blob: f4646ae13a719834993b2d0854c3bccfee37d2aa [file] [log] [blame]
/**
* This module describes the _digest APIs used in Phobos. All digests follow
* these APIs. Additionally, this module contains useful helper methods which
* can be used with every _digest type.
*
$(SCRIPT inhibitQuickIndex = 1;)
$(DIVC quickindex,
$(BOOKTABLE ,
$(TR $(TH Category) $(TH Functions)
)
$(TR $(TDNW Template API) $(TD $(MYREF isDigest) $(MYREF DigestType) $(MYREF hasPeek)
$(MYREF hasBlockSize)
$(MYREF ExampleDigest) $(MYREF _digest) $(MYREF hexDigest) $(MYREF makeDigest)
)
)
$(TR $(TDNW OOP API) $(TD $(MYREF Digest)
)
)
$(TR $(TDNW Helper functions) $(TD $(MYREF toHexString))
)
$(TR $(TDNW Implementation helpers) $(TD $(MYREF digestLength) $(MYREF WrapperDigest))
)
)
)
* APIs:
* There are two APIs for digests: The template API and the OOP API. The template API uses structs
* and template helpers like $(LREF isDigest). The OOP API implements digests as classes inheriting
* the $(LREF Digest) interface. All digests are named so that the template API struct is called "$(B x)"
* and the OOP API class is called "$(B x)Digest". For example we have $(D MD5) <--> $(D MD5Digest),
* $(D CRC32) <--> $(D CRC32Digest), etc.
*
* The template API is slightly more efficient. It does not have to allocate memory dynamically,
* all memory is allocated on the stack. The OOP API has to allocate in the finish method if no
* buffer was provided. If you provide a buffer to the OOP APIs finish function, it doesn't allocate,
* but the $(LREF Digest) classes still have to be created using $(D new) which allocates them using the GC.
*
* The OOP API is useful to change the _digest function and/or _digest backend at 'runtime'. The benefit here
* is that switching e.g. Phobos MD5Digest and an OpenSSLMD5Digest implementation is ABI compatible.
*
* If just one specific _digest type and backend is needed, the template API is usually a good fit.
* In this simplest case, the template API can even be used without templates: Just use the "$(B x)" structs
* directly.
*
* License: $(HTTP www.boost.org/LICENSE_1_0.txt, Boost License 1.0).
* Authors:
* Johannes Pfau
*
* Source: $(PHOBOSSRC std/_digest/_package.d)
*
* CTFE:
* Digests do not work in CTFE
*
* TODO:
* Digesting single bits (as opposed to bytes) is not implemented. This will be done as another
* template constraint helper (hasBitDigesting!T) and an additional interface (BitDigest)
*/
/* Copyright Johannes Pfau 2012.
* Distributed under the Boost Software License, Version 1.0.
* (See accompanying file LICENSE_1_0.txt or copy at
* http://www.boost.org/LICENSE_1_0.txt)
*/
module std.digest;
public import std.ascii : LetterCase;
import std.meta : allSatisfy;
import std.range.primitives;
import std.traits;
///
@system unittest
{
import std.digest.crc;
//Simple example
char[8] hexHash = hexDigest!CRC32("The quick brown fox jumps over the lazy dog");
assert(hexHash == "39A34F41");
//Simple example, using the API manually
CRC32 context = makeDigest!CRC32();
context.put(cast(ubyte[])"The quick brown fox jumps over the lazy dog");
ubyte[4] hash = context.finish();
assert(toHexString(hash) == "39A34F41");
}
///
@system unittest
{
//Generating the hashes of a file, idiomatic D way
import std.digest.crc, std.digest.md, std.digest.sha;
import std.stdio;
// Digests a file and prints the result.
void digestFile(Hash)(string filename)
if (isDigest!Hash)
{
auto file = File(filename);
auto result = digest!Hash(file.byChunk(4096 * 1024));
writefln("%s (%s) = %s", Hash.stringof, filename, toHexString(result));
}
void main(string[] args)
{
foreach (name; args[1 .. $])
{
digestFile!MD5(name);
digestFile!SHA1(name);
digestFile!CRC32(name);
}
}
}
///
@system unittest
{
//Generating the hashes of a file using the template API
import std.digest.crc, std.digest.md, std.digest.sha;
import std.stdio;
// Digests a file and prints the result.
