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p3t3r67x0/openssl_commands.md

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Some list of openssl commands for check and verify your keys
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openssl_commands.md

openssl

Install

Install the OpenSSL on Debian based systems

sudo apt-get install openssl

Commands

Create a private key

openssl genrsa -out server.key 4096

Generate a new private key and certificate signing request

openssl req -out server.csr -new -newkey rsa:4096 -nodes -keyout server.key

Generate a self-signed certificate

openssl req -x509 -sha256 -nodes -days 365 -newkey rsa:4096 -keyout server.key -out server.crt

Generate a certificate signing request (CSR) for an existing private key

openssl req -out server.csr -key server.key -new

Generate a certificate signing request based on an existing certificate

openssl x509 -x509toreq -in server.crt -out server.csr -signkey server.key

Remove a passphrase from a private key

openssl rsa -in server.pem -out newserver.pem

Parse a list of revoked serial numbers

openssl crl -inform DER -text -noout -in list.crl

Check a certificate signing request (CSR)

openssl req -text -noout -verify -in server.csr

Check a private key

openssl rsa -in server.key -check

Check a public key

openssl rsa -inform PEM -pubin -in pub.key -text -noout
openssl pkey -inform PEM -pubin -in pub.key -text -noout

Check a certificate

openssl x509 -in server.crt -text -noout
openssl x509 -in server.cer -text -noout

Check a PKCS#12 file (.pfx or .p12)

openssl pkcs12 -info -in server.p12

Verify a private key matches an certificate

openssl x509 -noout -modulus -in server.crt | openssl md5
openssl rsa -noout -modulus -in server.key | openssl md5
openssl req -noout -modulus -in server.csr | openssl md5

Display all certificates including intermediates

openssl s_client -connect www.paypal.com:443

Convert a DER file (.crt .cer .der) to PEM

openssl x509 -inform der -in server.cer -out server.pem

Convert a PEM file to DER

openssl x509 -outform der -in server.pem -out server.der

Convert a PKCS#12 file (.pfx .p12) containing a private key and certificates to PEM

openssl pkcs12 -in server.pfx -out server.pem -nodes

Convert a PEM certificate file and a private key to PKCS#12 (.pfx .p12)

openssl pkcs12 -export -out server.pfx -inkey server.key -in server.crt -certfile CACert.crt

Generate a Diffie Hellman key

openssl dhparam -out dhparam.pem 2048

Encrypt files with rsautl

openssl rsautl -encrypt -in plaintext.txt -out encrypted.txt -pubin -inkey pubkey.pem

Decrypt files with rsautl

openssl rsautl -decrypt -in encrypted.txt -out plaintext.txt -inkey privkey.pem
@endermetin60
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<script src="https://gist.github.com/webtobesocial/5313b0d7abc25e06c2d78f8b767d4bc3.js"></script>

@rustymagnet3000
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do you know to check a hex formatted public key?

For example, if you extract Public Key from Cert in Hex format

openssl x509 -modulus -noout < stackexchangecom.crt | sed s/Modulus=//

@lolgear
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lolgear commented Jul 31, 2018

@webtobesocial

It would be nice to extend this list by:

  • openssl req utility with -subj flag.
  • openssl pkcs12 output with -passout flag.

@christianlaguerre
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Verifying that a Certificate is issued by a CA

openssl verify -verbose -CAfile cacert.pem server.crt

@egberts
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egberts commented Mar 18, 2022 •
edited

Expert OpenSSL Stuff

Insert selected attributes into a specific section of openssl.cnf (only with 'openssl ca', or 'openssl x509 -req'; sorry, nothing for 'openssl req')

openssl ... -extfile <(printf "subjectAltName=DNS:example.com,DNS:www.example.com") ...

as in:

openssl genrsa -out ca.key 2048
openssl req -new -x509 -days 365 -key ca.key -subj "/C=CN/ST=GD/L=SZ/O=Acme, Inc./CN=Acme Root CA" -out ca.crt
openssl req -newkey rsa:2048 -nodes -keyout server.key -subj "/C=CN/ST=GD/L=SZ/O=Acme, Inc./CN=*.example.com" -out server.csr
openssl x509 -req -extfile <(printf "subjectAltName=DNS:example.com,DNS:www.example.com") -days 365 -in server.csr -CA ca.crt -CAkey ca.key -CAcreateserial -out server.crt

Be not influenced by default settings provided by /usr/lib/ssl/openssl.cnf

env OPENSSL_CONF=/dev/null openssl -config your-config ...

Strip "/-BEGIN CERTIFICATE-/" (caused by -text) from PEM file using sed before using as pure PEM

  openssl s_client -connect ${CERT} 2>/dev/null |\
  sed -ne '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/p' |\
  openssl x509 -noout -subject -dates

@egberts
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egberts commented Mar 18, 2022

Verifying that a Certificate is issued by a CA

openssl verify -verbose -CAfile cacert.pem server.crt

Yeah, good one, @christianlaguerre.

one may want to ALSO add the following -no-CApath CLI option as well.

That is, unless you do not mind openssl checking against the /etc/ssl/certs trusted certs for all your execution of openssl.

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