php 7.2 mycrypt install

Centos 8 の php 7.2 で　mcrypt　をインストールする

```bash
cat /etc/redhat-release
CentOS Linux release 8.3.2011
```

*20210512*

```bash
dnf module install -y php:7.4
dnf install -y php-pear php-devel php-devel
dnf install -y php-pgsql php-mbstring php-pecl-zip php-xml php-intl
dnf install -y epel-release
dnf install -y libmcrypt-devel libmcrypt

pecl install mcrypt-1.0.4
```

```bash
dnf install -y httpd php php-pear 
dnf install -y gcc make autoconf pkg-config php-pear php-xml php-devel
dnf install -y epel-release
dnf install -y libmcrypt  libmcrypt-devel
```

出力

```text
You should add “extension=mcrypt.so” to php.ini
```

php.ini に追記

```text
    886 ;;;;
    887 ; Note: packaged extension modules are now loaded via the .ini files
    888 ; found in the directory /etc/php.d; these are loaded by default.
    889 ;;;;
    890 extension=mcrypt.so
    891 ;;;;;;;;;;;;;;;;;;;
    892 ; Module Settings ;
    893 ;;;;;;;;;;;;;;;;;;;
```

サンプルコード

```php
<?php
    # --- ENCRYPTION ---

    # the key should be random binary, use scrypt, bcrypt or PBKDF2 to
    # convert a string into a key
    # key is specified using hexadecimal
    $key = pack('H*', "bcb04b7e103a0cd8b54763051cef08bc55abe029fdebae5e1d417e2ffb2a00a3");
    
    # show key size use either 16, 24 or 32 byte keys for AES-128, 192
    # and 256 respectively
    $key_size =  strlen($key);
    echo "Key size: " . $key_size . "\n";
    
    $plaintext = "This string was AES-256 / CBC / ZeroBytePadding encrypted.";

    # create a random IV to use with CBC encoding
    $iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC);
    $iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);
    
    # creates a cipher text compatible with AES (Rijndael block size = 128)
    # to keep the text confidential 
    # only suitable for encoded input that never ends with value 00h
    # (because of default zero padding)
    $ciphertext = mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $key,
                                 $plaintext, MCRYPT_MODE_CBC, $iv);

    # prepend the IV for it to be available for decryption
    $ciphertext = $iv . $ciphertext;
    
    # encode the resulting cipher text so it can be represented by a string
    $ciphertext_base64 = base64_encode($ciphertext);

    echo  $ciphertext_base64 . "\n";

    # === WARNING ===

    # Resulting cipher text has no integrity or authenticity added
    # and is not protected against padding oracle attacks.
    
    # --- DECRYPTION ---
    
    $ciphertext_dec = base64_decode($ciphertext_base64);
    
    # retrieves the IV, iv_size should be created using mcrypt_get_iv_size()
    $iv_dec = substr($ciphertext_dec, 0, $iv_size);
    
    # retrieves the cipher text (everything except the $iv_size in the front)
    $ciphertext_dec = substr($ciphertext_dec, $iv_size);

    # may remove 00h valued characters from end of plain text
    $plaintext_dec = mcrypt_decrypt(MCRYPT_RIJNDAEL_128, $key,
                                    $ciphertext_dec, MCRYPT_MODE_CBC, $iv_dec);
    echo '$plaintext_dec'. "\n";
    echo  $plaintext_dec . "\n";
?>
```

```text
Key size: 32
gzBK1+mHPxMAn/Rk1SXzCOaKY60u+9AhxyBKlAmad6ulWr8undGIWMxAagdQPbCparAZUhH+R+S9e6Yu7a0IbD2yy/f6NiCUpbzHOP2QygY=
$plaintext_dec
This string was AES-256 / CBC / ZeroBytePadding encrypted.
```