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I am able to generate a self-signed CA certificate and generate intermediate CA cert.

Now I tried to generate a end-user certificate that should not be able to sign other certificates. So I opened openssl.cnf and change the line in v3_req to basicConstraints=CA:FALSE and generate a .csr using -extensions v3_req and sign it using intermediate CA.

Next I tried to sign another .csr with it and strangely it did the signing. When I tried, the verification was OK.

I completely mixed and I don`t knwo what to do.

So Any idea what is wrong? These are the commands I used.

openssl req -x509 -extensions v3_ca -newkey rsa:2048 -keyout root_ca.key -out root_ca.crt -days 365 -subj /C=US/ST=abc/L=abc/O=test/OU=mine/CN=CA/emailAddress=ca@ca.ca -passout pass:123456

openssl req -new -extensions v3_ca -newkey rsa:2048 -keyout s1.key -out s1.csr -days 365 -subj /C=US/ST=abc/L=abc/O=test/OU=mine/CN=s1/emailAddress=s1@ca.ca -passout pass:123456

openssl ca -policy policy_anything -outdir ./ -out s1.crt -cert root_ca.crt -infiles s1.csr -CAkey root_ca.key

openssl req -new -extensions v3_req -newkey rsa:2048 -keyout client.key -out client.csr -days 365 -subj /C=US/ST=abc/L=abc/O=test/OU=mine/CN=s1/emailAddress=s1@ca.ca -passout pass:123456

openssl ca -policy policy_match -outdir ./ -out client.crt -cert s1.crt -infiles client.csr -CAkey s1.key

openssl req -new -extensions v3_req -newkey rsa:2048 -keyout client2.key -out client2.csr -days 365 -subj /C=US/ST=abc/L=abc/O=test/OU=mine/CN=s1/emailAddress=s1@ca.ca -passout pass:123456

openssl ca -policy policy_match -outdir ./ -out client2.crt -cert client.crt -infiles client2.csr -CAkey client.key

cat root_ca.crt s1.crt client.crt > ca.pem

openssl verify -CAfile ca.pem client2.crt

This is the config file:

HOME = .


oid_section = new_oids

[ new_oids ]

[ ca ]

default_ca = CA_default

[ CA_default ]

dir = /root/new

certs = $dir/certs

crl_dir = $dir/crl

database = $dir/index.txt

new_certs_dir = $dir/newcerts

certificate = $dir/root_ca.crt

serial = $dir/serial

crlnumber = /root/index.txt

crl = $dir/crl.pem

private_key = $dir/root_ca.key

RANDFILE = $dir/private/.rand

x509_extensions = usr_cert

name_opt = ca_default

cert_opt = ca_default

default_days = 365

default_crl_days = 30

default_md = sha1

preserve = no

policy = policy_match

[ policy_match ]

countryName = match

stateOrProvinceName = match

organizationName = match

organizationalUnitName = optional

commonName = supplied

emailAddress = optional

[ policy_anything ]

countryName = optional

stateOrProvinceName = optional

localityName = optional

organizationName = optional

organizationalUnitName = optional

commonName = supplied

emailAddress = optional

[ req ]

default_bits = 1024

default_keyfile = privkey.pem

distinguished_name = req_distinguished_name

attributes = req_attributes

x509_extensions = v3_ca

string_mask = nombstr

[ req_distinguished_name ]

countryName = Country Name (2 letter code)

countryName_default = AU

countryName_min = 2

countryName_max = 2

stateOrProvinceName = State or Province Name (full name)

stateOrProvinceName_default = Some-State

localityName = Locality Name (eg, city)

0.organizationName = Organization Name (eg, company)

0.organizationName_default = Internet Widgits Pty Ltd

organizationalUnitName = Organizational Unit Name (eg, section)

commonName = Common Name (eg, YOUR name)

commonName_max = 64

emailAddress = Email Address

emailAddress_max = 64

[ req_attributes ]

challengePassword = A challenge password

challengePassword_min = 4

challengePassword_max = 20

unstructuredName = An optional company name

[ usr_cert ]

basicConstraints = CA:FALSE

keyUsage = digitalSignature, nonRepudiation,keyEncipherment, dataEncipherment, keyAgreement

nsComment = "OpenSSL Generated Certificate"

subjectKeyIdentifier = hash

authorityKeyIdentifier = keyid,issuer

[ v3_req ]

basicConstraints = critical,CA:false

keyUsage = nonRepudiation

subjectKeyIdentifier = hash

authorityKeyIdentifier = keyid:always,issuer:always

[ v3_ca ]

subjectKeyIdentifier = hash

extendedKeyUsage = critical,serverAuth, clientAuth

basicConstraints = CA:true

keyUsage = cRLSign, keyCertSign, digitalSignature, nonRepudiation,keyEncipherment, dataEncipherment, keyAgreement, keyCertSign, cRLSign

