#!/usr/bin/env python

"""
Python wrapper of the botan crypto library
http://botan.randombit.net

(C) 2015 Jack Lloyd
(C) 2015 Uri  Blumenthal (extensions and patches)

Botan is released under the Simplified BSD License (see license.txt)
"""

import sys
from ctypes import *
from binascii import hexlify, unhexlify

"""
Module initialization
"""
if sys.platform == 'darwin':
    botan = CDLL('libbotan-1.11.dylib')
else:
    botan = CDLL('libbotan-1.11.so')

expected_api_rev = 20151015
botan_api_rev = botan.botan_ffi_api_version()

if botan_api_rev != expected_api_rev:
    raise Exception("Bad botan API rev got %d expected %d" % (botan_api_rev, expected_api_rev))

# Internal utilities
def _call_fn_returning_vec(guess, fn):

    buf = create_string_buffer(guess)
    buf_len = c_size_t(len(buf))

    rc = fn(buf, byref(buf_len))
    if rc < 0:
        if buf_len.value > len(buf):
            #print("Calling again with %d" % (buf_len.value))
            return _call_fn_returning_vec(buf_len.value, fn)
        else:
            raise Exception("Call failed: %d" % (rc))

    assert buf_len.value <= len(buf)
    return buf.raw[0:buf_len.value]

def _call_fn_returning_string(guess, fn):
    # Assumes that anything called with this is returning plain ASCII strings
    # (base64 data, algorithm names, etc)
    v = _call_fn_returning_vec(guess, fn)
    return v.decode('ascii')[:-1]

def _ctype_str(s):
    assert(type(s) == type(""))
    if sys.version_info[0] < 3:
        return s
    else:
        return s.encode('utf-8')

def _ctype_bits(s):
    # TODO typecheck for bytes in python3?
    if sys.version_info[0] < 3:
        return s
    else:
        if isinstance(s, bytes):
            return s
        elif isinstance(s, str):
            return s.encode('utf-8') # FIXME
        else:
            assert False

def _ctype_bufout(buf):
    if sys.version_info[0] < 3:
        return str(buf.raw)
    else:
        return buf.raw

def hex_encode(buf):
    return hexlify(buf).decode('ascii')

def hex_decode(buf):
    return unhexlify(buf)

"""
Versions
"""
def version_major():
    return botan.botan_version_major()

def version_minor():
    return botan.botan_version_minor()

def version_patch():
    return botan.botan_version_patch()

def version_string():
    botan.botan_version_string.restype = c_char_p
    return botan.botan_version_string().decode('ascii')

"""
RNG
"""
class rng(object):
    # Can also use type "system"
    def __init__(self, rng_type = 'system'):
        botan.botan_rng_init.argtypes = [c_void_p, c_char_p]
        self.rng = c_void_p(0)
        rc = botan.botan_rng_init(byref(self.rng), _ctype_str(rng_type))
        if rc != 0 or self.rng is None:
            raise Exception("No rng " + algo + " for you!")

    def __del__(self):
        botan.botan_rng_destroy.argtypes = [c_void_p]
        botan.botan_rng_destroy(self.rng)

    def reseed(self, bits = 256):
        botan.botan_rng_reseed.argtypes = [c_void_p, c_size_t]
        botan.botan_rng_reseed(self.rng, bits)

    def get(self, length):
        botan.botan_rng_get.argtypes = [c_void_p, POINTER(c_char), c_size_t]
        out = create_string_buffer(length)
        l = c_size_t(length)
        rc = botan.botan_rng_get(self.rng, out, l)
        return _ctype_bufout(out)

"""
Hash function
"""
class hash_function(object):
    def __init__(self, algo):
        botan.botan_hash_init.argtypes = [c_void_p, c_char_p, c_uint32]
        flags = c_uint32(0) # always zero in this API version
        self.hash = c_void_p(0)
        rc = botan.botan_hash_init(byref(self.hash), _ctype_str(algo), flags)
        if rc != 0 or self.hash is None:
            raise Exception("No hash " + algo + " for you!")

    def __del__(self):
        botan.botan_hash_destroy.argtypes = [c_void_p]
        botan.botan_hash_destroy(self.hash)

    def clear(self):
        botan.botan_hash_clear.argtypes = [c_void_p]
        return botan.botan_hash_clear(self.hash)

    def output_length(self):
        botan.botan_hash_output_length.argtypes = [c_void_p,POINTER(c_size_t)]
        l = c_size_t(0)
        rc = botan.botan_hash_output_length(self.hash, byref(l))
        return l.value

    def update(self, x):
        botan.botan_hash_update.argtypes = [c_void_p, POINTER(c_char), c_size_t]
        botan.botan_hash_update(self.hash, _ctype_bits(x), len(x))

    def final(self):
        botan.botan_hash_final.argtypes = [c_void_p, POINTER(c_char)]
        out = create_string_buffer(self.output_length())
        botan.botan_hash_final(self.hash, out)
        return _ctype_bufout(out)

