class OpenSSL::PKey::DH - RDoc Documentation (original) (raw)

An implementation of the Diffie-Hellman key exchange protocol based on discrete logarithms in finite fields, the same basis that DSA is built on.

Accessor methods for the Diffie-Hellman parameters¶ ↑

DH#p

The prime (an OpenSSL::BN) of the Diffie-Hellman parameters.

DH#g

The generator (an OpenSSL::BN) g of the Diffie-Hellman parameters.

DH#pub_key

The per-session public key (an OpenSSL::BN) matching the private key. This needs to be passed to DH#compute_key.

DH#priv_key

The per-session private key, an OpenSSL::BN.

Example of a key exchange¶ ↑

dh1 = OpenSSL::PKey::DH.new(2048) der = dh1.public_key.to_der dh2 = OpenSSL::PKey::DH.new(der) dh2.generate_key! symm_key1 = dh1.compute_key(dh2.pub_key) symm_key2 = dh2.compute_key(dh1.pub_key)

puts symm_key1 == symm_key2

Public Class Methods

generate(size [, generator]) → dh click to toggle source

Creates a new DH instance from scratch by generating the private and public components alike.

Parameters¶ ↑

• size is an integer representing the desired key size. Keys smaller than 1024 bits should be considered insecure.
• generator is a small number > 1, typically 2 or 5.

static VALUE ossl_dh_s_generate(int argc, VALUE *argv, VALUE klass) { DH *dh ; int g = 2; VALUE size, gen, obj;

if (rb_scan_args(argc, argv, "11", &size, &gen) == 2) {
    g = NUM2INT(gen);
}
dh = dh_generate(NUM2INT(size), g);
obj = dh_instance(klass, dh);
if (obj == Qfalse) {
    DH_free(dh);
    ossl_raise(eDHError, NULL);
}

return obj;

}

new → dh click to toggle source

new(string) → dh

new(size [, generator]) → dh

Either generates a DH instance from scratch or by reading already existing DH parameters from string. Note that when reading a DH instance from data that was encoded from a DH instance by using DH#to_pem or DH#to_der the result will not contain a public/private key pair yet. This needs to be generated using DH#generate_key! first.

Parameters¶ ↑

• size is an integer representing the desired key size. Keys smaller than 1024 bits should be considered insecure.
• generator is a small number > 1, typically 2 or 5.
• string contains the DER or PEM encoded key.

Examples¶ ↑

DH.new DH.new(1024) DH.new(1024, 5)

dh = DH.new(File.read('parameters.pem')) dh.generate_key!

static VALUE ossl_dh_initialize(int argc, VALUE *argv, VALUE self) { EVP_PKEY *pkey; DH *dh; int g = 2; BIO *in; VALUE arg, gen;

GetPKey(self, pkey);
if(rb_scan_args(argc, argv, "02", &arg, &gen) == 0) {
  dh = DH_new();
}
else if (RB_INTEGER_TYPE_P(arg)) {
    if (!NIL_P(gen)) {
        g = NUM2INT(gen);
    }
    if (!(dh = dh_generate(NUM2INT(arg), g))) {
        ossl_raise(eDHError, NULL);
    }
}
else {
    arg = ossl_to_der_if_possible(arg);
    in = ossl_obj2bio(&arg);
    dh = PEM_read_bio_DHparams(in, NULL, NULL, NULL);
    if (!dh){
        OSSL_BIO_reset(in);
        dh = d2i_DHparams_bio(in, NULL);
    }
    BIO_free(in);
    if (!dh) {
        ossl_raise(eDHError, NULL);
    }
}
if (!EVP_PKEY_assign_DH(pkey, dh)) {
    DH_free(dh);
    ossl_raise(eDHError, NULL);
}
return self;

}

Public Instance Methods

compute_key(pub_bn) → aString click to toggle source

Returns a String containing a shared secret computed from the other party's public value. See DH_compute_key() for further information.

