_length = 0

Expand Down Expand Up @@ -391,17 +390,17 @@ def build_tlv_file(tlv_file, sast_certificate_file, version, hash_algorithm, fil
serial_number = certificate.serial_number
serial_number = serial_number.to_bytes((serial_number.bit_length() + 7) // 8, byteorder = 'big')

signer_info = 3 + len(signer_name) + 3 + len(serial_number) + 3 + len(issuer_name)
tlv_data += struct.pack('> B H', HEADER_SIGNER_INFO, signer_info)
signer_info = struct.pack('> B H', HEADER_SIGNER_NAME, len(signer_name))
signer_info += signer_name

tlv_data += struct.pack('> B H', HEADER_SIGNER_NAME, len(signer_name))
tlv_data += signer_name
signer_info += struct.pack('> B H', HEADER_SERIAL_NUMBER, len(serial_number))
signer_info += serial_number

tlv_data += struct.pack('> B H', HEADER_SERIAL_NUMBER, len(serial_number))
tlv_data += serial_number
signer_info += struct.pack('> B H', HEADER_ISSUER_NAME, len(issuer_name))
signer_info += issuer_name

tlv_data += struct.pack('> B H', HEADER_ISSUER_NAME, len(issuer_name))
tlv_data += issuer_name
tlv_data += struct.pack('> B H', HEADER_SIGNER_INFO, len(signer_info))
tlv_data += signer_info

tlv_data += struct.pack('> B H', HEADER_SIGNATURE_INFO, 15)
tlv_data += struct.pack('> B H B', HEADER_HASH_ALGORITHM, 1, HASH_SHA512 if hash_algorithm == 'sha512' else HASH_SHA1)
Expand Down Expand Up @@ -520,7 +519,8 @@ def build_tlv_file(tlv_file, sast_certificate_file, version, hash_algorithm, fil
try:
with open(tlv_file, 'wb') as file:
file.write(tlv_data[:signature_index])
file.write(struct.pack('> B H', HEADER_SIGNATURE, len(signature)) + signature)
file.write(struct.pack('> B H', HEADER_SIGNATURE, len(signature)))
file.write(signature)
file.write(tlv_data[signature_index:])

except (PermissionError, IsADirectoryError) as error:
Expand Down

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