"""
Message authentication codes
"""
class message_authentication_code(object):
    def __init__(self, algo):
        botan.botan_mac_init.argtypes = [c_void_p, c_char_p, c_uint32]
        flags = c_uint32(0) # always zero in this API version
        self.mac = c_void_p(0)
        rc = botan.botan_mac_init(byref(self.mac), _ctype_str(algo), flags)
        if rc != 0 or self.mac is None:
            raise Exception("No mac " + algo + " for you!")

    def __del__(self):
        botan.botan_mac_destroy.argtypes = [c_void_p]
        botan.botan_mac_destroy(self.mac)

    def clear(self):
        botan.botan_mac_clear.argtypes = [c_void_p]
        return botan.botan_mac_clear(self.mac)

    def output_length(self):
        botan.botan_mac_output_length.argtypes = [c_void_p, POINTER(c_size_t)]
        l = c_size_t(0)
        rc = botan.botan_mac_output_length(self.mac, byref(l))
        return l.value

    def set_key(self, key):
        botan.botan_mac_set_key.argtypes = [c_void_p, POINTER(c_char), c_size_t]
        return botan.botan_mac_set_key(self.mac, key, len(key))

    def update(self, x):
        botan.botan_mac_update.argtypes = [c_void_p, POINTER(c_char), c_size_t]
        botan.botan_mac_update(self.mac, x, len(x))

    def final(self):
        botan.botan_mac_final.argtypes = [c_void_p, POINTER(c_char)]
        out = create_string_buffer(self.output_length())
        botan.botan_mac_final(self.mac, out)
        return _ctype_bufout(out)

class cipher(object):
    def __init__(self, algo, encrypt = True):
        botan.botan_cipher_init.argtypes = [c_void_p,c_char_p, c_uint32]
        flags = 0 if encrypt else 1
        self.cipher = c_void_p(0)
        rc = botan.botan_cipher_init(byref(self.cipher), _ctype_str(algo), flags)
        if rc != 0 or self.cipher is None:
            raise Exception("No cipher " + algo + " for you!")

    def __del__(self):
        botan.botan_cipher_destroy.argtypes = [c_void_p]
        botan.botan_cipher_destroy(self.cipher)

    def default_nonce_length(self):
        botan.botan_cipher_get_default_nonce_length.argtypes = [c_void_p, POINTER(c_size_t)]
        l = c_size_t(0)
        botan.botan_cipher_get_default_nonce_length(self.cipher, byref(l))
        return l.value

    def update_granularity(self):
        botan.botan_cipher_get_update_granularity.argtypes = [c_void_p, POINTER(c_size_t)]
        l = c_size_t(0)
        botan.botan_cipher_get_update_granularity(self.cipher, byref(l))
        return l.value

    def key_length(self):
        kmin = c_size_t(0)
        kmax = c_size_t(0)
        botan.botan_cipher_query_keylen(self.cipher, byref(kmin), byref(kmax))
        return kmin.value, kmax.value

    def tag_length(self):
        botan.botan_cipher_get_tag_length.argtypes = [c_void_p, POINTER(c_size_t)]
        l = c_size_t(0)
        botan.botan_cipher_get_tag_length(self.cipher, byref(l))
        return l.value

    def is_authenticated(self):
        return self.tag_length() > 0

    def valid_nonce_length(self, nonce_len):
        botan.botan_cipher_valid_nonce_length.argtypes = [c_void_p, c_size_t]
        rc = botan.botan_cipher_valid_nonce_length(self.cipher, nonce_len)
        if rc < 0:
            raise Exception('Error calling valid_nonce_length')
        return True if rc == 1 else False

    def clear(self):
        botan.botan_cipher_clear.argtypes = [c_void_p]
        botan.botan_cipher_clear(self.cipher)

    def set_key(self, key):
        botan.botan_cipher_set_key.argtypes = [c_void_p, POINTER(c_char), c_size_t]
        botan.botan_cipher_set_key(self.cipher, key, len(key))

    def set_assoc_data(self, ad):
        botan.botan_cipher_set_associated_data.argtypes = [c_void_p, POINTER(c_char), c_size_t]
        botan.botan_cipher_set_associated_data(self.cipher, ad, len(ad))

