Implementation of an X.509 certificate as specified in RFC 5280. Provides access to a certificate's attributes and allows certificates to be read from a string, but also supports the creation of new certificates from scratch.

Reading a certificate from a file

Certificate is capable of handling DER-encoded certificates and certificates encoded in OpenSSL's PEM format.

raw = File.read "cert.cer" # DER- or PEM-encoded
certificate = OpenSSL::X509::Certificate.new raw

Saving a certificate to a file

A certificate may be encoded in DER format

cert = ...
File.open("cert.cer", "wb") { |f| f.print cert.to_der }

or in PEM format

cert = ...
File.open("cert.pem", "wb") { |f| f.print cert.to_pem }

X.509 certificates are associated with a private/public key pair, typically a RSA, DSA or ECC key (see also OpenSSL::PKey::RSA, OpenSSL::PKey::DSA and OpenSSL::PKey::EC), the public key itself is stored within the certificate and can be accessed in form of an OpenSSL::PKey. Certificates are typically used to be able to associate some form of identity with a key pair, for example web servers serving pages over HTTPs use certificates to authenticate themselves to the user.

The public key infrastructure (PKI) model relies on trusted certificate authorities (“root CAs”) that issue these certificates, so that end users need to base their trust just on a selected few authorities that themselves again vouch for subordinate CAs issuing their certificates to end users.

The OpenSSL::X509 module provides the tools to set up an independent PKI, similar to scenarios where the 'openssl' command line tool is used for issuing certificates in a private PKI.

Creating a root CA certificate and an end-entity certificate

First, we need to create a “self-signed” root certificate. To do so, we need to generate a key first. Please note that the choice of “1” as a serial number is considered a security flaw for real certificates. Secure choices are integers in the two-digit byte range and ideally not sequential but secure random numbers, steps omitted here to keep the example concise.

root_key = OpenSSL::PKey::RSA.new 2048 # the CA's public/private key
root_ca = OpenSSL::X509::Certificate.new
root_ca.version = 2 # cf. RFC 5280 - to make it a "v3" certificate
root_ca.serial = 1
root_ca.subject = OpenSSL::X509::Name.parse "/DC=org/DC=ruby-lang/CN=Ruby CA"
root_ca.issuer = root_ca.subject # root CA's are "self-signed"
root_ca.public_key = root_key.public_key
root_ca.not_before = Time.now
root_ca.not_after = root_ca.not_before + 2 * 365 * 24 * 60 * 60 # 2 years validity
ef = OpenSSL::X509::ExtensionFactory.new
ef.subject_certificate = root_ca
ef.issuer_certificate = root_ca
root_ca.add_extension(ef.create_extension("basicConstraints","CA:TRUE",true))
root_ca.add_extension(ef.create_extension("keyUsage","keyCertSign, cRLSign", true))
root_ca.add_extension(ef.create_extension("subjectKeyIdentifier","hash",false))
root_ca.add_extension(ef.create_extension("authorityKeyIdentifier","keyid:always",false))
root_ca.sign(root_key, OpenSSL::Digest::SHA256.new)

The next step is to create the end-entity certificate using the root CA certificate.

key = OpenSSL::PKey::RSA.new 2048
cert = OpenSSL::X509::Certificate.new
cert.version = 2
cert.serial = 2
cert.subject = OpenSSL::X509::Name.parse "/DC=org/DC=ruby-lang/CN=Ruby certificate"
cert.issuer = root_ca.subject # root CA is the issuer
cert.public_key = key.public_key
cert.not_before = Time.now
cert.not_after = cert.not_before + 1 * 365 * 24 * 60 * 60 # 1 years validity
ef = OpenSSL::X509::ExtensionFactory.new
ef.subject_certificate = cert
ef.issuer_certificate = root_ca
cert.add_extension(ef.create_extension("keyUsage","digitalSignature", true))
cert.add_extension(ef.create_extension("subjectKeyIdentifier","hash",false))
cert.sign(root_key, OpenSSL::Digest::SHA256.new)
Methods
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Class Public methods
Certificate.new => cert
Certificate.new(string) => cert
static VALUE
ossl_x509_initialize(int argc, VALUE *argv, VALUE self)
{
    BIO *in;
    X509 *x509, *x = DATA_PTR(self);
    VALUE arg;

