IO::Socket::SSL::Utils

Section: User Contributed Perl Documentation (3)
Updated: 2021-03-19
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NAME

IO::Socket::SSL::Utils -- loading, storing, creating certificates and keys

SYNOPSIS

    use IO::Socket::SSL::Utils;
    my $cert = PEM_file2cert('cert.pem');  # load certificate from file
    my $string = PEM_cert2string($cert);   # convert certificate to PEM string
    CERT_free($cert);                      # free memory within OpenSSL

    my $key = KEY_create_rsa(2048);        # create new 2048-bit RSA key
    PEM_string2file($key,"key.pem");       # and write it to file
    KEY_free($key);                        # free memory within OpenSSL

DESCRIPTION

This module provides various utility functions to work with certificates and private keys, shielding some of the complexity of the underlying Net::SSLeay and OpenSSL.

FUNCTIONS

•

Functions converting between string or file and certificates and keys. They croak if the operation cannot be completed.

PEM_file2cert(file) -> cert
PEM_cert2file(cert,file)
PEM_string2cert(string) -> cert
PEM_cert2string(cert) -> string
PEM_file2key(file) -> key
PEM_key2file(key,file)
PEM_string2key(string) -> key
PEM_key2string(key) -> string

•

Functions for cleaning up. Each loaded or created cert and key must be freed to not leak memory.

CERT_free(cert)
KEY_free(key)

•

KEY_create_rsa(bits) -> key

Creates an RSA key pair, bits defaults to 2048.

•

KEY_create_ec(curve) -> key

Creates an EC key, curve defaults to "prime256v1".

•

CERT_asHash(cert,[digest_algo]) -> hash

Extracts the information from the certificate into a hash and uses the given digest_algo (default: SHA-256) to determine digest of pubkey and cert. The resulting hash contains:

subject: Hash with the parts of the subject, e.g. commonName, countryName, organizationName, stateOrProvinceName, localityName. If there are multiple values for any of these parts the hash value will be an array ref with the values in order instead of just a scalar.
subjectAltNames: Array with list of alternative names. Each entry in the list is of "[type,value]", where "type" can be OTHERNAME, EMAIL, DNS, X400, DIRNAME, EDIPARTY, URI, IP or RID.
issuer: Hash with the parts of the issuer, e.g. commonName, countryName, organizationName, stateOrProvinceName, localityName. If there are multiple values for any of these parts the hash value will be an array ref with the values in order instead of just a scalar.
not_before, not_after: The time frame, where the certificate is valid, as time_t, e.g. can be converted with localtime or similar functions.
serial: The serial number
crl_uri: List of URIs for CRL distribution.
ocsp_uri: List of URIs for revocation checking using OCSP.
keyusage: List of keyUsage information in the certificate.
extkeyusage: List of extended key usage information from the certificate. Each entry in this list consists of a hash with oid, nid, ln and sn.
pubkey_digest_xxx: Binary digest of the pubkey using the given digest algorithm, e.g. pubkey_digest_sha256 if (the default) SHA-256 was used.
x509_digest_xxx: Binary digest of the X.509 certificate using the given digest algorithm, e.g. x509_digest_sha256 if (the default) SHA-256 was used.
fingerprint_xxx: Fingerprint of the certificate using the given digest algorithm, e.g. fingerprint_sha256 if (the default) SHA-256 was used. Contrary to digest_* this is an ASCII string with a list if hexadecimal numbers, e.g. ``73:59:75:5C:6D...''.
signature_alg: Algorithm used to sign certificate, e.g. "sha256WithRSAEncryption".
ext: List of extensions. Each entry in the list is a hash with oid, nid, sn, critical flag (boolean) and data (string representation given by X509V3_EXT_print).
version: Certificate version, usually 2 (x509v3)

•

CERT_create(hash) -> (cert,key)

Creates a certificate based on the given hash. If the issuer is not specified the certificate will be self-signed. The following keys can be given:

subject

Hash with the parts of the subject, e.g. commonName, countryName, ... as described in "CERT_asHash". Default points to IO::Socket::SSL.

not_before

A time_t value when the certificate starts to be valid. Defaults to current time.

not_after

A time_t value when the certificate ends to be valid. Defaults to current time plus one 365 days.

serial

The serial number. If not given a random number will be used.

version

The version of the certificate, default 2 (x509v3).

CA true|false

If true declare certificate as CA, defaults to false.

purpose string|array|hash

Set the purpose of the certificate. The different purposes can be given as a string separated by non-word character, as array or hash. With string or array each purpose can be prefixed with '+' (enable) or '-' (disable) and same can be done with the value when given as a hash. By default enabling the purpose is assumed.

If the CA option is given and true the defaults ``ca,sslca,emailca,objca'' are assumed, but can be overridden with explicit purpose. If the CA option is given and false the defaults ``server,client'' are assumed. If no CA option and no purpose is given it defaults to ``server,client''.

Purpose affects basicConstraints, keyUsage, extKeyUsage and netscapeCertType. The following purposes are defined (case is not important):

    client
    server
    email
    objsign

    CA
    sslCA
    emailCA
    objCA

    emailProtection
    codeSigning
    timeStamping

    digitalSignature
    nonRepudiation
    keyEncipherment
    dataEncipherment
    keyAgreement
    keyCertSign
    cRLSign
    encipherOnly
    decipherOnly

Examples:

     # root-CA for SSL certificates
     purpose => 'sslCA'   # or CA => 1

     # server certificate and CA (typically self-signed)
     purpose => 'sslCA,server'

     # client certificate
     purpose => 'client',

ext [{ sn => .., data => ... }, ... ]

List of extensions. The type of the extension can be specified as name with "sn" or as NID with "nid" and the data with "data". These data must be in the same syntax as expected within openssl.cnf, e.g. something like "OCSP;URI=http://...". Additionally the critical flag can be set with "critical =" 1>.

key key

use given key as key for certificate, otherwise a new one will be generated and returned

issuer_cert cert

set issuer for new certificate

issuer_key key

sign new certificate with given key

issuer [ cert, key ]

Instead of giving issuer_key and issuer_cert as separate arguments they can be given both together.

digest algorithm

specify the algorithm used to sign the certificate, default SHA-256.

AUTHOR

Steffen Ullrich