    def start(self, nonce):
        botan.botan_cipher_start.argtypes = [c_void_p, POINTER(c_char), c_size_t]
        botan.botan_cipher_start(self.cipher, nonce, len(nonce))

    def _update(self, txt, final):
        botan.botan_cipher_update.argtypes = [c_void_p, c_uint32,
                                              POINTER(c_char), c_size_t, POINTER(c_size_t),
                                              POINTER(c_char), c_size_t, POINTER(c_size_t)]

        inp = txt if txt else ''
        inp_sz = c_size_t(len(inp))
        inp_consumed = c_size_t(0)
        out = create_string_buffer(inp_sz.value + (self.tag_length() if final else 0))
        out_sz = c_size_t(len(out))
        out_written = c_size_t(0)
        flags = c_uint32(1 if final else 0)

        botan.botan_cipher_update(self.cipher, flags,
                                  out, out_sz, byref(out_written),
                                  cast(inp, c_char_p), inp_sz, byref(inp_consumed))

        # buffering not supported yet
        assert inp_consumed.value == inp_sz.value
        return out.raw[0:out_written.value]

    def update(self, txt):
        return self._update(txt, False)

    def finish(self, txt = None):
        return self._update(txt, True)


"""
Bcrypt
"""
def bcrypt(passwd, rng, work_factor = 10):
    botan.botan_bcrypt_generate.argtypes = [POINTER(c_char), POINTER(c_size_t),
                                            c_char_p, c_void_p, c_size_t, c_uint32]
    out_len = c_size_t(64)
    out = create_string_buffer(out_len.value)
    flags = c_uint32(0)
    rc = botan.botan_bcrypt_generate(out, byref(out_len), passwd, rng.rng, c_size_t(work_factor), flags)
    if rc != 0:
        raise Exception('botan bcrypt failed, error %s' % (rc))
    b = out.raw[0:out_len.value]
    if b[-1] == '\x00':
        b = b[:-1]
    return b

def check_bcrypt(passwd, bcrypt):
    rc = botan.botan_bcrypt_is_valid(passwd, bcrypt)
    return (rc == 0)

"""
PBKDF
"""
def pbkdf(algo, password, out_len, iterations = 10000, salt = rng().get(12)):
    botan.botan_pbkdf.argtypes = [c_char_p, POINTER(c_char), c_size_t, c_char_p, c_void_p, c_size_t, c_size_t]
    out_buf = create_string_buffer(out_len)
    botan.botan_pbkdf(_ctype_str(algo), out_buf, out_len, _ctype_str(password), salt, len(salt), iterations)
    return (salt,iterations,out_buf.raw)

def pbkdf_timed(algo, password, out_len, ms_to_run = 300, salt = rng().get(12)):
    botan.botan_pbkdf_timed.argtypes = [c_char_p, POINTER(c_char), c_size_t, c_char_p,
                                        c_void_p, c_size_t, c_size_t, POINTER(c_size_t)]
    out_buf = create_string_buffer(out_len)
    iterations = c_size_t(0)
    botan.botan_pbkdf_timed(_ctype_str(algo), out_buf, out_len, _ctype_str(password), salt, len(salt), ms_to_run, byref(iterations))
    return (salt,iterations.value,out_buf.raw)

"""
KDF
"""
def kdf(algo, secret, out_len, salt):
    botan.botan_kdf.argtypes = [c_char_p, POINTER(c_char), c_size_t, POINTER(c_char), c_size_t, POINTER(c_char), c_size_t]
    out_buf = create_string_buffer(out_len)
    out_sz = c_size_t(out_len)
    botan.botan_kdf(_ctype_str(algo), out_buf, out_sz, secret, len(secret), salt, len(salt))
    return out_buf.raw[0:out_sz.value]

"""
Public and private keys
"""
class public_key(object):
    def __init__(self, obj = c_void_p(0)):
        self.pubkey = obj

    def __del__(self):
        botan.botan_pubkey_destroy.argtypes = [c_void_p]
        botan.botan_pubkey_destroy(self.pubkey)

    def estimated_strength(self):
        botan.botan_pubkey_estimated_strength.argtypes = [c_void_p, POINTER(c_size_t)]
        r = c_size_t(0)
        botan.botan_pubkey_estimated_strength(self.pubkey, byref(r))
        return r.value

    def algo_name(self):
        botan.botan_pubkey_algo_name.argtypes = [c_void_p, POINTER(c_char), POINTER(c_size_t)]
        return _call_fn_returning_string(32, lambda b,bl: botan.botan_pubkey_algo_name(self.pubkey, b, bl))

