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DEFINITIONS
This source file includes following definitions.
- GetCipherPtr
- ossl_cipher_new
- ossl_cipher_free
- ossl_cipher_alloc
- ossl_cipher_initialize
- ossl_cipher_copy
- add_cipher_name_to_ary
- ossl_s_ciphers
- ossl_cipher_reset
- ossl_cipher_init
- ossl_cipher_encrypt
- ossl_cipher_decrypt
- ossl_cipher_pkcs5_keyivgen
- ossl_cipher_update_long
- ossl_cipher_update
- ossl_cipher_final
- ossl_cipher_name
- ossl_cipher_set_key
- ossl_cipher_set_iv
- ossl_cipher_set_auth_data
- ossl_cipher_get_auth_tag
- ossl_cipher_set_auth_tag
- ossl_cipher_is_authenticated
- ossl_cipher_set_key_length
- ossl_cipher_set_padding
- CIPHER_0ARG_INT
/*
* 'OpenSSL for Ruby' project
* Copyright (C) 2001-2002 Michal Rokos <m.rokos@sh.cvut.cz>
* All rights reserved.
*/
/*
* This program is licensed under the same licence as Ruby.
* (See the file 'LICENCE'.)
*/
#include "ossl.h"
#define NewCipher(klass) \
TypedData_Wrap_Struct((klass), &ossl_cipher_type, 0)
#define AllocCipher(obj, ctx) do { \
(ctx) = EVP_CIPHER_CTX_new(); \
if (!(ctx)) \
ossl_raise(rb_eRuntimeError, NULL); \
RTYPEDDATA_DATA(obj) = (ctx); \
} while (0)
#define GetCipherInit(obj, ctx) do { \
TypedData_Get_Struct((obj), EVP_CIPHER_CTX, &ossl_cipher_type, (ctx)); \
} while (0)
#define GetCipher(obj, ctx) do { \
GetCipherInit((obj), (ctx)); \
if (!(ctx)) { \
ossl_raise(rb_eRuntimeError, "Cipher not inititalized!"); \
} \
} while (0)
#define SafeGetCipher(obj, ctx) do { \
OSSL_Check_Kind((obj), cCipher); \
GetCipher((obj), (ctx)); \
} while (0)
/*
* Classes
*/
VALUE cCipher;
VALUE eCipherError;
static VALUE ossl_cipher_alloc(VALUE klass);
static void ossl_cipher_free(void *ptr);
static const rb_data_type_t ossl_cipher_type = {
"OpenSSL/Cipher",
{
0, ossl_cipher_free,
},
0, 0, RUBY_TYPED_FREE_IMMEDIATELY,
};
/*
* PUBLIC
*/
const EVP_CIPHER *
GetCipherPtr(VALUE obj)
{
EVP_CIPHER_CTX *ctx;
SafeGetCipher(obj, ctx);
return EVP_CIPHER_CTX_cipher(ctx);
}
VALUE
ossl_cipher_new(const EVP_CIPHER *cipher)
{
VALUE ret;
EVP_CIPHER_CTX *ctx;
ret = ossl_cipher_alloc(cCipher);
AllocCipher(ret, ctx);
if (EVP_CipherInit_ex(ctx, cipher, NULL, NULL, NULL, -1) != 1)
ossl_raise(eCipherError, NULL);
return ret;
}
/*
* PRIVATE
*/
static void
ossl_cipher_free(void *ptr)
{
EVP_CIPHER_CTX_free(ptr);
}
static VALUE
ossl_cipher_alloc(VALUE klass)
{
return NewCipher(klass);
}
/*
* call-seq:
* Cipher.new(string) -> cipher
*
* The string must contain a valid cipher name like "AES-128-CBC" or "3DES".
*
* A list of cipher names is available by calling OpenSSL::Cipher.ciphers.
*/
static VALUE
ossl_cipher_initialize(VALUE self, VALUE str)
{
EVP_CIPHER_CTX *ctx;
const EVP_CIPHER *cipher;
char *name;
unsigned char dummy_key[EVP_MAX_KEY_LENGTH] = { 0 };
name = StringValueCStr(str);
GetCipherInit(self, ctx);
if (ctx) {
ossl_raise(rb_eRuntimeError, "Cipher already inititalized!");
}
AllocCipher(self, ctx);
if (!(cipher = EVP_get_cipherbyname(name))) {
ossl_raise(rb_eRuntimeError, "unsupported cipher algorithm (%"PRIsVALUE")", str);
}
/*
* EVP_CipherInit_ex() allows to specify NULL to key and IV, however some
* ciphers don't handle well (OpenSSL's bug). [Bug #2768]
*
* The EVP which has EVP_CIPH_RAND_KEY flag (such as DES3) allows
* uninitialized key, but other EVPs (such as AES) does not allow it.
