A serialized PHP value, in the format used by PHP's built-in serialize and
unserialize functions. This format closely mirrors PHP's data model:
it supports all of PHP's scalar types (NULL, booleans, numbers, strings),
associative arrays, objects, and recursive data structures using references.
The only PHP values not supported by this format are resources,
which usually correspond to native file or connection handles and cannot be
meaningfully serialized.
There is no official documentation for this data format;
this spec was created based on the PHP source code and the behavior of
serialize/unserialize. PHP makes no guarantees about compatibility of
serialized data between PHP versions, but in practice, the format has
remained fully backwards-compatible - values serialized by an older
PHP version can be unserialized on any newer PHP version.
This spec supports serialized values from PHP 7.3 or any earlier version.
This page hosts a formal specification of Serialized PHP value using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.
digraph {
rankdir=LR;
node [shape=plaintext];
subgraph cluster__php_serialized_value {
label="PhpSerializedValue";
graph[style=dotted];
php_serialized_value__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="type_pos">0</TD><TD PORT="type_size">1</TD><TD>u1→ValueType</TD><TD PORT="type_type">type</TD></TR>
<TR><TD PORT="contents_pos">1</TD><TD PORT="contents_size">...</TD><TD>switch (type)</TD><TD PORT="contents_type">contents</TD></TR>
</TABLE>>];
php_serialized_value__seq_contents_switch [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#F0F2E4">case</TD><TD BGCOLOR="#F0F2E4">type</TD></TR>
<TR><TD>:value_type_custom_serialized_object</TD><TD PORT="case0">CustomSerializedObjectContents</TD></TR>
<TR><TD>:value_type_php_3_object</TD><TD PORT="case1">Php3ObjectContents</TD></TR>
<TR><TD>:value_type_object</TD><TD PORT="case2">ObjectContents</TD></TR>
<TR><TD>:value_type_variable_reference</TD><TD PORT="case3">IntContents</TD></TR>
<TR><TD>:value_type_php_6_string</TD><TD PORT="case4">StringContents</TD></TR>
<TR><TD>:value_type_float</TD><TD PORT="case5">FloatContents</TD></TR>
<TR><TD>:value_type_object_reference</TD><TD PORT="case6">IntContents</TD></TR>
<TR><TD>:value_type_null</TD><TD PORT="case7">NullContents</TD></TR>
<TR><TD>:value_type_bool</TD><TD PORT="case8">BoolContents</TD></TR>
<TR><TD>:value_type_int</TD><TD PORT="case9">IntContents</TD></TR>
<TR><TD>:value_type_array</TD><TD PORT="case10">ArrayContents</TD></TR>
<TR><TD>:value_type_string</TD><TD PORT="case11">StringContents</TD></TR>
</TABLE>>];
subgraph cluster__count_prefixed_mapping {
label="PhpSerializedValue::CountPrefixedMapping";
graph[style=dotted];
count_prefixed_mapping__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="num_entries_dec_pos">0</TD><TD PORT="num_entries_dec_size">...</TD><TD>str(term=58, ASCII)</TD><TD PORT="num_entries_dec_type">num_entries_dec</TD></TR>
<TR><TD PORT="opening_brace_pos">...</TD><TD PORT="opening_brace_size">1</TD><TD></TD><TD PORT="opening_brace_type">opening_brace</TD></TR>
<TR><TD PORT="entries_pos">...</TD><TD PORT="entries_size">...</TD><TD>MappingEntry</TD><TD PORT="entries_type">entries</TD></TR>
<TR><TD COLSPAN="4" PORT="entries__repeat">repeat num_entries times</TD></TR>
<TR><TD PORT="closing_brace_pos">...</TD><TD PORT="closing_brace_size">1</TD><TD></TD><TD PORT="closing_brace_type">closing_brace</TD></TR>
