Crypt::AuthEnc::CCM - Authenticated encryption in CCM mode
### OO interface
use Crypt::AuthEnc::CCM;
# encrypt and authenticate
my $ae = Crypt::AuthEnc::CCM->new("AES", $key, $iv, $adata, $tag_len, $pt_len);
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::CCM->new("AES", $key, $iv, $adata, $tag_len, $pt_len);
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::CCM qw(ccm_encrypt_authenticate ccm_decrypt_verify);
($ciphertext, $tag) = ccm_encrypt_authenticate('AES', $key, $nonce, $adata, $tag_len, $plaintext);
$plaintext = ccm_decrypt_verify('AES', $key, $nonce, $adata, $ciphertext, $tag);
CCM is a encrypt+authenticate mode that is centered around using AES (or any 16-byte cipher) as a primitive.
Unlike EAX and OCB mode, it is only meant for packet mode where the length of the input is known in advance.
Nothing is exported by default.
You can export selected functions:
use Crypt::AuthEnc::CCM qw(ccm_encrypt_authenticate ccm_decrypt_verify);
my ($ciphertext, $tag) = ccm_encrypt_authenticate($cipher, $key, $nonce, $adata, $tag_len, $plaintext);
# $cipher .. 'AES' or name of any other cipher with 16-byte block len
# $key ..... key of proper length (e.g. 128/192/256bits for AES)
# $nonce ... unique nonce/salt (no need to keep it secret)
# $adata ... additional authenticated data
# $tag_len . required length of output tag
CCM parameters should follow http://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-38c.pdf
# tag length: 4, 6, 8, 10, 12, 14, 16 (reasonable minimum is 8)
# nonce length: 7, 8, 9, 10, 11, 12, 13 (if you are not sure, use 11)
# BEWARE nonce length determines max. enc/dec data size: max_data_size = 2^(8*(15-nonce_len))
my $plaintext = ccm_decrypt_verify($cipher, $key, $nonce, $adata, $ciphertext, $tag);
# on error returns undef
my $ae = Crypt::AuthEnc::CCM->new($cipher, $key, $nonce, $adata, $tag_len, $pt_len);
# $cipher .. 'AES' or name of any other cipher with 16-byte block len
# $key ..... key of proper length (e.g. 128/192/256bits for AES)
# $nonce ... unique nonce/salt (no need to keep it secret)
# $adata ... additional authenticated data
# $tag_len . required length of output tag
# $pt_len .. expected length of plaintext/ciphertext to encrypt/decrypt
$ciphertext = $ae->encrypt_add($data); # can be called multiple times
my $tag = $ae->encrypt_done; # returns $tag value
$plaintext = $ae->decrypt_add($ciphertext); # can be called multiple times
my $tag = $ae->decrypt_done; # returns $tag value
#or
my $result = $ae->decrypt_done($tag); # returns 1 (success) or 0 (failure)
my $ae_new = $ae->clone;
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