* Calling EVP_CipherUpdate() without initializing key causes SEGV so we
* set the data filled with "\0" as the key by default.
*/
if (EVP_CipherInit_ex(ctx, cipher, NULL, dummy_key, NULL, -1) != 1)
ossl_raise(eCipherError, NULL);
return self;
}
static VALUE
ossl_cipher_copy(VALUE self, VALUE other)
{
EVP_CIPHER_CTX *ctx1, *ctx2;
rb_check_frozen(self);
if (self == other) return self;
GetCipherInit(self, ctx1);
if (!ctx1) {
AllocCipher(self, ctx1);
}
SafeGetCipher(other, ctx2);
if (EVP_CIPHER_CTX_copy(ctx1, ctx2) != 1)
ossl_raise(eCipherError, NULL);
return self;
}
static void*
add_cipher_name_to_ary(const OBJ_NAME *name, VALUE ary)
{
rb_ary_push(ary, rb_str_new2(name->name));
return NULL;
}
/*
* call-seq:
* OpenSSL::Cipher.ciphers -> array[string...]
*
* Returns the names of all available ciphers in an array.
*/
static VALUE
ossl_s_ciphers(VALUE self)
{
VALUE ary;
ary = rb_ary_new();
OBJ_NAME_do_all_sorted(OBJ_NAME_TYPE_CIPHER_METH,
(void(*)(const OBJ_NAME*,void*))add_cipher_name_to_ary,
(void*)ary);
return ary;
}
/*
* call-seq:
* cipher.reset -> self
*
* Fully resets the internal state of the Cipher. By using this, the same
* Cipher instance may be used several times for encryption or decryption tasks.
*
* Internally calls EVP_CipherInit_ex(ctx, NULL, NULL, NULL, NULL, -1).
*/
static VALUE
ossl_cipher_reset(VALUE self)
{
EVP_CIPHER_CTX *ctx;
GetCipher(self, ctx);
if (EVP_CipherInit_ex(ctx, NULL, NULL, NULL, NULL, -1) != 1)
ossl_raise(eCipherError, NULL);
return self;
}
static VALUE
ossl_cipher_init(int argc, VALUE *argv, VALUE self, int mode)
{
EVP_CIPHER_CTX *ctx;
unsigned char key[EVP_MAX_KEY_LENGTH], *p_key = NULL;
unsigned char iv[EVP_MAX_IV_LENGTH], *p_iv = NULL;
VALUE pass, init_v;
if(rb_scan_args(argc, argv, "02", &pass, &init_v) > 0){
/*
* oops. this code mistakes salt for IV.
* We deprecated the arguments for this method, but we decided
* keeping this behaviour for backward compatibility.
*/
VALUE cname = rb_class_path(rb_obj_class(self));
rb_warn("arguments for %"PRIsVALUE"#encrypt and %"PRIsVALUE"#decrypt were deprecated; "
"use %"PRIsVALUE"#pkcs5_keyivgen to derive key and IV",
cname, cname, cname);
StringValue(pass);
GetCipher(self, ctx);
if (NIL_P(init_v)) memcpy(iv, "OpenSSL for Ruby rulez!", sizeof(iv));
else{
StringValue(init_v);
if (EVP_MAX_IV_LENGTH > RSTRING_LEN(init_v)) {
memset(iv, 0, EVP_MAX_IV_LENGTH);
memcpy(iv, RSTRING_PTR(init_v), RSTRING_LEN(init_v));
}
else memcpy(iv, RSTRING_PTR(init_v), sizeof(iv));
}
EVP_BytesToKey(EVP_CIPHER_CTX_cipher(ctx), EVP_md5(), iv,
(unsigned char *)RSTRING_PTR(pass), RSTRING_LENINT(pass), 1, key, NULL);
p_key = key;
p_iv = iv;
}
else {
GetCipher(self, ctx);
}
if (EVP_CipherInit_ex(ctx, NULL, NULL, p_key, p_iv, mode) != 1) {
ossl_raise(eCipherError, NULL);
}
return self;
}
/*
* call-seq:
* cipher.encrypt -> self
*
* Initializes the Cipher for encryption.
