mbedtls/scripts/generate_psa_constants.py
Gilles Peskine daea26f70f Correct and simplify block-based cipher modes
OFB and CFB are streaming modes. XTS is a not a cipher mode but it
doesn't use a separate padding step. This leaves only CBC as a block
cipher mode that needs a padding step.

Since CBC is the only mode that uses a separate padding step, and is
likely to remain the only mode in the future, encode the padding mode
directly in the algorithm constant, rather than building up an
algorithm value from a chaining mode and a padding mode. This greatly
simplifies the interface as well as some parts of the implementation.
2018-09-20 11:58:22 +02:00

266 lines
9.2 KiB
Python
Executable file

#!/usr/bin/env python
import os
import re
import sys
output_template = '''\
/* Automatically generated by generate_psa_constant.py. DO NOT EDIT. */
static const char *psa_strerror(psa_status_t status)
{
switch (status) {
%(status_cases)s
default: return NULL;
}
}
static const char *psa_ecc_curve_name(psa_ecc_curve_t curve)
{
switch (curve) {
%(ecc_curve_cases)s
default: return NULL;
}
}
static const char *psa_hash_algorithm_name(psa_algorithm_t hash_alg)
{
switch (hash_alg) {
%(hash_algorithm_cases)s
default: return NULL;
}
}
static int psa_snprint_key_type(char *buffer, size_t buffer_size,
psa_key_type_t type)
{
size_t required_size = 0;
switch (type) {
%(key_type_cases)s
default:
%(key_type_code)s{
return snprintf(buffer, buffer_size,
"0x%%08lx", (unsigned long) type);
}
break;
}
buffer[0] = 0;
return required_size;
}
static int psa_snprint_algorithm(char *buffer, size_t buffer_size,
psa_algorithm_t alg)
{
size_t required_size = 0;
switch (alg) {
%(algorithm_cases)s
default:
%(algorithm_code)s{
return snprintf(buffer, buffer_size,
"0x%%08lx", (unsigned long) alg);
}
break;
}
buffer[0] = 0;
return required_size;
}
static int psa_snprint_key_usage(char *buffer, size_t buffer_size,
psa_key_usage_t usage)
{
size_t required_size = 0;
if (usage == 0) {
if (buffer_size > 1) {
buffer[0] = '0';
buffer[1] = 0;
} else if (buffer_size == 1) {
buffer[0] = 0;
}
return 1;
}
%(key_usage_code)s
if (usage != 0) {
if (required_size != 0) {
append(&buffer, buffer_size, &required_size, " | ", 3);
}
required_size += snprintf(buffer, buffer_size - required_size,
"0x%%08x", usage);
} else {
buffer[0] = 0;
}
return required_size;
}
/* End of automatically generated file. */
'''
key_type_from_curve_template = '''if (%(tester)s(type)) {
append_with_curve(&buffer, buffer_size, &required_size,
"%(builder)s", %(builder_length)s,
PSA_KEY_TYPE_GET_CURVE(type));
} else '''
algorithm_from_hash_template = '''if (%(tester)s(alg)) {
append_with_hash(&buffer, buffer_size, &required_size,
"%(builder)s", %(builder_length)s,
PSA_ALG_GET_HASH(alg));
} else '''
bit_test_template = '''\
if (%(var)s & %(flag)s) {
if (required_size != 0) {
append(&buffer, buffer_size, &required_size, " | ", 3);
}
append(&buffer, buffer_size, &required_size, "%(flag)s", %(length)d);
%(var)s ^= %(flag)s;
}\
'''
class MacroCollector:
def __init__(self):
self.statuses = set()
self.key_types = set()
self.key_types_from_curve = {}
self.ecc_curves = set()
self.algorithms = set()
self.hash_algorithms = set()
self.algorithms_from_hash = {}
self.key_usages = set()
# "#define" followed by a macro name with either no parameters
# or a single parameter. Grab the macro name in group 1, the
# parameter name if any in group 2 and the definition in group 3.
definition_re = re.compile(r'\s*#\s*define\s+(\w+)(?:\s+|\((\w+)\)\s*)(.+)(?:/[*/])?')
def read_line(self, line):
m = re.match(self.definition_re, line)
if not m:
return
name, parameter, definition = m.groups()
if name.endswith('_FLAG') or name.endswith('MASK'):
# Macro only to build actual values
return
elif (name.startswith('PSA_ERROR_') or name == 'PSA_SUCCESS') \
and not parameter:
self.statuses.add(name)
elif name.startswith('PSA_KEY_TYPE_') and not parameter:
self.key_types.add(name)
