OpenSSL::PKey::DSA

Class

DSA, the Digital Signature Algorithm, is specified in NIST’s FIPS 186-3. It is an asymmetric public key algorithm that may be used similar to e.g. RSA. Please note that for OpenSSL versions prior to 1.0.0 the digest algorithms OpenSSL::Digest::DSS (equivalent to SHA) or OpenSSL::Digest::DSS1 (equivalent to SHA-1) must be used for issuing signatures with a DSA key using OpenSSL::PKey#sign. Starting with OpenSSL 1.0.0, digest algorithms are no longer restricted, any Digest may be used for signing.

Class Methods

DSA.generate(size) → dsa

ext/openssl/ossl_pkey_dsa.c View on GitHub

          
            static VALUE
ossl_dsa_s_generate(VALUE klass, VALUE size)
{
    DSA *dsa = dsa_generate(NUM2INT(size)); /* err handled by dsa_instance */
    VALUE obj = dsa_instance(klass, dsa);

    if (obj == Qfalse) {
        DSA_free(dsa);
        ossl_raise(eDSAError, NULL);
    }

    return obj;
}

Creates a new DSA instance by generating a private/public key pair from scratch.

Parameters

size is an integer representing the desired key size.

DSA.new([size | string [, pass]) → dsa

ext/openssl/ossl_pkey_dsa.c View on GitHub

          
            static VALUE
ossl_dsa_initialize(int argc, VALUE *argv, VALUE self)
{
    EVP_PKEY *pkey;
    DSA *dsa;
    BIO *in;
    char *passwd = NULL;
    VALUE arg, pass;

    GetPKey(self, pkey);
    if(rb_scan_args(argc, argv, "02", &arg, &pass) == 0) {
        dsa = DSA_new();
    }
    else if (FIXNUM_P(arg)) {
        if (!(dsa = dsa_generate(FIX2INT(arg)))) {
            ossl_raise(eDSAError, NULL);
        }
    }
    else {
        if (!NIL_P(pass)) passwd = StringValuePtr(pass);
        arg = ossl_to_der_if_possible(arg);
        in = ossl_obj2bio(&arg);
        dsa = PEM_read_bio_DSAPrivateKey(in, NULL, ossl_pem_passwd_cb, passwd);
        if (!dsa) {
            OSSL_BIO_reset(in);
            dsa = PEM_read_bio_DSA_PUBKEY(in, NULL, NULL, NULL);
        }
        if (!dsa) {
            OSSL_BIO_reset(in);
            dsa = d2i_DSAPrivateKey_bio(in, NULL);
        }
        if (!dsa) {
            OSSL_BIO_reset(in);
            dsa = d2i_DSA_PUBKEY_bio(in, NULL);
        }
        if (!dsa) {
            OSSL_BIO_reset(in);
            dsa = PEM_read_bio_DSAPublicKey(in, NULL, NULL, NULL);
        }
        BIO_free(in);
        if (!dsa) {
            ERR_clear_error();
            ossl_raise(eDSAError, "Neither PUB key nor PRIV key");
        }
    }
    if (!EVP_PKEY_assign_DSA(pkey, dsa)) {
        DSA_free(dsa);
        ossl_raise(eDSAError, NULL);
    }

    return self;
}

Creates a new DSA instance by reading an existing key from string.

Parameters

size is an integer representing the desired key size.
string contains a DER or PEM encoded key.
pass is a string that contains an optional password.

Examples

DSA.new -> dsa
DSA.new(1024) -> dsa
DSA.new(File.read('dsa.pem')) -> dsa
DSA.new(File.read('dsa.pem'), 'mypassword') -> dsa

Instance Methods

dsa.export([cipher, password]) → aString

ext/openssl/ossl_pkey_dsa.c View on GitHub

          
            static VALUE
ossl_dsa_export(int argc, VALUE *argv, VALUE self)
{
    EVP_PKEY *pkey;
    BIO *out;
    const EVP_CIPHER *ciph = NULL;
    char *passwd = NULL;
    VALUE cipher, pass, str;