Parameters¶ ↑

• pub_bn is a OpenSSL::BN, not the DH instance returned by DH#public_key as that contains the DH parameters only.

static VALUE ossl_dh_compute_key(VALUE self, VALUE pub) { DH *dh; const BIGNUM *pub_key, *dh_p; VALUE str; int len;

GetDH(self, dh);
DH_get0_pqg(dh, &dh_p, NULL, NULL);
if (!dh_p)
    ossl_raise(eDHError, "incomplete DH");
pub_key = GetBNPtr(pub);
len = DH_size(dh);
str = rb_str_new(0, len);
if ((len = DH_compute_key((unsigned char *)RSTRING_PTR(str), pub_key, dh)) < 0) {
    ossl_raise(eDHError, NULL);
}
rb_str_set_len(str, len);

return str;

}

export → aString click to toggle source

Encodes this DH to its PEM encoding. Note that any existing per-session public/private keys will not get encoded, just the Diffie-Hellman parameters will be encoded.

static VALUE ossl_dh_export(VALUE self) { DH *dh; BIO *out; VALUE str;

GetDH(self, dh);
if (!(out = BIO_new(BIO_s_mem()))) {
    ossl_raise(eDHError, NULL);
}
if (!PEM_write_bio_DHparams(out, dh)) {
    BIO_free(out);
    ossl_raise(eDHError, NULL);
}
str = ossl_membio2str(out);

return str;

}

generate_key! → self click to toggle source

Generates a private and public key unless a private key already exists. If this DH instance was generated from public DH parameters (e.g. by encoding the result of DH#public_key), then this method needs to be called first in order to generate the per-session keys before performing the actual key exchange.

Example¶ ↑

dh = OpenSSL::PKey::DH.new(2048) public_key = dh.public_key public_key.generate_key! puts public_key.private?

static VALUE ossl_dh_generate_key(VALUE self) { DH *dh;

GetDH(self, dh);
if (!DH_generate_key(dh))
    ossl_raise(eDHError, "Failed to generate key");
return self;

}

initialize_copy(p1) click to toggle source

static VALUE ossl_dh_initialize_copy(VALUE self, VALUE other) { EVP_PKEY *pkey; DH *dh, *dh_other; const BIGNUM *pub, *priv;

GetPKey(self, pkey);
if (EVP_PKEY_base_id(pkey) != EVP_PKEY_NONE)
    ossl_raise(eDHError, "DH already initialized");
GetDH(other, dh_other);

dh = DHparams_dup(dh_other);
if (!dh)
    ossl_raise(eDHError, "DHparams_dup");
EVP_PKEY_assign_DH(pkey, dh);

DH_get0_key(dh_other, &pub, &priv);
if (pub) {
    BIGNUM *pub2 = BN_dup(pub);
    BIGNUM *priv2 = BN_dup(priv);

    if (!pub2 || (priv && !priv2)) {
        BN_clear_free(pub2);
        BN_clear_free(priv2);
        ossl_raise(eDHError, "BN_dup");
    }
    DH_set0_key(dh, pub2, priv2);
}

return self;

}

params → hash click to toggle source

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

static VALUE ossl_dh_get_params(VALUE self) { DH *dh; VALUE hash; const BIGNUM *p, *q, *g, *pub_key, *priv_key;

GetDH(self, dh);
DH_get0_pqg(dh, &p, &q, &g);
DH_get0_key(dh, &pub_key, &priv_key);

hash = rb_hash_new();
rb_hash_aset(hash, rb_str_new2("p"), ossl_bn_new(p));
rb_hash_aset(hash, rb_str_new2("q"), ossl_bn_new(q));
rb_hash_aset(hash, rb_str_new2("g"), ossl_bn_new(g));
rb_hash_aset(hash, rb_str_new2("pub_key"), ossl_bn_new(pub_key));
rb_hash_aset(hash, rb_str_new2("priv_key"), ossl_bn_new(priv_key));

return hash;