elif name.startswith('PSA_KEY_TYPE_') and parameter == 'curve':
self.key_types_from_curve[name] = name[:13] + 'IS_' + name[13:]
elif name.startswith('PSA_ECC_CURVE_') and not parameter:
self.ecc_curves.add(name)
elif name.startswith('PSA_ALG_') and not parameter:
if name in ['PSA_ALG_ECDSA_BASE',
'PSA_ALG_RSA_PKCS1V15_SIGN_BASE']:
# Ad hoc skipping of duplicate names for some numerical values
return
self.algorithms.add(name)
# Ad hoc detection of hash algorithms
if re.search(r'0x010000[0-9A-Fa-f]{2}', definition):
self.hash_algorithms.add(name)
elif name.startswith('PSA_ALG_') and parameter == 'hash_alg':
if name in ['PSA_ALG_DSA', 'PSA_ALG_ECDSA']:
# A naming irregularity
tester = name[:8] + 'IS_RANDOMIZED_' + name[8:]
else:
tester = name[:8] + 'IS_' + name[8:]
self.algorithms_from_hash[name] = tester
elif name.startswith('PSA_KEY_USAGE_') and not parameter:
self.key_usages.add(name)
else:
# Other macro without parameter
return
def read_file(self, header_file):
for line in header_file:
self.read_line(line)
def make_return_case(self, name):
return 'case %(name)s: return "%(name)s";' % {'name': name}
def make_append_case(self, name):
template = ('case %(name)s: '
'append(&buffer, buffer_size, &required_size, "%(name)s", %(length)d); '
'break;')
return template % {'name': name, 'length': len(name)}
def make_inner_append_case(self, name):
template = ('case %(name)s: '
'append(buffer, buffer_size, required_size, "%(name)s", %(length)d); '
'break;')
return template % {'name': name, 'length': len(name)}
def make_bit_test(self, var, flag):
return bit_test_template % {'var': var,
'flag': flag,
'length': len(flag)}
def make_status_cases(self):
return '\n '.join(map(self.make_return_case,
sorted(self.statuses)))
def make_ecc_curve_cases(self):
return '\n '.join(map(self.make_return_case,
sorted(self.ecc_curves)))
def make_key_type_cases(self):
return '\n '.join(map(self.make_append_case,
sorted(self.key_types)))
def make_key_type_from_curve_code(self, builder, tester):
return key_type_from_curve_template % {'builder': builder,
'builder_length': len(builder),
'tester': tester}
def make_key_type_code(self):
d = self.key_types_from_curve
make = self.make_key_type_from_curve_code
return ''.join([make(k, d[k]) for k in sorted(d.keys())])
def make_hash_algorithm_cases(self):
return '\n '.join(map(self.make_return_case,
sorted(self.hash_algorithms)))
def make_algorithm_cases(self):
return '\n '.join(map(self.make_append_case,
sorted(self.algorithms)))
def make_algorithm_from_hash_code(self, builder, tester):
return algorithm_from_hash_template % {'builder': builder,
'builder_length': len(builder),
'tester': tester}
def make_algorithm_code(self):
d = self.algorithms_from_hash
make = self.make_algorithm_from_hash_code
return ''.join([make(k, d[k]) for k in sorted(d.keys())])
def make_key_usage_code(self):
return '\n'.join([self.make_bit_test('usage', bit)
for bit in sorted(self.key_usages)])
def write_file(self, output_file):
data = {}
data['status_cases'] = self.make_status_cases()
data['ecc_curve_cases'] = self.make_ecc_curve_cases()
data['key_type_cases'] = self.make_key_type_cases()
data['key_type_code'] = self.make_key_type_code()
data['hash_algorithm_cases'] = self.make_hash_algorithm_cases()
data['algorithm_cases'] = self.make_algorithm_cases()
data['algorithm_code'] = self.make_algorithm_code()
data['key_usage_code'] = self.make_key_usage_code()
output_file.write(output_template % data)
def generate_psa_constants(header_file_name, output_file_name):
collector = MacroCollector()
with open(header_file_name) as header_file:
collector.read_file(header_file)
temp_file_name = output_file_name + '.tmp'
with open(temp_file_name, 'w') as output_file:
collector.write_file(output_file)
os.rename(temp_file_name, output_file_name)
if __name__ == '__main__':
if not os.path.isdir('programs') and os.path.isdir('../programs'):
os.chdir('..')
generate_psa_constants('include/psa/crypto.h',
'programs/psa/psa_constant_names_generated.c')