Digest::SHA(3p) Perl Programmers Reference Guide Digest::SHA(3p) #
Digest::SHA(3p) Perl Programmers Reference Guide Digest::SHA(3p)
NNAAMMEE #
Digest::SHA - Perl extension for SHA-1/224/256/384/512
SSYYNNOOPPSSIISS #
In programs:
# Functional interface
use Digest::SHA qw(sha1 sha1_hex sha1_base64 ...);
$digest = sha1($data);
$digest = sha1_hex($data);
$digest = sha1_base64($data);
$digest = sha256($data);
$digest = sha384_hex($data);
$digest = sha512_base64($data);
# Object-oriented
use Digest::SHA;
$sha = Digest::SHA->new($alg);
$sha->add($data); # feed data into stream
$sha->addfile(*F);
$sha->addfile($filename);
$sha->add_bits($bits);
$sha->add_bits($data, $nbits);
$sha_copy = $sha->clone; # make copy of digest object
$state = $sha->getstate; # save current state to string
$sha->putstate($state); # restore previous $state
$digest = $sha->digest; # compute digest
$digest = $sha->hexdigest;
$digest = $sha->b64digest;
From the command line:
$ shasum files
$ shasum --help
SSYYNNOOPPSSIISS ((HHMMAACC--SSHHAA)) #
# Functional interface only
use Digest::SHA qw(hmac_sha1 hmac_sha1_hex ...);
$digest = hmac_sha1($data, $key);
$digest = hmac_sha224_hex($data, $key);
$digest = hmac_sha256_base64($data, $key);
AABBSSTTRRAACCTT #
Digest::SHA is a complete implementation of the NIST Secure Hash
Standard. It gives Perl programmers a convenient way to calculate SHA-1,
SHA-224, SHA-256, SHA-384, SHA-512, SHA-512/224, and SHA-512/256 message
digests. The module can handle all types of input, including partial-
byte data.
DDEESSCCRRIIPPTTIIOONN #
Digest::SHA is written in C for speed. If your platform lacks a C
compiler, you can install the functionally equivalent (but much slower)
Digest::SHA::PurePerl module.
The programming interface is easy to use: it's the same one found in
CPAN's Digest module. So, if your applications currently use Digest::MD5
and you'd prefer the stronger security of SHA, it's a simple matter to
convert them.
The interface provides two ways to calculate digests: all-at-once, or in
stages. To illustrate, the following short program computes the SHA-256
digest of "hello world" using each approach:
use Digest::SHA qw(sha256_hex);
$data = "hello world";
@frags = split(//, $data);
# all-at-once (Functional style)
$digest1 = sha256_hex($data);
# in-stages (OOP style)
$state = Digest::SHA->new(256);
for (@frags) { $state->add($_) }
$digest2 = $state->hexdigest;
print $digest1 eq $digest2 ?
"whew!\n" : "oops!\n";
To calculate the digest of an n-bit message where _n is not a multiple of
8, use the _aa_dd_dd____bb_ii_tt_ss_((_)) method. For example, consider the 446-bit message
consisting of the bit-string "110" repeated 148 times, followed by "11".
Here's how to display its SHA-1 digest:
use Digest::SHA;
$bits = "110" x 148 . "11";
$sha = Digest::SHA->new(1)->add_bits($bits);
print $sha->hexdigest, "\n";
Note that for larger bit-strings, it's more efficient to use the two-
argument version _a_d_d___b_i_t_s_(_$_d_a_t_a_, _$_n_b_i_t_s_), where _$_d_a_t_a is in the customary
packed binary format used for Perl strings.
The module also lets you save intermediate SHA states to a string. The
_gg_ee_tt_ss_tt_aa_tt_ee_((_)) method generates portable, human-readable text describing the
current state of computation. You can subsequently restore that state
with _pp_uu_tt_ss_tt_aa_tt_ee_((_)) to resume where the calculation left off.
To see what a state description looks like, just run the following:
use Digest::SHA;
print Digest::SHA->new->add("Shaw" x 1962)->getstate;
As an added convenience, the Digest::SHA module offers routines to
calculate keyed hashes using the HMAC-SHA-1/224/256/384/512 algorithms.
