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Add EVP_PKEY KEM operations #1062

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1 change: 1 addition & 0 deletions ext/openssl/extconf.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -163,6 +163,7 @@ def find_openssl_library
have_func("EVP_MD_CTX_get_pkey_ctx(NULL)", evp_h)
have_func("EVP_PKEY_eq(NULL, NULL)", evp_h)
have_func("EVP_PKEY_dup(NULL)", evp_h)
have_func("EVP_PKEY_encapsulate_init(NULL, NULL)", evp_h)

# added in 3.2.0
have_func("SSL_get0_group_name(NULL)", ssl_h)
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120 changes: 120 additions & 0 deletions ext/openssl/ossl_pkey.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1514,6 +1514,122 @@ ossl_pkey_derive(int argc, VALUE *argv, VALUE self)
return str;
}

#ifdef HAVE_EVP_PKEY_ENCAPSULATE_INIT
/*
* call-seq:
* pkey.encapsulate -> [ciphertext, shared_secret]
*
* Performs a key encapsulation operation using the public components of
* _pkey_.
*
* See also the man page EVP_PKEY_encapsulate(3).
*/
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static VALUE
ossl_pkey_encapsulate(VALUE self)
{
EVP_PKEY *pkey;
EVP_PKEY_CTX *ctx;
VALUE ciphertext, shared_secret;
size_t ciphertextlen, shared_secretlen;
int state;

GetPKey(self, pkey);
ctx = EVP_PKEY_CTX_new(pkey, /* engine */NULL);
if (!ctx)
ossl_raise(ePKeyError, "EVP_PKEY_CTX_new");
if (EVP_PKEY_encapsulate_init(ctx, NULL) <= 0) {
EVP_PKEY_CTX_free(ctx);
ossl_raise(ePKeyError, "EVP_PKEY_encapsulate_init");
}
if (EVP_PKEY_encapsulate(ctx, NULL, &ciphertextlen, NULL, &shared_secretlen) <= 0) {
EVP_PKEY_CTX_free(ctx);
ossl_raise(ePKeyError, "EVP_PKEY_encapsulate");
}
if (ciphertextlen > LONG_MAX || shared_secretlen > LONG_MAX) {
EVP_PKEY_CTX_free(ctx);
rb_raise(ePKeyError, "encapsulated data would be too large");
}
ciphertext = ossl_str_new(NULL, (long)ciphertextlen, &state);
if (state) {
EVP_PKEY_CTX_free(ctx);
rb_jump_tag(state);
}
shared_secret = ossl_str_new(NULL, (long)shared_secretlen, &state);
if (state) {
EVP_PKEY_CTX_free(ctx);
rb_jump_tag(state);
}
if (EVP_PKEY_encapsulate(ctx,
(unsigned char *)RSTRING_PTR(ciphertext),
&ciphertextlen,
(unsigned char *)RSTRING_PTR(shared_secret),
&shared_secretlen) <= 0) {
EVP_PKEY_CTX_free(ctx);
ossl_raise(ePKeyError, "EVP_PKEY_encapsulate");
}
EVP_PKEY_CTX_free(ctx);
rb_str_set_len(ciphertext, ciphertextlen);
rb_str_set_len(shared_secret, shared_secretlen);
return rb_assoc_new(ciphertext, shared_secret);
}

/*
* call-seq:
* pkey.decapsulate(ciphertext) -> shared_secret
*
* Performs a key decapsulation operation using the private components of
* _pkey_.
*
* See also the man page EVP_PKEY_decapsulate(3).
*/
static VALUE
ossl_pkey_decapsulate(VALUE self, VALUE ciphertext)
{
EVP_PKEY *pkey;
EVP_PKEY_CTX *ctx;
VALUE shared_secret;
size_t shared_secretlen;
int state;

