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A quick reference for using OpenSSL tool / library under Linux base system.


Checking version
openssl version -a
How fast it runs on the system using four CPU cores and testing RSA algorithm
openssl speed -multi 4 rsa
Get basic help
openssl help
Generate 20 random bytes and show them on screen
openssl rand -hex 20


Encoding a file using Base64
openssl base64 -in
Encoding some text using Base64
echo -n "some text" | openssl base64
Base64 decode a file with output to another file
openssl base64 -d -in encode­ -out decode­


List digest algorithms available
openssl list -diges­t-a­lgo­rithms
Hash a file using SHA256
openssl dgst -sha256
Hash a file using SHA256 with its output in binary form (no output hex encoding)
No ASCII or encoded characters will be printed out to the console, just pure bytes. You can append ' | xxd'
openssl dgst -binary -sha256
Hash text using SHA3-512
echo -n "some text" | openssl dgst -sha3-512
Create HMAC - SHA384 of a file using a specific key in bytes
openssl dgst -SHA384 -mac HMAC -macopt hexkey:369bd7d655
Create HMAC - SHA512 of some text
echo -n "some text" | openssl dgst -mac HMAC -macopt hexkey­:36­9bd­7d655 -sha512


List elliptic curves available
openssl ecparam -list_­curves
Create 4096 bits RSA public­-pr­ivate key pair
openssl genrsa -out pub_pr­iv.key 4096
Display detailed private key information
openssl rsa -text -in pub_priv.key -noout
Encrypt public-private key pair using AES-256 algorithm
openssl rsa -in pub_priv.key -out encrypted.key -aes256
Remove keys file encryption and save them to another file
openssl rsa -in encrypted.key -out cleartext.key
Copy the public key of the public-private key pair file to another file
openssl rsa -in pub_priv.key -pubout -out pubkey.key
Encrypt a file using RSA public key
openssl rsautl -encrypt -inkey pubkey.key -pubin -in cleartext.file -out ciphertext.file
Decrypt a file using RSA private key
openssl rsautl -decrypt -inkey pub_priv.key -in ciphertext.file -out decrypted.file
Create private key using the P-224 elliptic curve
openssl ecparam -name secp224k1 -genkey -out ecpriv.key
Encrypt private key using 3DES algorithm
openssl ec -in ecP384priv.key -des3 -out ecP384priv_enc.key


List all supported symmetric encryption ciphers
openssl enc -list
Encrypt a file using an ASCII encoded password provided and AES-128-ECB algorithm
openssl enc -aes-128-ecb -in cleartext.file -out ciphertext.file -pass pass:thisisthepassword
Decrypt a file using AES-256-CBC and a keyfile
openssl enc -d -aes-256-cbc -in ciphertext.file -out cleartext.file -pass file:./key.file
Encrypt a file using a specific encryption key (K) provided as hex digits
openssl enc -aes-128-ecb -in cleartext.file -out ciphertext.file -K 1881807b2d1b3d22f14e9ec52563d981 -nosalt
Encrypt a file using ARIA 256 in CBC block cipher mode using a specified encryption key (K:256 bits) and initialization vector (iv:128 bits)
openssl enc -aria-256-cbc -in cleartext.file -out ciphertext.file -K f92d2e986b7a2a01683b4c40d0cbcf6feaa669ef2bb5ec3a25ce85d9548291c1 -iv 470bc29762496046882b61ecee68e07c -nosalt
Encrypt a file using Camellia 192 algorithm in COUNTER block cipher mode with key and iv provided
openssl enc -camellia-192-ctr -in cleartext.file -out ciphertext.file -K 6c7a1b3487d28d3bf444186d7c529b48d67dd6206c7a1b34 -iv 470bc29762496046882b61ecee68e07c


Generate DSA parameters for the private key. 2048 bits length
openssl dsaparam -out dsaparam.pem 2048
Generate DSA public-private key for signing documents and protect it using AES128 algorithm
openssl gendsa -out dsaprivatekey.pem -aes-128-cbc dsaparam.pem
Copy the public key of the DSA public-private key file to another file
openssl dsa -in dsaprivatekey.pem -pubout -out dsapublickey.pem
To print out the contents of a DSA key pair file
openssl dsa -in dsaprivatekey.pem -text -noout
Signing the sha-256 hash of a file using RSA private key
openssl dgst -sha256 -sign rsakey.key -out document.pdf
Verify a SHA-256 file signature using a public key
openssl dgst -sha256 -verify publickey.pem -signature original.file
Signing the sha3-512 hash of a file using DSA private key
openssl pkeyutl -sign -pkeyopt digest:sha3-512 -in document.docx -inkey dsaprivatekey.pem -out
Verify DSA signature
openssl pkeyutl -verify -sigfile -inkey dsakey.pem -in document.docx
Create a private key using P-384 Elliptic Curve
openssl ecparam -name secp384r1 -genkey -out ecP384priv.key
Encrypt private key using 3DES algorithm
openssl ec -in ecP384priv.key -des3 -out ecP384priv_enc.key
Sign a PDF file using Elliptic Curves with the generated key
openssl pkeyutl -sign -inkey ecP384priv_enc.key -pkeyopt digest:sha3-512 -in document.pdf -out
Verify the file's signature. If it's ok you must receive "Signature Verified Successfully"
openssl pkeyutl -verify -in document.pdf -sigfile -inkey ecP384priv_enc.key


