The creator provided us with three certificates .crt
- andromeda.crt
- corius.crt
- mechi.crt
and a file called
- challenge
Let's open a certificate to see what's inside it:
$ openssl x509 -in andromeda.crt -text -noout Certificate:
Data:
Version: 1 (0x0)
Serial Number:
f2:45:8e:91:cd:3d:df:65
Signature Algorithm: sha256WithRSAEncryption
Issuer: C = US, ST = Nevada, L = Unknown, O = Cyborg, emailAddress = [email protected]
Validity
Not Before: Aug 17 18:48:05 2020 GMT
Not After : Aug 17 18:48:05 2021 GMT
Subject: C = US, ST = Nevada, L = Unknown, O = Cyborg, emailAddress = [email protected]
Subject Public Key Info:
Public Key Algorithm: rsaEncryption
RSA Public-Key: (2048 bit)
Modulus:
00:ae:7a:71:65:28:0f:3b:af:b7:bd:0c:cf:96:8f:
4a:ec:3c:bb:e3:26:6a:16:78:28:25:b5:15:e5:f6:
41:ff:ba:fc:a3:96:96:91:7e:c8:69:bd:5e:02:39:
01:95:5c:dc:22:b7:f8:f7:01:70:13:dd:41:7d:24:
18:95:1f:37:96:47:6f:bd:96:78:af:69:6f:25:ec:
3d:eb:6f:6b:45:bd:76:99:f6:06:40:ff:9b:9d:6d:
47:4a:64:90:21:91:7c:53:d1:12:b8:d0:c7:03:95:
51:1f:c7:30:72:34:60:50:4e:85:6e:cf:1c:9b:a3:
71:4f:ff:f8:fe:96:5c:75:4a:d7:2d:a0:b0:71:04:
33:59:0c:df:09:7d:2c:19:86:d1:fa:e4:21:2d:c1:
31:27:f1:90:48:9d:2b:15:26:dc:60:c9:78:88:ee:
01:c9:19:05:a4:49:b7:ff:22:df:6b:b8:0c:c6:35:
71:22:a3:90:3b:d8:27:09:84:00:ff:75:d6:20:b2:
9e:ea:f3:8b:23:68:d8:2a:7e:e9:62:e7:a9:cc:f0:
3d:35:2b:2a:e3:c7:9b:3d:56:49:ed:4d:1f:c0:6f:
3a:a1:32:fa:45:8f:bd:4c:0d:14:06:54:97:51:9b:
f9:bd:f3:05:d1:7b:b6:53:da:b5:75:fa:ce:48:83:
01:15
Exponent: 3 (0x3)
Signature Algorithm: sha256WithRSAEncryption
91:40:73:6d:2d:14:da:a1:1c:88:a4:2d:e5:d7:ef:54:8b:4b:
4e:2f:63:62:1d:21:7d:29:05:16:bc:56:bd:75:44:2b:96:f0:
84:eb:fa:7b:16:e5:4a:7f:44:78:b1:c6:55:8c:a2:c5:66:12:
96:d6:50:8c:ef:ea:b3:98:1d:c6:21:ce:fd:f4:7b:b7:2f:6d:
41:04:bc:01:b8:6e:00:34:61:a9:84:67:83:96:72:79:ea:86:
30:6b:a2:61:b7:86:f8:cf:52:fa:78:9b:86:3b:ab:5c:0e:27:
d8:f3:4c:a3:27:3b:a1:fd:9b:36:f7:17:49:53:20:d1:89:c9:
19:5a:3a:3b:be:7c:74:c0:b1:52:27:33:3e:f0:f4:ad:fe:82:
4f:f1:f9:12:21:3c:c1:01:82:ce:f0:a0:c7:4e:0c:ae:15:f1:
45:4b:8b:ac:38:24:48:1a:c1:8f:de:ca:1f:21:ed:ad:0f:7a:
4f:e2:a1:31:28:9f:38:a9:82:b8:8b:de:90:39:6c:32:5e:e9:
3e:4a:18:e2:98:8e:d6:bc:9c:1b:1c:52:91:c7:05:26:21:41:
95:8f:2c:2e:9e:43:6e:3f:c9:57:2d:a7:8a:32:74:2a:e1:79:
76:ee:bf:4a:47:54:79:72:80:09:cd:a1:4f:d8:d2:8a:1a:46:
8b:d1:1a:24
Interesting... It seems that a message was encrypted with RSA using a 2048 bit key. It's a big key so we can't factorize the modulus,but the exponent is the lowest value, e=3.
If we check the other two certificates we can see that their message was encrypted also with a 2048 bit RSA and an exponent of 3. Let's keep that in mind.