[ crl_ext ]

authorityKeyIdentifier = keyid:always,issuer:always

[ proxy_cert_ext ]

basicConstraints = CA:FALSE

nsComment = "OpenSSL Generated Certificate"

subjectKeyIdentifier = hash

authorityKeyIdentifier = keyid,issuer:always

proxyCertInfo = critical,language:id-ppl-anyLanguage,pathlen:3,policy:foo

share|improve this question
As I wrote, I generated a cert which should not be able to sign other certs(by doing ca:false in config file), but it is able to do that. Why? –  Hamed JML Aug 21 '12 at 5:27
Weird. Your openssl ca ... -CAkey ... should give an error, as -CAkey is only valid on openssl x509 (on ca, -keyfile should be used). Can you check alias openssl and which openssl, as well as $SSLEAY_CONF and OPENSSL_CONF? This could be the cause, as your [req] section contains v3_ca, and therefore all your requests would output a self-signed certificate instead of a certificate request. –  tricasse Aug 23 '12 at 11:37
I think I wrote it wrong. the option is -keyfile and when I use a wrong ca public key file, the verification fails. –  Hamed JML Aug 24 '12 at 9:21
Where you able to try the steps I suggested in my comment below? They should generate a valid root ca + intermediate ca + final user cert on any OpenSSL setup; they'll just use default values from the default/sample OpenSSL configuration. You might then add your customisations like rsa:2048, and adapt the config file to your liking. –  tricasse Aug 24 '12 at 22:48
And if it's not working with my proposal, then we can investigate if something is wrong with your setup... see the checks I suggested. –  tricasse Aug 24 '12 at 22:50

1 Answer 1

up vote 3 down vote accepted

Did you try with basicConstraints=critical,CA:false?

PS: The 'ca' utility doesn't currently check the validity of the CA certificate it is signing with. So it will happily sign with an invalid CA but the verification routines will reject it.

The following, while a bit verbose, should work; can you try it on your setup and report any issues?

#SSLEAY_CONFIG="-config yourfile.cnf"
ROOTCA_SUBJ="-subj /C=US/ST=abc/L=abc/O=test/OU=mine/CN=RootCA/emailAddress=rootca@example.org"
CA_SUBJ="-subj /C=US/ST=abc/L=abc/O=test/OU=mine/CN=CA/emailAddress=ca@example.org"
CERT_SUBJ="-subj /C=US/ST=abc/L=abc/O=test/OU=mine/CN=cert/emailAddress=cert@example.org"
mkdir "$DIR" "$DIR"/certs "$DIR"/crl "$DIR"/newcerts "$DIR"/private
touch "$DIR"/index.txt
echo 01 > "$DIR"/crlnumber

# create Root CA
mkdir rootCA rootCA/certs rootCA/crl rootCA/newcerts rootCA/private
openssl req $SSLEAY_CONFIG -new -keyout rootCA/private/rootCAkey.pem -out rootCA/rootCAreq.pem $ROOTCA_SUBJ -passout "$ROOTCA_PASS"
openssl ca $SSLEAY_CONFIG -create_serial -out rootCA/rootCAcert.pem -days 1095 -batch -keyfile rootCA/private/rootCAkey.pem -passin "$ROOTCA_PASS" -selfsign -extensions v3_ca -infiles rootCA/rootCAreq.pem

# create Intermediate CA
mkdir CA CA/certs CA/crl CA/newcerts CA/private
openssl req $SSLEAY_CONFIG -new -keyout CA/private/CAkey.pem -out CA/CAreq.pem -days 365 $CA_SUBJ -passout "$CA_PASS"
openssl ca $SSLEAY_CONFIG -cert rootCA/rootCAcert.pem -keyfile rootCA/private/rootCAkey.pem -passin "$ROOTCA_PASS" -policy policy_anything -out CA/CAcert.pem -extensions v3_ca -infiles CA/CAreq.pem

# create Final Cert
mkdir cert cert/private
openssl req $SSLEAY_CONFIG -new -keyout cert/private/certkey.pem -out cert/certreq.pem -days 365 $CERT_SUBJ -passout "$CERT_PASS"
openssl ca $SSLEAY_CONFIG -cert CA/CAcert.pem -keyfile CA/private/CAkey.pem -passin "$CA_PASS" -policy policy_anything -out cert/cert.pem -infiles cert/certreq.pem
cat rootCA/rootCAcert.pem CA/CAcert.pem > myCA.pem
openssl verify -CAfile myCA.pem cert/cert.pem

When you run openssl verify, -CAfile implies you trust this certificate. So -CAfile should only contain the root-CA, and optionally the intermediate-CA; else it will always return OK. Other certificates should be added through the -untrusted option.

Therefore, if you give it a cert2.pem certificate, signed by the final cert.pem certificate, you'll get:

$ cat CA/CAcert.pem cert/cert.pem > notrust.pem
$ openssl verify -CAfile myCA.pem -untrusted notrust.pem cert2/cert2.pem
    cert2/cert2.pem: C = US, ST = abc, L = abc, O = test, OU = mine, CN = cert, emailAddress = cert@example.org
    error 24 at 1 depth lookup:invalid CA certificate
share|improve this answer
Yes, I tried it and my question is why this does not work!? –  Hamed JML Aug 22 '12 at 4:24
Can you provide us with a copy of your .cnf file? –  tricasse Aug 22 '12 at 18:06
As well as the steps you did to get there (or a link to a howto you might have followed) –  tricasse Aug 22 '12 at 18:16
Added. But it get very very long. Perhaps most of it was really not needed, but maybe it is. –  Hamed JML Aug 23 '12 at 4:24
I used the final cert to sign another certificate, and when I tried to verify it using openssl, it showed verification OK. –  Hamed JML Aug 25 '12 at 5:22

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