</TABLE>>];
count_prefixed_mapping__inst__num_entries [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">id</TD><TD BGCOLOR="#E0FFE0">value</TD></TR>
<TR><TD>num_entries</TD><TD>num_entries_dec.to_i</TD></TR>
</TABLE>>];
}
subgraph cluster__float_contents {
label="PhpSerializedValue::FloatContents";
graph[style=dotted];
float_contents__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="colon_pos">0</TD><TD PORT="colon_size">1</TD><TD></TD><TD PORT="colon_type">colon</TD></TR>
<TR><TD PORT="value_dec_pos">1</TD><TD PORT="value_dec_size">...</TD><TD>str(term=59, ASCII)</TD><TD PORT="value_dec_type">value_dec</TD></TR>
</TABLE>>];
}
subgraph cluster__length_prefixed_quoted_string {
label="PhpSerializedValue::LengthPrefixedQuotedString";
graph[style=dotted];
length_prefixed_quoted_string__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="len_data_dec_pos">0</TD><TD PORT="len_data_dec_size">...</TD><TD>str(term=58, ASCII)</TD><TD PORT="len_data_dec_type">len_data_dec</TD></TR>
<TR><TD PORT="opening_quote_pos">...</TD><TD PORT="opening_quote_size">1</TD><TD></TD><TD PORT="opening_quote_type">opening_quote</TD></TR>
<TR><TD PORT="data_pos">...</TD><TD PORT="data_size">len_data</TD><TD></TD><TD PORT="data_type">data</TD></TR>
<TR><TD PORT="closing_quote_pos">...</TD><TD PORT="closing_quote_size">1</TD><TD></TD><TD PORT="closing_quote_type">closing_quote</TD></TR>
</TABLE>>];
length_prefixed_quoted_string__inst__len_data [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">id</TD><TD BGCOLOR="#E0FFE0">value</TD></TR>
<TR><TD>len_data</TD><TD>len_data_dec.to_i</TD></TR>
</TABLE>>];
}
subgraph cluster__object_contents {
label="PhpSerializedValue::ObjectContents";
graph[style=dotted];
object_contents__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="colon1_pos">0</TD><TD PORT="colon1_size">1</TD><TD></TD><TD PORT="colon1_type">colon1</TD></TR>
<TR><TD PORT="class_name_pos">1</TD><TD PORT="class_name_size">...</TD><TD>LengthPrefixedQuotedString</TD><TD PORT="class_name_type">class_name</TD></TR>
<TR><TD PORT="colon2_pos">...</TD><TD PORT="colon2_size">1</TD><TD></TD><TD PORT="colon2_type">colon2</TD></TR>
<TR><TD PORT="properties_pos">...</TD><TD PORT="properties_size">...</TD><TD>CountPrefixedMapping</TD><TD PORT="properties_type">properties</TD></TR>
</TABLE>>];
}
subgraph cluster__array_contents {
label="PhpSerializedValue::ArrayContents";
graph[style=dotted];
array_contents__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="colon_pos">0</TD><TD PORT="colon_size">1</TD><TD></TD><TD PORT="colon_type">colon</TD></TR>
<TR><TD PORT="elements_pos">1</TD><TD PORT="elements_size">...</TD><TD>CountPrefixedMapping</TD><TD PORT="elements_type">elements</TD></TR>
</TABLE>>];
}
subgraph cluster__custom_serialized_object_contents {
label="PhpSerializedValue::CustomSerializedObjectContents";
graph[style=dotted];
custom_serialized_object_contents__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="colon1_pos">0</TD><TD PORT="colon1_size">1</TD><TD></TD><TD PORT="colon1_type">colon1</TD></TR>
<TR><TD PORT="class_name_pos">1</TD><TD PORT="class_name_size">...</TD><TD>LengthPrefixedQuotedString</TD><TD PORT="class_name_type">class_name</TD></TR>
<TR><TD PORT="colon2_pos">...</TD><TD PORT="colon2_size">1</TD><TD></TD><TD PORT="colon2_type">colon2</TD></TR>
<TR><TD PORT="len_data_dec_pos">...</TD><TD PORT="len_data_dec_size">...</TD><TD>str(term=58, ASCII)</TD><TD PORT="len_data_dec_type">len_data_dec</TD></TR>