    def encoding(self, pem = False):
        botan.botan_pubkey_export.argtypes = [c_void_p, POINTER(c_char), POINTER(c_size_t), c_uint32]
        flag = 1 if pem else 0
        return _call_fn_returning_vec(0, lambda b,bl: botan.botan_pubkey_export(self.pubkey, b, bl, flag))

    def fingerprint(self, hash = 'SHA-256'):
        botan.botan_pubkey_fingerprint.argtypes = [c_void_p, c_char_p,
                                                   POINTER(c_char), POINTER(c_size_t)]

        n = hash_function(hash).output_length()
        buf = create_string_buffer(n)
        buf_len = c_size_t(n)

        botan.botan_pubkey_fingerprint(self.pubkey, _ctype_str(hash), buf, byref(buf_len))
        return hex_encode(buf[0:buf_len.value])

class private_key(object):
    def __init__(self, alg, param, rng):
        botan.botan_privkey_create_rsa.argtypes = [c_void_p, c_void_p, c_size_t]
        botan.botan_privkey_create_ecdsa.argtypes = [c_void_p, c_void_p, c_char_p]
        botan.botan_privkey_create_ecdh.argtypes = [c_void_p, c_void_p, c_char_p]
        botan.botan_privkey_create_mceliece.argtypes = [c_void_p, c_void_p, c_size_t, c_size_t]

        self.privkey = c_void_p(0)

        if alg == 'rsa':
            botan.botan_privkey_create_rsa(byref(self.privkey), rng.rng, param)
        elif alg == 'ecdsa':
            botan.botan_privkey_create_ecdsa(byref(self.privkey), rng.rng, _ctype_str(param))
        elif alg == 'ecdh':
            botan.botan_privkey_create_ecdh(byref(self.privkey), rng.rng, _ctype_str(param))
        elif alg in ['mce', 'mceliece']:
            botan.botan_privkey_create_mceliece(byref(self.privkey), rng.rng, param[0], param[1])
        else:
            raise Exception('Unknown public key algo ' + alg)

        if self.privkey is None:
            raise Exception('Error creating ' + alg + ' key')

    def __del__(self):
        botan.botan_privkey_destroy.argtypes = [c_void_p]
        botan.botan_privkey_destroy(self.privkey)

    def get_public_key(self):
        botan.botan_privkey_export_pubkey.argtypes = [c_void_p, c_void_p]

        pub = c_void_p(0)
        botan.botan_privkey_export_pubkey(byref(pub), self.privkey)
        return public_key(pub)

    def export(self):
        botan.botan_privkey_export.argtypes = [c_void_p,POINTER(c_char),c_void_p]

        n = 4096
        buf = create_string_buffer(n)
        buf_len = c_size_t(n)

        rc = botan.botan_privkey_export(self.privkey, buf, byref(buf_len))
        if rc != 0:
            buf = create_string_buffer(buf_len.value)
            botan.botan_privkey_export(self.privkey, buf, byref(buf_len))
        return buf[0:buf_len.value]

class pk_op_encrypt(object):
    def __init__(self, key, padding):
        botan.botan_pk_op_encrypt_create.argtypes = [c_void_p, c_void_p, c_char_p, c_uint32]
        self.op = c_void_p(0)
        flags = c_uint32(0) # always zero in this ABI
        print("Padding is ", padding)
        botan.botan_pk_op_encrypt_create(byref(self.op), key.pubkey, _ctype_str(padding), flags)
        if not self.op:
            raise Exception("No pk op for you")

    def __del__(self):
        botan.botan_pk_op_encrypt_destroy.argtypes = [c_void_p]
        botan.botan_pk_op_encrypt_destroy(self.op)

    def encrypt(self, msg, rng):
        botan.botan_pk_op_encrypt.argtypes = [c_void_p, c_void_p,
                                              POINTER(c_char), POINTER(c_size_t),
                                              POINTER(c_char), c_size_t]

        outbuf_sz = c_size_t(4096) #?!?!
        outbuf = create_string_buffer(outbuf_sz.value)
        ll = len(msg)
        #print("encrypt: len=%d" % ll)
        #if sys.version_info[0] > 2:
        #    msg = cast(msg, c_char_p)
        #    ll = c_size_t(ll)
        botan.botan_pk_op_encrypt(self.op, rng.rng, outbuf, byref(outbuf_sz), msg, ll)
        #print("encrypt: outbuf_sz.value=%d" % outbuf_sz.value)
        return outbuf.raw[0:outbuf_sz.value]


