我有一些pyopenssl提供给我的数据,'0\r\x82\x0bexample.com'
。这应该是SubjectAltname X509扩展名的值。我尝试使用pyasn1(并基于其中一个pyasn1示例)对此扩展的ASN1规范的必要部分进行编码:
from pyasn1.type import univ, constraint, char, namedtype
from pyasn1.codec.der.decoder import decode
MAX = 64
class DirectoryString(univ.Choice):
componentType = namedtype.NamedTypes(
namedtype.NamedType(
'teletexString', char.TeletexString().subtype(
subtypeSpec=constraint.ValueSizeConstraint(1, MAX))),
namedtype.NamedType(
'printableString', char.PrintableString().subtype(
subtypeSpec=constraint.ValueSizeConstraint(1, MAX))),
namedtype.NamedType(
'universalString', char.UniversalString().subtype(
subtypeSpec=constraint.ValueSizeConstraint(1, MAX))),
namedtype.NamedType(
'utf8String', char.UTF8String().subtype(
subtypeSpec=constraint.ValueSizeConstraint(1, MAX))),
namedtype.NamedType(
'bmpString', char.BMPString().subtype(
subtypeSpec=constraint.ValueSizeConstraint(1, MAX))),
namedtype.NamedType(
'ia5String', char.IA5String().subtype(
subtypeSpec=constraint.ValueSizeConstraint(1, MAX))),
)
class AttributeValue(DirectoryString):
pass
class AttributeType(univ.ObjectIdentifier):
pass
class AttributeTypeAndValue(univ.Sequence):
componentType = namedtype.NamedTypes(
namedtype.NamedType('type', AttributeType()),
namedtype.NamedType('value', AttributeValue()),
)
class RelativeDistinguishedName(univ.SetOf):
componentType = AttributeTypeAndValue()
class RDNSequence(univ.SequenceOf):
componentType = RelativeDistinguishedName()
class Name(univ.Choice):
componentType = namedtype.NamedTypes(
namedtype.NamedType('', RDNSequence()),
)
class Extension(univ.Sequence):
componentType = namedtype.NamedTypes(
namedtype.NamedType('extnID', univ.ObjectIdentifier()),
namedtype.DefaultedNamedType('critical', univ.Boolean('False')),
namedtype.NamedType('extnValue', univ.OctetString()),
)
class Extensions(univ.SequenceOf):
componentType = Extension()
sizeSpec = univ.SequenceOf.sizeSpec + constraint.ValueSizeConstraint(1, MAX)
class GeneralName(univ.Choice):
componentType = namedtype.NamedTypes(
# namedtype.NamedType('otherName', AnotherName()),
namedtype.NamedType('rfc822Name', char.IA5String()),
namedtype.NamedType('dNSName', char.IA5String()),
# namedtype.NamedType('x400Address', ORAddress()),
namedtype.NamedType('directoryName', Name()),
# namedtype.NamedType('ediPartyName', EDIPartyName()),
namedtype.NamedType('uniformResourceIdentifier', char.IA5String()),
namedtype.NamedType('iPAddress', univ.OctetString()),
namedtype.NamedType('registeredID', univ.ObjectIdentifier()),
)
class GeneralNames(univ.SequenceOf):
componentType = GeneralName()
sizeSpec = univ.SequenceOf.sizeSpec + constraint.ValueSizeConstraint(1, MAX)
class SubjectAltName(GeneralNames):
pass
print decode('0\r\x82\x0bexample.com', asn1Spec=GeneralNames())
很明显,我在结尾处有点无聊,没有完全指定
GeneralName
类型。但是,测试字符串应该包含一个dNSName
,而不是跳过的值之一,因此我希望它不重要。当程序运行时,它会失败,并出现一个我无法解释的错误:
Traceback (most recent call last):
File "x509.py", line 94, in <module>
print decode('0\r\x82\x0bexample.com', asn1Spec=GeneralNames())
File "/usr/lib/pymodules/python2.6/pyasn1/v1/codec/ber/decoder.py", line 493, in __call__
length, stGetValueDecoder, decodeFun
File "/usr/lib/pymodules/python2.6/pyasn1/v1/codec/ber/decoder.py", line 202, in valueDecoder
substrate, asn1Spec
File "/usr/lib/pymodules/python2.6/pyasn1/v1/codec/ber/decoder.py", line 453, in __call__
__chosenSpec.getTypeMap().has_key(tagSet):
File "/usr/lib/pymodules/python2.6/pyasn1/v1/type/univ.py", line 608, in getTypeMap
return Set.getComponentTypeMap(self)
File "/usr/lib/pymodules/python2.6/pyasn1/v1/type/univ.py", line 535, in getComponentTypeMap
def getComponentTypeMap(self): return self._componentType.getTypeMap(1)
File "/usr/lib/pymodules/python2.6/pyasn1/v1/type/namedtype.py", line 126, in getTypeMap
'Duplicate type %s in map %s'%(k,self.__typeMap)
pyasn1.error.PyAsn1Error: Duplicate type TagSet(Tag(tagClass=0, tagFormat=0, tagId=22)) in map {TagSet(Tag(tagClass=0, tagFormat=0, tagId=22)): IA5String()}
任何关于我哪里出错以及如何用pyasn1成功解析这个扩展类型的提示都将非常感谢。
最佳答案
我在Pyasn1用户列表上发布了这个问题,而IlyaEtingoff(Pyasn1的作者)指出了我的错误。简言之,需要为NamedType
中的每个GeneralName.componentType
提供标记信息。这是通过subtype
方法完成的。例如,而不是:
namedtype.NamedType('rfc822Name', char.IA5String()),
定义应为:
namedtype.NamedType('rfc822Name', char.IA5String().subtype(
implicitTag=tag.Tag(tag.tagClassContext,
tag.tagFormatSimple, 1))),
其中,
1
来自asn.1一般名称的定义:GeneralName ::= CHOICE {
otherName [0] OtherName,
rfc822Name [1] IA5String,
dNSName [2] IA5String,
x400Address [3] ORAddress,
directoryName [4] Name,
ediPartyName [5] EDIPartyName,
uniformResourceIdentifier [6] IA5String,
iPAddress [7] OCTET STRING,
registeredID [8] OBJECT IDENTIFIER
}
为
componentType
的每个字段定义标记后,解析成功:(GeneralNames().setComponentByPosition(
0, GeneralName().setComponentByPosition(1, IA5String('example.com'))), '')
关于python - 如何使用pyasn1解析subjectAltName扩展数据?,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/5519958/