1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<HTML>
<HEAD>
<TITLE> [pycrypto] [PATCH] PEM: Decode AES-192-CBC and AES-256-CBC keys
</TITLE>
<LINK REL="Index" HREF="index.html" >
<LINK REL="made" HREF="mailto:pycrypto%40lists.dlitz.net?Subject=Re%3A%20%5Bpycrypto%5D%20%5BPATCH%5D%20PEM%3A%20Decode%20AES-192-CBC%20and%20AES-256-CBC%20keys&In-Reply-To=%3C20150810140959.505F989282%40agraf.me%3E">
<META NAME="robots" CONTENT="index,nofollow">
<style type="text/css">
pre {
white-space: pre-wrap; /* css-2.1, curent FF, Opera, Safari */
}
</style>
<META http-equiv="Content-Type" content="text/html; charset=us-ascii">
<LINK REL="Previous" HREF="000847.html">
<LINK REL="Next" HREF="000849.html">
</HEAD>
<BODY BGCOLOR="#ffffff">
<H1>[pycrypto] [PATCH] PEM: Decode AES-192-CBC and AES-256-CBC keys</H1>
<B>Alexander Graf</B>
<A HREF="mailto:pycrypto%40lists.dlitz.net?Subject=Re%3A%20%5Bpycrypto%5D%20%5BPATCH%5D%20PEM%3A%20Decode%20AES-192-CBC%20and%20AES-256-CBC%20keys&In-Reply-To=%3C20150810140959.505F989282%40agraf.me%3E"
TITLE="[pycrypto] [PATCH] PEM: Decode AES-192-CBC and AES-256-CBC keys">mail at agraf.me
</A><BR>
<I>Mon Aug 10 06:47:47 PDT 2015</I>
<P><UL>
<LI>Previous message: <A HREF="000847.html">[pycrypto] pycrypto Digest, Vol 75, Issue 2
</A></li>
<LI>Next message: <A HREF="000849.html">[pycrypto] Documentation error in "https://www.dlitz.net/software/pycrypto/api/current/"
</A></li>
<LI> <B>Messages sorted by:</B>
<a href="date.html#848">[ date ]</a>
<a href="thread.html#848">[ thread ]</a>
<a href="subject.html#848">[ subject ]</a>
<a href="author.html#848">[ author ]</a>
</LI>
</UL>
<HR>
<!--beginarticle-->
<PRE>Adds support for AES-192-CBC and AES-256-CBC ciphers to the PEM decode()
function. This also adds a deriveKey() function which stretches the
password to a key as required for decrypting, replacing PBKDF1 for 192
and 256 bits.
---
lib/Crypto/IO/PEM.py | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)
diff --git a/lib/Crypto/IO/PEM.py b/lib/Crypto/IO/PEM.py
index 89a5689..11dd782 100644
--- a/lib/Crypto/IO/PEM.py
+++ b/lib/Crypto/IO/PEM.py
@@ -110,6 +110,27 @@ def decode(pem_data, passphrase=None):
been provided or if the passphrase is incorrect.
"""
+ def deriveKey(password, salt, keySize):
+ """Stretch the password to a key as required for decrypting.
+
+ This algorithm was derived from the Go source, which itself derived it
+ from the OpenSSL source.
+
+ <A HREF="https://golang.org/src/crypto/x509/pem_decrypt.go">https://golang.org/src/crypto/x509/pem_decrypt.go</A>
+ """
+ out = b''
+ digest = b''
+ i = 0
+ while i < keySize:
+ md5 = MD5.new()
+ md5.update(digest)
+ md5.update(tobytes(password))
+ md5.update(salt)
+ digest = md5.digest()
+ out = out + digest
+ i = i + len(digest)
+ return out[:keySize]
+
# Verify Pre-Encapsulation Boundary
r = re.compile("\s*-----BEGIN (.*)-----\n")
m = r.match(pem_data)
@@ -147,6 +168,12 @@ def decode(pem_data, passphrase=None):
elif algo == "AES-128-CBC":
key = PBKDF1(passphrase, salt[:8], 16, 1, MD5)
objdec = AES.new(key, AES.MODE_CBC, salt)
+ elif algo == "AES-192-CBC":
+ key = deriveKey(passphrase, salt[:8], 24)
+ objdec = AES.new(key, AES.MODE_CBC, salt)
+ elif algo == "AES-256-CBC":
+ key = deriveKey(passphrase, salt[:8], 32)
+ objdec = AES.new(key, AES.MODE_CBC, salt)
else:
raise ValueError("Unsupport PEM encryption algorithm.")
lines = lines[2:]
--
2.1.4
</PRE>
<!--endarticle-->
<HR>
<P><UL>
<!--threads-->
<LI>Previous message: <A HREF="000847.html">[pycrypto] pycrypto Digest, Vol 75, Issue 2
</A></li>
<LI>Next message: <A HREF="000849.html">[pycrypto] Documentation error in "https://www.dlitz.net/software/pycrypto/api/current/"
</A></li>
<LI> <B>Messages sorted by:</B>
<a href="date.html#848">[ date ]</a>
<a href="thread.html#848">[ thread ]</a>
<a href="subject.html#848">[ subject ]</a>
<a href="author.html#848">[ author ]</a>
</LI>
</UL>
<hr>
<a href="http://lists.dlitz.net/cgi-bin/mailman/listinfo/pycrypto">More information about the pycrypto
mailing list</a><br>
</body></html>
|