These services exist in functional form only, and mimic the style and
behavior of the _ss_hh_aa_((_)), _ss_hh_aa____hh_ee_xx_((_)), and _ss_hh_aa____bb_aa_ss_ee_66_44_((_)) functions.
# Test vector from draft-ietf-ipsec-ciph-sha-256-01.txt
use Digest::SHA qw(hmac_sha256_hex);
print hmac_sha256_hex("Hi There", chr(0x0b) x 32), "\n";
UUNNIICCOODDEE AANNDD SSIIDDEE EEFFFFEECCTTSS #
Perl supports Unicode strings as of version 5.6. Such strings may
contain wide characters, namely, characters whose ordinal values are
greater than 255. This can cause problems for digest algorithms such as
SHA that are specified to operate on sequences of bytes.
The rule by which Digest::SHA handles a Unicode string is easy to state,
but potentially confusing to grasp: the string is interpreted as a
sequence of byte values, where each byte value is equal to the ordinal
value (viz. code point) of its corresponding Unicode character. That
way, the Unicode string 'abc' has exactly the same digest value as the
ordinary string 'abc'.
Since a wide character does not fit into a byte, the Digest::SHA routines
croak if they encounter one. Whereas if a Unicode string contains no
wide characters, the module accepts it quite happily. The following code
illustrates the two cases:
$str1 = pack('U*', (0..255));
print sha1_hex($str1); # ok
$str2 = pack('U*', (0..256));
print sha1_hex($str2); # croaks
Be aware that the digest routines silently convert UTF-8 input into its
equivalent byte sequence in the native encoding (cf. utf8::downgrade).
This side effect influences only the way Perl stores the data internally,
but otherwise leaves the actual value of the data intact.
NNIISSTT SSTTAATTEEMMEENNTT OONN SSHHAA--11 #
NIST acknowledges that the work of Prof. Xiaoyun Wang constitutes a
practical collision attack on SHA-1. Therefore, NIST encourages the
rapid adoption of the SHA-2 hash functions (e.g. SHA-256) for
applications requiring strong collision resistance, such as digital
signatures.
ref. <http://csrc.nist.gov/groups/ST/hash/statement.html>
PPAADDDDIINNGG OOFF BBAASSEE6644 DDIIGGEESSTTSS #
By convention, CPAN Digest modules do nnoott pad their Base64 output.
Problems can occur when feeding such digests to other software that
expects properly padded Base64 encodings.
For the time being, any necessary padding must be done by the user.
Fortunately, this is a simple operation: if the length of a
Base64-encoded digest isn't a multiple of 4, simply append "=" characters
to the end of the digest until it is:
while (length($b64_digest) % 4) {
$b64_digest .= '=';
}
To illustrate, _s_h_a_2_5_6___b_a_s_e_6_4_(_"_a_b_c_"_) is computed to be
ungWv48Bz+pBQUDeXa4iI7ADYaOWF3qctBD/YfIAFa0
which has a length of 43. So, the properly padded version is
ungWv48Bz+pBQUDeXa4iI7ADYaOWF3qctBD/YfIAFa0=
EEXXPPOORRTT #
None by default.
EEXXPPOORRTTAABBLLEE FFUUNNCCTTIIOONNSS #
Provided your C compiler supports a 64-bit type (e.g. the _l_o_n_g _l_o_n_g of
C99, or _____i_n_t_6_4 used by Microsoft C/C++), all of these functions will be
available for use. Otherwise, you won't be able to perform the SHA-384
and SHA-512 transforms, both of which require 64-bit operations.
_F_u_n_c_t_i_o_n_a_l _s_t_y_l_e
sshhaa11(($$ddaattaa,, ......))
sshhaa222244(($$ddaattaa,, ......))
sshhaa225566(($$ddaattaa,, ......))
sshhaa338844(($$ddaattaa,, ......))
sshhaa551122(($$ddaattaa,, ......))
sshhaa551122222244(($$ddaattaa,, ......))
sshhaa551122225566(($$ddaattaa,, ......))