    GetPKeyDSA(self, pkey);
    rb_scan_args(argc, argv, "02", &cipher, &pass);
    if (!NIL_P(cipher)) {
        ciph = GetCipherPtr(cipher);
        if (!NIL_P(pass)) {
            StringValue(pass);
            if (RSTRING_LENINT(pass) < OSSL_MIN_PWD_LEN)
                ossl_raise(eOSSLError, "OpenSSL requires passwords to be at least four characters long");
            passwd = RSTRING_PTR(pass);
        }
    }
    if (!(out = BIO_new(BIO_s_mem()))) {
        ossl_raise(eDSAError, NULL);
    }
    if (DSA_HAS_PRIVATE(pkey->pkey.dsa)) {
        if (!PEM_write_bio_DSAPrivateKey(out, pkey->pkey.dsa, ciph,
                                         NULL, 0, ossl_pem_passwd_cb, passwd)){
            BIO_free(out);
            ossl_raise(eDSAError, NULL);
        }
    } else {
        if (!PEM_write_bio_DSA_PUBKEY(out, pkey->pkey.dsa)) {
            BIO_free(out);
            ossl_raise(eDSAError, NULL);
        }
    }
    str = ossl_membio2str(out);

    return str;
}

Encodes this DSA to its PEM encoding.

Parameters

cipher is an OpenSSL::Cipher.
password is a string containing your password.

Examples

DSA.to_pem -> aString
DSA.to_pem(cipher, 'mypassword') -> aString

dsa.params → hash

ext/openssl/ossl_pkey_dsa.c View on GitHub

          
            static VALUE
ossl_dsa_get_params(VALUE self)
{
    EVP_PKEY *pkey;
    VALUE hash;

    GetPKeyDSA(self, pkey);

    hash = rb_hash_new();

    rb_hash_aset(hash, rb_str_new2("p"), ossl_bn_new(pkey->pkey.dsa->p));
    rb_hash_aset(hash, rb_str_new2("q"), ossl_bn_new(pkey->pkey.dsa->q));
    rb_hash_aset(hash, rb_str_new2("g"), ossl_bn_new(pkey->pkey.dsa->g));
    rb_hash_aset(hash, rb_str_new2("pub_key"), ossl_bn_new(pkey->pkey.dsa->pub_key));
    rb_hash_aset(hash, rb_str_new2("priv_key"), ossl_bn_new(pkey->pkey.dsa->priv_key));

    return hash;
}

Stores all parameters of key to the hash INSECURE: PRIVATE INFORMATIONS CAN LEAK OUT!!! Don’t use :-)) (I’s up to you)

dsa.private? → true | false

ext/openssl/ossl_pkey_dsa.c View on GitHub

          
            static VALUE
ossl_dsa_is_private(VALUE self)
{
    EVP_PKEY *pkey;

    GetPKeyDSA(self, pkey);

    return (DSA_PRIVATE(self, pkey->pkey.dsa)) ? Qtrue : Qfalse;
}

Indicates whether this DSA instance has a private key associated with it or not. The private key may be retrieved with DSA#private_key.

dsa.public? → true | false

ext/openssl/ossl_pkey_dsa.c View on GitHub

          
            static VALUE
ossl_dsa_is_public(VALUE self)
{
    EVP_PKEY *pkey;

    GetPKeyDSA(self, pkey);

    return (pkey->pkey.dsa->pub_key) ? Qtrue : Qfalse;
}

Indicates whether this DSA instance has a public key associated with it or not. The public key may be retrieved with DSA#public_key.

dsa.public_key → aDSA

ext/openssl/ossl_pkey_dsa.c View on GitHub

          
            static VALUE
ossl_dsa_to_public_key(VALUE self)
{
    EVP_PKEY *pkey;
    DSA *dsa;
    VALUE obj;

    GetPKeyDSA(self, pkey);
    /* err check performed by dsa_instance */
    dsa = DSAPublicKey_dup(pkey->pkey.dsa);
    obj = dsa_instance(CLASS_OF(self), dsa);
    if (obj == Qfalse) {
        DSA_free(dsa);
        ossl_raise(eDSAError, NULL);
    }
    return obj;
}

Returns a new DSA instance that carries just the public key information. If the current instance has also private key information, this will no longer be present in the new instance. This feature is helpful for publishing the public key information without leaking any of the private information.

Example

dsa = OpenSSL::PKey::DSA.new(2048) # has public and private information
pub_key = dsa.public_key # has only the public part available
pub_key_der = pub_key.to_der # it's safe to publish this

dsa.syssign(string) → aString

ext/openssl/ossl_pkey_dsa.c View on GitHub

          
            static VALUE
ossl_dsa_sign(VALUE self, VALUE data)
{
    EVP_PKEY *pkey;
    unsigned int buf_len;
    VALUE str;

    GetPKeyDSA(self, pkey);
    if (!pkey->pkey.dsa->q)
        ossl_raise(eDSAError, "incomplete DSA");
    if (!DSA_PRIVATE(self, pkey->pkey.dsa))
        ossl_raise(eDSAError, "Private DSA key needed!");
    StringValue(data);
    str = rb_str_new(0, ossl_dsa_buf_size(pkey));
    if (!DSA_sign(0, (unsigned char *)RSTRING_PTR(data), RSTRING_LENINT(data),
                  (unsigned char *)RSTRING_PTR(str),
                  &buf_len, pkey->pkey.dsa)) { /* type is ignored (0) */
        ossl_raise(eDSAError, NULL);
    }
    rb_str_set_len(str, buf_len);

    return str;
}

Computes and returns the DSA signature of string, where string is expected to be an already-computed message digest of the original input data. The signature is issued using the private key of this DSA instance.