    if (rb_scan_args(argc, argv, "01", &arg) == 0) {
        /* create just empty X509Cert */
        return self;
    }
    arg = ossl_to_der_if_possible(arg);
    in = ossl_obj2bio(arg);
    x509 = PEM_read_bio_X509(in, &x, NULL, NULL);
    DATA_PTR(self) = x;
    if (!x509) {
        OSSL_BIO_reset(in);
        x509 = d2i_X509_bio(in, &x);
        DATA_PTR(self) = x;
    }
    BIO_free(in);
    if (!x509) ossl_raise(eX509CertError, NULL);

    return self;
}
Instance Public methods
cert.add_extension(extension) => extension
static VALUE
ossl_x509_add_extension(VALUE self, VALUE extension)
{
    X509 *x509;
    X509_EXTENSION *ext;

    GetX509(self, x509);
    ext = DupX509ExtPtr(extension);
    if (!X509_add_ext(x509, ext, -1)) { /* DUPs ext - FREE it */
        X509_EXTENSION_free(ext);
        ossl_raise(eX509CertError, NULL);
    }
    X509_EXTENSION_free(ext);

    return extension;
}
cert.check_private_key(key)

Checks if 'key' is PRIV key for this cert

static VALUE
ossl_x509_check_private_key(VALUE self, VALUE key)
{
    X509 *x509;
    EVP_PKEY *pkey;

    /* not needed private key, but should be */
    pkey = GetPrivPKeyPtr(key); /* NO NEED TO DUP */
    GetX509(self, x509);
    if (!X509_check_private_key(x509, pkey)) {
        OSSL_Warning("Check private key:%s", OSSL_ErrMsg());
        return Qfalse;
    }

    return Qtrue;
}
cert.extensions => [extension...]
static VALUE
ossl_x509_get_extensions(VALUE self)
{
    X509 *x509;
    int count, i;
    X509_EXTENSION *ext;
    VALUE ary;

    GetX509(self, x509);
    count = X509_get_ext_count(x509);
    if (count < 0) {
        return rb_ary_new();
    }
    ary = rb_ary_new2(count);
    for (i=0; i<count; i++) {
        ext = X509_get_ext(x509, i); /* NO DUP - don't free! */
        rb_ary_push(ary, ossl_x509ext_new(ext));
    }

    return ary;
}
cert.extensions = [ext...] => [ext...]
static VALUE
ossl_x509_set_extensions(VALUE self, VALUE ary)
{
    X509 *x509;
    X509_EXTENSION *ext;
    int i;

    Check_Type(ary, T_ARRAY);
    /* All ary's members should be X509Extension */
    for (i=0; i<RARRAY_LEN(ary); i++) {
        OSSL_Check_Kind(RARRAY_PTR(ary)[i], cX509Ext);
    }
    GetX509(self, x509);
    sk_X509_EXTENSION_pop_free(x509->cert_info->extensions, X509_EXTENSION_free);
    x509->cert_info->extensions = NULL;
    for (i=0; i<RARRAY_LEN(ary); i++) {
        ext = DupX509ExtPtr(RARRAY_PTR(ary)[i]);

        if (!X509_add_ext(x509, ext, -1)) { /* DUPs ext - FREE it */
            X509_EXTENSION_free(ext);
            ossl_raise(eX509CertError, NULL);
        }
        X509_EXTENSION_free(ext);
    }

    return ary;
}
inspect()
static VALUE
ossl_x509_inspect(VALUE self)
{
    VALUE str;
    const char *cname = rb_class2name(rb_obj_class(self));

    str = rb_str_new2("#<");
    rb_str_cat2(str, cname);
    rb_str_cat2(str, " ");

    rb_str_cat2(str, "subject=");
    rb_str_append(str, rb_inspect(ossl_x509_get_subject(self)));
    rb_str_cat2(str, ", ");

    rb_str_cat2(str, "issuer=");
    rb_str_append(str, rb_inspect(ossl_x509_get_issuer(self)));
    rb_str_cat2(str, ", ");

    rb_str_cat2(str, "serial=");
    rb_str_append(str, rb_inspect(ossl_x509_get_serial(self)));
    rb_str_cat2(str, ", ");

    rb_str_cat2(str, "not_before=");
    rb_str_append(str, rb_inspect(ossl_x509_get_not_before(self)));
    rb_str_cat2(str, ", ");

    rb_str_cat2(str, "not_after=");
    rb_str_append(str, rb_inspect(ossl_x509_get_not_after(self)));

    str = rb_str_cat2(str, ">");

    return str;
}
cert.issuer => name
static VALUE
ossl_x509_get_issuer(VALUE self)
{
    X509 *x509;
    X509_NAME *name;

