OpenSSL unable to get local issuer Cert Return Code 20

Question

Whenever I try to connect to Google (or any other site) using OpenSSL with the following command:

s_client -connect google.com:443 -showcerts

I get the following error:

.....

Verify return code: 20 (unable to get local issuer certificate)

I do have the right CA installed. I also tried Exporting the CA and using it with -CAfile, but I still get the same error.

I exported the CAs as PKCS#12 using certmgr.msc. Afterwards I converted them to a .pem file using:

OpenSSL> pkcs12 -in D:/Certs/RootCertsNewu.pfx -clcerts -nokeys -out D:/Certs/Roo
tCertsNew.pem

Using that I tried to connect againt:

OpenSSL> s_client -connect google.com:443 -CAfile D:\Certs\RootCertsNew.pem

But I got the same response as before. I also read, that this could have something to do with the Intermediate CA, so I created a .pem file with the CA and the intermediate CA. That didn't work either. Can someone help me?

Also somehow the verification progress seems to start with GeoTrust, not Equifax, as supposed.

OpenSSL> s_client -connect google.com:443 -showcerts -CAfile D:\Certs\google-ca.
pem
Loading 'screen' into random state - done
CONNECTED(0000017C)
depth=2 C = US, O = GeoTrust Inc., CN = GeoTrust Global CA
verify error:num=20:unable to get local issuer certificate
verify return:0
---

Traitorous

Answer 1

Go to Google Internet Authority and download their CA file.

Next convert it from DER to PEM:

$ openssl x509 -in GIAG2.crt -inform DER -out google-ca.pem -outform PEM

Finally, perform the following:

$ openssl s_client -connect google.com:443 -showcerts -CAfile google-ca.pem

Below is a similar run for me.

---

$ openssl s_client -connect google.com:443 -showcerts -CAfile google-ca.pem 
CONNECTED(00000003)
depth=3 C = US, O = Equifax, OU = Equifax Secure Certificate Authority
verify return:1
depth=2 C = US, O = GeoTrust Inc., CN = GeoTrust Global CA
verify return:1
depth=1 C = US, O = Google Inc, CN = Google Internet Authority G2
verify return:1
depth=0 C = US, ST = California, L = Mountain View, O = Google Inc, CN = *.google.com
verify return:1
---
Certificate chain
 0 s:/C=US/ST=California/L=Mountain View/O=Google Inc/CN=*.google.com
   i:/C=US/O=Google Inc/CN=Google Internet Authority G2
-----BEGIN CERTIFICATE-----
MIIHMzCCBhugAwIBAgIIRu5X4fKYZFAwDQYJKoZIhvcNAQEFBQAwSTELMAkGA1UE
BhMCVVMxEzARBgNVBAoTCkdvb2dsZSBJbmMxJTAjBgNVBAMTHEdvb2dsZSBJbnRl
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lv6su2jEZsHnFYYDfZ1wZEjzgd5fK5I=
-----END CERTIFICATE-----
 1 s:/C=US/O=Google Inc/CN=Google Internet Authority G2
   i:/C=US/O=GeoTrust Inc./CN=GeoTrust Global CA
-----BEGIN CERTIFICATE-----
MIIEBDCCAuygAwIBAgIDAjppMA0GCSqGSIb3DQEBBQUAMEIxCzAJBgNVBAYTAlVT
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-----END CERTIFICATE-----
 2 s:/C=US/O=GeoTrust Inc./CN=GeoTrust Global CA
   i:/C=US/O=Equifax/OU=Equifax Secure Certificate Authority
-----BEGIN CERTIFICATE-----
MIIDfTCCAuagAwIBAgIDErvmMA0GCSqGSIb3DQEBBQUAME4xCzAJBgNVBAYTAlVT
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b8ravHNjkOR/ez4iyz0H7V84dJzjA1BOoa+Y7mHyhD8S
-----END CERTIFICATE-----
---
Server certificate
subject=/C=US/ST=California/L=Mountain View/O=Google Inc/CN=*.google.com
issuer=/C=US/O=Google Inc/CN=Google Internet Authority G2
---
No client certificate CA names sent
---
SSL handshake has read 4429 bytes and written 446 bytes
---
New, TLSv1/SSLv3, Cipher is ECDHE-RSA-AES128-GCM-SHA256
Server public key is 2048 bit
Secure Renegotiation IS supported
Compression: NONE
Expansion: NONE
SSL-Session:
    Protocol  : TLSv1.2
    Cipher    : ECDHE-RSA-AES128-GCM-SHA256
    Session-ID: 4BAFE5B7837B250D672F58EA7F457F76FD93043387CCC4875934150304F85DF5
    Session-ID-ctx: 
    Master-Key: 57CCB72C3AB87C8ED25561CC523EAB5C8A4450E3E905A61FA822C9BFF8D468C478E52E18A06CCD97F06FA89893368337
    Key-Arg   : None
    PSK identity: None
    PSK identity hint: None
    SRP username: None
    TLS session ticket lifetime hint: 100800 (seconds)
    TLS session ticket:
    0000 - 8f c1 a1 ba 2f e0 02 bf-53 a9 79 87 d2 ae d4 be   ..../...S.y.....
    0010 - b7 5c f8 bc a1 69 b2 2f-d7 cb 3e b3 36 9c f5 b6   .\...i./..>.6...
    0020 - 31 4d 63 93 17 ed 43 3b-bc 9a 83 44 49 1f 78 85   1Mc...C;...DI.x.
    0030 - f1 33 11 da c2 ce bd 7c-80 67 c7 4e e1 c1 6b ff   .3.....|.g.N..k.
    0040 - 95 5f 24 ae bd 76 58 3e-12 de 14 33 33 38 f2 38   ._$..vX>...338.8
    0050 - 71 37 77 99 8d 42 49 09-21 ac d9 5e 30 82 86 f1   q7w..BI.!..^0...
    0060 - bc f8 a0 36 56 e5 72 f3-44 04 d3 81 d3 9f 65 ff   ...6V.r.D.....e.
    0070 - da a0 1f d8 6c a3 6e 03-9b 42 48 32 cc 4d e2 e1   ....l.n..BH2.M..
    0080 - 08 21 1e 47 23 76 ee 14-22 b1 21 5a 84 52 d7 e1   .!.G#v..".!Z.R..
    0090 - 6d 1c 6d fd                                       m.m.

    Start Time: 1389972014
    Timeout   : 300 (sec)
    Verify return code: 0 (ok)
---
DONE

Bazar

That did't work unfortunately. What I noticed, is that on my computer it seems to begin with the GeoTrust Certificate, not the Equifax, as on yours – Traitorous

@Traitorous Can you copy paste your entire output by appending the -debug flag? – Zales

Answer 2

This worked for me:

openssl s_client -connect *<host>:<port>* -CApath */path/to/certs/*

I got the same error code when I tried to specify what the certificate and the key was, so I tried the above command instead and it worked. Just add your pem file to a directory and point -CApath to it.

Hope this helps.

Gorgonzola