}

params_ok? → true | false click to toggle source

Validates the Diffie-Hellman parameters associated with this instance. It checks whether a safe prime and a suitable generator are used. If this is not the case, false is returned.

static VALUE ossl_dh_check_params(VALUE self) { DH *dh; int codes;

GetDH(self, dh);
if (!DH_check(dh, &codes)) {
    return Qfalse;
}

return codes == 0 ? Qtrue : Qfalse;

}

private? → true | false click to toggle source

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

static VALUE ossl_dh_is_private(VALUE self) { DH *dh; const BIGNUM *bn;

GetDH(self, dh);
DH_get0_key(dh, NULL, &bn);

#if !defined(OPENSSL_NO_ENGINE) return (bn || DH_get0_engine(dh)) ? Qtrue : Qfalse; #else return bn ? Qtrue : Qfalse; #endif }

public? → true | false click to toggle source

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

static VALUE ossl_dh_is_public(VALUE self) { DH *dh; const BIGNUM *bn;

GetDH(self, dh);
DH_get0_key(dh, &bn, NULL);

return bn ? Qtrue : Qfalse;

}

public_key → aDH click to toggle source

Returns a new DH instance that carries just the public information, i.e. the prime p and the generator g, but no public/private key yet. Such a pair may be generated using DH#generate_key!. The “public key” needed for a key exchange with DH#compute_key is considered as per-session information and may be retrieved with DH#pub_key once a key pair has been generated. If the current instance already contains private information (and thus a valid public/private key pair), this information will no longer be present in the new instance generated by DH#public_key. This feature is helpful for publishing the Diffie-Hellman parameters without leaking any of the private per-session information.

Example¶ ↑

dh = OpenSSL::PKey::DH.new(2048) public_key = dh.public_key parameters = public_key.to_der

static VALUE ossl_dh_to_public_key(VALUE self) { DH *orig_dh, *dh; VALUE obj;

GetDH(self, orig_dh);
dh = DHparams_dup(orig_dh); /* err check perfomed by dh_instance */
obj = dh_instance(rb_obj_class(self), dh);
if (obj == Qfalse) {
    DH_free(dh);
    ossl_raise(eDHError, NULL);
}

return obj;

}

set_key(pub_key, priv_key) → self

Sets pub_key and priv_key for the DH instance. priv_key may be nil.

set_pqg(p, q, g) → self

Sets p, q, g to the DH instance.

to_der → aString click to toggle source

Encodes this DH to its DER encoding. Note that any existing per-session public/private keys will not get encoded, just the Diffie-Hellman parameters will be encoded.

static VALUE ossl_dh_to_der(VALUE self) { DH *dh; unsigned char *p; long len; VALUE str;

GetDH(self, dh);
if((len = i2d_DHparams(dh, NULL)) <= 0)
    ossl_raise(eDHError, NULL);
str = rb_str_new(0, len);
p = (unsigned char *)RSTRING_PTR(str);
if(i2d_DHparams(dh, &p) < 0)
    ossl_raise(eDHError, NULL);
ossl_str_adjust(str, p);

return str;

}

to_pem → aString

Encodes this DH to its PEM encoding. Note that any existing per-session public/private keys will not get encoded, just the Diffie-Hellman parameters will be encoded.

to_s → aString

Encodes this DH to its PEM encoding. Note that any existing per-session public/private keys will not get encoded, just the Diffie-Hellman parameters will be encoded.

to_text → aString click to toggle source

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

static VALUE ossl_dh_to_text(VALUE self) { DH *dh; BIO *out; VALUE str;

GetDH(self, dh);
if (!(out = BIO_new(BIO_s_mem()))) {
    ossl_raise(eDHError, NULL);
}
if (!DHparams_print(out, dh)) {
    BIO_free(out);
    ossl_raise(eDHError, NULL);
}
str = ossl_membio2str(out);

return str;

}