mcrypt_generic_init(3) [php man page]

MCRYPT_GENERIC_INIT(3)							 1						    MCRYPT_GENERIC_INIT(3)

mcrypt_generic_init - This function initializes all buffers needed for encryption

SYNOPSIS

       int mcrypt_generic_init (resource  $td, string  $key, string  $iv)

DESCRIPTION

	You need to call this function before every call to mcrypt_generic(3) or mdecrypt_generic(3).

PARAMETERS

	      o $td
		- The encryption descriptor.

	      o $key
		- The maximum length of the key should be the one obtained by calling mcrypt_enc_get_key_size(3) and every value smaller than this
		is legal.

	      o $iv
		-  The	IV  should  normally  have  the  size  of  the	algorithms  block  size,  but  you  must  obtain  the  size   by   calling
		mcrypt_enc_get_iv_size(3).  IV is ignored in ECB. IV MUST exist in CFB, CBC, STREAM, nOFB and OFB modes. It needs to be random and
		unique (but not secret). The same IV must be used for encryption/decryption. If you do not want to use it you  should  set  it	to
		zeros, but this is not recommended.

RETURN VALUES

	The  function  returns	a negative value on error: -3 when the key length was incorrect, -4 when there was a memory allocation problem and
       any other return value is an unknown error. If an error occurs a warning will be displayed accordingly.	FALSE  is  returned  if  incorrect
       parameters were passed.

SEE ALSO

       mcrypt_module_open(3).

PHP Documentation Group 												    MCRYPT_GENERIC_INIT(3)

MCRYPT_GENERIC(3)							 1							 MCRYPT_GENERIC(3)

mcrypt_generic - This function encrypts data

SYNOPSIS

       string mcrypt_generic (resource	$td, string  $data)

DESCRIPTION

	This function encrypts data. The data is padded with " " to make sure the length of the data is n * blocksize. This function returns the
       encrypted data. Note that the length of the returned string can in fact be longer than the input, due to the padding of the data.

	If you want to store the encrypted data in a database make sure to store the entire string as returned by mcrypt_generic,  or  the  string
       will not entirely decrypt properly. If your original string is 10 characters long and the block size is 8 (use mcrypt_enc_get_block_size(3)
       to determine the blocksize), you would need at least 16 characters in your database field. Note the string returned by  mdecrypt_generic(3)
       will be 16 characters as well...use rtrim($str, "") to remove the padding.

	If you are for example storing the data in a MySQL database remember that varchar fields automatically have trailing spaces removed during
       insertion. As encrypted data can end in a space (ASCII 32), the data will be damaged by this removal. Store data in a tinyblob/tinytext (or
       larger) field instead.

PARAMETERS

	      o $td
		-  The encryption descriptor.  The encryption handle should always be initialized with mcrypt_generic_init(3) with a key and an IV
		before	calling  this  function.  Where  the  encryption  is  done,  you  should  free	 the   encryption   buffers   by   calling
		mcrypt_generic_deinit(3). See mcrypt_module_open(3) for an example.

	      o $data
		- The data to encrypt.

RETURN VALUES

	Returns the encrypted data.

SEE ALSO

       mdecrypt_generic(3), mcrypt_generic_init(3), mcrypt_generic_deinit(3).

PHP Documentation Group 													 MCRYPT_GENERIC(3)