Logically joins the arguments into a single string, and returns its
SHA-1/224/256/384/512 digest encoded as a binary string.
sshhaa11__hheexx(($$ddaattaa,, ......))
sshhaa222244__hheexx(($$ddaattaa,, ......))
sshhaa225566__hheexx(($$ddaattaa,, ......))
sshhaa338844__hheexx(($$ddaattaa,, ......))
sshhaa551122__hheexx(($$ddaattaa,, ......))
sshhaa551122222244__hheexx(($$ddaattaa,, ......))
sshhaa551122225566__hheexx(($$ddaattaa,, ......))
Logically joins the arguments into a single string, and returns its
SHA-1/224/256/384/512 digest encoded as a hexadecimal string.
sshhaa11__bbaassee6644(($$ddaattaa,, ......))
sshhaa222244__bbaassee6644(($$ddaattaa,, ......))
sshhaa225566__bbaassee6644(($$ddaattaa,, ......))
sshhaa338844__bbaassee6644(($$ddaattaa,, ......))
sshhaa551122__bbaassee6644(($$ddaattaa,, ......))
sshhaa551122222244__bbaassee6644(($$ddaattaa,, ......))
sshhaa551122225566__bbaassee6644(($$ddaattaa,, ......))
Logically joins the arguments into a single string, and returns its
SHA-1/224/256/384/512 digest encoded as a Base64 string.
It's important to note that the resulting string does nnoott contain the
padding characters typical of Base64 encodings. This omission is
deliberate, and is done to maintain compatibility with the family of
CPAN Digest modules. See "PADDING OF BASE64 DIGESTS" for details.
_O_O_P _s_t_y_l_e
nneeww(($$aallgg))
Returns a new Digest::SHA object. Allowed values for _$_a_l_g are 1,
224, 256, 384, 512, 512224, or 512256. It's also possible to use
common string representations of the algorithm (e.g. "sha256",
"SHA-384"). If the argument is missing, SHA-1 will be used by
default.
Invoking _n_e_w as an instance method will reset the object to the
initial state associated with _$_a_l_g. If the argument is missing, the
object will continue using the same algorithm that was selected at
creation.
rreesseett(($$aallgg))
This method has exactly the same effect as _n_e_w_(_$_a_l_g_). In fact, _r_e_s_e_t
is just an alias for _n_e_w.
hhaasshhssiizzee
Returns the number of digest bits for this object. The values are
160, 224, 256, 384, 512, 224, and 256 for SHA-1, SHA-224, SHA-256,
SHA-384, SHA-512, SHA-512/224 and SHA-512/256, respectively.
aallggoorriitthhmm
Returns the digest algorithm for this object. The values are 1, 224,
256, 384, 512, 512224, and 512256 for SHA-1, SHA-224, SHA-256,
SHA-384, SHA-512, SHA-512/224, and SHA-512/256, respectively.
cclloonnee
Returns a duplicate copy of the object.
aadddd(($$ddaattaa,, ......))
Logically joins the arguments into a single string, and uses it to
update the current digest state. In other words, the following
statements have the same effect:
$sha->add("a"); $sha->add("b"); $sha->add("c");
$sha->add("a")->add("b")->add("c");
$sha->add("a", "b", "c");
$sha->add("abc");
The return value is the updated object itself.
aadddd__bbiittss(($$ddaattaa,, $$nnbbiittss))
aadddd__bbiittss(($$bbiittss))
Updates the current digest state by appending bits to it. The return
value is the updated object itself.
The first form causes the most-significant _$_n_b_i_t_s of _$_d_a_t_a to be
appended to the stream. The _$_d_a_t_a argument is in the customary
binary format used for Perl strings.
The second form takes an ASCII string of "0" and "1" characters as
its argument. It's equivalent to
$sha->add_bits(pack("B*", $bits), length($bits));
So, the following two statements do the same thing:
$sha->add_bits("111100001010");
$sha->add_bits("\xF0\xA0", 12);
Note that SHA-1 and SHA-2 use _m_o_s_t_-_s_i_g_n_i_f_i_c_a_n_t_-_b_i_t _o_r_d_e_r_i_n_g for their
internal state. This means that
$sha3->add_bits("110");
is equivalent to
$sha3->add_bits("1")->add_bits("1")->add_bits("0");
aaddddffiillee((**FFIILLEE))
Reads from _F_I_L_E until EOF, and appends that data to the current
state. The return value is the updated object itself.
aaddddffiillee(($$ffiilleennaammee [[,, $$mmooddee]]))
Reads the contents of _$_f_i_l_e_n_a_m_e, and appends that data to the current
state. The return value is the updated object itself.
