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CryptX-0.088
⭐ Starred 36 / Crypt::AuthEnc::ChaCha20Poly1305
Security Advisories (2)
CVE-2026-41565 (2026-05-28)

CryptX versions before 0.088_001 for Perl have a stack buffer overflow in four AEAD decrypt_verify helpers. The gcm_decrypt_verify, ccm_decrypt_verify, chacha20poly1305_decrypt_verify and eax_decrypt_verify XS routines copied the caller-supplied authentication tag into a fixed 144-byte stack buffer (MAXBLOCKSIZE) without checking the supplied length. A longer tag overwrites the stack past the buffer. Version 0.088 added the clamp to gcm_decrypt_verify, and 0.088_001 added it to the other three. Any caller of an affected helper that forwards an attacker-controlled tag longer than the buffer can trigger the overflow.

CVE-2026-13758 (2026-06-29)

CryptX versions before 0.088_001 for Perl compare AEAD authentication tags in non-constant time in the streaming decrypt_done path. The decrypt_done($tag) form compares it against the computed tag with memNE (memcmp() != 0), which short-circuits on the first differing byte, so its run time depends on the number of matching leading bytes. This affects all five AEAD modes: GCM, CCM, ChaCha20Poly1305, EAX and OCB. The one-shot *_decrypt_verify helpers are unaffected; they verify the tag inside libtomcrypt with a constant-time comparison. The timing difference is a tag-verification oracle. An attacker who can submit many candidate tags for the same nonce, ciphertext and associated data while measuring the timing precisely enough may recover the expected tag byte by byte and forge a message that verifies.

NAME

Crypt::AuthEnc::ChaCha20Poly1305 - Authenticated encryption in ChaCha20-Poly1305 mode

SYNOPSIS

### OO interface
use Crypt::AuthEnc::ChaCha20Poly1305;

# encrypt and authenticate
my $ae = Crypt::AuthEnc::ChaCha20Poly1305->new($key, $iv);
$ae->adata_add('additional_authenticated_data1');
$ae->adata_add('additional_authenticated_data2');
my $ct = $ae->encrypt_add('data1');
$ct .= $ae->encrypt_add('data2');
$ct .= $ae->encrypt_add('data3');
my $tag = $ae->encrypt_done();

# decrypt and verify
my $ae = Crypt::AuthEnc::ChaCha20Poly1305->new($key, $iv);
$ae->adata_add('additional_authenticated_data1');
$ae->adata_add('additional_authenticated_data2');
my $pt = $ae->decrypt_add('ciphertext1');
$pt .= $ae->decrypt_add('ciphertext2');
$pt .= $ae->decrypt_add('ciphertext3');
my $tag = $ae->decrypt_done();
die "decrypt failed" unless $tag eq $expected_tag;

#or
my $result = $ae->decrypt_done($expected_tag); # 0 or 1

### functional interface
use Crypt::AuthEnc::ChaCha20Poly1305 qw(chacha20poly1305_encrypt_authenticate chacha20poly1305_decrypt_verify);

my ($ciphertext, $tag) = chacha20poly1305_encrypt_authenticate($key, $iv, $adata, $plaintext);
my $plaintext = chacha20poly1305_decrypt_verify($key, $iv, $adata, $ciphertext, $tag);

DESCRIPTION

Provides encryption and authentication based on ChaCha20 + Poly1305 as defined in RFC 7539 - https://tools.ietf.org/html/rfc7539

EXPORT

Nothing is exported by default.

You can export selected functions:

use Crypt::AuthEnc::ChaCha20Poly1305 qw(chacha20poly1305_encrypt_authenticate chacha20poly1305_decrypt_verify);

FUNCTIONS

chacha20poly1305_encrypt_authenticate

my ($ciphertext, $tag) = chacha20poly1305_encrypt_authenticate($key, $iv, $adata, $plaintext);

# $key ..... key of proper length (128 or 256 bits / 16 or 32 bytes)
# $iv ...... initialization vector (64 or 96 bits / 8 or 12 bytes)
# $adata ... additional authenticated data (optional)

chacha20poly1305_decrypt_verify

my $plaintext = chacha20poly1305_decrypt_verify($key, $iv, $adata, $ciphertext, $tag);
# on error returns undef

METHODS

new

my $ae = Crypt::AuthEnc::ChaCha20Poly1305->new($key, $iv);

# $key ..... encryption key of proper length (128 or 256 bits / 16 or 32 bytes)
# $iv ...... initialization vector (64 or 96 bits / 8 or 12 bytes)

adata_add

Add additional authenticated data. Can be called before the first encrypt_add or decrypt_add;

$ae->adata_add($aad_data);                     # can be called multiple times

encrypt_add

$ciphertext = $ae->encrypt_add($data);         # can be called multiple times

encrypt_done

$tag = $ae->encrypt_done();                    # returns $tag value

decrypt_add

$plaintext = $ae->decrypt_add($ciphertext);    # can be called multiple times

decrypt_done

my $tag = $ae->decrypt_done;           # returns $tag value
#or
my $result = $ae->decrypt_done($tag);  # returns 1 (success) or 0 (failure)

set_iv

my $ae = Crypt::AuthEnc::ChaCha20Poly1305->new($key)->set_iv($iv);
# $iv ...... initialization vector (64 or 96 bits / 8 or 12 bytes)

set_iv_rfc7905

See https://tools.ietf.org/html/rfc7905

my $ae = Crypt::AuthEnc::ChaCha20Poly1305->new($key)->set_iv_rfc7905($iv, $seqnum);
# $iv ...... initialization vector (96 bits / 12 bytes)
# $seqnum .. 64bit integer (sequence number)

clone

my $ae_new = $ae->clone;

SEE ALSO