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```{index} single: IO::Socket::SSL::Utils
```

# IO::Socket::SSL::Utils

loading, storing, creating certificates and keys

## SYNOPSIS

```perl
use IO::Socket::SSL::Utils;

$cert = PEM_file2cert('cert.pem');     # load certificate from file
my $hash = CERT_asHash($cert);         # get details from certificate
PEM_cert2file($cert,'cert.pem');       # write certificate to file
CERT_free($cert);                      # free memory within OpenSSL

@certs = PEM_file2certs('chain.pem');  # load multiple certificates from file
PEM_certs2file('chain.pem', @certs);   # write multiple certificates to file
CERT_free(@certs);                     # free memory for all within OpenSSL

my $cert = PEM_string2cert($pem);      # load certificate from PEM string
$pem = PEM_cert2string($cert);         # convert certificate to PEM string

$key = KEY_create_rsa(2048);           # create new 2048-bit RSA key
PEM_key2file($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\_file2certs(file) -> @certs
    - PEM\_certs2file(file,@certs)
    - 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(@certs)
    - KEY\_free(@keys)
- 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 cryptographically random 32-bit value is
        generated using `Net::SSLeay::RAND_bytes`.

    - 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):

        ```text
        client
        server
        email
        objsign

        CA
        sslCA
        emailCA
        objCA

        emailProtection
        codeSigning
        timeStamping

        digitalSignature
        nonRepudiation
        keyEncipherment
        dataEncipherment
        keyAgreement
        keyCertSign
        cRLSign
        encipherOnly
        decipherOnly
        ```

        Examples:

        ```perl
        # 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.

    - ignore\_invalid\_args

        ignore any unknown arguments which might be in the argument list (which might be
        in the arguments for example as result from CERT\_asHash)

## AUTHOR

Steffen Ullrich