Examples

Building an OpenSSL context using a JKS through PyJKS:

import jks
import OpenSSL

ASN1 = OpenSSL.crypto.FILETYPE_ASN1

def jksfile2context(jks_file, passphrase, key_alias, key_password=None):

    keystore = jks.KeyStore.load(jks_file, passphrase)
    pk_entry = keystore.private_keys[key_alias]

    # if the key could not be decrypted using the store password,
    # decrypt with a custom password now
    if not pk_entry.is_decrypted():
        pk_entry.decrypt(key_password)

    pkey = OpenSSL.crypto.load_privatekey(ASN1, pk_entry.pkey)
    public_cert = OpenSSL.crypto.load_certificate(ASN1, pk_entry.cert_chain[0][1])
    trusted_certs = [OpenSSL.crypto.load_certificate(ASN1, cert.cert)
                     for alias, cert in keystore.certs]

    ctx = OpenSSL.SSL.Context(OpenSSL.SSL.TLSv1_METHOD)
    ctx.use_privatekey(pkey)
    ctx.use_certificate(public_cert)
    ctx.check_privatekey() # want to know ASAP if there is a problem
    cert_store = ctx.get_cert_store()
    for cert in trusted_certs:
        cert_store.add_cert(cert)

    return ctx

Reading a JKS or JCEKS keystore and dumping out its contents in the PEM format:

from __future__ import print_function
import sys, base64, textwrap
import jks

def print_pem(der_bytes, type):
    print("-----BEGIN %s-----" % type)
    print("\r\n".join(textwrap.wrap(base64.b64encode(der_bytes).decode('ascii'), 64)))
    print("-----END %s-----" % type)

ks = jks.KeyStore.load("keystore.jks", "XXXXXXXX")
# if any of the keys in the store use a password that is not the same as the store password:
# ks.entries["key1"].decrypt("key_password")

for alias, pk in ks.private_keys.items():
    print("Private key: %s" % pk.alias)
    if pk.algorithm_oid == jks.util.RSA_ENCRYPTION_OID:
        print_pem(pk.pkey, "RSA PRIVATE KEY")
    else:
        print_pem(pk.pkey_pkcs8, "PRIVATE KEY")

    for c in pk.cert_chain:
        print_pem(c[1], "CERTIFICATE")
    print()

for alias, c in ks.certs.items():
    print("Certificate: %s" % c.alias)
    print_pem(c.cert, "CERTIFICATE")
    print()

for alias, sk in ks.secret_keys.items():
    print("Secret key: %s" % sk.alias)
    print("  Algorithm: %s" % sk.algorithm)
    print("  Key size: %d bits" % sk.key_size)
    print("  Key: %s" % "".join("{:02x}".format(b) for b in bytearray(sk.key)))
    print()

Generating a basic self signed certificate with OpenSSL and saving it in a jks keystore:

import OpenSSL
import jks

# generate key
key = OpenSSL.crypto.PKey()
key.generate_key(OpenSSL.crypto.TYPE_RSA, 2048)

# generate a self signed certificate
cert = OpenSSL.crypto.X509()
cert.get_subject().CN = 'my.server.example.com'
cert.set_serial_number(473289472)
cert.gmtime_adj_notBefore(0)
cert.gmtime_adj_notAfter(365*24*60*60)
cert.set_issuer(cert.get_subject())
cert.set_pubkey(key)
cert.sign(key, 'sha256')

# dumping the key and cert to ASN1
dumped_cert = OpenSSL.crypto.dump_certificate(OpenSSL.crypto.FILETYPE_ASN1, cert)
dumped_key = OpenSSL.crypto.dump_privatekey(OpenSSL.crypto.FILETYPE_ASN1, key)

# creating a private key entry
pke = jks.PrivateKeyEntry.new('self signed cert', [dumped_cert], dumped_key, 'rsa_raw')

# if we want the private key entry to have a unique password, we can encrypt it beforehand
# if it is not ecrypted when saved, it will be encrypted with the same password as the keystore
#pke.encrypt('my_private_key_password')

# creating a jks keystore with the private key, and saving it
keystore = jks.KeyStore.new('jks', [pke])
keystore.save('./my_keystore.jks', 'my_password')