class pk_op_decrypt(object):
    def __init__(self, key, padding):
        botan.botan_pk_op_decrypt_create.argtypes = [c_void_p, c_void_p, c_char_p, c_uint32]
        self.op = c_void_p(0)
        flags = c_uint32(0) # always zero in this ABI
        botan.botan_pk_op_decrypt_create(byref(self.op), key.privkey, _ctype_str(padding), flags)
        if not self.op:
            raise Exception("No pk op for you")

    def __del__(self):
        botan.botan_pk_op_decrypt_destroy.argtypes = [c_void_p]
        botan.botan_pk_op_decrypt_destroy(self.op)

    def decrypt(self, msg):
        botan.botan_pk_op_decrypt.argtypes = [c_void_p,
                                              POINTER(c_char), POINTER(c_size_t),
                                              POINTER(c_char), c_size_t]

        outbuf_sz = c_size_t(4096) #?!?!
        outbuf = create_string_buffer(outbuf_sz.value)
        ll = len(msg)
        botan.botan_pk_op_decrypt(self.op, outbuf, byref(outbuf_sz), _ctype_bits(msg), ll)
        return outbuf.raw[0:outbuf_sz.value]

class pk_op_sign(object):
    def __init__(self, key, padding):
        botan.botan_pk_op_sign_create.argtypes = [c_void_p, c_void_p, c_char_p, c_uint32]
        self.op = c_void_p(0)
        flags = c_uint32(0) # always zero in this ABI
        botan.botan_pk_op_sign_create(byref(self.op), key.privkey, _ctype_str(padding), flags)
        if not self.op:
            raise Exception("No pk op for you")

    def __del__(self):
        botan.botan_pk_op_sign_destroy.argtypes = [c_void_p]
        botan.botan_pk_op_sign_destroy(self.op)

    def update(self, msg):
        botan.botan_pk_op_sign_update.argtypes = [c_void_p,  POINTER(c_char), c_size_t]
        botan.botan_pk_op_sign_update(self.op, _ctype_str(msg), len(msg))

    def finish(self, rng):
        botan.botan_pk_op_sign_finish.argtypes = [c_void_p, c_void_p, POINTER(c_char), POINTER(c_size_t)]
        outbuf_sz = c_size_t(4096) #?!?!
        outbuf = create_string_buffer(outbuf_sz.value)
        botan.botan_pk_op_sign_finish(self.op, rng.rng, outbuf, byref(outbuf_sz))
        return outbuf.raw[0:outbuf_sz.value]

class pk_op_verify(object):
    def __init__(self, key, padding):
        botan.botan_pk_op_verify_create.argtypes = [c_void_p, c_void_p, c_char_p, c_uint32]
        self.op = c_void_p(0)
        flags = c_uint32(0) # always zero in this ABI
        botan.botan_pk_op_verify_create(byref(self.op), key.pubkey, _ctype_str(padding), flags)
        if not self.op:
            raise Exception("No pk op for you")

    def __del__(self):
        botan.botan_pk_op_verify_destroy.argtypes = [c_void_p]
        botan.botan_pk_op_verify_destroy(self.op)

    def update(self, msg):
        botan.botan_pk_op_verify_update.argtypes = [c_void_p, POINTER(c_char), c_size_t]
        botan.botan_pk_op_verify_update(self.op, _ctype_bits(msg), len(msg))

    def check_signature(self, signature):
        botan.botan_pk_op_verify_finish.argtypes = [c_void_p, POINTER(c_char), c_size_t]
        rc = botan.botan_pk_op_verify_finish(self.op, _ctype_bits(signature), len(signature))
        if rc == 0:
            return True
        return False

"""
MCEIES encryption
Must be used with McEliece keys
"""
def mceies_encrypt(mce, rng, aead, pt, ad):
    botan.botan_mceies_encrypt.argtypes = [c_void_p, c_void_p, c_char_p, POINTER(c_char), c_size_t,
                                           POINTER(c_char), c_size_t, POINTER(c_char), POINTER(c_size_t)]

    return _call_fn_returning_vec(0, lambda b,bl:
                                  botan.botan_mceies_encrypt(mce.pubkey,
                                                             rng.rng,
                                                             _ctype_str(aead),
                                                             _ctype_bits(pt),
                                                             len(pt),
                                                             _ctype_bits(ad),
                                                             len(ad),
                                                             b, bl))

def mceies_decrypt(mce, aead, pt, ad):
    botan.botan_mceies_decrypt.argtypes = [c_void_p, c_char_p, POINTER(c_char), c_size_t,
                                           POINTER(c_char), c_size_t, POINTER(c_char), POINTER(c_size_t)]

