CODEWITHSUNDEEP
pythonencodingcryptographyrsapublic-key
Marie Wing Li
Marie Wing Li

Reputation: 11

Import RSA key into Python

I am trying to import an RSA (Public) key into Python using RSA.importkey but I am getting RSA Key is not supported.

Here is the code I have written:

f = open('pub.key','rb')
data = f.read()
imported = RSA.importkey(data)
f.close()

Here is a screen shot of the key I am trying to import: RSA_Public_Key

Can someone please help me out?

enter image description here

[UPDATE]: I've done some more research and the key is in MS PUBLICKEYBLOB format which I guess is not compatible with PyCrypto? IS there anything else I can use to import this

Upvotes: 1

Views: 4182

Answers (2)

strawbot
strawbot

Reputation: 391

Try:

from Crypto.PublicKey import RSA

e = 65537
n = int(
    b'9d0d7835dcba39c7f19bd2608f92134c487c5c9c2f07ca7798106b435e0e5a7fd1ce3efe10c4a4455ab48a2f628f87fab3ca87e7266379e8e159f7e50d7a8c2c204603f0a0be19767c7823b4ad5bae69016fcc03a70660a797d60d574f54bcfa6da170e8423d77d4ae8b9225792b67def24a5525caa077f9e49e6508423f9cbf',
    16)
d = int(
    b'78fa2e36376010304f91bb5d7c5a869905611ea984a4d8b6852168aecd1dfb6268881a07f57cb41964849bc9627fb3bc4f905c5d97399b67e3673d47a67db891552a87d4febc726d2ca6dd7fa3f9b1ecd411a27bd8e42043b9f0c9602976d3f6d48bda747f0b4d4c13db135b7a44f5badde8d30e15316b68da4d896297438f29',
    16)
pri_key = RSA.construct((n, e, d))
pub_key = pri_key.public_key()

Upvotes: 0

r3mainer
r3mainer

Reputation: 24547

I don't think Python's Crypto.PublicKey module supports PUBLICKEYBLOB keys, but it's not that hard to extract something usable.

Since you provided your data in the form of an image (please don't), I'll show you how the process works with this key instead:

0000000: 0602 0000 00a4 0000 5253 4131 0008 0000  ........RSA1....
0000010: 0100 0100 7597 4c3b 8446 de2c 2af4 95a8  ....u.L;.F.,*...
0000020: 5dc0 cd6d dad7 d492 1e13 8234 6a70 8d8f  ]..m.......4jp..
0000030: 7cf7 0492 557f f1a2 27b2 9e41 ac90 8091  |...U...'..A....
0000040: 1893 c2b1 7bad 2bf3 ffaf db2b 51be 1da3  ....{.+....+Q...
0000050: 27e3 a757 085a bec1 1df6 04f8 1cbe 5bb1  '..W.Z........[.
0000060: 67fb e4c8 da75 0070 b117 7024 6c09 6374  g....u.p..p$l.ct
0000070: ac4b 0a1d 71ae 7fae 65b8 c586 79c5 7e9f  .K..q...e...y.~.
0000080: 9860 4c52 b929 62cb 2329 ed31 9174 7b7b  .`LR.)b.#).1.t{{
0000090: 0b26 1bf2 7d67 bfda 7a40 daf2 614d 94a5  .&..}[email protected]..
00000a0: 7dad 596b ad9e a33a 39c6 5b6e 9fd2 bb36  }.Yk...:9.[n...6
00000b0: b5f5 d265 f52c 30d8 c117 bdaf 2800 9620  ...e.,0.....(.. 
00000c0: 46a7 2d62 030c d7d0 75a0 0b07 ead4 1fca  F.-b....u.......
00000d0: e8d9 4edb 38f2 2675 cb12 a688 709b e1ea  ..N.8.&u....p...
00000e0: 32dc f871 7250 41e6 1781 6827 428e dfe5  2..qrPA...h'B...
00000f0: dea1 72d9 3bfb e59d 3011 6992 cd60 2be2  ..r.;...0.i..`+.
0000100: d546 3c28 cf9d 304a f7ad b9fb 0f91 fe2e  .F<(..0J........
0000110: be18 f1ce                                ....

The only two pieces of information you actually need are the public exponent e and the modulus n. You can find e as a 32-bit little-endian number eight bytes after the RSA1 token. In this case, 01000100 is 0x10001, or 65537. The remainder of the key is the modulus, which is also in little-endian order.

Here's a bit of Python code that will convert this information into a regular key:

from Crypto.PublicKey import RSA
e = 65537L
n = int('75974c3b8446de2c2af495a85dc0cd6ddad7d4921e1382346a708d8f7cf70492557ff1a2'\
        '27b29e41ac9080911893c2b17bad2bf3ffafdb2b51be1da327e3a757085abec11df604f8'\
        '1cbe5bb167fbe4c8da750070b11770246c096374ac4b0a1d71ae7fae65b8c58679c57e9f'\
        '98604c52b92962cb2329ed3191747b7b0b261bf27d67bfda7a40daf2614d94a57dad596b'\
        'ad9ea33a39c65b6e9fd2bb36b5f5d265f52c30d8c117bdaf2800962046a72d62030cd7d0'\
        '75a00b07ead41fcae8d94edb38f22675cb12a688709be1ea32dcf871725041e617816827'\
        '428edfe5dea172d93bfbe59d30116992cd602be2d5463c28cf9d304af7adb9fb0f91fe2e'\
        'be18f1ce'.decode('hex')[::-1].encode('hex'), 16)
key_params = (n, e)
pub_key = RSA.construct(key_params)
print pub_key.exportKey()

And here's the output:

-----BEGIN PUBLIC KEY-----
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAzvEYvi7+kQ/7ua33SjCd
zyg8RtXiK2DNkmkRMJ3l+zvZcqHe5d+OQidogRfmQVBycfjcMurhm3CIphLLdSby
ONtO2ejKH9TqBwugddDXDANiLadGIJYAKK+9F8HYMCz1ZdL1tTa70p9uW8Y5OqOe
rWtZrX2llE1h8tpAetq/Z33yGyYLe3t0kTHtKSPLYim5UkxgmJ9+xXmGxbhlrn+u
cR0KS6x0YwlsJHAXsXAAddrI5PtnsVu+HPgE9h3BvloIV6fjJ6MdvlEr26//8yut
e7HCkxiRgJCsQZ6yJ6Lxf1WSBPd8j41wajSCEx6S1Nfabc3AXaiV9Cos3kaEO0yX
dQIDAQAB
-----END PUBLIC KEY-----

Upvotes: 2

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