<!-- GENERATED by docs/sphinx/bin/20-reference (p5) from Digest/SHA1.rs. Do not edit. -->

```{index} single: Digest::SHA1
```

# Digest::SHA1

```{pperl-module-badges} Digest::SHA1
```

Compute SHA-1 message digests through the interface of Digest::SHA1,
the CPAN module older code uses where newer code uses Digest::SHA.

The **functional interface** (`sha1`, `sha1_hex`, `sha1_base64`) hashes
its arguments in one call. The **object interface**
(`Digest::SHA1->new`, `add`, `addfile`, `digest`) takes the data in
pieces. Every digest comes as raw bytes (20), lowercase hex (40) or
unpadded Base64 (27). `sha1_transform` is the bare SHA-1 compression
of one block, for the FIPS 186 random-number construction.

The digests are computed by the engine of the built-in Digest::SHA,
which uses the processor's SHA instructions where it has them, so the
two modules always agree.

This is a native implementation of Digest::SHA1 2.13's `SHA1.xs`; its
`Digest/SHA1.pm` is used unchanged.


## Synopsis

```perl
use Digest::SHA1 qw(sha1_hex sha1_base64);

print sha1_hex('abc'), "\n";      # a9993e364706816aba3e25717850c26c9cd0d89d
print sha1_base64('abc'), "\n";   # qZk+NkcGgWq6PiVxeFDCbJzQ2J0

my $ctx = Digest::SHA1->new;
$ctx->add('a', 'b');
$ctx->add('c');
print $ctx->hexdigest, "\n";      # the same as sha1_hex('abc')
```

## Differences from upstream

Two, each where perl 5.44 with SHA1.xs fails
(t/81-xs-native/Digest-SHA1/150-or-better.t):

- `sha1_transform` given more than 64 bytes uses the first 64. perl5
  copies the whole string into a 64-byte buffer and aborts with
  "buffer overflow detected".
- A method called on the class name instead of an object
  (`Digest::SHA1->add($data)`) dies "Not a reference to a Digest::SHA1
  object". perl5 crashes.

## Functions

### Functional digests

#### [`sha1`](SHA1/sha1)

Compute the SHA-1 digest of the concatenated arguments in one call.

Also available as `Digest::SHA1::sha1_base64`, `Digest::SHA1::sha1_hex`.

#### [`sha1_transform`](SHA1/sha1_transform)

The SHA-1 compression function over one 64-byte block, from the standard initial state: the 20-byte result, with no padding and no length.

### OO lifecycle

#### [`new`](SHA1/new)

Create a Digest::SHA1 object, or reset an existing one.

#### `clone`

Copy a Digest::SHA1 object, the data added so far included, into a new object of the same class.

**Synopsis**

```perl
my $so_far = $ctx->clone->hexdigest;   # $ctx keeps going
```

### OO input

#### [`add`](SHA1/add)

Append data to the message being hashed.

#### [`addfile`](SHA1/addfile)

Append everything that can be read from a filehandle to the message.

### OO output

#### [`b64digest`](SHA1/b64digest)

Finish the message and return its digest, then reset the object to the empty message.

Also available as `Digest::SHA1::digest`, `Digest::SHA1::hexdigest`.

```{toctree}
:hidden:
:maxdepth: 1

SHA1/new
SHA1/add
SHA1/addfile
SHA1/b64digest
SHA1/sha1
SHA1/sha1_transform
```