void digestFile(Hash)(ref Hash hash, string filename)
if (isDigest!Hash)
{
File file = File(filename);
//As digests imlement OutputRange, we could use std.algorithm.copy
//Let's do it manually for now
foreach (buffer; file.byChunk(4096 * 1024))
hash.put(buffer);
auto result = hash.finish();
writefln("%s (%s) = %s", Hash.stringof, filename, toHexString(result));
}
void uMain(string[] args)
{
MD5 md5;
SHA1 sha1;
CRC32 crc32;
md5.start();
sha1.start();
crc32.start();
foreach (arg; args[1 .. $])
{
digestFile(md5, arg);
digestFile(sha1, arg);
digestFile(crc32, arg);
}
}
}
///
@system unittest
{
import std.digest.crc, std.digest.md, std.digest.sha;
import std.stdio;
// Digests a file and prints the result.
void digestFile(Digest hash, string filename)
{
File file = File(filename);
//As digests implement OutputRange, we could use std.algorithm.copy
//Let's do it manually for now
foreach (buffer; file.byChunk(4096 * 1024))
hash.put(buffer);
ubyte[] result = hash.finish();
writefln("%s (%s) = %s", typeid(hash).toString(), filename, toHexString(result));
}
void umain(string[] args)
{
auto md5 = new MD5Digest();
auto sha1 = new SHA1Digest();
auto crc32 = new CRC32Digest();
foreach (arg; args[1 .. $])
{
digestFile(md5, arg);
digestFile(sha1, arg);
digestFile(crc32, arg);
}
}
}
version (StdDdoc)
version = ExampleDigest;
version (ExampleDigest)
{
/**
* This documents the general structure of a Digest in the template API.
* All digest implementations should implement the following members and therefore pass
* the $(LREF isDigest) test.
*
* Note:
* $(UL
* $(LI A digest must be a struct (value type) to pass the $(LREF isDigest) test.)
* $(LI A digest passing the $(LREF isDigest) test is always an $(D OutputRange))
* )
*/
struct ExampleDigest
{
public:
/**
* Use this to feed the digest with data.
* Also implements the $(REF isOutputRange, std,range,primitives)
* interface for $(D ubyte) and $(D const(ubyte)[]).
* The following usages of $(D put) must work for any type which
* passes $(LREF isDigest):
* Example:
* ----
* ExampleDigest dig;
* dig.put(cast(ubyte) 0); //single ubyte
* dig.put(cast(ubyte) 0, cast(ubyte) 0); //variadic
* ubyte[10] buf;
* dig.put(buf); //buffer
* ----
*/
@trusted void put(scope const(ubyte)[] data...)
{
}
/**
* This function is used to (re)initialize the digest.
* It must be called before using the digest and it also works as a 'reset' function
* if the digest has already processed data.
*/
@trusted void start()
{
}
/**
* The finish function returns the final hash sum and resets the Digest.
*
* Note:
* The actual type returned by finish depends on the digest implementation.
* $(D ubyte[16]) is just used as an example. It is guaranteed that the type is a
* static array of ubytes.
*
* $(UL
* $(LI Use $(LREF DigestType) to obtain the actual return type.)
* $(LI Use $(LREF digestLength) to obtain the length of the ubyte array.)
* )
*/
@trusted ubyte[16] finish()
{
return (ubyte[16]).init;
}
}
}
///
@system unittest
{
//Using the OutputRange feature
import std.algorithm.mutation : copy;
import std.digest.md;
import std.range : repeat;
auto oneMillionRange = repeat!ubyte(cast(ubyte)'a', 1000000);
auto ctx = makeDigest!MD5();
copy(oneMillionRange, &ctx); //Note: You must pass a pointer to copy!
assert(ctx.finish().toHexString() == "7707D6AE4E027C70EEA2A935C2296F21");
}
/**
* Use this to check if a type is a digest. See $(LREF ExampleDigest) to see what
* a type must provide to pass this check.
*
* Note:
* This is very useful as a template constraint (see examples)
*
* BUGS:
* $(UL
* $(LI Does not yet verify that put takes scope parameters.)