Ok, let's check the challenge file.
$ cat challengeTo: "Andromeda" <[email protected]>, "Mechi" <[email protected]>, "Corius" <[email protected]>
From: "Dr Greez" <[email protected]>
Subject: Request for supplies
MIME-Version: 1.0
Content-Type: application/pkcs7-mime; smime-type=enveloped-data; name=smime.p7m
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename=smime.p7m
MIIFkQYJKoZIhvcNAQcDoIIFgjCCBX4CAQAxggSXMIIBggIBADBsMF8xCzAJBgNV
BAYTAlVTMQ8wDQYDVQQIDAZOZXZhZGExEDAOBgNVBAcMB1Vua25vd24xDzANBgNV
BAoMBkN5Ym9yZzEcMBoGCSqGSIb3DQEJARYNbWVjaGlAY3liLm9yZwIJAKDnC94/ ...
Hmmm, the file is s/mime file of a pkcs#7 enveloped data object. To read that we need to extract the pkcs7 object and parse it.
$ openssl smime -in challenge -pk7out -out challenge.pm7
$ openssl asn1parse -in challenge.pm7 0:d=0 hl=4 l=1425 cons: SEQUENCE
4:d=1 hl=2 l= 9 prim: OBJECT :pkcs7-envelopedData
15:d=1 hl=4 l=1410 cons: cont [ 0 ]
19:d=2 hl=4 l=1406 cons: SEQUENCE
23:d=3 hl=2 l= 1 prim: INTEGER :00
26:d=3 hl=4 l=1175 cons: SET
30:d=4 hl=4 l= 386 cons: SEQUENCE
34:d=5 hl=2 l= 1 prim: INTEGER :00
37:d=5 hl=2 l= 108 cons: SEQUENCE
39:d=6 hl=2 l= 95 cons: SEQUENCE
41:d=7 hl=2 l= 11 cons: SET
43:d=8 hl=2 l= 9 cons: SEQUENCE
45:d=9 hl=2 l= 3 prim: OBJECT :countryName
50:d=9 hl=2 l= 2 prim: PRINTABLESTRING :US
54:d=7 hl=2 l= 15 cons: SET
56:d=8 hl=2 l= 13 cons: SEQUENCE
58:d=9 hl=2 l= 3 prim: OBJECT :stateOrProvinceName
63:d=9 hl=2 l= 6 prim: UTF8STRING :Nevada
71:d=7 hl=2 l= 16 cons: SET
73:d=8 hl=2 l= 14 cons: SEQUENCE
75:d=9 hl=2 l= 3 prim: OBJECT :localityName
80:d=9 hl=2 l= 7 prim: UTF8STRING :Unknown
89:d=7 hl=2 l= 15 cons: SET
91:d=8 hl=2 l= 13 cons: SEQUENCE
93:d=9 hl=2 l= 3 prim: OBJECT :organizationName
98:d=9 hl=2 l= 6 prim: UTF8STRING :Cyborg
106:d=7 hl=2 l= 28 cons: SET
108:d=8 hl=2 l= 26 cons: SEQUENCE
110:d=9 hl=2 l= 9 prim: OBJECT :emailAddress
121:d=9 hl=2 l= 13 prim: IA5STRING :[email protected]
136:d=6 hl=2 l= 9 prim: INTEGER :A0E70BDE3FCA6562
147:d=5 hl=2 l= 11 cons: SEQUENCE
149:d=6 hl=2 l= 9 prim: OBJECT :rsaEncryption
160:d=5 hl=4 l= 256 prim: OCTET STRING [HEX DUMP]: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
420:d=4 hl=4 l= 387 cons: SEQUENCE
424:d=5 hl=2 l= 1 prim: INTEGER :00
427:d=5 hl=2 l= 109 cons: SEQUENCE
429:d=6 hl=2 l= 96 cons: SEQUENCE
431:d=7 hl=2 l= 11 cons: SET
433:d=8 hl=2 l= 9 cons: SEQUENCE
435:d=9 hl=2 l= 3 prim: OBJECT :countryName
440:d=9 hl=2 l= 2 prim: PRINTABLESTRING :US
444:d=7 hl=2 l= 15 cons: SET
446:d=8 hl=2 l= 13 cons: SEQUENCE
448:d=9 hl=2 l= 3 prim: OBJECT :stateOrProvinceName
453:d=9 hl=2 l= 6 prim: UTF8STRING :Nevada
461:d=7 hl=2 l= 16 cons: SET
463:d=8 hl=2 l= 14 cons: SEQUENCE
465:d=9 hl=2 l= 3 prim: OBJECT :localityName
470:d=9 hl=2 l= 7 prim: UTF8STRING :Unknown
479:d=7 hl=2 l= 15 cons: SET
481:d=8 hl=2 l= 13 cons: SEQUENCE
483:d=9 hl=2 l= 3 prim: OBJECT :organizationName
488:d=9 hl=2 l= 6 prim: UTF8STRING :Cyborg
496:d=7 hl=2 l= 29 cons: SET
498:d=8 hl=2 l= 27 cons: SEQUENCE
500:d=9 hl=2 l= 9 prim: OBJECT :emailAddress
