def convert_kirbi_to_ccache(input_filename, output_filename):
with open(input_filename, 'rb') as fi:
krb_cred = decoder.decode(fi.read(), asn1Spec=KRB_CRED())[0]
enc_krb_cred_part = decoder.decode(krb_cred['enc-part']['cipher'], asn1Spec=EncKrbCredPart())[0]
ccache = CCache()
ccache.headers = []
header = Header()
header['tag'] = 1
header['taglen'] = 8
header['tagdata'] = '\xff\xff\xff\xff\x00\x00\x00\x00'
ccache.headers.append(header)
krb_cred_info = enc_krb_cred_part['ticket-info'][0]
tmpPrincipal = types.Principal()
tmpPrincipal.from_asn1(krb_cred_info, 'prealm', 'pname')
ccache.principal = Principal()
ccache.principal.fromPrincipal(tmpPrincipal)
credential = Credential()
server = types.Principal()
server.from_asn1(krb_cred_info, 'srealm', 'sname')
tmpServer = Principal()
tmpServer.fromPrincipal(server)
credential['client'] = ccache.principal
credential['server'] = tmpServer
credential['is_skey'] = 0
credential['key'] = KeyBlock()
credential['key']['keytype'] = int(krb_cred_info['key']['keytype'])
credential['key']['keyvalue'] = str(krb_cred_info['key']['keyvalue'])
credential['key']['keylen'] = len(credential['key']['keyvalue'])
credential['time'] = Times()
# credential['time']['authtime'] = ccache.toTimeStamp(types.KerberosTime.from_asn1(krb_cred_info['authtime']))
credential['time']['starttime'] = ccache.toTimeStamp(types.KerberosTime.from_asn1(krb_cred_info['starttime']))
credential['time']['endtime'] = ccache.toTimeStamp(types.KerberosTime.from_asn1(krb_cred_info['endtime']))
credential['time']['renew_till'] = ccache.toTimeStamp(types.KerberosTime.from_asn1(krb_cred_info['renew-till']))
flags = ccache.reverseFlags(krb_cred_info['flags'])
credential['tktflags'] = flags
credential['num_address'] = 0
credential.ticket = CountedOctetString()
credential.ticket['data'] = encoder.encode(krb_cred['tickets'][0].clone(tagSet=Ticket.tagSet, cloneValueFlag=True))
credential.ticket['length'] = len(credential.ticket['data'])
credential.secondTicket = CountedOctetString()
credential.secondTicket['data'] = ''
credential.secondTicket['length'] = 0
ccache.credentials.append(credential)
ccache.saveFile(output_filename)