* $(LI Should check that finish() returns a ubyte[num] array)
* )
*/
template isDigest(T)
{
import std.range : isOutputRange;
enum bool isDigest = isOutputRange!(T, const(ubyte)[]) && isOutputRange!(T, ubyte) &&
is(T == struct) &&
is(typeof(
{
T dig = void; //Can define
dig.put(cast(ubyte) 0, cast(ubyte) 0); //varags
dig.start(); //has start
auto value = dig.finish(); //has finish
}));
}
///
@system unittest
{
import std.digest.crc;
static assert(isDigest!CRC32);
}
///
@system unittest
{
import std.digest.crc;
void myFunction(T)()
if (isDigest!T)
{
T dig;
dig.start();
auto result = dig.finish();
}
myFunction!CRC32();
}
/**
* Use this template to get the type which is returned by a digest's $(LREF finish) method.
*/
template DigestType(T)
{
static if (isDigest!T)
{
alias DigestType =
ReturnType!(typeof(
{
T dig = void;
return dig.finish();
}));
}
else
static assert(false, T.stringof ~ " is not a digest! (fails isDigest!T)");
}
///
@system unittest
{
import std.digest.crc;
assert(is(DigestType!(CRC32) == ubyte[4]));
}
///
@system unittest
{
import std.digest.crc;
CRC32 dig;
dig.start();
DigestType!CRC32 result = dig.finish();
}
/**
* Used to check if a digest supports the $(D peek) method.
* Peek has exactly the same function signatures as finish, but it doesn't reset
* the digest's internal state.
*
* Note:
* $(UL
* $(LI This is very useful as a template constraint (see examples))
* $(LI This also checks if T passes $(LREF isDigest))
* )
*/
template hasPeek(T)
{
enum bool hasPeek = isDigest!T &&
is(typeof(
{
T dig = void; //Can define
DigestType!T val = dig.peek();
}));
}
///
@system unittest
{
import std.digest.crc, std.digest.md;
assert(!hasPeek!(MD5));
assert(hasPeek!CRC32);
}
///
@system unittest
{
import std.digest.crc;
void myFunction(T)()
if (hasPeek!T)
{
T dig;
dig.start();
auto result = dig.peek();
}
myFunction!CRC32();
}
/**
* Checks whether the digest has a $(D blockSize) member, which contains the
* digest's internal block size in bits. It is primarily used by $(REF HMAC, std,digest,hmac).
*/
template hasBlockSize(T)
if (isDigest!T)
{
enum bool hasBlockSize = __traits(compiles, { size_t blockSize = T.blockSize; });
}
///
@system unittest
{
import std.digest.hmac, std.digest.md;
static assert(hasBlockSize!MD5 && MD5.blockSize == 512);
static assert(hasBlockSize!(HMAC!MD5) && HMAC!MD5.blockSize == 512);
}
package template isDigestibleRange(Range)
{
import std.digest.md;
import std.range : isInputRange, ElementType;
enum bool isDigestibleRange = isInputRange!Range && is(typeof(
{
MD5 ha; //Could use any conformant hash
ElementType!Range val;
ha.put(val);
}));
}
/**
* This is a convenience function to calculate a hash using the template API.
* Every digest passing the $(LREF isDigest) test can be used with this function.
*
* Params:
* range= an $(D InputRange) with $(D ElementType) $(D ubyte), $(D ubyte[]) or $(D ubyte[num])
*/
DigestType!Hash digest(Hash, Range)(auto ref Range range)
if (!isArray!Range
&& isDigestibleRange!Range)
{
import std.algorithm.mutation : copy;
Hash hash;
hash.start();
copy(range, &hash);
return hash.finish();
}
///
@system unittest
{
import std.digest.md;
import std.range : repeat;
auto testRange = repeat!ubyte(cast(ubyte)'a', 100);
auto md5 = digest!MD5(testRange);
}
/**
* This overload of the digest function handles arrays.
*
* Params:
* data= one or more arrays of any type
*/
DigestType!Hash digest(Hash, T...)(scope const T data)
if (allSatisfy!(isArray, typeof(data)))
{
Hash hash;
hash.start();
foreach (datum; data)
hash.put(cast(const(ubyte[]))datum);
return hash.finish();
}
///
@system unittest
{
import std.digest.crc, std.digest.md, std.digest.sha;
auto md5 = digest!MD5( "The quick brown fox jumps over the lazy dog");
auto sha1 = digest!SHA1( "The quick brown fox jumps over the lazy dog");
auto crc32 = digest!CRC32("The quick brown fox jumps over the lazy dog");
assert(toHexString(crc32) == "39A34F41");
}
///
@system unittest
{
import std.digest.crc;
auto crc32 = digest!CRC32("The quick ", "brown ", "fox jumps over the lazy dog");
assert(toHexString(crc32) == "39A34F41");
}
/**
* This is a convenience function similar to $(LREF digest), but it returns the string
* representation of the hash. Every digest passing the $(LREF isDigest) test can be used with this
* function.