*
* Make sure to call Cipher#encrypt or Cipher#decrypt before using any of the
* following methods:
* * [key=, iv=, random_key, random_iv, pkcs5_keyivgen]
*
* Internally calls EVP_CipherInit_ex(ctx, NULL, NULL, NULL, NULL, 1).
*/
static VALUE
ossl_cipher_encrypt(int argc, VALUE *argv, VALUE self)
{
return ossl_cipher_init(argc, argv, self, 1);
}
/*
* call-seq:
* cipher.decrypt -> self
*
* Initializes the Cipher for decryption.
*
* Make sure to call Cipher#encrypt or Cipher#decrypt before using any of the
* following methods:
* * [key=, iv=, random_key, random_iv, pkcs5_keyivgen]
*
* Internally calls EVP_CipherInit_ex(ctx, NULL, NULL, NULL, NULL, 0).
*/
static VALUE
ossl_cipher_decrypt(int argc, VALUE *argv, VALUE self)
{
return ossl_cipher_init(argc, argv, self, 0);
}
/*
* call-seq:
* cipher.pkcs5_keyivgen(pass [, salt [, iterations [, digest]]] ) -> nil
*
* Generates and sets the key/IV based on a password.
*
* WARNING: This method is only PKCS5 v1.5 compliant when using RC2, RC4-40,
* or DES with MD5 or SHA1. Using anything else (like AES) will generate the
* key/iv using an OpenSSL specific method. This method is deprecated and
* should no longer be used. Use a PKCS5 v2 key generation method from
* OpenSSL::PKCS5 instead.
*
* === Parameters
* +salt+ must be an 8 byte string if provided.
* +iterations+ is a integer with a default of 2048.
* +digest+ is a Digest object that defaults to 'MD5'
*
* A minimum of 1000 iterations is recommended.
*
*/
static VALUE
ossl_cipher_pkcs5_keyivgen(int argc, VALUE *argv, VALUE self)
{
EVP_CIPHER_CTX *ctx;
const EVP_MD *digest;
VALUE vpass, vsalt, viter, vdigest;
unsigned char key[EVP_MAX_KEY_LENGTH], iv[EVP_MAX_IV_LENGTH], *salt = NULL;
int iter;
rb_scan_args(argc, argv, "13", &vpass, &vsalt, &viter, &vdigest);
StringValue(vpass);
if(!NIL_P(vsalt)){
StringValue(vsalt);
if(RSTRING_LEN(vsalt) != PKCS5_SALT_LEN)
ossl_raise(eCipherError, "salt must be an 8-octet string");
salt = (unsigned char *)RSTRING_PTR(vsalt);
}
iter = NIL_P(viter) ? 2048 : NUM2INT(viter);
digest = NIL_P(vdigest) ? EVP_md5() : GetDigestPtr(vdigest);
GetCipher(self, ctx);
EVP_BytesToKey(EVP_CIPHER_CTX_cipher(ctx), digest, salt,
(unsigned char *)RSTRING_PTR(vpass), RSTRING_LENINT(vpass), iter, key, iv);
if (EVP_CipherInit_ex(ctx, NULL, NULL, key, iv, -1) != 1)
ossl_raise(eCipherError, NULL);
OPENSSL_cleanse(key, sizeof key);
OPENSSL_cleanse(iv, sizeof iv);
return Qnil;
}
static int
ossl_cipher_update_long(EVP_CIPHER_CTX *ctx, unsigned char *out, long *out_len_ptr,
const unsigned char *in, long in_len)
{
int out_part_len;
long out_len = 0;
#define UPDATE_LENGTH_LIMIT INT_MAX
#if SIZEOF_LONG > UPDATE_LENGTH_LIMIT
if (in_len > UPDATE_LENGTH_LIMIT) {
const int in_part_len = (UPDATE_LENGTH_LIMIT / 2 + 1) & ~1;
do {
if (!EVP_CipherUpdate(ctx, out ? (out + out_len) : 0,
&out_part_len, in, in_part_len))
return 0;
out_len += out_part_len;
in += in_part_len;
} while ((in_len -= in_part_len) > UPDATE_LENGTH_LIMIT);
}
#endif
if (!EVP_CipherUpdate(ctx, out ? (out + out_len) : 0,
&out_part_len, in, (int)in_len))
return 0;
if (out_len_ptr) *out_len_ptr = out_len += out_part_len;
return 1;
}
/*
* call-seq:
* cipher.update(data [, buffer]) -> string or buffer
*
* Encrypts data in a streaming fashion. Hand consecutive blocks of data
* to the +update+ method in order to encrypt it. Returns the encrypted
* data chunk. When done, the output of Cipher#final should be additionally
* added to the result.