By default, _$_f_i_l_e_n_a_m_e is simply opened and read; no special modes or
I/O disciplines are used. To change this, set the optional _$_m_o_d_e
argument to one of the following values:
"b" read file in binary mode
"U" use universal newlines
"0" use BITS mode
The "U" mode is modeled on Python's "Universal Newlines" concept,
whereby DOS and Mac OS line terminators are converted internally to
UNIX newlines before processing. This ensures consistent digest
values when working simultaneously across multiple file systems. TThhee
""UU"" mmooddee iinnfflluueenncceess oonnllyy tteexxtt ffiilleess, namely those passing Perl's _-_T
test; binary files are processed with no translation whatsoever.
The BITS mode ("0") interprets the contents of _$_f_i_l_e_n_a_m_e as a logical
stream of bits, where each ASCII '0' or '1' character represents a 0
or 1 bit, respectively. All other characters are ignored. This
provides a convenient way to calculate the digest values of partial-
byte data by using files, rather than having to write separate
programs employing the _a_d_d___b_i_t_s method.
ggeettssttaattee
Returns a string containing a portable, human-readable representation
of the current SHA state.
ppuuttssttaattee(($$ssttrr))
Returns a Digest::SHA object representing the SHA state contained in
_$_s_t_r. The format of _$_s_t_r matches the format of the output produced
by method _g_e_t_s_t_a_t_e. If called as a class method, a new object is
created; if called as an instance method, the object is reset to the
state contained in _$_s_t_r.
dduummpp(($$ffiilleennaammee))
Writes the output of _g_e_t_s_t_a_t_e to _$_f_i_l_e_n_a_m_e. If the argument is
missing, or equal to the empty string, the state information will be
written to STDOUT.
llooaadd(($$ffiilleennaammee))
Returns a Digest::SHA object that results from calling _p_u_t_s_t_a_t_e on
the contents of _$_f_i_l_e_n_a_m_e. If the argument is missing, or equal to
the empty string, the state information will be read from STDIN.
ddiiggeesstt
Returns the digest encoded as a binary string.
Note that the _d_i_g_e_s_t method is a read-once operation. Once it has
been performed, the Digest::SHA object is automatically reset in
preparation for calculating another digest value. Call
_$_s_h_a_-_>_c_l_o_n_e_-_>_d_i_g_e_s_t if it's necessary to preserve the original digest
state.
hheexxddiiggeesstt
Returns the digest encoded as a hexadecimal string.
Like _d_i_g_e_s_t, this method is a read-once operation. Call
_$_s_h_a_-_>_c_l_o_n_e_-_>_h_e_x_d_i_g_e_s_t if it's necessary to preserve the original
digest state.
bb6644ddiiggeesstt
Returns the digest encoded as a Base64 string.
Like _d_i_g_e_s_t, this method is a read-once operation. Call
_$_s_h_a_-_>_c_l_o_n_e_-_>_b_6_4_d_i_g_e_s_t if it's necessary to preserve the original
digest state.
It's important to note that the resulting string does nnoott contain the
padding characters typical of Base64 encodings. This omission is
deliberate, and is done to maintain compatibility with the family of
CPAN Digest modules. See "PADDING OF BASE64 DIGESTS" for details.
_H_M_A_C_-_S_H_A_-_1_/_2_2_4_/_2_5_6_/_3_8_4_/_5_1_2 #
hhmmaacc__sshhaa11(($$ddaattaa,, $$kkeeyy))
hhmmaacc__sshhaa222244(($$ddaattaa,, $$kkeeyy))
hhmmaacc__sshhaa225566(($$ddaattaa,, $$kkeeyy))
hhmmaacc__sshhaa338844(($$ddaattaa,, $$kkeeyy))
hhmmaacc__sshhaa551122(($$ddaattaa,, $$kkeeyy))
hhmmaacc__sshhaa551122222244(($$ddaattaa,, $$kkeeyy))
hhmmaacc__sshhaa551122225566(($$ddaattaa,, $$kkeeyy))
Returns the HMAC-SHA-1/224/256/384/512 digest of _$_d_a_t_a/_$_k_e_y, with the
result encoded as a binary string. Multiple _$_d_a_t_a arguments are
allowed, provided that _$_k_e_y is the last argument in the list.