*
* Params:
* order= the order in which the bytes are processed (see $(LREF toHexString))
* range= an $(D InputRange) with $(D ElementType) $(D ubyte), $(D ubyte[]) or $(D ubyte[num])
*/
char[digestLength!(Hash)*2] hexDigest(Hash, Order order = Order.increasing, Range)(ref Range range)
if (!isArray!Range && isDigestibleRange!Range)
{
return toHexString!order(digest!Hash(range));
}
///
@system unittest
{
import std.digest.md;
import std.range : repeat;
auto testRange = repeat!ubyte(cast(ubyte)'a', 100);
assert(hexDigest!MD5(testRange) == "36A92CC94A9E0FA21F625F8BFB007ADF");
}
/**
* This overload of the hexDigest function handles arrays.
*
* Params:
* order= the order in which the bytes are processed (see $(LREF toHexString))
* data= one or more arrays of any type
*/
char[digestLength!(Hash)*2] hexDigest(Hash, Order order = Order.increasing, T...)(scope const T data)
if (allSatisfy!(isArray, typeof(data)))
{
return toHexString!order(digest!Hash(data));
}
///
@system unittest
{
import std.digest.crc;
assert(hexDigest!(CRC32, Order.decreasing)("The quick brown fox jumps over the lazy dog") == "414FA339");
}
///
@system unittest
{
import std.digest.crc;
assert(hexDigest!(CRC32, Order.decreasing)("The quick ", "brown ", "fox jumps over the lazy dog") == "414FA339");
}
/**
* This is a convenience function which returns an initialized digest, so it's not necessary to call
* start manually.
*/
Hash makeDigest(Hash)()
{
Hash hash;
hash.start();
return hash;
}
///
@system unittest
{
import std.digest.md;
auto md5 = makeDigest!MD5();
md5.put(0);
assert(toHexString(md5.finish()) == "93B885ADFE0DA089CDF634904FD59F71");
}
/*+*************************** End of template part, welcome to OOP land **************************/
/**
* This describes the OOP API. To understand when to use the template API and when to use the OOP API,
* see the module documentation at the top of this page.
*
* The Digest interface is the base interface which is implemented by all digests.
*
* Note:
* A Digest implementation is always an $(D OutputRange)
*/
interface Digest
{
public:
/**
* Use this to feed the digest with data.
* Also implements the $(REF isOutputRange, std,range,primitives)
* interface for $(D ubyte) and $(D const(ubyte)[]).
*
* Example:
* ----
* void test(Digest dig)
* {
* dig.put(cast(ubyte) 0); //single ubyte
* dig.put(cast(ubyte) 0, cast(ubyte) 0); //variadic
* ubyte[10] buf;
* dig.put(buf); //buffer
* }
* ----
*/
@trusted nothrow void put(scope const(ubyte)[] data...);
/**
* Resets the internal state of the digest.
* Note:
* $(LREF finish) calls this internally, so it's not necessary to call
* $(D reset) manually after a call to $(LREF finish).
*/
@trusted nothrow void reset();
/**
* This is the length in bytes of the hash value which is returned by $(LREF finish).
* It's also the required size of a buffer passed to $(LREF finish).
*/
@trusted nothrow @property size_t length() const;
/**
* The finish function returns the hash value. It takes an optional buffer to copy the data
* into. If a buffer is passed, it must be at least $(LREF length) bytes big.
*/
@trusted nothrow ubyte[] finish();
///ditto
nothrow ubyte[] finish(ubyte[] buf);
//@@@BUG@@@ http://d.puremagic.com/issues/show_bug.cgi?id=6549
/*in
{
assert(buf.length >= this.length);
}*/
/**
* This is a convenience function to calculate the hash of a value using the OOP API.
*/
final @trusted nothrow ubyte[] digest(scope const(void[])[] data...)