Parameters

string is a message digest of the original input data to be signed

Example

dsa = OpenSSL::PKey::DSA.new(2048)
doc = "Sign me"
digest = OpenSSL::Digest::SHA1.digest(doc)
sig = dsa.syssign(digest)

dsa.sysverify(digest, sig) → true | false

ext/openssl/ossl_pkey_dsa.c View on GitHub

          
            static VALUE
ossl_dsa_verify(VALUE self, VALUE digest, VALUE sig)
{
    EVP_PKEY *pkey;
    int ret;

    GetPKeyDSA(self, pkey);
    StringValue(digest);
    StringValue(sig);
    /* type is ignored (0) */
    ret = DSA_verify(0, (unsigned char *)RSTRING_PTR(digest), RSTRING_LENINT(digest),
                     (unsigned char *)RSTRING_PTR(sig), RSTRING_LENINT(sig), pkey->pkey.dsa);
    if (ret < 0) {
        ossl_raise(eDSAError, NULL);
    }
    else if (ret == 1) {
        return Qtrue;
    }

    return Qfalse;
}

Verifies whether the signature is valid given the message digest input. It does so by validating sig using the public key of this DSA instance.

Parameters

digest is a message digest of the original input data to be signed
sig is a DSA signature value

Example

dsa = OpenSSL::PKey::DSA.new(2048)
doc = "Sign me"
digest = OpenSSL::Digest::SHA1.digest(doc)
sig = dsa.syssign(digest)
puts dsa.sysverify(digest, sig) # => true

dsa.to_der → aString

ext/openssl/ossl_pkey_dsa.c View on GitHub

          
            static VALUE
ossl_dsa_to_der(VALUE self)
{
    EVP_PKEY *pkey;
    int (*i2d_func)_((DSA*, unsigned char**));
    unsigned char *p;
    long len;
    VALUE str;

    GetPKeyDSA(self, pkey);
    if(DSA_HAS_PRIVATE(pkey->pkey.dsa))
        i2d_func = (int(*)_((DSA*,unsigned char**)))i2d_DSAPrivateKey;
    else
        i2d_func = i2d_DSA_PUBKEY;
    if((len = i2d_func(pkey->pkey.dsa, NULL)) <= 0)
        ossl_raise(eDSAError, NULL);
    str = rb_str_new(0, len);
    p = (unsigned char *)RSTRING_PTR(str);
    if(i2d_func(pkey->pkey.dsa, &p) < 0)
        ossl_raise(eDSAError, NULL);
    ossl_str_adjust(str, p);

    return str;
}

Encodes this DSA to its DER encoding.

          
            static VALUE
ossl_dsa_to_text(VALUE self)
{
    EVP_PKEY *pkey;
    BIO *out;
    VALUE str;

    GetPKeyDSA(self, pkey);
    if (!(out = BIO_new(BIO_s_mem()))) {
        ossl_raise(eDSAError, NULL);
    }
    if (!DSA_print(out, pkey->pkey.dsa, 0)) { /* offset = 0 */
        BIO_free(out);
        ossl_raise(eDSAError, NULL);
    }
    str = ossl_membio2str(out);

    return str;
}

Prints all parameters of key to buffer INSECURE: PRIVATE INFORMATIONS CAN LEAK OUT!!! Don’t use :-)) (I’s up to you)

OpenSSL::PKey::DSA

DSA.generate(size) → dsa

Parameters

DSA.new([size | string [, pass]) → dsa

Parameters

Examples

dsa.export([cipher, password]) → aString

Parameters

Examples

dsa.params → hash

dsa.private? → true | false

dsa.public? → true | false

dsa.public_key → aDSA

Example

dsa.syssign(string) → aString

Parameters

Example

dsa.sysverify(digest, sig) → true | false

Parameters

Example

dsa.to_der → aString

dsa.to_pem([cipher, password]) → aString

dsa.to_s([cipher, password]) → aString

dsa.to_text → aString