    #msg = cast(msg, c_char_p)
    #ll = c_size_t(ll)

    return _call_fn_returning_vec(0, lambda b,bl:
                                  botan.botan_mceies_decrypt(mce.privkey,
                                                             _ctype_str(aead),
                                                             _ctype_bits(pt),
                                                             len(pt),
                                                             _ctype_bits(ad),
                                                             len(ad),
                                                             b, bl))

class pk_op_key_agreement(object):
    def __init__(self, key, kdf):
        botan.botan_pk_op_key_agreement_create.argtypes = [c_void_p, c_void_p, c_char_p, c_uint32]
        botan.botan_pk_op_key_agreement_export_public.argtypes = [c_void_p, POINTER(c_char), POINTER(c_size_t)]
        self.op = c_void_p(0)
        flags = c_uint32(0) # always zero in this ABI
        botan.botan_pk_op_key_agreement_create(byref(self.op), key.privkey, kdf, flags)
        if not self.op:
            raise Exception("No key agreement for you")

        self.m_public_value = _call_fn_returning_vec(0, lambda b, bl: botan.botan_pk_op_key_agreement_export_public(key.privkey, b, bl))

    def __del__(self):
        botan.botan_pk_op_key_agreement_destroy.argtypes = [c_void_p]
        botan.botan_pk_op_key_agreement_destroy(self.op)

    def public_value(self):
        return self.m_public_value

    def agree(self, other, key_len, salt):
        botan.botan_pk_op_key_agreement.argtypes = [c_void_p, POINTER(c_char), POINTER(c_size_t),
                                                    POINTER(c_char), c_size_t, POINTER(c_char), c_size_t]

        return _call_fn_returning_vec(key_len,
                                      lambda b,bl: botan.botan_pk_op_key_agreement(self.op, b, bl,
                                                                                   other, len(other),
                                                                                   salt, len(salt)))

class x509_cert(object):
    def __init__(self, filename):
        botan.botan_x509_cert_load_file.argtypes = [POINTER(c_void_p), c_char_p]
        self.x509_cert = c_void_p(0)
        botan.botan_x509_cert_load_file(byref(self.x509_cert), _ctype_str(filename))

    def __del__(self):
        botan.botan_x509_cert_destroy.argtypes = [c_void_p]
        botan.botan_x509_cert_destroy(self.x509_cert)

    # TODO: have these convert to a python datetime
    def time_starts(self):
        botan.botan_x509_cert_get_time_starts.argtypes = [c_void_p, POINTER(c_char), POINTER(c_size_t)]
        return _call_fn_returning_string(16, lambda b,bl: botan.botan_x509_cert_get_time_starts(self.x509_cert, b, bl))

    def time_expires(self):
        botan.botan_x509_cert_get_time_expires.argtypes = [c_void_p, POINTER(c_char), POINTER(c_size_t)]
        return _call_fn_returning_string(16, lambda b,bl: botan.botan_x509_cert_get_time_expires(self.x509_cert, b, bl))

    def to_string(self):
        botan.botan_x509_cert_to_string.argtypes = [c_void_p, POINTER(c_char), POINTER(c_size_t)]
        return _call_fn_returning_string(0, lambda b,bl: botan.botan_x509_cert_to_string(self.x509_cert, b, bl))

    def fingerprint(self, hash_algo = 'SHA-256'):
        botan.botan_x509_cert_get_fingerprint.argtypes = [c_void_p, c_char_p,
                                                          POINTER(c_char), POINTER(c_size_t)]

        n = hash_function(hash_algo).output_length() * 3
        return _call_fn_returning_string(n, lambda b,bl: botan.botan_x509_cert_get_fingerprint(self.x509_cert, _ctype_str(hash_algo), b, bl))

    def serial_number(self):
        botan.botan_x509_cert_get_serial_number.argtypes = [c_void_p, POINTER(c_char), POINTER(c_size_t)]
        return _call_fn_returning_vec(0, lambda b,bl: botan.botan_x509_cert_get_serial_number(self.x509_cert, b, bl))

    def authority_key_id(self):
        botan.botan_x509_cert_get_authority_key_id.argtypes = [c_void_p, POINTER(c_char), POINTER(c_size_t)]
        return _call_fn_returning_vec(0, lambda b,bl: botan.botan_x509_cert_get_authority_key_id(self.x509_cert, b, bl))

    def subject_key_id(self):
        botan.botan_x509_cert_get_subject_key_id.argtypes = [c_void_p, POINTER(c_char), POINTER(c_size_t)]
        return _call_fn_returning_vec(0, lambda b,bl: botan.botan_x509_cert_get_subject_key_id(self.x509_cert, b, bl))

    def subject_public_key_bits(self):
        botan.botan_x509_cert_get_public_key_bits.argtypes = [c_void_p, POINTER(c_char), POINTER(c_size_t)]
        return _call_fn_returning_vec(0, lambda b,bl: botan.botan_x509_cert_get_public_key_bits(self.x509_cert, b, bl))