<TR><TD PORT="opening_brace_pos">...</TD><TD PORT="opening_brace_size">1</TD><TD></TD><TD PORT="opening_brace_type">opening_brace</TD></TR>
<TR><TD PORT="data_pos">...</TD><TD PORT="data_size">len_data</TD><TD></TD><TD PORT="data_type">data</TD></TR>
<TR><TD PORT="closing_quote_pos">...</TD><TD PORT="closing_quote_size">1</TD><TD></TD><TD PORT="closing_quote_type">closing_quote</TD></TR>
</TABLE>>];
custom_serialized_object_contents__inst__len_data [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">id</TD><TD BGCOLOR="#E0FFE0">value</TD></TR>
<TR><TD>len_data</TD><TD>len_data_dec.to_i</TD></TR>
</TABLE>>];
}
subgraph cluster__null_contents {
label="PhpSerializedValue::NullContents";
graph[style=dotted];
null_contents__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="semicolon_pos">0</TD><TD PORT="semicolon_size">1</TD><TD></TD><TD PORT="semicolon_type">semicolon</TD></TR>
</TABLE>>];
}
subgraph cluster__php_3_object_contents {
label="PhpSerializedValue::Php3ObjectContents";
graph[style=dotted];
php_3_object_contents__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="colon_pos">0</TD><TD PORT="colon_size">1</TD><TD></TD><TD PORT="colon_type">colon</TD></TR>
<TR><TD PORT="properties_pos">1</TD><TD PORT="properties_size">...</TD><TD>CountPrefixedMapping</TD><TD PORT="properties_type">properties</TD></TR>
</TABLE>>];
}
subgraph cluster__bool_contents {
label="PhpSerializedValue::BoolContents";
graph[style=dotted];
bool_contents__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="colon_pos">0</TD><TD PORT="colon_size">1</TD><TD></TD><TD PORT="colon_type">colon</TD></TR>
<TR><TD PORT="value_dec_pos">1</TD><TD PORT="value_dec_size">1</TD><TD>u1→BoolValue</TD><TD PORT="value_dec_type">value_dec</TD></TR>
<TR><TD PORT="semicolon_pos">2</TD><TD PORT="semicolon_size">1</TD><TD></TD><TD PORT="semicolon_type">semicolon</TD></TR>
</TABLE>>];
bool_contents__inst__value [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">id</TD><TD BGCOLOR="#E0FFE0">value</TD></TR>
<TR><TD>value</TD><TD>value_dec == :bool_value_true</TD></TR>
</TABLE>>];
}
subgraph cluster__string_contents {
label="PhpSerializedValue::StringContents";
graph[style=dotted];
string_contents__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="colon_pos">0</TD><TD PORT="colon_size">1</TD><TD></TD><TD PORT="colon_type">colon</TD></TR>
<TR><TD PORT="string_pos">1</TD><TD PORT="string_size">...</TD><TD>LengthPrefixedQuotedString</TD><TD PORT="string_type">string</TD></TR>
<TR><TD PORT="semicolon_pos">...</TD><TD PORT="semicolon_size">1</TD><TD></TD><TD PORT="semicolon_type">semicolon</TD></TR>
</TABLE>>];
string_contents__inst__value [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">id</TD><TD BGCOLOR="#E0FFE0">value</TD></TR>
<TR><TD>value</TD><TD>string.data</TD></TR>
</TABLE>>];
}
subgraph cluster__int_contents {
label="PhpSerializedValue::IntContents";
graph[style=dotted];
int_contents__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="colon_pos">0</TD><TD PORT="colon_size">1</TD><TD></TD><TD PORT="colon_type">colon</TD></TR>
<TR><TD PORT="value_dec_pos">1</TD><TD PORT="value_dec_size">...</TD><TD>str(term=59, ASCII)</TD><TD PORT="value_dec_type">value_dec</TD></TR>
</TABLE>>];
int_contents__inst__value [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">id</TD><TD BGCOLOR="#E0FFE0">value</TD></TR>
<TR><TD>value</TD><TD>value_dec.to_i</TD></TR>
