#!/usr/local/bin/python2.7
#
# Read  bunch of ASN.1/PEM plain/encrypted private keys in PKCS#8 
# format on stdin, parse each into plain text, then build substrate from it
#
from pyasn1.codec.der import decoder, encoder
from pyasn1_modules import rfc5208, pem
import sys

if len(sys.argv) != 1:
    print("""Usage:
$ cat pkcs8key.pem | %s""" % sys.argv[0])
    sys.exit(-1)
    
cnt = 0

while 1:
    idx, substrate = pem.readPemBlocksFromFile(sys.stdin, ('-----BEGIN PRIVATE KEY-----', '-----END PRIVATE KEY-----'), ('-----BEGIN ENCRYPTED PRIVATE KEY-----', '-----END ENCRYPTED PRIVATE KEY-----') )
    if not substrate:
        break

    if idx == 0:
        asn1Spec = rfc5208.PrivateKeyInfo()
    elif idx == 1:
        asn1Spec = rfc5208.EncryptedPrivateKeyInfo()
    else:
        break

    key, rest = decoder.decode(substrate, asn1Spec=asn1Spec)

    if rest: substrate = substrate[:-len(rest)]
        
    print(key.prettyPrint())

    assert encoder.encode(key) == substrate, 'pkcs8 recode fails'
        
    cnt = cnt + 1
    
print('*** %s PKCS#8 key(s) de/serialized' % cnt)