"""
Tests and examples
"""
def test():

    def test_version():
        print("\n%s" % version_string())
        print("v%d.%d.%d\n" % (version_major(), version_minor(), version_patch()))

    def test_kdf():
        print("KDF2(SHA-1)   %s" %
              hex_encode(kdf('KDF2(SHA-1)', hex_decode('701F3480DFE95F57941F804B1B2413EF'), 7,
                             hex_decode('55A4E9DD5F4CA2EF82'))))

    def test_pbkdf():
        print("PBKDF2(SHA-1) %s" %
              hex_encode(pbkdf('PBKDF2(SHA-1)', '', 32, 10000, hex_decode('0001020304050607'))[2]))
        print("good output   %s\n" %
              '59B2B1143B4CB1059EC58D9722FB1C72471E0D85C6F7543BA5228526375B0127')

        (salt,iterations,psk) = pbkdf_timed('PBKDF2(SHA-256)', 'xyz', 32, 200)

        print("PBKDF2(SHA-256) x=timed, y=iterated; salt = %s (len=%d)  #iterations = %d\n" %
              (hex_encode(salt), len(salt), iterations))

        print('x %s' % hex_encode(psk))
        print('y %s\n' % (hex_encode(pbkdf('PBKDF2(SHA-256)', 'xyz', 32, iterations, salt)[2])))

    def test_hmac():

        hmac = message_authentication_code('HMAC(SHA-256)')
        hmac.set_key(hex_decode('0102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F20'))
        hmac.update(hex_decode('616263'))

        hmac_vec = hex_decode('A21B1F5D4CF4F73A4DD939750F7A066A7F98CC131CB16A6692759021CFAB8181')
        hmac_output = hmac.final()

        if hmac_output != hmac_vec:
            print("Bad HMAC:\t%s" % hex_encode(hmac_output))
            print("vs good: \t%s" % hex_encode(hmac_vec))
        else:
            print("HMAC output correct: %s\n" % hex_encode(hmac_output))

    def test_rng():
        user_rng = rng("user")

        print("rng output:\n\t%s\n\t%s\n\t%s\n" %
              (hex_encode(user_rng.get(42)),
               hex_encode(user_rng.get(13)),
               hex_encode(user_rng.get(9))))

    def test_hash():
        md5 = hash_function('MD5')
        assert md5.output_length() == 16
        md5.update('h')
        md5.update('i')
        h1 = md5.final()
        print("md5 hash: %s (%s)\n" % (hex_encode(h1), '49f68a5c8493ec2c0bf489821c21fc3b'))

        md5.update(hex_decode('f468025b'))
        h2 = md5.final()
        print("md5 hash: %s (%s)\n" % (hex_encode(h2), '47efd2be302a937775e93dea281b6751'))

    def test_cipher():
        for mode in ['AES-128/CTR-BE', 'Serpent/GCM', 'ChaCha20Poly1305']:
            enc = cipher(mode, encrypt=True)

            (kmin,kmax) = enc.key_length()
            print("%s: default nonce=%d update_size=%d key_min=%d key_max=%d" %
                  (mode, enc.default_nonce_length(), enc.update_granularity(), kmin, kmax))
            iv = rng().get(enc.default_nonce_length())
            key = rng().get(kmax)
            pt = rng().get(21)

            print("  plaintext %s (%d)"   % (hex_encode(pt), len(pt)))

            enc.set_key(key)
            enc.start(iv)
            assert len(enc.update('')) == 0
            ct = enc.finish(pt)
            print("  ciphertext %s (%d)" % (hex_encode(ct), len(ct)))

            dec = cipher(mode, encrypt=False)
            dec.set_key(key)
            dec.start(iv)
            decrypted = dec.finish(ct)

            print("  decrypted %s %d\n" % (hex_encode(decrypted), len(decrypted)))


    def test_mceliece():
        mce_priv = private_key('mce', [2960,57], rng())
        mce_pub = mce_priv.get_public_key()

        mce_plaintext = 'mce plaintext'
        mce_ad = 'mce AD'
        mce_ciphertext = mceies_encrypt(mce_pub, rng(), 'ChaCha20Poly1305', mce_plaintext, mce_ad)

        print("mceies len(pt)=%d  len(ct)=%d", (len(mce_plaintext), len(mce_ciphertext)))