*
* === Parameters
* +data+ is a nonempty string.
* +buffer+ is an optional string to store the result.
*/
static VALUE
ossl_cipher_update(int argc, VALUE *argv, VALUE self)
{
EVP_CIPHER_CTX *ctx;
unsigned char *in;
long in_len, out_len;
VALUE data, str;
rb_scan_args(argc, argv, "11", &data, &str);
StringValue(data);
in = (unsigned char *)RSTRING_PTR(data);
if ((in_len = RSTRING_LEN(data)) == 0)
ossl_raise(rb_eArgError, "data must not be empty");
GetCipher(self, ctx);
out_len = in_len+EVP_CIPHER_CTX_block_size(ctx);
if (out_len <= 0) {
ossl_raise(rb_eRangeError,
"data too big to make output buffer: %ld bytes", in_len);
}
if (NIL_P(str)) {
str = rb_str_new(0, out_len);
} else {
StringValue(str);
rb_str_resize(str, out_len);
}
if (!ossl_cipher_update_long(ctx, (unsigned char *)RSTRING_PTR(str), &out_len, in, in_len))
ossl_raise(eCipherError, NULL);
assert(out_len < RSTRING_LEN(str));
rb_str_set_len(str, out_len);
return str;
}
/*
* call-seq:
* cipher.final -> string
*
* Returns the remaining data held in the cipher object. Further calls to
* Cipher#update or Cipher#final will return garbage. This call should always
* be made as the last call of an encryption or decryption operation, after
* after having fed the entire plaintext or ciphertext to the Cipher instance.
*
* If an authenticated cipher was used, a CipherError is raised if the tag
* could not be authenticated successfully. Only call this method after
* setting the authentication tag and passing the entire contents of the
* ciphertext into the cipher.
*/
static VALUE
ossl_cipher_final(VALUE self)
{
EVP_CIPHER_CTX *ctx;
int out_len;
VALUE str;
GetCipher(self, ctx);
str = rb_str_new(0, EVP_CIPHER_CTX_block_size(ctx));
if (!EVP_CipherFinal_ex(ctx, (unsigned char *)RSTRING_PTR(str), &out_len))
ossl_raise(eCipherError, NULL);
assert(out_len <= RSTRING_LEN(str));
rb_str_set_len(str, out_len);
return str;
}
/*
* call-seq:
* cipher.name -> string
*
* Returns the name of the cipher which may differ slightly from the original
* name provided.
*/
static VALUE
ossl_cipher_name(VALUE self)
{
EVP_CIPHER_CTX *ctx;
GetCipher(self, ctx);
return rb_str_new2(EVP_CIPHER_name(EVP_CIPHER_CTX_cipher(ctx)));
}
/*
* call-seq:
* cipher.key = string -> string
*
* Sets the cipher key. To generate a key, you should either use a secure
* random byte string or, if the key is to be derived from a password, you
* should rely on PBKDF2 functionality provided by OpenSSL::PKCS5. To
* generate a secure random-based key, Cipher#random_key may be used.
*
* Only call this method after calling Cipher#encrypt or Cipher#decrypt.
*/
static VALUE
ossl_cipher_set_key(VALUE self, VALUE key)
{
EVP_CIPHER_CTX *ctx;
int key_len;
StringValue(key);
GetCipher(self, ctx);
key_len = EVP_CIPHER_CTX_key_length(ctx);
if (RSTRING_LEN(key) != key_len)
ossl_raise(rb_eArgError, "key must be %d bytes", key_len);
if (EVP_CipherInit_ex(ctx, NULL, NULL, (unsigned char *)RSTRING_PTR(key), NULL, -1) != 1)
ossl_raise(eCipherError, NULL);
return key;
}
/*
* call-seq:
* cipher.iv = string -> string
*
* Sets the cipher IV. Please note that since you should never be using ECB
* mode, an IV is always explicitly required and should be set prior to
* encryption. The IV itself can be safely transmitted in public, but it
* should be unpredictable to prevent certain kinds of attacks. You may use
* Cipher#random_iv to create a secure random IV.
