Not able to decrypt SSL data with Private Keys

Question

Hi there,

I m trying to decrypt SSL encrypted data using wireshark, but i m not able to do so. I have provided the RSA keys and the key location in the wireshark, also i m using TLS_RSA_WITH_RC4_128_SHA, so typically Diffie Helmann concept is outta context here. The following is the snap from the debug,

ssl_association_remove removing TCP 443 - http handle 04453A50 Private key imported: KeyID 5d:bf:fb:fa:7f:5a:a7:57:7f:30:80:36:39:15:d5:1a:... ssl_init IPv4 addr '2.56.4.2' (2.56.4.2) port '443' filename 'C:\Documents and Settings\Administrator\Desktop\latest_server.key' password(only for p12 file) '' ssl_init private key file C:\Documents and Settings\Administrator\Desktop\latest_server.key successfully loaded. association_add TCP port 443 protocol http handle 04453A50 dissect_ssl enter frame #22 (first time) ssl_session_init: initializing ptr 0566222C size 588 conversation = 05661DF4, ssl_session = 0566222C record: offset = 0, reported_length_remaining = 94 dissect_ssl3_record: content_type 22 decrypt_ssl3_record: app_data len 89, ssl state 0x00 association_find: TCP port 1479 found 00000000 packet_from_server: is from server - FALSE decrypt_ssl3_record: using client decoder decrypt_ssl3_record: no decoder available dissect_ssl3_handshake iteration 1 type 1 offset 5 length 85 bytes, remaining 94 packet_from_server: is from server - FALSE ssl_find_private_key server 2.56.4.2:443 dissect_ssl3_hnd_hello_common found CLIENT RANDOM -> state 0x01 dissect_ssl enter frame #24 (first time) conversation = 05661DF4, ssl_session = 0566222C record: offset = 0, reported_length_remaining = 1145 dissect_ssl3_record found version 0x0301 -> state 0x11 dissect_ssl3_record: content_type 22 decrypt_ssl3_record: app_data len 74, ssl state 0x11 packet_from_server: is from server - TRUE decrypt_ssl3_record: using server decoder decrypt_ssl3_record: no decoder available dissect_ssl3_handshake iteration 1 type 2 offset 5 length 70 bytes, remaining 79 dissect_ssl3_hnd_hello_common found SERVER RANDOM -> state 0x13 dissect_ssl3_hnd_srv_hello found CIPHER 0x0005 -> state 0x17 dissect_ssl3_hnd_srv_hello trying to generate keys ssl_generate_keyring_material not enough data to generate key (0x17 required 0x37 or 0x57) dissect_ssl3_hnd_srv_hello can't generate keyring material record: offset = 79, reported_length_remaining = 1066 dissect_ssl3_record: content_type 22 decrypt_ssl3_record: app_data len 1052, ssl state 0x17 packet_from_server: is from server - TRUE decrypt_ssl3_record: using server decoder decrypt_ssl3_record: no decoder available dissect_ssl3_handshake iteration 1 type 11 offset 84 length 1048 bytes, remaining 1136 record: offset = 1136, reported_length_remaining = 9 dissect_ssl3_record: content_type 22 decrypt_ssl3_record: app_data len 4, ssl state 0x17 packet_from_server: is from server - TRUE decrypt_ssl3_record: using server decoder decrypt_ssl3_record: no decoder available dissect_ssl3_handshake iteration 1 type 14 offset 1141 length 0 bytes, remaining 1145 dissect_ssl enter frame #25 (first time) conversation = 05661DF4, ssl_session = 0566222C record: offset = 0, reported_length_remaining = 186 dissect_ssl3_record: content_type 22 decrypt_ssl3_record: app_data len 134, ssl state 0x17 packet_from_server: is from server - FALSE decrypt_ssl3_record: using client decoder decrypt_ssl3_record: no decoder available dissect_ssl3_handshake iteration 1 type 16 offset 5 length 130 bytes, remaining 139 pre master encrypted[128]: 71 de ea fa d9 77 eb f9 36 dc 59 30 4d 64 71 79 c6 31 a4 13 e8 cc cc 8e 45 0e 08 e4 c7 e7 b6 50 54 e9 80 f1 eb 3e 7d 4a 68 e2 1f f5 e6 ca 84 ec 33 39 9e 4a f8 fa ff 35 a8 a2 e9 4a 88 aa 46 77 16 46 52 06 89 56 57 31 7b d5 b2 41 d6 2b c6 95 21 cb 8a 71 cb e2 1f 05 c1 a9 bd 52 43 d0 d7 6b b5 75 00 