</TABLE>>];
}
subgraph cluster__mapping_entry {
label="PhpSerializedValue::MappingEntry";
graph[style=dotted];
mapping_entry__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="key_pos">0</TD><TD PORT="key_size">...</TD><TD>PhpSerializedValue</TD><TD PORT="key_type">key</TD></TR>
<TR><TD PORT="value_pos">...</TD><TD PORT="value_size">...</TD><TD>PhpSerializedValue</TD><TD PORT="value_type">value</TD></TR>
</TABLE>>];
}
}
php_serialized_value__seq:contents_type -> php_serialized_value__seq_contents_switch [style=bold];
php_serialized_value__seq_contents_switch:case0 -> custom_serialized_object_contents__seq [style=bold];
php_serialized_value__seq_contents_switch:case1 -> php_3_object_contents__seq [style=bold];
php_serialized_value__seq_contents_switch:case2 -> object_contents__seq [style=bold];
php_serialized_value__seq_contents_switch:case3 -> int_contents__seq [style=bold];
php_serialized_value__seq_contents_switch:case4 -> string_contents__seq [style=bold];
php_serialized_value__seq_contents_switch:case5 -> float_contents__seq [style=bold];
php_serialized_value__seq_contents_switch:case6 -> int_contents__seq [style=bold];
php_serialized_value__seq_contents_switch:case7 -> null_contents__seq [style=bold];
php_serialized_value__seq_contents_switch:case8 -> bool_contents__seq [style=bold];
php_serialized_value__seq_contents_switch:case9 -> int_contents__seq [style=bold];
php_serialized_value__seq_contents_switch:case10 -> array_contents__seq [style=bold];
php_serialized_value__seq_contents_switch:case11 -> string_contents__seq [style=bold];
php_serialized_value__seq:type_type -> php_serialized_value__seq:contents_type [color="#404040"];
count_prefixed_mapping__seq:entries_type -> mapping_entry__seq [style=bold];
count_prefixed_mapping__inst__num_entries:num_entries_type -> count_prefixed_mapping__seq:entries__repeat [color="#404040"];
count_prefixed_mapping__seq:num_entries_dec_type -> count_prefixed_mapping__inst__num_entries [color="#404040"];
length_prefixed_quoted_string__inst__len_data:len_data_type -> length_prefixed_quoted_string__seq:data_size [color="#404040"];
length_prefixed_quoted_string__seq:len_data_dec_type -> length_prefixed_quoted_string__inst__len_data [color="#404040"];
object_contents__seq:class_name_type -> length_prefixed_quoted_string__seq [style=bold];
object_contents__seq:properties_type -> count_prefixed_mapping__seq [style=bold];
array_contents__seq:elements_type -> count_prefixed_mapping__seq [style=bold];
custom_serialized_object_contents__seq:class_name_type -> length_prefixed_quoted_string__seq [style=bold];
custom_serialized_object_contents__inst__len_data:len_data_type -> custom_serialized_object_contents__seq:data_size [color="#404040"];
custom_serialized_object_contents__seq:len_data_dec_type -> custom_serialized_object_contents__inst__len_data [color="#404040"];
php_3_object_contents__seq:properties_type -> count_prefixed_mapping__seq [style=bold];
bool_contents__seq:value_dec_type -> bool_contents__inst__value [color="#404040"];
string_contents__seq:string_type -> length_prefixed_quoted_string__seq [style=bold];
length_prefixed_quoted_string__seq:data_type -> string_contents__inst__value [color="#404040"];
int_contents__seq:value_dec_type -> int_contents__inst__value [color="#404040"];
mapping_entry__seq:key_type -> php_serialized_value__seq [style=bold];
mapping_entry__seq:value_type -> php_serialized_value__seq [style=bold];
}