*
* Only call this method after calling Cipher#encrypt or Cipher#decrypt.
*
* If not explicitly set, the OpenSSL default of an all-zeroes ("\\0") IV is
* used.
*/
static VALUE
ossl_cipher_set_iv(VALUE self, VALUE iv)
{
EVP_CIPHER_CTX *ctx;
int iv_len;
StringValue(iv);
GetCipher(self, ctx);
iv_len = EVP_CIPHER_CTX_iv_length(ctx);
if (RSTRING_LEN(iv) != iv_len)
ossl_raise(rb_eArgError, "iv must be %d bytes", iv_len);
if (EVP_CipherInit_ex(ctx, NULL, NULL, NULL, (unsigned char *)RSTRING_PTR(iv), -1) != 1)
ossl_raise(eCipherError, NULL);
return iv;
}
#ifdef HAVE_AUTHENTICATED_ENCRYPTION
/*
* call-seq:
* cipher.auth_data = string -> string
*
* Sets the cipher's additional authenticated data. This field must be
* set when using AEAD cipher modes such as GCM or CCM. If no associated
* data shall be used, this method must *still* be called with a value of "".
* The contents of this field should be non-sensitive data which will be
* added to the ciphertext to generate the authentication tag which validates
* the contents of the ciphertext.
*
* The AAD must be set prior to encryption or decryption. In encryption mode,
* it must be set after calling Cipher#encrypt and setting Cipher#key= and
* Cipher#iv=. When decrypting, the authenticated data must be set after key,
* iv and especially *after* the authentication tag has been set. I.e. set it
* only after calling Cipher#decrypt, Cipher#key=, Cipher#iv= and
* Cipher#auth_tag= first.
*/
static VALUE
ossl_cipher_set_auth_data(VALUE self, VALUE data)
{
EVP_CIPHER_CTX *ctx;
unsigned char *in;
long in_len, out_len;
StringValue(data);
in = (unsigned char *) RSTRING_PTR(data);
in_len = RSTRING_LEN(data);
GetCipher(self, ctx);
if (!ossl_cipher_update_long(ctx, NULL, &out_len, in, in_len))
ossl_raise(eCipherError, "couldn't set additional authenticated data");
return data;
}
/*
* call-seq:
* cipher.auth_tag(tag_len = 16) -> String
*
* Gets the authentication tag generated by Authenticated Encryption Cipher
* modes (GCM for example). This tag may be stored along with the ciphertext,
* then set on the decryption cipher to authenticate the contents of the
* ciphertext against changes. If the optional integer parameter +tag_len+ is
* given, the returned tag will be +tag_len+ bytes long. If the parameter is
* omitted, the maximum length of 16 bytes will be returned. For maximum
* security, the default of 16 bytes should be chosen.
*
* The tag may only be retrieved after calling Cipher#final.
*/
static VALUE
ossl_cipher_get_auth_tag(int argc, VALUE *argv, VALUE self)
{
VALUE vtag_len, ret;
EVP_CIPHER_CTX *ctx;
int tag_len = 16;
if (rb_scan_args(argc, argv, "01", &vtag_len) == 1)
tag_len = NUM2INT(vtag_len);
GetCipher(self, ctx);
if (!(EVP_CIPHER_CTX_flags(ctx) & EVP_CIPH_FLAG_AEAD_CIPHER))
ossl_raise(eCipherError, "authentication tag not supported by this cipher");
ret = rb_str_new(NULL, tag_len);
if (!EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, tag_len, RSTRING_PTR(ret)))
ossl_raise(eCipherError, "retrieving the authentication tag failed");
return ret;
}
/*
* call-seq:
* cipher.auth_tag = string -> string
*
* Sets the authentication tag to verify the contents of the
* ciphertext. The tag must be set after calling Cipher#decrypt,
* Cipher#key= and Cipher#iv=, but before assigning the associated
* authenticated data using Cipher#auth_data= and of course, before
* decrypting any of the ciphertext. After all decryption is
* performed, the tag is verified automatically in the call to
* Cipher#final.