511:d=9 hl=2 l= 14 prim: IA5STRING :[email protected]
527:d=6 hl=2 l= 9 prim: INTEGER :A9ED2806CD914835
538:d=5 hl=2 l= 11 cons: SEQUENCE
540:d=6 hl=2 l= 9 prim: OBJECT :rsaEncryption
551:d=5 hl=4 l= 256 prim: OCTET STRING [HEX DUMP]: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
811:d=4 hl=4 l= 390 cons: SEQUENCE
815:d=5 hl=2 l= 1 prim: INTEGER :00
818:d=5 hl=2 l= 112 cons: SEQUENCE
820:d=6 hl=2 l= 99 cons: SEQUENCE
822:d=7 hl=2 l= 11 cons: SET
824:d=8 hl=2 l= 9 cons: SEQUENCE
826:d=9 hl=2 l= 3 prim: OBJECT :countryName
831:d=9 hl=2 l= 2 prim: PRINTABLESTRING :US
835:d=7 hl=2 l= 15 cons: SET
837:d=8 hl=2 l= 13 cons: SEQUENCE
839:d=9 hl=2 l= 3 prim: OBJECT :stateOrProvinceName
844:d=9 hl=2 l= 6 prim: UTF8STRING :Nevada
852:d=7 hl=2 l= 16 cons: SET
854:d=8 hl=2 l= 14 cons: SEQUENCE
856:d=9 hl=2 l= 3 prim: OBJECT :localityName
861:d=9 hl=2 l= 7 prim: UTF8STRING :Unknown
870:d=7 hl=2 l= 15 cons: SET
872:d=8 hl=2 l= 13 cons: SEQUENCE
874:d=9 hl=2 l= 3 prim: OBJECT :organizationName
879:d=9 hl=2 l= 6 prim: UTF8STRING :Cyborg
887:d=7 hl=2 l= 32 cons: SET
889:d=8 hl=2 l= 30 cons: SEQUENCE
891:d=9 hl=2 l= 9 prim: OBJECT :emailAddress
902:d=9 hl=2 l= 17 prim: IA5STRING :[email protected]
921:d=6 hl=2 l= 9 prim: INTEGER :F2458E91CD3DDF65
932:d=5 hl=2 l= 11 cons: SEQUENCE
934:d=6 hl=2 l= 9 prim: OBJECT :rsaEncryption
945:d=5 hl=4 l= 256 prim: OCTET STRING [HEX DUMP]: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
1205:d=3 hl=3 l= 221 cons: SEQUENCE
1208:d=4 hl=2 l= 9 prim: OBJECT :pkcs7-data
1219:d=4 hl=2 l= 29 cons: SEQUENCE
1221:d=5 hl=2 l= 9 prim: OBJECT :aes-256-cbc
1232:d=5 hl=2 l= 16 prim: OCTET STRING [HEX DUMP]:5F78552BA3D2F1568309953F73694305
1250:d=4 hl=3 l= 176 prim: cont [ 0 ]
From the output we can see that the same message was sent to the three recipients of 256 length. From the last hex dump we can see that the data sent after this dump is encrypted by AES-256 in CBC mode with an IV of
5F78552BA3D2F1568309953F73694305
The public key in the RSA system is a tuple of integers (N,e), where N is the product of two primes p and q.
The secret key is given by an integer d satisfying
Encryption of a message M produces the ciphertext
,which can be decrypted using d by computing
The secret key may be given by
if the Chinese Remainder Theorem is used to improve the speed of decryption.
The Chinese Remainder Theorem tells us that when given pairwise coprime positive integers
and arbitary integers
the system of simultaneous congruences
. . .
has a solution,and the solution is unique modulo
So to find a solution to a system of congruences using the Chinese Remainder Theorem we should:
-
Compute
-
For each
compute
-
For each
using Euclid's extended algorithm.
-
The integer
is a solution to the system of congruences, and
is the unique solution modulo N.
Now that we know and thus
, we will have to solve this system of equations to find M which is the plaintext message:
Using the Chinese Remainder Theorem we showed before we can construct and find the solution to this system. Let's start coding...