{
this.reset();
foreach (datum; data)
this.put(cast(ubyte[]) datum);
return this.finish();
}
}
///
@system unittest
{
//Using the OutputRange feature
import std.algorithm.mutation : copy;
import std.digest.md;
import std.range : repeat;
auto oneMillionRange = repeat!ubyte(cast(ubyte)'a', 1000000);
auto ctx = new MD5Digest();
copy(oneMillionRange, ctx);
assert(ctx.finish().toHexString() == "7707D6AE4E027C70EEA2A935C2296F21");
}
///
@system unittest
{
import std.digest.crc, std.digest.md, std.digest.sha;
ubyte[] md5 = (new MD5Digest()).digest("The quick brown fox jumps over the lazy dog");
ubyte[] sha1 = (new SHA1Digest()).digest("The quick brown fox jumps over the lazy dog");
ubyte[] crc32 = (new CRC32Digest()).digest("The quick brown fox jumps over the lazy dog");
assert(crcHexString(crc32) == "414FA339");
}
///
@system unittest
{
import std.digest.crc;
ubyte[] crc32 = (new CRC32Digest()).digest("The quick ", "brown ", "fox jumps over the lazy dog");
assert(crcHexString(crc32) == "414FA339");
}
@system unittest
{
import std.range : isOutputRange;
assert(!isDigest!(Digest));
assert(isOutputRange!(Digest, ubyte));
}
///
@system unittest
{
void test(Digest dig)
{
dig.put(cast(ubyte) 0); //single ubyte
dig.put(cast(ubyte) 0, cast(ubyte) 0); //variadic
ubyte[10] buf;
dig.put(buf); //buffer
}
}
/*+*************************** End of OOP part, helper functions follow ***************************/
/**
* See $(LREF toHexString)
*/
enum Order : bool
{
increasing, ///
decreasing ///
}
/**
* Used to convert a hash value (a static or dynamic array of ubytes) to a string.
* Can be used with the OOP and with the template API.
*
* The additional order parameter can be used to specify the order of the input data.
* By default the data is processed in increasing order, starting at index 0. To process it in the
* opposite order, pass Order.decreasing as a parameter.
*
* The additional letterCase parameter can be used to specify the case of the output data.
* By default the output is in upper case. To change it to the lower case
* pass LetterCase.lower as a parameter.
*
* Note:
* The function overloads returning a string allocate their return values
* using the GC. The versions returning static arrays use pass-by-value for
* the return value, effectively avoiding dynamic allocation.
*/
char[num*2] toHexString(Order order = Order.increasing, size_t num, LetterCase letterCase = LetterCase.upper)
(in ubyte[num] digest)
{
static if (letterCase == LetterCase.upper)
{
import std.ascii : hexDigits = hexDigits;
}
else
{
import std.ascii : hexDigits = lowerHexDigits;
}
char[num*2] result;
size_t i;
static if (order == Order.increasing)
{
foreach (u; digest)
{
result[i++] = hexDigits[u >> 4];
result[i++] = hexDigits[u & 15];
}
}
else
{
size_t j = num - 1;
while (i < num*2)
{
result[i++] = hexDigits[digest[j] >> 4];
result[i++] = hexDigits[digest[j] & 15];
j--;
}
}
return result;
}
///ditto
char[num*2] toHexString(LetterCase letterCase, Order order = Order.increasing, size_t num)(in ubyte[num] digest)
{
return toHexString!(order, num, letterCase)(digest);
}
///ditto
string toHexString(Order order = Order.increasing, LetterCase letterCase = LetterCase.upper)
(in ubyte[] digest)
{
static if (letterCase == LetterCase.upper)
{
import std.ascii : hexDigits = hexDigits;
}
else
{
import std.ascii : hexDigits = lowerHexDigits;
}
auto result = new char[digest.length*2];
size_t i;
static if (order == Order.increasing)
{
foreach (u; digest)
{
result[i++] = hexDigits[u >> 4];
result[i++] = hexDigits[u & 15];
}
}
else
{
import std.range : retro;
foreach (u; retro(digest))
{
result[i++] = hexDigits[u >> 4];
result[i++] = hexDigits[u & 15];
