如何用Python gnupg模块验证gnupg签名？

我用Python gnupg模块验证签名有问题.
使用此模块,我可以加密和签名文件：

gpg.encrypt_file(stream,encrypt_for,sign=sign_by,passphrase=key_passwd,output=file_out)

这样的加密文件可以通过命令行gpg解密,输出：

gpg: encrypted with 2048-bit ELG-E key,ID 518CD1AD,created 2011-04-14
            "client"
gpg: Signature made 04/14/11 13:36:14 using DSA key ID C7C006DD
gpg: Good signature from "server"

它也可以通过Python gnupg模块解密,输出文件有解密内容,
但我无法验证签名.解密和验证的代码：

def decrypt_file(file_in,file_out,key_passwd):
    gpg = gnupg.GPG()
    f = open(file_in,"rb")
    data = f.read()
    f.close()
    gpg.decrypt(data,output=file_out)
    verified = gpg.verify(data)
    if not verified:
        raise ValueError("Signature Could not be verified!")

我得到的例外：

decrypting file...
Exception in thread Thread-12:
Traceback (most recent call last):
    File "c:\Python26\lib\threading.py",line 534,in __bootstrap_inner
        self.run()
    File "c:\Python26\lib\threading.py",line 486,in run
        self.__target(*self.__args,**self.__kwargs)
    File "c:\Python26\lib\site-packages\gnupg.py",line 202,in _read_response
        result.handle_status(keyword,value)
    File "c:\Python26\lib\site-packages\gnupg.py",line 731,in handle_status
        raise ValueError("UnkNown status message: %r" % key)
ValueError: UnkNown status message: u'UNEXPECTED'

Traceback (most recent call last):
    File "ht_gnupg.py",line 32,in test()
    File "ht_gnupg.py",line 27,in test
        decrypt_file('test_p.enc','test_p.txt','client')
    File "ht_gnupg.py",line 18,in decrypt_file
        raise ValueError("Signature Could not be verified!")
ValueError: Signature Could not be verified!

我使用来自python-gnupg-0.2.7.win32.exe的gnupg-0.2.7和ActiveStatus Python 2.6.

我也试过gpg.verify_file()但是我得到了同样的错误.文件是ASCII装甲,看起来像：

-----BEGIN PGP MESSAGE-----
Version: GnuPG v1.4.9 (MingW32)

hQIOA0EAndRRjNGtEAf/YxMQaFMnBwT3Per6ypoMYaO1AKQikRgJJMJ90a/EoZ44
...
=G6Ai
-----END PGP MESSAGE-----

如何验证命令行gpg的签名？

最佳答案

有关示例脚本的信息,请参阅this gist,其中显示了解密时如何验证签名.

代码(截至2011-04-05)如下：

from cStringIO import StringIO
import gnupg
import logging
import os
import shutil

def generate_key(gpg,first_name,last_name,domain,passphrase=None):
    "Generate a key"
    params = {
        'Key-Type': 'DSA','Key-Length': 1024,'Subkey-Type': 'ELG-E','Subkey-Length': 2048,'Name-Comment': 'A test user','Expire-Date': 0,}
    params['Name-Real'] = '%s %s' % (first_name,last_name)
    params['Name-Email'] = ("%s.%s@%s" % (first_name,domain)).lower()
    if passphrase is None:
        passphrase = ("%s%s" % (first_name[0],last_name)).lower()
    params['Passphrase'] = passphrase
    cmd = gpg.gen_key_input(**params)
    return gpg.gen_key(cmd)

def init_logging():
    logging.basicConfig(level=logging.DEBUG,filename="gpg.log",filemode="w",format="%(asctime)s %(levelname)-5s %(name)-10s %(threadName)-10s %(message)s")

def print_info(decrypted):
    print('User name: %s' % decrypted.username)
    print('Key id: %s' % decrypted.key_id)
    print('Signature id: %s' % decrypted.signature_id)
    #print('Signature timestamp: %s' % decrypted.sig_timestamp)
    print('Fingerprint: %s' % decrypted.fingerprint)

def main():
    init_logging()
    if os.path.exists('keys'):
        shutil.rmtree('keys')
    gpg = gnupg.GPG(gnupghome='keys')
    key = generate_key(gpg,"Andrew","Able","alpha.com",passphrase="andy")
    andrew = key.fingerprint
    key = generate_key(gpg,"Barbara","brown","beta.com")
    barbara = key.fingerprint
    #First - without signing
    data = 'Top secret'
    encrypted = gpg.encrypt_file(StringIO(data),barbara,#sign=andrew,passphrase='andy',output='encrypted.txt')
    assert encrypted.status == 'encryption ok'
    # Data is in encrypted.txt. Read it in and verify/decrypt it.
    data = open('encrypted.txt','r').read()
    decrypted = gpg.decrypt(data,passphrase='bbrown',output='decrypted.txt')
    print_info(decrypted)
    #Now with signing
    data = 'Top secret'
    encrypted = gpg.encrypt_file(StringIO(data),sign=andrew,output='decrypted.txt')
    print_info(decrypted)

if __name__ == '__main__':
    main()