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Properly initialize AEAD cipher flags in OpenSSL backend #20853

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Properly initialize AEAD cipher flags in OpenSSL backend #20853

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7de1357
properly initialize AEAD cipher flags in OpenSSL backend
jordikroon Jan 6, 2026
59cba53
allow null AAD parameter in openssl_encrypt/decrypt
jordikroon Jan 7, 2026
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4 changes: 2 additions & 2 deletions ext/openssl/openssl.c
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Original file line number Diff line number Diff line change
Expand Up @@ -4481,7 +4481,7 @@ PHP_FUNCTION(openssl_encrypt)
zend_string *ret;
zval *tag = NULL;

if (zend_parse_parameters(ZEND_NUM_ARGS(), "sss|lszsl", &data, &data_len, &method, &method_len,
if (zend_parse_parameters(ZEND_NUM_ARGS(), "sss|lszs!l", &data, &data_len, &method, &method_len,
&password, &password_len, &options, &iv, &iv_len, &tag, &aad, &aad_len, &tag_len) == FAILURE) {
RETURN_THROWS();
}
Expand All @@ -4503,7 +4503,7 @@ PHP_FUNCTION(openssl_decrypt)
size_t data_len, method_len, password_len, iv_len = 0, tag_len = 0, aad_len = 0;
zend_string *ret;

if (zend_parse_parameters(ZEND_NUM_ARGS(), "sss|lss!s", &data, &data_len, &method, &method_len,
if (zend_parse_parameters(ZEND_NUM_ARGS(), "sss|lss!s!", &data, &data_len, &method, &method_len,
&password, &password_len, &options, &iv, &iv_len, &tag, &tag_len, &aad, &aad_len) == FAILURE) {
RETURN_THROWS();
}
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4 changes: 2 additions & 2 deletions ext/openssl/openssl.stub.php
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Original file line number Diff line number Diff line change
Expand Up @@ -662,9 +662,9 @@ function openssl_digest(string $data, string $digest_algo, bool $binary = false)
/**
* @param string $tag
*/
function openssl_encrypt(#[\SensitiveParameter] string $data, string $cipher_algo, #[\SensitiveParameter] string $passphrase, int $options = 0, string $iv = "", &$tag = null, string $aad = "", int $tag_length = 16): string|false {}
function openssl_encrypt(#[\SensitiveParameter] string $data, string $cipher_algo, #[\SensitiveParameter] string $passphrase, int $options = 0, string $iv = "", &$tag = null, ?string $aad = "", int $tag_length = 16): string|false {}

function openssl_decrypt(string $data, string $cipher_algo, #[\SensitiveParameter] string $passphrase, int $options = 0, string $iv = "", ?string $tag = null, string $aad = ""): string|false {}
function openssl_decrypt(string $data, string $cipher_algo, #[\SensitiveParameter] string $passphrase, int $options = 0, string $iv = "", ?string $tag = null, ?string $aad = ""): string|false {}

function openssl_cipher_iv_length(string $cipher_algo): int|false {}

Expand Down
6 changes: 3 additions & 3 deletions ext/openssl/openssl_arginfo.h
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11 changes: 10 additions & 1 deletion ext/openssl/openssl_backend_common.c
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Expand Up @@ -1637,6 +1637,13 @@ void php_openssl_load_cipher_mode(struct php_openssl_cipher_mode *mode, const EV
{
int cipher_mode = EVP_CIPHER_mode(cipher_type);
memset(mode, 0, sizeof(struct php_openssl_cipher_mode));

#if defined(EVP_CIPH_FLAG_AEAD_CIPHER)
if (EVP_CIPHER_flags(cipher_type) & EVP_CIPH_FLAG_AEAD_CIPHER) {
php_openssl_set_aead_flags(mode);
}
#endif
Comment on lines +1641 to +1645
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@bukka bukka Jan 12, 2026

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It would be better to add EVP_CIPH_SIV_MODE to the switch if exists and set the right mode if there are some differences.