        mce_decrypt = mceies_decrypt(mce_priv, 'ChaCha20Poly1305', mce_ciphertext, mce_ad)

        print("mce_pub %s/SHA-1 fingerprint: %s\nEstimated strength %s bits (len %d)\n" %
              (mce_pub.algo_name(), mce_pub.fingerprint("SHA-1"),
               mce_pub.estimated_strength(), len(mce_pub.encoding())
              )
        )

    def test_rsa():
        rsapriv = private_key('rsa', 1536, rng())
        rsapub = rsapriv.get_public_key()

        print("rsapub %s SHA-1 fingerprint: %s estimated strength %d (len %d)" %
              (rsapub.algo_name(), rsapub.fingerprint("SHA-1"),
               rsapub.estimated_strength(), len(rsapub.encoding())
              )
        )

        dec = pk_op_decrypt(rsapriv, "EME1(SHA-256)")
        enc = pk_op_encrypt(rsapub, "EME1(SHA-256)")

        sys_rng = rng()
        symkey = sys_rng.get(32)
        ctext = enc.encrypt(symkey, sys_rng)
        print("ptext  \'%s\'" % hex_encode(symkey))
        print("ctext   \'%s\'" % hex_encode(ctext))
        print("decrypt \'%s\'\n" % hex_encode(dec.decrypt(ctext)))

        signer = pk_op_sign(rsapriv, 'EMSA4(SHA-384)')

        signer.update('messa')
        signer.update('ge')
        sig = signer.finish(rng())

        print("EMSA4(SHA-384) signature: %s" % hex_encode(sig))

        verify = pk_op_verify(rsapub, 'EMSA4(SHA-384)')

        verify.update('mess')
        verify.update('age')
        print("good sig accepted? %s" % verify.check_signature(sig))

        verify.update('mess of things')
        verify.update('age')
        print("bad sig accepted?  %s" % verify.check_signature(sig))

        verify.update('message')
        print("good sig accepted? %s\n" % verify.check_signature(sig))

    def test_dh():
        a_rng = rng('user')
        b_rng = rng('user')

        for dh_grp in ['secp256r1', 'curve25519']:
            dh_kdf = 'KDF2(SHA-384)'.encode('utf-8')
            a_dh_priv = private_key('ecdh', dh_grp, rng())
            a_dh_pub = a_dh_priv.get_public_key()

            b_dh_priv = private_key('ecdh', dh_grp, rng())
            b_dh_pub = b_dh_priv.get_public_key()

            a_dh = pk_op_key_agreement(a_dh_priv, dh_kdf)
            b_dh = pk_op_key_agreement(b_dh_priv, dh_kdf)

            a_salt = a_rng.get(8)
            b_salt = b_rng.get(8)

            print("ecdh %s pubs:\n  %s (salt %s)\n  %s (salt %s)\n" %
                  (dh_grp,
                   hex_encode(a_dh.public_value()),
                   hex_encode(a_salt),
                   hex_encode(b_dh.public_value()),
                   hex_encode(b_salt)))

            a_key = a_dh.agree(b_dh.public_value(), 32, a_salt + b_salt)
            b_key = b_dh.agree(a_dh.public_value(), 32, a_salt + b_salt)

            print("ecdh %s shared:\n  %s\n  %s\n" %
                  (dh_grp, hex_encode(a_key), hex_encode(b_key)))

    def test_certs():
        cert = x509_cert("src/tests/data/ecc/CSCA.CSCA.csca-germany.1.crt")
        print("CSCA (Germany) Certificate\nDetails:")
        print("SHA-1 fingerprint: %s" % cert.fingerprint("SHA-1"))
        print("Expected:          32:42:1C:C3:EC:54:D7:E9:43:EC:51:F0:19:23:BD:85:1D:F2:1B:B9")

        print("Not before:        %s" % cert.time_starts())
        print("Not after:         %s" % cert.time_expires())

        print("Serial number:     %s" % hex_encode(cert.serial_number()))
        print("Authority Key ID:  %s" % hex_encode(cert.authority_key_id()))
        print("Subject   Key ID:  %s" % hex_encode(cert.subject_key_id()))
        print("Public key bits:\n%s\n" % hex_encode(cert.subject_public_key_bits()))

        print(cert.to_string())

    test_version()
    test_kdf()
    test_pbkdf()
    test_hmac()
    test_rng()
    test_hash()
    test_cipher()
    test_mceliece()
    test_rsa()
    test_dh()
    test_certs()


def main(args = None):
    if args is None:
        args = sys.argv
    test()

if __name__ == '__main__':
    sys.exit(main())