1a ca 1a 4f 47 b1 38 91 5d 3f 22 8c f8 af ec 07 7c be 64 08 a5 ae 63 32 04 56 62 3f d7 ssl_decrypt_pre_master_secret:RSA_private_decrypt pcry_private_decrypt: stripping 0 bytes, decr_len 128 decrypted_unstrip_pre_master[128]: 81 e2 42 e6 47 c6 f7 a1 cf f5 65 c5 e6 09 b4 7a d9 ed 35 60 a4 d0 71 b3 29 ca 96 c4 cc fc ec b9 6c cb 19 50 91 a8 83 92 93 20 7d 3c 2d 34 82 f5 b8 fe 3d 2c 27 2f 6b 6d 13 3a f8 16 8f c9 d4 75 d8 85 64 7b b9 8e 4d 4d 11 e6 5c bb 69 0f 01 b8 ab 0e db 7b 1f 76 a9 0f f5 57 a5 65 ae 5a 59 2e 58 19 0b f4 bc 40 4b e6 4a db 33 27 9b a6 1c a3 57 3d 8e 3f 10 9e 1e ae f5 d2 39 26 25 7e b5 cf ssl_decrypt_pre_master_secret wrong pre_master_secret length (128, expected 48) dissect_ssl3_handshake can't decrypt pre master secret record: offset = 139, reported_length_remaining = 47 dissect_ssl3_record: content_type 20 dissect_ssl3_change_cipher_spec packet_from_server: is from server - FALSE ssl_change_cipher CLIENT record: offset = 145, reported_length_remaining = 41 dissect_ssl3_record: content_type 22 decrypt_ssl3_record: app_data len 36, ssl state 0x17 packet_from_server: is from server - FALSE decrypt_ssl3_record: using client decoder decrypt_ssl3_record: no decoder available dissect_ssl3_handshake iteration 1 type 250 offset 150 length 1576909 bytes, remaining 186 dissect_ssl enter frame #26 (first time) conversation = 05661DF4, ssl_session = 0566222C record: offset = 0, reported_length_remaining = 47 dissect_ssl3_record: content_type 20 dissect_ssl3_change_cipher_spec packet_from_server: is from server - TRUE ssl_change_cipher SERVER record: offset = 6, reported_length_remaining = 41 dissect_ssl3_record: content_type 22 decrypt_ssl3_record: app_data len 36, ssl state 0x17 packet_from_server: is from server - TRUE decrypt_ssl3_record: using server decoder decrypt_ssl3_record: no decoder available dissect_ssl3_handshake iteration 1 type 187 offset 11 length 2702752 bytes, remaining 47 dissect_ssl enter frame #27 (first time) conversation = 05661DF4, ssl_session = 0566222C record: offset = 0, reported_length_remaining = 322 dissect_ssl3_record: content_type 23 decrypt_ssl3_record: app_data len 317, ssl state 0x17 packet_from_server: is from server - FALSE decrypt_ssl3_record: using client decoder decrypt_ssl3_record: no decoder available association_find: TCP port 1479 found 00000000 association_find: TCP port 443 found 04B14C48 dissect_ssl enter frame #28 (first time) conversation = 05661DF4, ssl_session = 0566222C record: offset = 0, reported_length_remaining = 320 dissect_ssl3_record: content_type 23 decrypt_ssl3_record: app_data len 315, ssl state 0x17 packet_from_server: is from server - TRUE decrypt_ssl3_record: using server decoder decrypt_ssl3_record: no decoder available association_find: TCP port 443 found 04B14C48 dissect_ssl enter frame #29 (first time) conversation = 05661DF4, ssl_session = 0566222C record: offset = 0, reported_length_remaining = 1460 need_desegmentation: offset = 0, reported_length_remaining = 1460 dissect_ssl enter frame #31 (first time) conversation = 05661DF4, ssl_session = 0566222C record: offset = 0, reported_length_remaining = 2920 need_desegmentation: offset = 0, reported_length_remaining = 2920 dissect_ssl enter frame #32 (first time) conversation = 05661DF4, ssl_session = 0566222C record: offset = 0, reported_length_remaining = 4380 need_desegmentation: offset = 0, reported_length_remaining = 4380 dissect_ssl enter frame #33 (first time) conversation = 05661DF4, ssl_session = 0566222C record: offset = 0, reported_length_remaining = 5840 need_desegmentation: offset = 0, reported_length_remaining = 5840 dissect_ssl enter frame #35 (first time) conversation = 05661DF4, ssl_session = 0566222C record: offset = 0, reported_length_remaining = 7300 need_desegmentation: offset = 0, reported_length_remaining = 7300

