class OpenSSL::PKey::DH
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 toDH#compute_key
. - DH#priv_key
-
The per-session private key, an
OpenSSL::BN
.
Example of a key exchange¶ ↑
# you may send the parameters (der) and own public key (pub1) publicly # to the participating party dh1 = OpenSSL::PKey::DH.new(2048) der = dh1.to_der pub1 = dh1.pub_key # the other party generates its per-session key pair dhparams = OpenSSL::PKey::DH.new(der) dh2 = OpenSSL::PKey.generate_key(dhparams) pub2 = dh2.pub_key symm_key1 = dh1.compute_key(pub2) symm_key2 = dh2.compute_key(pub1) puts symm_key1 == symm_key2 # => true
Public Class Methods
Creates a new DH
instance from scratch by generating random parameters and a key pair.
See also OpenSSL::PKey.generate_parameters
and OpenSSL::PKey.generate_key
.
size
-
The desired key size in bits.
generator
-
The generator.
# File openssl/lib/openssl/pkey.rb, line 118 def generate(size, generator = 2, &blk) dhparams = OpenSSL::PKey.generate_parameters("DH", { "dh_paramgen_prime_len" => size, "dh_paramgen_generator" => generator, }, &blk) OpenSSL::PKey.generate_key(dhparams) end
Creates a new instance of OpenSSL::PKey::DH
.
If called without arguments, an empty instance without any parameter or key components is created. Use set_pqg
to manually set the parameters afterwards (and optionally set_key
to set private and public key components).
If a String is given, tries to parse it as a DER- or PEM- encoded parameters. See also OpenSSL::PKey.read
which can parse keys of any kinds.
The DH.new
(size [, generator]) form is an alias of DH.generate
.
string
-
A String that contains the DER or PEM encoded key.
size
-
See
DH.generate
. generator
-
See
DH.generate
.
Examples:
# Creating an instance from scratch # Note that this is deprecated and will not work on OpenSSL 3.0 or later. dh = OpenSSL::PKey::DH.new dh.set_pqg(bn_p, nil, bn_g) # Generating a parameters and a key pair dh = OpenSSL::PKey::DH.new(2048) # An alias of OpenSSL::PKey::DH.generate(2048) # Reading DH parameters dh_params = OpenSSL::PKey::DH.new(File.read('parameters.pem')) # loads parameters only dh = OpenSSL::PKey.generate_key(dh_params) # generates a key pair
static VALUE ossl_dh_initialize(int argc, VALUE *argv, VALUE self) { EVP_PKEY *pkey; int type; DH *dh; BIO *in = NULL; VALUE arg; TypedData_Get_Struct(self, EVP_PKEY, &ossl_evp_pkey_type, pkey); if (pkey) rb_raise(rb_eTypeError, "pkey already initialized"); /* The DH.new(size, generator) form is handled by lib/openssl/pkey.rb */ if (rb_scan_args(argc, argv, "01", &arg) == 0) { dh = DH_new(); if (!dh) ossl_raise(eDHError, "DH_new"); goto legacy; } arg = ossl_to_der_if_possible(arg); in = ossl_obj2bio(&arg); /* * On OpenSSL <= 1.1.1 and current versions of LibreSSL, the generic * routine does not support DER-encoded parameters */ dh = d2i_DHparams_bio(in, NULL); if (dh) goto legacy; OSSL_BIO_reset(in); pkey = ossl_pkey_read_generic(in, Qnil); BIO_free(in); if (!pkey) ossl_raise(eDHError, "could not parse pkey"); type = EVP_PKEY_base_id(pkey); if (type != EVP_PKEY_DH) { EVP_PKEY_free(pkey); rb_raise(eDHError, "incorrect pkey type: %s", OBJ_nid2sn(type)); } RTYPEDDATA_DATA(self) = pkey; return self; legacy: BIO_free(in); pkey = EVP_PKEY_new(); if (!pkey || EVP_PKEY_assign_DH(pkey, dh) != 1) { EVP_PKEY_free(pkey); DH_free(dh); ossl_raise(eDHError, "EVP_PKEY_assign_DH"); } RTYPEDDATA_DATA(self) = pkey; return self; }
Public Instance Methods
Returns a String containing a shared secret computed from the other party’s public value.
This method is provided for backwards compatibility, and calls derive
internally.
Parameters¶ ↑
-
pub_bn is a
OpenSSL::BN
, not theDH
instance returned byDH#public_key
as that contains theDH
parameters only.
# File openssl/lib/openssl/pkey.rb, line 49 def compute_key(pub_bn) # FIXME: This is constructing an X.509 SubjectPublicKeyInfo and is very # inefficient obj = OpenSSL::ASN1.Sequence([ OpenSSL::ASN1.Sequence([ OpenSSL::ASN1.ObjectId("dhKeyAgreement"), OpenSSL::ASN1.Sequence([ OpenSSL::ASN1.Integer(p), OpenSSL::ASN1.Integer(g), ]), ]), OpenSSL::ASN1.BitString(OpenSSL::ASN1.Integer(pub_bn).to_der), ]) derive(OpenSSL::PKey.read(obj.to_der)) end
Serializes the DH
parameters to a PEM-encoding.
Note that any existing per-session public/private keys will not get encoded, just the Diffie-Hellman parameters will be encoded.
PEM-encoded parameters will look like:
-----BEGIN DH PARAMETERS----- [...] -----END DH PARAMETERS-----
See also public_to_pem
(X.509 SubjectPublicKeyInfo) and private_to_pem
(PKCS #8 PrivateKeyInfo or EncryptedPrivateKeyInfo) for serialization with the private or public key components.
static VALUE ossl_dh_export(VALUE self) { OSSL_3_const 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; }
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.
