如何在pycrypto中验证由openssl创建的签名？

Question

我在openssl中创建了私钥和公钥，并签署了一些数据：

openssl genrsa -out private.pem 1024
openssl rsa -in private.pem -out public.pem -outform PEM -pubout
echo 'data to sign' > data.txt
openssl dgst -md5 < data.txt > hash
openssl rsautl -sign -inkey private.pem -keyform PEM -in hash  > signature

现在我在用python尝试验证这些数据：

pubKey = open('public.pem').read()
data = open('data.txt').read()
signature = open('signature').read()

from Crypto import PublicKey
key = PublicKey.RSA.importKey(pubKey)
pub = key.publickey()
hash = MD5.new(data).hexdigest()
# here, hash is same, as contents of 'hash' file
print pub.verify(hash, signature) # <-- here

问题是，pub.verify这个函数希望第二个参数是一个包含大数字的单元素列表。而我不知道怎么把文件signature中的二进制数据转换成这个整数。每个关于pycrypto的例子都是从pycrypto生成的签名，而key.sign()生成的签名格式是(1832273432...2340234L, )。但我不知道怎么使用外部的签名。

如果有必要，下面是一些额外的信息，我不太清楚怎么理解：

简要的技术信息：

• 数字签名的格式：PKCS#7 “Signed-Data”
• 公钥的处理方式：DSS
• 密钥长度：512 – 1024位
• 公钥指数：2 + 1
• 公钥格式：X.509 v3证书
• 消息摘要算法：MD5或RIPEMD-160 16

Answer 1

这里是解决方案。

from Crypto.Util import number
signature  = number.bytes_to_long(signature) #Convert the signature to long
print pub.verify(hash, (signature,) ) #Pass tuple to verify

Answer 2

我也遇到过同样的问题，这里有一些用openssl和python生成和验证的例子。希望能对某些人有所帮助...

Bash:

#!/bin/bash
# Generate keys
openssl genrsa -out priv.pem
# Export public key
openssl rsa -pubout -in priv.pem -out pub.pem
# Create test file
echo test123 > test.txt
# Create SHA1 signature
openssl dgst -sha1 -sign priv.pem -out test.txt.sig test.txt
# Verify SHA1 signature
openssl dgst -sha1 -verify pub.pem -signature test.txt.sig test.txt

Python:

#!/usr/bin/python
from Crypto.Signature import PKCS1_v1_5
from Crypto.PublicKey import RSA
from Crypto.Hash import SHA
from Crypto import Random
# Read public key from file
fd = open('pub.pem', 'r')
key_data = fd.read()
fd.close()
# Load public key
key = RSA.importKey(key_data)
# Read test file
fd = open('test.txt', 'r')
message = fd.read()
fd.close()
# Create SHA1 hash object
h = SHA.new(message)
# Create PKCS1 handler
cipher = PKCS1_v1_5.new(key)
# Read signature file
fd = open('test.txt.sig', 'r')
signature = fd.read()
fd.close()
# Verify signature
print cipher.verify(h, signature)
# Read private key from file
fd = open('priv.pem', 'r')
priv_key_data = fd.read()
fd.close()
# Load private key
priv_key = RSA.importKey(priv_key_data)
# Create PKCS1 handler
priv_cipher = PKCS1_v1_5.new(priv_key)
# Sign hash of test file content and compare
signature2 = priv_cipher.sign(h)
if signature == signature2:
    print "Match!! :)"

经过进一步阅读，我了解到（https://en.wikipedia.org/wiki/PKCS_1）PKCS1_PSS是现在应该用来创建签名的新方案。

这两个脚本需要做一些修改：

Bash:

#!/bin/bash
# Generate keys
openssl genrsa -out priv.pem
# Export public key
openssl rsa -pubout -in priv.pem -out pub.pem
# Create test file
echo test123 > test.txt
# Create SHA1 signature
openssl dgst -sha1 -sigopt rsa_padding_mode:pss -sigopt rsa_pss_saltlen:-1 -sign priv.pem -out test.txt.sig test.txt
# Verify SHA1 signature
openssl dgst -sha1 -sigopt rsa_padding_mode:pss -sigopt rsa_pss_saltlen:-1 -verify pub.pem -signature test.txt.sig test.txt

Python:

#!/usr/bin/python
from Crypto.Signature import PKCS1_PSS
from Crypto.PublicKey import RSA
from Crypto.Hash import SHA
from Crypto import Random
# Read public key from file
fd = open('pub.pem', 'r')
key_data = fd.read()
fd.close()
# Load public key
key = RSA.importKey(key_data)
# Read test file
fd = open('test.txt', 'r')
message = fd.read()
fd.close()
# Create SHA1 hash object
h = SHA.new(message)
# Create PKCS1 handler
cipher = PKCS1_PSS.new(key)
# Read signature file
fd = open('test.txt.sig', 'r')
signature = fd.read()
fd.close()
# Verify signature
print cipher.verify(h, signature)
# Read private key from file
fd = open('priv.pem', 'r')
priv_key_data = fd.read()
fd.close()
# Load private key
priv_key = RSA.importKey(priv_key_data)
# Create PKCS1 handler
priv_cipher = PKCS1_PSS.new(priv_key)
# Sign hash of test file content and compare
signature2 = priv_cipher.sign(h)
# PKCS1_PSS signatures always differ!
#if signature == signature2:
#    print "Match!! :)"

Answer 3

你需要的是 Crypto.Signature 这个模块。关于 Crypto.Signature.PKCS1_v1_5 的具体说明可以查看它的文档：

key = RSA.importKey(open('pubkey.der').read())
h = SHA.new(message)
verifier = PKCS1_v1_5.new(key)
if verifier.verify(h, signature):
   print "The signature is authentic."
else:
   print "The signature is not authentic."