switch (cipher_mode) {
case EVP_CIPH_GCM_MODE:
case EVP_CIPH_CCM_MODE:
Expand Down Expand Up @@ -1797,7 +1804,9 @@ zend_result php_openssl_cipher_update(const EVP_CIPHER *cipher_type,
return FAILURE;
}

if (mode->is_aead && !EVP_CipherUpdate(cipher_ctx, NULL, &i, (const unsigned char *) aad, (int) aad_len)) {
/* Only pass AAD to OpenSSL if caller provided it.
This makes NULL mean zero AAD items, while "" with len 0 means one empty AAD item. */
if (mode->is_aead && aad != NULL && !EVP_CipherUpdate(cipher_ctx, NULL, &i, (const unsigned char *)aad, (int)aad_len)) {
Comment on lines +1807 to +1809
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@bukka bukka Jan 12, 2026

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Is this for SIV or is this for all modes. I thought that empty string won't make difference but I guess it might.

In general allowing null should be fine for master so it's not really a problem. Just want to know the reasoning as I haven't checked this propertly.

php_openssl_store_errors();
php_error_docref(NULL, E_WARNING, "Setting of additional application data failed");
return FAILURE;
Expand Down
47 changes: 47 additions & 0 deletions ext/openssl/tests/gh20851_aad_empty.phpt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,47 @@
--TEST--
openssl: AES-256-SIV AEAD tag and AAD roundtrip
--EXTENSIONS--
openssl
--FILE--
<?php
$algo = 'aes-256-siv';
$key = str_repeat('1', 64);
$tag = '';
$aad = '';
$input = 'Hello world!';

$ciphertext = openssl_encrypt(
'Hello world!',
$algo,
$key,
OPENSSL_RAW_DATA,
'', // IV is empty for this cipher in PHP
$tag, // gets filled with the SIV
$aad,
16
);

echo 'input: ' . $input . PHP_EOL;
echo 'tag: ' . bin2hex($tag) . PHP_EOL;
echo 'ciphertext: ' . bin2hex($ciphertext) . PHP_EOL;
echo 'combined: ' . bin2hex($tag . $ciphertext) . PHP_EOL;

$dec = openssl_decrypt(
$ciphertext,
$algo,
$key,
OPENSSL_RAW_DATA,
'',
$tag,
$aad
);

echo 'decrypted: ' . var_export($dec, true) . PHP_EOL;
?>
--EXPECTF--
input: Hello world!
tag: f6c98e3e785947502a09994d2757f9c1
ciphertext: a430a41a9bc089fa45ad27be
combined: f6c98e3e785947502a09994d2757f9c1a430a41a9bc089fa45ad27be
decrypted: 'Hello world!'

47 changes: 47 additions & 0 deletions ext/openssl/tests/gh20851_aad_null.phpt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,47 @@
--TEST--
openssl: AES-256-SIV AEAD tag and AAD roundtrip
--EXTENSIONS--
openssl
--FILE--
<?php
$algo = 'aes-256-siv';
$key = str_repeat('1', 64);
$tag = '';
$aad = null;
$input = 'Hello world!';

$ciphertext = openssl_encrypt(
'Hello world!',
$algo,
$key,
OPENSSL_RAW_DATA,
'', // IV is empty for this cipher in PHP
$tag, // gets filled with the SIV
$aad,
16
);

echo 'input: ' . $input . PHP_EOL;
echo 'tag: ' . bin2hex($tag) . PHP_EOL;
echo 'ciphertext: ' . bin2hex($ciphertext) . PHP_EOL;
echo 'combined: ' . bin2hex($tag . $ciphertext) . PHP_EOL;

$dec = openssl_decrypt(
$ciphertext,
$algo,
$key,
OPENSSL_RAW_DATA,
'',
$tag,
$aad
);

echo 'decrypted: ' . var_export($dec, true) . PHP_EOL;
?>
--EXPECTF--
input: Hello world!
tag: c06f0df087e2784c5560ce5d0b378311
ciphertext: 72fffba74d7bc3ddcceeb6d1
combined: c06f0df087e2784c5560ce5d0b37831172fffba74d7bc3ddcceeb6d1
decrypted: 'Hello world!'

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