Generating a CSR file and a 4096 bits RSA key pair
openssl req -newkey rsa:4096 -keyout private.key -out request.csr
Display Certificate Signing Request ( CSR ) content
openssl req -text -noout -in request.csr
Display the public key contained in the CSR file
openssl req -pubkey -noout -in request.csr
Creating a Certificate Signing Request ( CSR ) using an existing private key. This can be useful when you need to renew the public digital certificate without changing the private key.
openssl req -new -key private.key -out request.csr
Create EC P384 curve parameters file to generate a CSR using Elliptic Curves in the next step.
openssl genpkey -genparam -algorithm EC -out EC_params.pem -pkeyopt ec_paramgen_curve:secp384r1 -pkeyopt ec_param_enc:named_curve
Create a CSR file using Elliptic Curve P384 parameters file created in the previous step. Instead of using RSA keys.
openssl req -newkey ec:EC_params.pem -keyout EC_P384_priv.key -out EC_request.csr
Create a self-signed certificate, a new 2048 bits RSA key pair with one year of validity
openssl req -newkey rsa:2048 -nodes -keyout priv.key -x509 -days 365 -out cert.crt
Create and sign a new certificate using the CSR file and the private key for signing ( you must have a openssl.cnf file prepared )
openssl ca -in request.csr -out certificate.crt -config ./CA/config/openssl.cnf
Display PEM format certif­icate information
openssl x509 -text -noout -in cert.crt
Display certificate information in Abstract Sintax Notation One (ASN.1)
openssl asn1parse -in cert.crt
Extract the certif­icate's public key
openssl x509 -pubkey -noout -in cert.crt
Extract the public key's modulus in the certificate
openssl x509 -modulus -noout -in cert.crt
Extract the domain certificate from an HTTPS/TLS connection
openssl s_client -connect | openssl x509 -out certificate.crt
Convert a certificate from PEM to DER format
openssl x509 -inform PEM -outform DER -in cert.crt -out cert.der
Checking whether the certificate pubic key matches a private key and request file. One step per file. Must match in the output hashes.
openssl x509 -modulus -in certificate.crt -noout | openssl dgst -sha256
openssl rsa -modulus -in private.key -noout | openssl dgst -sha256
openssl req -modulus -in request.csr -noout | openssl dgst -sha256


List all cipher suites supported
openssl ciphers -V 'ALL'
List all cipher suites supported with AES
openssl ciphers -V 'AES'
List all cipher suites supporting CAMELLIA & SHA256 algorithms.
openssl ciphers -V 'CAMELLIA+SHA256'
TLS connection to a server using port 443 (HTTPS)
openssl s_client -connect
TLS connection to a server using v1.2
openssl s_client -tls1_2 -connect
TLS connection & disable v1.0
openssl s_client -no_tls1
TLS connection using a specific cipher suite
openssl s_client -cipher DHE-RSA-AES256-GCM-SHA384
TLS connection displaying all certificates provided by server
openssl s_client -showcerts
Setting up a listening port to receive TLS connections using a certificate, the private key & supporting only TLS 1.2
openssl s_server -port 443 -cert cert.crt -key priv.key -tls1_2
Extract the domain certificate from an HTTPS/TLS connection
openssl s_client -connect | openssl x509 -out certificate.crt
nmap command: Display enabled cipher-suites over an HTTPS/TLS Connection
nmap --script ssl-enum-ciphers -p 443
nmap command: Display enabled cipher-suites over a TLS (HTTPS) Connection using SNI. (change it to desired IP & domain name)
nmap --script ssl-enum-ciphers


Convert a certif­icate from PEM (base64) to DER (binary) format
openssl x509 -in certif­ica­te.pem -outform DER -out certif­ica­te.der
Insert certificate & private key into PKCS #12 format file. These files can be imported in windows certificate manager or to a Java Key Store (jks) file
openssl pkcs12 -export -out cert_key.p12 -inkey private.key -in certificate.crt
To show the contents of a PKCS #12 file
openssl pkcs12 -in cert_k­ey.p12
Convert the .p12 file into a Java Key Store. This commnad uses java keytool instead of openssl.
keytool -importkeystore -destkeystore javakeystore.jks -srckeystore cert_key.p12 -srcstoretype pkcs12
Convert PEM certificate to PKCS #7 format
openssl crl2pkcs7 -nocrl -certfile certificate.crt -out cert.p7b
Convert a PKCS #7 file from PEM to DER
openssl pkcs7 -in cert.p7b -outform DER -out p7.der


[ ca ]
default_ca = CA_default

[ CA_default ]
dir = ./pers­onalCA
database = $dir/i­nde­x.txt
new_ce­rts_dir = $dir/newcerts

certif­icate = $dir/c­ace­rt.pem
serial = $dir/s­erial
rand_s­erial = yes
privat­e_key = $dir/p­riv­ate­/ca­key.pem
RANDFILE = $dir/private/.rand

defaul­t_days = 365
defaul­t_c­rl_­days= 30
default_md = SHA256

policy = policy_any
email_­in_dn = no

name_opt = ca_default
cert_opt = ca_default
copy_e­xte­nsions = none

[ policy_any ]
countr­yName = supplied
stateO­rPr­ovi­nceName = optional
organi­zat­ionName = optional
organi­zat­ion­alU­nitName = optional
commonName = supplied
emailA­ddress = optional


- All openssl commands were tested using OpenSSL version 1.1.1f
- All nmap commands were tested using nmap version 7.80. nmap is compiled using openssl libraries.
- The default format for almost all operations in openssl is PEM, however you can always specify a DER format using arguments or export to other formats with approp­riate commands indicated on the document.


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