pd_crypto

Cryptography related functionality to deal with encrypted PDF content. More...

Files
file	pd_crypto.h

Typedefs
typedef struct pd_crypto *	pd_crypto

Functions
pd_crypto	pd_crypto_create (PDDictionaryRef trailerDict, PDDictionaryRef options)
void	pd_crypto_destroy (pd_crypto crypto)
PDInteger	pd_crypto_unescape (char *str)
PDInteger	pd_crypto_unescape_explicit_len (char *str, int len)
PDInteger	pd_crypto_escape (char **dst, const char *src, PDInteger srcLen)
PDInteger	pd_crypto_secure (char **dst, const char *src, PDInteger srcLen)
PDBool	pd_crypto_authenticate_user (pd_crypto crypto, const char *password)
PDInteger	pd_crypto_encrypt (pd_crypto crypto, PDInteger obid, PDInteger genid, char **dst, char *src, PDInteger len)
void	pd_crypto_decrypt (pd_crypto crypto, PDInteger obid, PDInteger genid, char *data)
void	pd_crypto_convert (pd_crypto crypto, PDInteger obid, PDInteger genid, char *data, PDInteger len)
PDStringRef	pd_crypto_get_filter (pd_crypto crypto)
PDStringRef	pd_crypto_get_subfilter (pd_crypto crypto)
PDInteger	pd_crypto_get_version (pd_crypto crypto)
PDInteger	pd_crypto_get_revision (pd_crypto crypto)
PDBool	pd_crypto_get_encrypt_metadata_bool (pd_crypto crypto)
pd_crypto_method	pd_crypto_get_method (pd_crypto crypto)
pd_auth_event	pd_crypto_get_auth_event (pd_crypto crypto)

Detailed Description

Cryptography related functionality to deal with encrypted PDF content.

The pd_crypto object.

Typedef Documentation

typedef struct pd_crypto* pd_crypto

Cryptography module for PDF encryption/decryption.

Note

If PD_SUPPORT_CRYPTO is not set, this structure is a dummy object.

The pd_crypto object.

Function Documentation

PDBool pd_crypto_authenticate_user	(	pd_crypto	crypto,
		const char *	password
	)

Supply a user password.

Parameters

crypto	The crypto object.
password	The user password.

Returns

true if the password was valid, false if not

void pd_crypto_convert	(	pd_crypto	crypto,
		PDInteger	obid,
		PDInteger	genid,
		char *	data,
		PDInteger	len
	)

Convert data of length len owned by object obid with generation number genid to/from encrypted version.

This is the "low level" function used by the above two methods to encrypt/decrypt content. This version does not escape/unescape or add/remove parentheses, which the above ones do. This version is used directly for streams which aren't escaped.

Parameters

crypto	Crypto instance.
obid	Object ID of owning object.
genid	Generation number of owning object.
data	Data to convert.
len	Length of data.

pd_crypto pd_crypto_create	(	PDDictionaryRef	trailerDict,
		PDDictionaryRef	options
	)

Create crypto object with given configuration.

Parameters

trailerDict	The pd_dict of the Trailer dictionary of the given PDF. Needed to obtain the /ID key.
options	The pd_dict of the Encrypt dictionary of the given PDF.

Returns

Instance with given options or NULL if unsupported.

void pd_crypto_decrypt	(	pd_crypto	crypto,
		PDInteger	obid,
		PDInteger	genid,
		char *	data
	)

Decrypt, unescape and NUL-terminate the value of data in-place.

Parameters

crypto	Crypto instance.
obid	The object ID of the object whose content is being decrypted.
genid	The generation number of the object whose content is being decrypted.
data	The data to decrypt. The content will be in-place replaced with the new data.

void pd_crypto_destroy

(

pd_crypto

crypto

)

Destroy crypto object, freeing up resources.

PDInteger pd_crypto_encrypt	(	pd_crypto	crypto,
		PDInteger	obid,
		PDInteger	genid,
		char **	dst,
		char *	src,
		PDInteger	len
	)

Encrypt the value of src of length len and store the value in dst, escaped and parenthesized.

Parameters

crypto	Crypto instance.
obid	The object ID of the object whose content is being encrypted.
genid	The generation number of the object whose content is being encrypted.
dst	Pointer to char buffer into which results will be stored. Should not be pre-allocated.
src	The data to encrypt. The content will be in-place encrypted but escaped results go into *dst.
len	Length of data in bytes.

Returns

Length of encrypted string, including parentheses and escaping.

PDInteger pd_crypto_escape	(	char **	dst,
		const char *	src,
		PDInteger	srcLen
	)

Escape a string. The result will be wrapped in parentheses.

Strings, in particular encrypted strings, are stored using escaping to prevent null termination in the middle of strings and PDF misinterpretations and other nastiness.

Escaping is done to control chars, such as ,
, , , and unreadable ascii characters using (s) (1, 2 or 3).

Parameters

dst	Pointer to destination string. Should not be pre-allocated.
src	String to escape.
srcLen	Length of string.

Returns

The length of the escaped string.

PDInteger pd_crypto_secure	(	char **	dst,
		const char *	src,
		PDInteger	srcLen
	)

Generate a secure string from a given input string.

The input string may optionally be wrapped in parentheses. The resulting string will be, regardless of input string.

This method is roughly the equivalent of doing len = pd_crypto_unescape_explicit_len(src, srcLen); pd_crypto_escape(dst, src, len);

Parameters

dst	Pointer to destination string. Should not be pre-allocated.
src	String to escape.
srcLen	Length of string.

Returns

The length of the escaped string.

PDInteger pd_crypto_unescape

(

char *

str

)

Unescape a PDF string which may optionally be wrapped in parentheses. The result is not wrapped in parentheses. The string is unescaped in-place and NUL-terminated.

Strings, in particular encrypted strings, are stored using escaping to prevent null termination in the middle of strings and PDF misinterpretations and other nastiness.

Escaping is done to control chars, such as ,
, , , and unreadable ascii characters using (s) (1, 2 or 3).

Parameters

str	The string.

Returns

The length of the unescaped string.

PDInteger pd_crypto_unescape_explicit_len	(	char *	str,
		int	len
	)

Unescape a PDF string, explicitly defining the length of the string to allow for potential mid-NULs. May optionally be wrapped in parentheses. The result is not wrapped in parentheses. The string is unescaped in-place and NUL-terminated.

Strings, in particular encrypted strings, are stored using escaping to prevent null termination in the middle of strings and PDF misinterpretations and other nastiness.

Escaping is done to control chars, such as ,
, , , and unreadable ascii characters using (s) (1, 2 or 3).

Parameters

str	The string.
len	The length of the string;

Returns

The length of the unescaped string.