61 lines
2.4 KiB
PHP
61 lines
2.4 KiB
PHP
<?php
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/**
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* Application-layer encryption for sensitive mobile API payloads.
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* AES-256-GCM (IV prepended) + HKDF-SHA256 session key from the Bearer token (info: qdb-aes).
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* Legacy CBC envelopes are accepted for compatibility with older app builds.
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*/
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function qdb_sensitive_envelope(string $plainJson, string $tokenHex): array {
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$key = hkdf_session_key_from_token($tokenHex);
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return [
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'encrypted' => true,
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'alg' => 'A256GCM',
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'payload' => base64_encode(qdb_aes256_gcm_encrypt_bytes($plainJson, $key)),
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];
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}
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function qdb_decrypt_sensitive_envelope(array $envelope, string $tokenHex): string {
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if (empty($envelope['encrypted']) || !isset($envelope['payload']) || !is_string($envelope['payload'])) {
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throw new InvalidArgumentException('Invalid encrypted envelope');
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}
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$raw = base64_decode($envelope['payload'], true);
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if ($raw === false) {
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throw new InvalidArgumentException('Invalid base64 payload');
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}
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$key = hkdf_session_key_from_token($tokenHex);
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$alg = isset($envelope['alg']) && is_string($envelope['alg']) ? $envelope['alg'] : 'A256CBC';
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return match ($alg) {
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'A256GCM' => qdb_aes256_gcm_decrypt_bytes($raw, $key),
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'A256CBC' => aes256_cbc_decrypt_bytes($raw, $key),
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default => throw new InvalidArgumentException('Unsupported encrypted envelope algorithm'),
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};
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}
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function qdb_aes256_gcm_encrypt_bytes(string $plain, string $key): string {
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$key = str_pad(substr($key, 0, 32), 32, "\0");
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$iv = random_bytes(12);
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$tag = '';
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$cipher = openssl_encrypt($plain, 'aes-256-gcm', $key, OPENSSL_RAW_DATA, $iv, $tag, '');
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if ($cipher === false || strlen($tag) !== 16) {
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throw new RuntimeException('openssl_encrypt failed');
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}
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return $iv . $cipher . $tag;
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}
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function qdb_aes256_gcm_decrypt_bytes(string $data, string $key): string {
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$ivLen = 12;
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$tagLen = 16;
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if (strlen($data) <= $ivLen + $tagLen) {
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throw new InvalidArgumentException('cipher too short');
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}
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$key = str_pad(substr($key, 0, 32), 32, "\0");
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$iv = substr($data, 0, $ivLen);
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$tag = substr($data, -$tagLen);
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$ct = substr($data, $ivLen, -$tagLen);
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$plain = openssl_decrypt($ct, 'aes-256-gcm', $key, OPENSSL_RAW_DATA, $iv, $tag, '');
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if ($plain === false) {
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throw new InvalidArgumentException('openssl_decrypt failed');
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}
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return $plain;
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}
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