Firstly we need to extract from the files the ciphertext of each message and the modulo it was encrypted with.
To extract the modulo of each certificate we use this simple openssl command:
openssl x509 -in andromeda.crt -modulus
To extract the ciphertext sent to each recipient we use the hex dumps from the pkcs7 object before.
Let's use the ciphetexts and moduli to code the attack and find the plaintext
import gmpy2
e = 3
n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
n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
n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
c1 = "B58E82BEA0E7A56624A98D12ABE2B6DC36C677A82D29AE3BA41A3EA60D71E3012EBB3B77C934E7DDEF1B773EAD7F6BB3151DF788CA456D896BCCA38B650F94A5AC1753A36C388A10DF5E8E3827D695B9F84AE512A5CEE43C78AF16353F4E0D90B9E2FC4ABD200D590F6CE531D1D7CFB2F774CAEBE442CA2E28A42C54C3E9383B6CDBC5C17AF2534AEC3921331AEC6EE929E63BB08CB1056039A8F5F6E30A751B0EC3DC6667A953508BAFADABEA06C41DD50B5056FAAF49AA5CDDB83A7E3ADA096C68D20AD76F1C29998745697371E3F715CD33BFEE04EFAED936148F9C70B600D2F80DF459EB67858509A6CC42EF22469D30C9C629EFA827CC3CDF0BEAEACF6A"
c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
c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
c1 = int(c1, 16)
c2 = int(c2, 16)
c3 = int(c3, 16)
n1 = int(n1, 16)
n2 = int(n2, 16)
n3 = int(n3, 16)
N = n1*n2*n3
N1 = N//n1
N2 = N//n2
N3 = N//n3
u1 = gmpy2.invert(N1, n1)
u2 = gmpy2.invert(N2, n2)
u3 = gmpy2.invert(N3, n3)
M = (c1*u1*N1 + c2*u2*N2 + c3*u3*N3) % N
m = gmpy2.iroot(M,e)[0]
print(hex(int(m)))output:
0x1ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff008bc717f3a42012d5311aa8f8ffb8f736c7e9e80fccaeaf2f618be5e277534f99
Success! This should be the AES-256 key which was used, it's only formatted in encryption-block formatting: https://tools.ietf.org/html/rfc2313#section-8.1
Let's see how it is formatted.
A block type BT, a padding string PS, and the data D shall be
formatted into an octet string EB, the encryption block.
EB = 00 || BT || PS || 00 || D . (1)
The block type BT shall be a single octet indicating the structure of
the encryption block. For this version of the document it shall have
value 00, 01, or 02. For a private- key operation, the block type
shall be 00 or 01. For a public-key operation, it shall be 02.
The padding string PS shall consist of k-3-||D|| octets. For block
type 00, the octets shall have value 00; for block type 01, they
shall have value FF; and for block type 02, they shall be
pseudorandomly generated and nonzero. This makes the length of the
encryption block EB equal to k.
Hmm.. So the key is this hex string:
8bc717f3a42012d5311aa8f8ffb8f736c7e9e80fccaeaf2f618be5e277534f99
Perfect! We have the key and the IV, let's go decrypt the message.
As we mentioned we need to decrypt the data after the last hexdump
1205:d=3 hl=3 l= 221 cons: SEQUENCE
1208:d=4 hl=2 l= 9 prim: OBJECT :pkcs7-data
1219:d=4 hl=2 l= 29 cons: SEQUENCE
1221:d=5 hl=2 l= 9 prim: OBJECT :aes-256-cbc
1232:d=5 hl=2 l= 16 prim: OCTET STRING [HEX DUMP]:5F78552BA3D2F1568309953F73694305
1250:d=4 hl=3 l= 176 prim: cont [ 0 ]
So 1250+hl=1250+3=1253, so we need to get the hex bytes after the 1253 byte.
Alright, to find the flag we must execute these commands:
$ openssl smime -in challenge -pk7out > base64file
Remove the PKCS7 headers so we can decode the base64 string.
base64 -d base64file | xxd -s 1253 -p | xxd -r -p > encrypted
Now that we have the encrypted message in ASCII form let's decrypt it using the AES-256-CBC IV and key we found earlier.
openssl aes-256-cbc -d -iv 5F78552BA3D2F1568309953F73694305 -K 8bc717f3a42012d5311aa8f8ffb8f736c7e9e80fccaeaf2f618be5e277534f99 -in encrypted
output:
Hello everyone,
We are out of microchips. Me and my team need more supplies! Hurry up, everyone has to be microchipped! Deliver the package here:
HTB{37.220464, -115.835938}
Success! We found the flag!