Deprecated in version 3.0. This method is incompatible with OpenSSL
3.0.0 or later.
See also OpenSSL::PKey.generate_key
.
Example:
# DEPRECATED USAGE: This will not work on OpenSSL 3.0 or later dh0 = OpenSSL::PKey::DH.new(2048) dh = dh0.public_key # #public_key only copies the DH parameters (contrary to the name) dh.generate_key! puts dh.private? # => true puts dh0.pub_key == dh.pub_key #=> false # With OpenSSL::PKey.generate_key dh0 = OpenSSL::PKey::DH.new(2048) dh = OpenSSL::PKey.generate_key(dh0) puts dh0.pub_key == dh.pub_key #=> false
# File openssl/lib/openssl/pkey.rb, line 91 def generate_key! if OpenSSL::OPENSSL_VERSION_NUMBER >= 0x30000000 raise DHError, "OpenSSL::PKey::DH is immutable on OpenSSL 3.0; " \ "use OpenSSL::PKey.generate_key instead" end unless priv_key tmp = OpenSSL::PKey.generate_key(self) set_key(tmp.pub_key, tmp.priv_key) end self end
static VALUE ossl_dh_initialize_copy(VALUE self, VALUE other) { EVP_PKEY *pkey; DH *dh, *dh_other; const BIGNUM *pub, *priv; TypedData_Get_Struct(self, EVP_PKEY, &ossl_evp_pkey_type, pkey); if (pkey) rb_raise(rb_eTypeError, "pkey already initialized"); GetDH(other, dh_other); dh = DHparams_dup(dh_other); if (!dh) ossl_raise(eDHError, "DHparams_dup"); 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); } pkey = EVP_PKEY_new(); if (!pkey || EVP_PKEY_assign_DH(pkey, dh) != 1) { EVP_PKEY_free(pkey); DH_free(dh); ossl_raise(eDHError, "EVP_PKEY_assign_DH"); } RTYPEDDATA_DATA(self) = pkey; return self; }
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) { OSSL_3_const 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; }
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.
See also the man page EVP_PKEY_param_check(3).
static VALUE ossl_dh_check_params(VALUE self) { int ret; #ifdef HAVE_EVP_PKEY_CHECK EVP_PKEY *pkey; EVP_PKEY_CTX *pctx; GetPKey(self, pkey); pctx = EVP_PKEY_CTX_new(pkey, /* engine */NULL); if (!pctx) ossl_raise(eDHError, "EVP_PKEY_CTX_new"); ret = EVP_PKEY_param_check(pctx); EVP_PKEY_CTX_free(pctx); #else DH *dh; int codes; GetDH(self, dh); ret = DH_check(dh, &codes) == 1 && codes == 0; #endif if (ret == 1) return Qtrue; else { /* DH_check_ex() will put error entry on failure */ ossl_clear_error(); return Qfalse; } }
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) { OSSL_3_const 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 *)dh)) ? Qtrue : Qfalse; #else return bn ? Qtrue : Qfalse; #endif }
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) { OSSL_3_const DH *dh; const BIGNUM *bn; GetDH(self, dh); DH_get0_key(dh, &bn, NULL); return bn ? Qtrue : Qfalse; }
Returns a new DH
instance that carries just the DH parameters.
Contrary to the method name, the returned DH
object contains only parameters and not the public key.
This method is provided for backwards compatibility. In most cases, there is no need to call this method.
For the purpose of re-generating the key pair while keeping the parameters, check OpenSSL::PKey.generate_key
.
Example:
# OpenSSL::PKey::DH.generate by default generates a random key pair dh1 = OpenSSL::PKey::DH.generate(2048) p dh1.priv_key #=> #<OpenSSL::BN 1288347...> dhcopy = dh1.public_key p dhcopy.priv_key #=> nil
# File openssl/lib/openssl/pkey.rb, line 33 def public_key DH.new(to_der) end
Sets pub_key and priv_key for the DH
instance. priv_key may be nil
.
Sets p, q, g to the DH
instance.
Serializes the DH
parameters to a DER-encoding
Note that any existing per-session public/private keys will not get encoded, just the Diffie-Hellman parameters will be encoded.
See also public_to_der
(X.509 SubjectPublicKeyInfo) and private_to_der
(PKCS #8 PrivateKeyInfo or EncryptedPrivateKeyInfo) for serialization with the private or public key components.
static VALUE ossl_dh_to_der(VALUE self) { OSSL_3_const 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; }
Serializes the DH
parameters to a PEM-encoding.
Note that any existing per-session public/private keys will not get encoded, just the Diffie-Hellman parameters will be encoded.
PEM-encoded parameters will look like:
-----BEGIN DH PARAMETERS----- [...] -----END DH PARAMETERS-----
See also public_to_pem
(X.509 SubjectPublicKeyInfo) and private_to_pem
(PKCS #8 PrivateKeyInfo or EncryptedPrivateKeyInfo) for serialization with the private or public key components.
Serializes the DH
parameters to a PEM-encoding.
Note that any existing per-session public/private keys will not get encoded, just the Diffie-Hellman parameters will be encoded.
PEM-encoded parameters will look like:
-----BEGIN DH PARAMETERS----- [...] -----END DH PARAMETERS-----
See also public_to_pem
(X.509 SubjectPublicKeyInfo) and private_to_pem
(PKCS #8 PrivateKeyInfo or EncryptedPrivateKeyInfo) for serialization with the private or public key components.