*/
static VALUE
ossl_cipher_set_auth_tag(VALUE self, VALUE vtag)
{
EVP_CIPHER_CTX *ctx;
unsigned char *tag;
int tag_len;
StringValue(vtag);
tag = (unsigned char *) RSTRING_PTR(vtag);
tag_len = RSTRING_LENINT(vtag);
GetCipher(self, ctx);
if (!(EVP_CIPHER_CTX_flags(ctx) & EVP_CIPH_FLAG_AEAD_CIPHER))
ossl_raise(eCipherError, "authentication tag not supported by this cipher");
if (!EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, tag_len, tag))
ossl_raise(eCipherError, "unable to set AEAD tag");
return vtag;
}
/*
* call-seq:
* cipher.authenticated? -> boolean
*
* Indicated whether this Cipher instance uses an Authenticated Encryption
* mode.
*/
static VALUE
ossl_cipher_is_authenticated(VALUE self)
{
EVP_CIPHER_CTX *ctx;
GetCipher(self, ctx);
return (EVP_CIPHER_CTX_flags(ctx) & EVP_CIPH_FLAG_AEAD_CIPHER) ? Qtrue : Qfalse;
}
#else
#define ossl_cipher_set_auth_data rb_f_notimplement
#define ossl_cipher_get_auth_tag rb_f_notimplement
#define ossl_cipher_set_auth_tag rb_f_notimplement
#define ossl_cipher_is_authenticated rb_f_notimplement
#endif
/*
* call-seq:
* cipher.key_len = integer -> integer
*
* Sets the key length of the cipher. If the cipher is a fixed length cipher
* then attempting to set the key length to any value other than the fixed
* value is an error.
*
* Under normal circumstances you do not need to call this method (and probably shouldn't).
*
* See EVP_CIPHER_CTX_set_key_length for further information.
*/
static VALUE
ossl_cipher_set_key_length(VALUE self, VALUE key_length)
{
int len = NUM2INT(key_length);
EVP_CIPHER_CTX *ctx;
GetCipher(self, ctx);
if (EVP_CIPHER_CTX_set_key_length(ctx, len) != 1)
ossl_raise(eCipherError, NULL);
return key_length;
}
/*
* call-seq:
* cipher.padding = integer -> integer
*
* Enables or disables padding. By default encryption operations are padded using standard block padding and the
* padding is checked and removed when decrypting. If the pad parameter is zero then no padding is performed, the
* total amount of data encrypted or decrypted must then be a multiple of the block size or an error will occur.
*
* See EVP_CIPHER_CTX_set_padding for further information.
*/
static VALUE
ossl_cipher_set_padding(VALUE self, VALUE padding)
{
EVP_CIPHER_CTX *ctx;
int pad = NUM2INT(padding);
GetCipher(self, ctx);
if (EVP_CIPHER_CTX_set_padding(ctx, pad) != 1)
ossl_raise(eCipherError, NULL);
return padding;
}
#define CIPHER_0ARG_INT(func) \
static VALUE \
ossl_cipher_##func(VALUE self) \
{ \
EVP_CIPHER_CTX *ctx; \
GetCipher(self, ctx); \
return INT2NUM(EVP_CIPHER_##func(EVP_CIPHER_CTX_cipher(ctx))); \
}
/*
* call-seq:
* cipher.key_len -> integer
*
* Returns the key length in bytes of the Cipher.
*/
CIPHER_0ARG_INT(key_length)
/*
* call-seq:
* cipher.iv_len -> integer
*
* Returns the expected length in bytes for an IV for this Cipher.
*/
CIPHER_0ARG_INT(iv_length)
/*
* call-seq:
* cipher.block_size -> integer
*
* Returns the size in bytes of the blocks on which this Cipher operates on.
*/
CIPHER_0ARG_INT(block_size)
/*
* INIT
*/
void
Init_ossl_cipher(void)
{
#if 0
mOSSL = rb_define_module("OpenSSL"); /* let rdoc know about mOSSL */
#endif
/* Document-class: OpenSSL::Cipher
*
* Provides symmetric algorithms for encryption and decryption. The
* algorithms that are available depend on the particular version
* of OpenSSL that is installed.