dissect_ssl enter frame #36 (first time) conversation = 05661DF4, ssl_session = 0566222C record: offset = 0, reported_length_remaining = 8214 dissect_ssl3_record: content_type 23 decrypt_ssl3_record: app_data len 8182, ssl state 0x17 packet_from_server: is from server - TRUE decrypt_ssl3_record: using server decoder decrypt_ssl3_record: no decoder available association_find: TCP port 443 found 04B14C48 record: offset = 8187, reported_length_remaining = 27 dissect_ssl3_record: content_type 21 decrypt_ssl3_record: app_data len 22, ssl state 0x17 packet_from_server: is from server - TRUE decrypt_ssl3_record: using server decoder decrypt_ssl3_record: no decoder available

I am using my servers (Apache) keys to decrypt the data.

Please let me know what needs to be done in this context.

Thanks,

Ananth !!

Answer 1

0

The debug data:

ssl_decrypt_pre_master_secret wrong pre_master_secret length (128, expected 48)
dissect_ssl3_handshake can't decrypt pre master secret

Usually indicate that the provided private key does not correspond to the certificate in that particular SSL session. Are you sure you provided the right key?

answered 10 Jul '13, 13:42

SYN-bit ♦♦
17.1k●9●57●245
accept rate: 20%

Yes. The key which was used in Apache servers SSL session ( in httpd.conf) was copied and placed in this wire shark

Thanks, Ananth !!

(10 Jul '13, 21:04) Ananth

Since your filename is "latest_server.key", could it be that between making the packet capture and copying the key, the key could have been changed on the server?

Here is how you can check whether the certificate and key really match. First extract the certificate from the packet capture. Go to the "Certificate" SSL handshake message (of the session you wish to decrypt). Expand the subtrees until you see a line like this:

Certificate ([email protected],id-at-commonName=public.sharkfest.local,id-at-organizationName=Sharkfest Lab,id-at-stateOrProvinceName=Noord-Holland,id-at-countryName=NL)

If there are more lines like that, then the CA chain is sent by the server too. Click on the first certificate (this will be the certificate with the common name of the server in it).

Now rightclick on the certificate and choose "Export Selected Packet Bytes..." and save the certificate to a file.

Now check whether the output of the following two cammands is the same:

openssl x509 -noout -modulus -inform DER -in certfile.cert
openssl rsa -noout -modulus -in privatekey.key

Or in a oneliner:

(openssl x509 -noout -modulus -inform DER -in certfile.cert ; openssl rsa -noout -modulus -in privatekey.key) | uniq | wc -l

If the key matches the certificate, the output will be "1", if it doesn't the output will be "2"

(11 Jul '13, 00:02) SYN-bit ♦♦

Now check whether the output of the following two cammands is the same:
openssl x509 -noout -modulus -inform DER -in certfile.cert
openssl rsa -noout -modulus -in privatekey.key

wouldn't that be a great extension for Wireshark to identify wrong keys during SSL decryption?

(11 Jul '13, 00:59) Kurt Knochner ♦

Yes it would @Kurt, it's been on my mind to add it... but time is not on my side unfortunately...

(11 Jul '13, 01:04) SYN-bit ♦♦

Is there already an enhancement request for this?

(11 Jul '13, 01:30) Kurt Knochner ♦

1

In Wireshark 2.0 (https://code.wireshark.org/review/10766), SSL keys will be matched by their public key instead of by a user-supplied address. Thus, the wrong key problem is solved.

(15 Oct '15, 10:37) Lekensteyn

Thus, the wrong key problem is solved.

perfect. +1 for that!

(22 Oct '15, 15:27) Kurt Knochner ♦

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