    GetX509(self, x509);
    if(!(name = X509_get_issuer_name(x509))) { /* NO DUP - don't free! */
        ossl_raise(eX509CertError, NULL);
    }

    return ossl_x509name_new(name);
}
cert.issuer = name => name
static VALUE
ossl_x509_set_issuer(VALUE self, VALUE issuer)
{
    X509 *x509;

    GetX509(self, x509);
    if (!X509_set_issuer_name(x509, GetX509NamePtr(issuer))) { /* DUPs name */
        ossl_raise(eX509CertError, NULL);
    }

    return issuer;
}
cert.not_after => time
static VALUE
ossl_x509_get_not_after(VALUE self)
{
    X509 *x509;
    ASN1_TIME *asn1time;

    GetX509(self, x509);
    if (!(asn1time = X509_get_notAfter(x509))) { /* NO DUP - don't free! */
        ossl_raise(eX509CertError, NULL);
    }

    return asn1time_to_time(asn1time);
}
cert.not_after = time => time
static VALUE
ossl_x509_set_not_after(VALUE self, VALUE time)
{
    X509 *x509;
    time_t sec;

    sec = time_to_time_t(time);
    GetX509(self, x509);
    if (!X509_time_adj(X509_get_notAfter(x509), 0, &sec)) {
        ossl_raise(eX509CertError, NULL);
    }

    return time;
}
cert.not_before => time
static VALUE
ossl_x509_get_not_before(VALUE self)
{
    X509 *x509;
    ASN1_UTCTIME *asn1time;

    GetX509(self, x509);
    if (!(asn1time = X509_get_notBefore(x509))) { /* NO DUP - don't free! */
        ossl_raise(eX509CertError, NULL);
    }

    return asn1time_to_time(asn1time);
}
cert.not_before = time => time
static VALUE
ossl_x509_set_not_before(VALUE self, VALUE time)
{
    X509 *x509;
    time_t sec;

    sec = time_to_time_t(time);
    GetX509(self, x509);
    if (!X509_time_adj(X509_get_notBefore(x509), 0, &sec)) {
        ossl_raise(eX509CertError, NULL);
    }

    return time;
}
cert.public_key => key
static VALUE
ossl_x509_get_public_key(VALUE self)
{
    X509 *x509;
    EVP_PKEY *pkey;

    GetX509(self, x509);
    if (!(pkey = X509_get_pubkey(x509))) { /* adds an reference */
        ossl_raise(eX509CertError, NULL);
    }

    return ossl_pkey_new(pkey); /* NO DUP - OK */
}
cert.public_key = key => key
static VALUE
ossl_x509_set_public_key(VALUE self, VALUE key)
{
    X509 *x509;

    GetX509(self, x509);
    if (!X509_set_pubkey(x509, GetPKeyPtr(key))) { /* DUPs pkey */
        ossl_raise(eX509CertError, NULL);
    }

    return key;
}
cert.serial => integer
static VALUE
ossl_x509_get_serial(VALUE self)
{
    X509 *x509;

    GetX509(self, x509);

    return asn1integer_to_num(X509_get_serialNumber(x509));
}
cert.serial = integer => integer
static VALUE
ossl_x509_set_serial(VALUE self, VALUE num)
{
    X509 *x509;

    GetX509(self, x509);

    x509->cert_info->serialNumber =
        num_to_asn1integer(num, X509_get_serialNumber(x509));

    return num;
}
cert.sign(key, digest) => self
static VALUE
ossl_x509_sign(VALUE self, VALUE key, VALUE digest)
{
    X509 *x509;
    EVP_PKEY *pkey;
    const EVP_MD *md;

    pkey = GetPrivPKeyPtr(key); /* NO NEED TO DUP */
    md = GetDigestPtr(digest);
    GetX509(self, x509);
    if (!X509_sign(x509, pkey, md)) {
        ossl_raise(eX509CertError, NULL);
    }

    return self;
}
cert.signature_algorithm => string
static VALUE
ossl_x509_get_signature_algorithm(VALUE self)
{
    X509 *x509;
    BIO *out;
    VALUE str;