*
* === Listing all supported algorithms
*
* A list of supported algorithms can be obtained by
*
* puts OpenSSL::Cipher.ciphers
*
* === Instantiating a Cipher
*
* There are several ways to create a Cipher instance. Generally, a
* Cipher algorithm is categorized by its name, the key length in bits
* and the cipher mode to be used. The most generic way to create a
* Cipher is the following
*
* cipher = OpenSSL::Cipher.new('<name>-<key length>-<mode>')
*
* That is, a string consisting of the hyphenated concatenation of the
* individual components name, key length and mode. Either all uppercase
* or all lowercase strings may be used, for example:
*
* cipher = OpenSSL::Cipher.new('AES-128-CBC')
*
* For each algorithm supported, there is a class defined under the
* Cipher class that goes by the name of the cipher, e.g. to obtain an
* instance of AES, you could also use
*
* # these are equivalent
* cipher = OpenSSL::Cipher::AES.new(128, :CBC)
* cipher = OpenSSL::Cipher::AES.new(128, 'CBC')
* cipher = OpenSSL::Cipher::AES.new('128-CBC')
*
* Finally, due to its wide-spread use, there are also extra classes
* defined for the different key sizes of AES
*
* cipher = OpenSSL::Cipher::AES128.new(:CBC)
* cipher = OpenSSL::Cipher::AES192.new(:CBC)
* cipher = OpenSSL::Cipher::AES256.new(:CBC)
*
* === Choosing either encryption or decryption mode
*
* Encryption and decryption are often very similar operations for
* symmetric algorithms, this is reflected by not having to choose
* different classes for either operation, both can be done using the
* same class. Still, after obtaining a Cipher instance, we need to
* tell the instance what it is that we intend to do with it, so we
* need to call either
*
* cipher.encrypt
*
* or
*
* cipher.decrypt
*
* on the Cipher instance. This should be the first call after creating
* the instance, otherwise configuration that has already been set could
* get lost in the process.
*
* === Choosing a key
*
* Symmetric encryption requires a key that is the same for the encrypting
* and for the decrypting party and after initial key establishment should
* be kept as private information. There are a lot of ways to create
* insecure keys, the most notable is to simply take a password as the key
* without processing the password further. A simple and secure way to
* create a key for a particular Cipher is
*
* cipher = OpenSSL::AES256.new(:CFB)
* cipher.encrypt
* key = cipher.random_key # also sets the generated key on the Cipher
*
* If you absolutely need to use passwords as encryption keys, you
* should use Password-Based Key Derivation Function 2 (PBKDF2) by
* generating the key with the help of the functionality provided by
* OpenSSL::PKCS5.pbkdf2_hmac_sha1 or OpenSSL::PKCS5.pbkdf2_hmac.
*
* Although there is Cipher#pkcs5_keyivgen, its use is deprecated and
* it should only be used in legacy applications because it does not use
* the newer PKCS#5 v2 algorithms.
*
* === Choosing an IV
*
* The cipher modes CBC, CFB, OFB and CTR all need an "initialization
* vector", or short, IV. ECB mode is the only mode that does not require
* an IV, but there is almost no legitimate use case for this mode
* because of the fact that it does not sufficiently hide plaintext
* patterns. Therefore
*
* <b>You should never use ECB mode unless you are absolutely sure that
* you absolutely need it</b>
*
* Because of this, you will end up with a mode that explicitly requires
* an IV in any case. Note that for backwards compatibility reasons,
* setting an IV is not explicitly mandated by the Cipher API. If not
* set, OpenSSL itself defaults to an all-zeroes IV ("\\0", not the
* character). Although the IV can be seen as public information, i.e.
* it may be transmitted in public once generated, it should still stay
* unpredictable to prevent certain kinds of attacks. Therefore, ideally
*
* <b>Always create a secure random IV for every encryption of your
* Cipher</b>
*
* A new, random IV should be created for every encryption of data. Think
* of the IV as a nonce (number used once) - it's public but random and
* unpredictable. A secure random IV can be created as follows
*
* cipher = ...
* cipher.encrypt
* key = cipher.random_key
* iv = cipher.random_iv # also sets the generated IV on the Cipher
*
* Although the key is generally a random value, too, it is a bad choice
* as an IV. There are elaborate ways how an attacker can take advantage
* of such an IV. As a general rule of thumb, exposing the key directly
* or indirectly should be avoided at all cost and exceptions only be
* made with good reason.
*
* === Calling Cipher#final
*
* ECB (which should not be used) and CBC are both block-based modes.
* This means that unlike for the other streaming-based modes, they
* operate on fixed-size blocks of data, and therefore they require a
* "finalization" step to produce or correctly decrypt the last block of
* data by appropriately handling some form of padding. Therefore it is
* essential to add the output of OpenSSL::Cipher#final to your
* encryption/decryption buffer or you will end up with decryption errors
* or truncated data.