GetPKey(self, pkey);
StringValue(ciphertext);

ctx = EVP_PKEY_CTX_new(pkey, /* engine */NULL);
if (!ctx)
ossl_raise(ePKeyError, "EVP_PKEY_CTX_new");
if (EVP_PKEY_decapsulate_init(ctx, NULL) <= 0) {
EVP_PKEY_CTX_free(ctx);
ossl_raise(ePKeyError, "EVP_PKEY_decapsulate_init");
}
if (EVP_PKEY_decapsulate(ctx, NULL, &shared_secretlen,
(unsigned char *)RSTRING_PTR(ciphertext),
RSTRING_LEN(ciphertext)) <= 0) {
EVP_PKEY_CTX_free(ctx);
ossl_raise(ePKeyError, "EVP_PKEY_decapsulate");
}
if (shared_secretlen > LONG_MAX) {
EVP_PKEY_CTX_free(ctx);
rb_raise(ePKeyError, "decapsulated data would be too large");
}
shared_secret = ossl_str_new(NULL, (long)shared_secretlen, &state);
if (state) {
EVP_PKEY_CTX_free(ctx);
rb_jump_tag(state);
}
if (EVP_PKEY_decapsulate(ctx,
(unsigned char *)RSTRING_PTR(shared_secret),
&shared_secretlen,
(unsigned char *)RSTRING_PTR(ciphertext),
RSTRING_LEN(ciphertext)) <= 0) {
EVP_PKEY_CTX_free(ctx);
ossl_raise(ePKeyError, "EVP_PKEY_decapsulate");
}
EVP_PKEY_CTX_free(ctx);
rb_str_set_len(shared_secret, shared_secretlen);
return shared_secret;
}
#endif

/*
* call-seq:
* pkey.encrypt(data [, options]) -> string
Expand Down Expand Up @@ -1769,6 +1885,10 @@ Init_ossl_pkey(void)
rb_define_method(cPKey, "verify_raw", ossl_pkey_verify_raw, -1);
rb_define_method(cPKey, "verify_recover", ossl_pkey_verify_recover, -1);
rb_define_method(cPKey, "derive", ossl_pkey_derive, -1);
#ifdef HAVE_EVP_PKEY_ENCAPSULATE_INIT
rb_define_method(cPKey, "encapsulate", ossl_pkey_encapsulate, 0);
rb_define_method(cPKey, "decapsulate", ossl_pkey_decapsulate, 1);
#endif
rb_define_method(cPKey, "encrypt", ossl_pkey_encrypt, -1);
rb_define_method(cPKey, "decrypt", ossl_pkey_decrypt, -1);

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22 changes: 22 additions & 0 deletions test/openssl/test_pkey.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -285,6 +285,28 @@ def test_ml_dsa
assert_equal(true, pub3.verify(nil, sig, "data"))
end

def test_ml_kem
# EVP_PKEY KEM APIs were added in OpenSSL 3.0.
omit "ML-KEM is not supported" unless openssl?(3, 5, 0)

pkey = OpenSSL::PKey.generate_key("ML-KEM-768")
raw_public_key = pkey.raw_public_key
raw_private_key = pkey.raw_private_key

assert_match(/type_name=ML-KEM-768/, pkey.inspect)
assert_equal(1184, raw_public_key.bytesize)
assert_equal(2400, raw_private_key.bytesize)

pubkey = OpenSSL::PKey.new_raw_public_key("ML-KEM-768", raw_public_key)
ciphertext, shared_secret = pubkey.encapsulate
assert_equal(1088, ciphertext.bytesize)
assert_equal(32, shared_secret.bytesize)
assert_equal(shared_secret, pkey.decapsulate(ciphertext))

privkey = OpenSSL::PKey.new_raw_private_key("ML-KEM-768", raw_private_key)
assert_equal(shared_secret, privkey.decapsulate(ciphertext))
end

def test_raw_initialize_errors
assert_raise(OpenSSL::PKey::PKeyError) { OpenSSL::PKey.new_raw_private_key("foo123", "xxx") }
assert_raise(OpenSSL::PKey::PKeyError) { OpenSSL::PKey.new_raw_private_key("ED25519", "xxx") }
Expand Down