    GetX509(self, x509);
    out = BIO_new(BIO_s_mem());
    if (!out) ossl_raise(eX509CertError, NULL);

    if (!i2a_ASN1_OBJECT(out, x509->cert_info->signature->algorithm)) {
        BIO_free(out);
        ossl_raise(eX509CertError, NULL);
    }
    str = ossl_membio2str(out);

    return str;
}
cert.subject => name
static VALUE
ossl_x509_get_subject(VALUE self)
{
    X509 *x509;
    X509_NAME *name;

    GetX509(self, x509);
    if (!(name = X509_get_subject_name(x509))) { /* NO DUP - don't free! */
        ossl_raise(eX509CertError, NULL);
    }

    return ossl_x509name_new(name);
}
cert.subject = name => name
static VALUE
ossl_x509_set_subject(VALUE self, VALUE subject)
{
    X509 *x509;

    GetX509(self, x509);
    if (!X509_set_subject_name(x509, GetX509NamePtr(subject))) { /* DUPs name */
        ossl_raise(eX509CertError, NULL);
    }

    return subject;
}
cert.to_der => string
static VALUE
ossl_x509_to_der(VALUE self)
{
    X509 *x509;
    VALUE str;
    long len;
    unsigned char *p;

    GetX509(self, x509);
    if ((len = i2d_X509(x509, NULL)) <= 0)
        ossl_raise(eX509CertError, NULL);
    str = rb_str_new(0, len);
    p = (unsigned char *)RSTRING_PTR(str);
    if (i2d_X509(x509, &p) <= 0)
        ossl_raise(eX509CertError, NULL);
    ossl_str_adjust(str, p);

    return str;
}
cert.to_pem => string
Also aliased as: to_s
static VALUE
ossl_x509_to_pem(VALUE self)
{
    X509 *x509;
    BIO *out;
    VALUE str;

    GetX509(self, x509);
    out = BIO_new(BIO_s_mem());
    if (!out) ossl_raise(eX509CertError, NULL);

    if (!PEM_write_bio_X509(out, x509)) {
        BIO_free(out);
        ossl_raise(eX509CertError, NULL);
    }
    str = ossl_membio2str(out);

    return str;
}
to_s()
Alias for: to_pem
cert.to_text => string
static VALUE
ossl_x509_to_text(VALUE self)
{
    X509 *x509;
    BIO *out;
    VALUE str;

    GetX509(self, x509);

    out = BIO_new(BIO_s_mem());
    if (!out) ossl_raise(eX509CertError, NULL);

    if (!X509_print(out, x509)) {
        BIO_free(out);
        ossl_raise(eX509CertError, NULL);
    }
    str = ossl_membio2str(out);

    return str;
}
cert.verify(key) => true | false

Checks that cert signature is made with PRIVversion of this PUBLIC 'key'

static VALUE
ossl_x509_verify(VALUE self, VALUE key)
{
    X509 *x509;
    EVP_PKEY *pkey;
    int i;

    pkey = GetPKeyPtr(key); /* NO NEED TO DUP */
    GetX509(self, x509);
    if ((i = X509_verify(x509, pkey)) < 0) {
        ossl_raise(eX509CertError, NULL);
    }
    if (i > 0) {
        return Qtrue;
    }

    return Qfalse;
}
cert.version => integer
static VALUE
ossl_x509_get_version(VALUE self)
{
    X509 *x509;

    GetX509(self, x509);

    return LONG2NUM(X509_get_version(x509));
}
cert.version = integer => integer
static VALUE
ossl_x509_set_version(VALUE self, VALUE version)
{
    X509 *x509;
    long ver;

    if ((ver = NUM2LONG(version)) < 0) {
        ossl_raise(eX509CertError, "version must be >= 0!");
    }
    GetX509(self, x509);
    if (!X509_set_version(x509, ver)) {
        ossl_raise(eX509CertError, NULL);
    }

    return version;
}