*
* Although this is not really necessary for streaming-mode ciphers, it is
* still recommended to apply the same pattern of adding the output of
* Cipher#final there as well - it also enables you to switch between
* modes more easily in the future.
*
* === Encrypting and decrypting some data
*
* data = "Very, very confidential data"
*
* cipher = OpenSSL::Cipher::AES.new(128, :CBC)
* cipher.encrypt
* key = cipher.random_key
* iv = cipher.random_iv
*
* encrypted = cipher.update(data) + cipher.final
* ...
* decipher = OpenSSL::Cipher::AES.new(128, :CBC)
* decipher.decrypt
* decipher.key = key
* decipher.iv = iv
*
* plain = decipher.update(encrypted) + decipher.final
*
* puts data == plain #=> true
*
* === Authenticated Encryption and Associated Data (AEAD)
*
* If the OpenSSL version used supports it, an Authenticated Encryption
* mode (such as GCM or CCM) should always be preferred over any
* unauthenticated mode. Currently, OpenSSL supports AE only in combination
* with Associated Data (AEAD) where additional associated data is included
* in the encryption process to compute a tag at the end of the encryption.
* This tag will also be used in the decryption process and by verifying
* its validity, the authenticity of a given ciphertext is established.
*
* This is superior to unauthenticated modes in that it allows to detect
* if somebody effectively changed the ciphertext after it had been
* encrypted. This prevents malicious modifications of the ciphertext that
* could otherwise be exploited to modify ciphertexts in ways beneficial to
* potential attackers.
*
* If no associated data is needed for encryption and later decryption,
* the OpenSSL library still requires a value to be set - "" may be used in
* case none is available. An example using the GCM (Galois Counter Mode):
*
* cipher = OpenSSL::Cipher.new("aes-128-gcm")
* cipher.encrypt
* key = cipher.random_key
* iv = cipher.random_iv
* cipher.auth_data = ""
*
* encrypted = cipher.update(data) + cipher.final
* tag = cipher.auth_tag
*
* decipher = OpenSSL::Cipher.new("aes-128-gcm")
* decipher.decrypt
* decipher.key = key
* decipher.iv = iv
* decipher.auth_tag = tag
* decipher.auth_data = ""
*
* plain = decipher.update(encrypted) + decipher.final
*
* puts data == plain #=> true
*/
cCipher = rb_define_class_under(mOSSL, "Cipher", rb_cObject);
eCipherError = rb_define_class_under(cCipher, "CipherError", eOSSLError);
rb_define_alloc_func(cCipher, ossl_cipher_alloc);
rb_define_copy_func(cCipher, ossl_cipher_copy);
rb_define_module_function(cCipher, "ciphers", ossl_s_ciphers, 0);
rb_define_method(cCipher, "initialize", ossl_cipher_initialize, 1);
rb_define_method(cCipher, "reset", ossl_cipher_reset, 0);
rb_define_method(cCipher, "encrypt", ossl_cipher_encrypt, -1);
rb_define_method(cCipher, "decrypt", ossl_cipher_decrypt, -1);
rb_define_method(cCipher, "pkcs5_keyivgen", ossl_cipher_pkcs5_keyivgen, -1);
rb_define_method(cCipher, "update", ossl_cipher_update, -1);
rb_define_method(cCipher, "final", ossl_cipher_final, 0);
rb_define_method(cCipher, "name", ossl_cipher_name, 0);
rb_define_method(cCipher, "key=", ossl_cipher_set_key, 1);
rb_define_method(cCipher, "auth_data=", ossl_cipher_set_auth_data, 1);
rb_define_method(cCipher, "auth_tag=", ossl_cipher_set_auth_tag, 1);
rb_define_method(cCipher, "auth_tag", ossl_cipher_get_auth_tag, -1);
rb_define_method(cCipher, "authenticated?", ossl_cipher_is_authenticated, 0);
rb_define_method(cCipher, "key_len=", ossl_cipher_set_key_length, 1);
rb_define_method(cCipher, "key_len", ossl_cipher_key_length, 0);
rb_define_method(cCipher, "iv=", ossl_cipher_set_iv, 1);
rb_define_method(cCipher, "iv_len", ossl_cipher_iv_length, 0);
rb_define_method(cCipher, "block_size", ossl_cipher_block_size, 0);
rb_define_method(cCipher, "padding=", ossl_cipher_set_padding, 1);
}
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