}
}
import std.exception : assumeUnique;
// memory was just created, so casting to immutable is safe
return () @trusted { return assumeUnique(result); }();
}
///ditto
string toHexString(LetterCase letterCase, Order order = Order.increasing)(in ubyte[] digest)
{
return toHexString!(order, letterCase)(digest);
}
//For more example unittests, see Digest.digest, digest
///
@safe unittest
{
import std.digest.crc;
//Test with template API:
auto crc32 = digest!CRC32("The quick ", "brown ", "fox jumps over the lazy dog");
//Lower case variant:
assert(toHexString!(LetterCase.lower)(crc32) == "39a34f41");
//Usually CRCs are printed in this order, though:
assert(toHexString!(Order.decreasing)(crc32) == "414FA339");
assert(toHexString!(LetterCase.lower, Order.decreasing)(crc32) == "414fa339");
}
///
@safe unittest
{
import std.digest.crc;
// With OOP API
auto crc32 = (new CRC32Digest()).digest("The quick ", "brown ", "fox jumps over the lazy dog");
//Usually CRCs are printed in this order, though:
assert(toHexString!(Order.decreasing)(crc32) == "414FA339");
}
@safe unittest
{
ubyte[16] data;
assert(toHexString(data) == "00000000000000000000000000000000");
assert(toHexString(cast(ubyte[4])[42, 43, 44, 45]) == "2A2B2C2D");
assert(toHexString(cast(ubyte[])[42, 43, 44, 45]) == "2A2B2C2D");
assert(toHexString!(Order.decreasing)(cast(ubyte[4])[42, 43, 44, 45]) == "2D2C2B2A");
assert(toHexString!(Order.decreasing, LetterCase.lower)(cast(ubyte[4])[42, 43, 44, 45]) == "2d2c2b2a");
assert(toHexString!(Order.decreasing)(cast(ubyte[])[42, 43, 44, 45]) == "2D2C2B2A");
}
/*+*********************** End of public helper part, private helpers follow ***********************/
/*
* Used to convert from a ubyte[] slice to a ref ubyte[N].
* This helper is used internally in the WrapperDigest template to wrap the template API's
* finish function.
*/
ref T[N] asArray(size_t N, T)(ref T[] source, string errorMsg = "")
{
assert(source.length >= N, errorMsg);
return *cast(T[N]*) source.ptr;
}
/*
* Returns the length (in bytes) of the hash value produced by T.
*/
template digestLength(T)
if (isDigest!T)
{
enum size_t digestLength = (ReturnType!(T.finish)).length;
}
@safe pure nothrow @nogc
unittest
{
import std.digest.md : MD5;
import std.digest.sha : SHA1, SHA256, SHA512;
assert(digestLength!MD5 == 16);
assert(digestLength!SHA1 == 20);
assert(digestLength!SHA256 == 32);
assert(digestLength!SHA512 == 64);
}
/**
* Wraps a template API hash struct into a Digest interface.
* Modules providing digest implementations will usually provide
* an alias for this template (e.g. MD5Digest, SHA1Digest, ...).
*/
class WrapperDigest(T)
if (isDigest!T) : Digest
{
protected:
T _digest;
public final:
/**
* Initializes the digest.
*/
this()
{
_digest.start();
}
/**
* Use this to feed the digest with data.
* Also implements the $(REF isOutputRange, std,range,primitives)
* interface for $(D ubyte) and $(D const(ubyte)[]).
*/
@trusted nothrow void put(scope const(ubyte)[] data...)
{
_digest.put(data);
}
/**
* Resets the internal state of the digest.
* Note:
* $(LREF finish) calls this internally, so it's not necessary to call
* $(D reset) manually after a call to $(LREF finish).
*/
@trusted nothrow void reset()
{
_digest.start();
}
/**
* This is the length in bytes of the hash value which is returned by $(LREF finish).
* It's also the required size of a buffer passed to $(LREF finish).
*/
@trusted nothrow @property size_t length() const pure
{
return digestLength!T;
}
/**
* The finish function returns the hash value. It takes an optional buffer to copy the data
* into. If a buffer is passed, it must have a length at least $(LREF length) bytes.