hhmmaacc__sshhaa11__hheexx(($$ddaattaa,, $$kkeeyy))
hhmmaacc__sshhaa222244__hheexx(($$ddaattaa,, $$kkeeyy))
hhmmaacc__sshhaa225566__hheexx(($$ddaattaa,, $$kkeeyy))
hhmmaacc__sshhaa338844__hheexx(($$ddaattaa,, $$kkeeyy))
hhmmaacc__sshhaa551122__hheexx(($$ddaattaa,, $$kkeeyy))
hhmmaacc__sshhaa551122222244__hheexx(($$ddaattaa,, $$kkeeyy))
hhmmaacc__sshhaa551122225566__hheexx(($$ddaattaa,, $$kkeeyy))
Returns the HMAC-SHA-1/224/256/384/512 digest of _$_d_a_t_a/_$_k_e_y, with the
result encoded as a hexadecimal string. Multiple _$_d_a_t_a arguments are
allowed, provided that _$_k_e_y is the last argument in the list.
hhmmaacc__sshhaa11__bbaassee6644(($$ddaattaa,, $$kkeeyy))
hhmmaacc__sshhaa222244__bbaassee6644(($$ddaattaa,, $$kkeeyy))
hhmmaacc__sshhaa225566__bbaassee6644(($$ddaattaa,, $$kkeeyy))
hhmmaacc__sshhaa338844__bbaassee6644(($$ddaattaa,, $$kkeeyy))
hhmmaacc__sshhaa551122__bbaassee6644(($$ddaattaa,, $$kkeeyy))
hhmmaacc__sshhaa551122222244__bbaassee6644(($$ddaattaa,, $$kkeeyy))
hhmmaacc__sshhaa551122225566__bbaassee6644(($$ddaattaa,, $$kkeeyy))
Returns the HMAC-SHA-1/224/256/384/512 digest of _$_d_a_t_a/_$_k_e_y, with the
result encoded as a Base64 string. Multiple _$_d_a_t_a arguments are
allowed, provided that _$_k_e_y is the last argument in the list.
It's important to note that the resulting string does nnoott contain the
padding characters typical of Base64 encodings. This omission is
deliberate, and is done to maintain compatibility with the family of
CPAN Digest modules. See "PADDING OF BASE64 DIGESTS" for details.
SSEEEE AALLSSOO #
Digest, Digest::SHA::PurePerl
The Secure Hash Standard (Draft FIPS PUB 180-4) can be found at:
<http://csrc.nist.gov/publications/drafts/fips180-4/Draft-FIPS180-4_Feb2011.pdf>
The Keyed-Hash Message Authentication Code (HMAC):
<http://csrc.nist.gov/publications/fips/fips198/fips-198a.pdf>
AAUUTTHHOORR #
Mark Shelor <mshelor@cpan.org>
AACCKKNNOOWWLLEEDDGGMMEENNTTSS #
The author is particularly grateful to
Gisle Aas
H. Merijn Brand
Sean Burke
Chris Carey
Alexandr Ciornii
Chris David
Jim Doble
Thomas Drugeon
Julius Duque
Jeffrey Friedl
Robert Gilmour
Brian Gladman
Jarkko Hietaniemi
Adam Kennedy
Mark Lawrence
Andy Lester
Alex Muntada
Steve Peters
Chris Skiscim
Martin Thurn
Gunnar Wolf
Adam Woodbury
"who by trained skill rescued life from such great billows and such thick
darkness and moored it in so perfect a calm and in so brilliant a light"
- Lucretius
CCOOPPYYRRIIGGHHTT AANNDD LLIICCEENNSSEE #
Copyright (C) 2003-2018 Mark Shelor
This library is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
perlartistic
perl v5.36.3 2019-12-30 Digest::SHA(3p)