*
* Example:
* --------
*
* import std.digest.md;
* ubyte[16] buf;
* auto hash = new WrapperDigest!MD5();
* hash.put(cast(ubyte) 0);
* auto result = hash.finish(buf[]);
* //The result is now in result (and in buf). If you pass a buffer which is bigger than
* //necessary, result will have the correct length, but buf will still have it's original
* //length
* --------
*/
nothrow ubyte[] finish(ubyte[] buf)
in
{
assert(buf.length >= this.length);
}
body
{
enum string msg = "Buffer needs to be at least " ~ digestLength!(T).stringof ~ " bytes " ~
"big, check " ~ typeof(this).stringof ~ ".length!";
asArray!(digestLength!T)(buf, msg) = _digest.finish();
return buf[0 .. digestLength!T];
}
///ditto
@trusted nothrow ubyte[] finish()
{
enum len = digestLength!T;
auto buf = new ubyte[len];
asArray!(digestLength!T)(buf) = _digest.finish();
return buf;
}
version (StdDdoc)
{
/**
* Works like $(D finish) but does not reset the internal state, so it's possible
* to continue putting data into this WrapperDigest after a call to peek.
*
* These functions are only available if $(D hasPeek!T) is true.
*/
@trusted ubyte[] peek(ubyte[] buf) const;
///ditto
@trusted ubyte[] peek() const;
}
else static if (hasPeek!T)
{
@trusted ubyte[] peek(ubyte[] buf) const
in
{
assert(buf.length >= this.length);
}
body
{
enum string msg = "Buffer needs to be at least " ~ digestLength!(T).stringof ~ " bytes " ~
"big, check " ~ typeof(this).stringof ~ ".length!";
asArray!(digestLength!T)(buf, msg) = _digest.peek();
return buf[0 .. digestLength!T];
}
@trusted ubyte[] peek() const
{
enum len = digestLength!T;
auto buf = new ubyte[len];
asArray!(digestLength!T)(buf) = _digest.peek();
return buf;
}
}
}
///
@system unittest
{
import std.digest.md;
//Simple example
auto hash = new WrapperDigest!MD5();
hash.put(cast(ubyte) 0);
auto result = hash.finish();
}
///
@system unittest
{
//using a supplied buffer
import std.digest.md;
ubyte[16] buf;
auto hash = new WrapperDigest!MD5();
hash.put(cast(ubyte) 0);
auto result = hash.finish(buf[]);
//The result is now in result (and in buf). If you pass a buffer which is bigger than
//necessary, result will have the correct length, but buf will still have it's original
//length
}
@safe unittest
{
// Test peek & length
import std.digest.crc;
auto hash = new WrapperDigest!CRC32();
assert(hash.length == 4);
hash.put(cast(const(ubyte[]))"The quick brown fox jumps over the lazy dog");
assert(hash.peek().toHexString() == "39A34F41");
ubyte[5] buf;
assert(hash.peek(buf).toHexString() == "39A34F41");
}
/**
* Securely compares two digest representations while protecting against timing
* attacks. Do not use `==` to compare digest representations.
*
* The attack happens as follows:
*
* $(OL
* $(LI An attacker wants to send harmful data to your server, which
* requires a integrity HMAC SHA1 token signed with a secret.)
* $(LI The length of the token is known to be 40 characters long due to its format,
* so the attacker first sends `"0000000000000000000000000000000000000000"`,
* then `"1000000000000000000000000000000000000000"`, and so on.)
* $(LI The given HMAC token is compared with the expected token using the
* `==` string comparison, which returns `false` as soon as the first wrong
* element is found. If a wrong element is found, then a rejection is sent
* back to the sender.)
* $(LI Eventually, the attacker is able to determine the first character in
* the correct token because the sever takes slightly longer to return a
* rejection. This is due to the comparison moving on to second item in
* the two arrays, seeing they are different, and then sending the rejection.)
* $(LI It may seem like too small of a difference in time for the attacker
* to notice, but security researchers have shown that differences as
* small as $(LINK2 http://www.cs.rice.edu/~dwallach/pub/crosby-timing2009.pdf,
* 20┬Ás can be reliably distinguished) even with network inconsistencies.)
* $(LI Repeat the process for each character until the attacker has the whole
* correct token and the server accepts the harmful data. This can be done
* in a week with the attacker pacing the attack to 10 requests per second
* with only one client.)
* )
*
* This function defends against this attack by always comparing every single
* item in the array if the two arrays are the same length. Therefore, this
* function is always $(BIGOH n) for ranges of the same length.
*
* This attack can also be mitigated via rate limiting and banning IPs which have too
* many rejected requests. However, this does not completely solve the problem,
* as the attacker could be in control of a bot net. To fully defend against
* the timing attack, rate limiting, banning IPs, and using this function
* should be used together.
*
* Params:
* r1 = A digest representation
* r2 = A digest representation
* Returns:
* `true` if both representations are equal, `false` otherwise
* See_Also:
* $(LINK2 https://en.wikipedia.org/wiki/Timing_attack, The Wikipedia article
* on timing attacks).
*/
bool secureEqual(R1, R2)(R1 r1, R2 r2)
if (isInputRange!R1 && isInputRange!R2 && !isInfinite!R1 && !isInfinite!R2 &&
(isIntegral!(ElementEncodingType!R1) || isSomeChar!(ElementEncodingType!R1)) &&
!is(CommonType!(ElementEncodingType!R1, ElementEncodingType!R2) == void))
{
static if (hasLength!R1 && hasLength!R2)
if (r1.length != r2.length)
return false;
int result;
static if (isRandomAccessRange!R1 && isRandomAccessRange!R2 &&
hasLength!R1 && hasLength!R2)
{
foreach (i; 0 .. r1.length)
result |= r1[i] ^ r2[i];
}
else static if (hasLength!R1 && hasLength!R2)
{
// Lengths are the same so we can squeeze out a bit of performance
// by not checking if r2 is empty
for (; !r1.empty; r1.popFront(), r2.popFront())
{
result |= r1.front ^ r2.front;
}
}
else
{
// Generic case, walk both ranges
for (; !r1.empty; r1.popFront(), r2.popFront())
{
if (r2.empty) return false;
result |= r1.front ^ r2.front;
}
if (!r2.empty) return false;
}
return result == 0;
}
///
@system pure unittest
{
import std.digest.hmac : hmac;
import std.digest.sha : SHA1;
import std.string : representation;
// a typical HMAC data integrity verification
auto secret = "A7GZIP6TAQA6OHM7KZ42KB9303CEY0MOV5DD6NTV".representation;
auto data = "data".representation;
string hex1 = data.hmac!SHA1(secret).toHexString;
string hex2 = data.hmac!SHA1(secret).toHexString;
string hex3 = "data1".representation.hmac!SHA1(secret).toHexString;
assert( secureEqual(hex1, hex2));
assert(!secureEqual(hex1, hex3));
}
@system pure unittest
{
import std.internal.test.dummyrange : ReferenceInputRange;
import std.range : takeExactly;
import std.string : representation;
import std.utf : byWchar, byDchar;
{
auto hex1 = "02CA3484C375EDD3C0F08D3F50D119E61077".representation;
auto hex2 = "02CA3484C375EDD3C0F08D3F50D119E610779018".representation;
assert(!secureEqual(hex1, hex2));
}
{
auto hex1 = "02CA3484C375EDD3C0F08D3F50D119E610779018"w.representation;
auto hex2 = "02CA3484C375EDD3C0F08D3F50D119E610779018"d.representation;
assert(secureEqual(hex1, hex2));
}
{
auto hex1 = "02CA3484C375EDD3C0F08D3F50D119E610779018".byWchar;
auto hex2 = "02CA3484C375EDD3C0F08D3F50D119E610779018".byDchar;
assert(secureEqual(hex1, hex2));
}
{
auto hex1 = "02CA3484C375EDD3C0F08D3F50D119E61077".byWchar;
auto hex2 = "02CA3484C375EDD3C0F08D3F50D119E610779018".byDchar;
assert(!secureEqual(hex1, hex2));
}
{
auto hex1 = new ReferenceInputRange!int([0, 1, 2, 3, 4, 5, 6, 7, 8]).takeExactly(9);
auto hex2 = new ReferenceInputRange!int([0, 1, 2, 3, 4, 5, 6, 7, 8]).takeExactly(9);
assert(secureEqual(hex1, hex2));
}
{
auto hex1 = new ReferenceInputRange!int([0, 1, 2, 3, 4, 5, 6, 7, 8]).takeExactly(9);
auto hex2 = new ReferenceInputRange!int([0, 1, 2, 3, 4, 5, 6, 7, 9]).takeExactly(9);
assert(!secureEqual(hex1, hex2));
}
}