2 title: "![SlunkCrypt](etc/img/SlunkCrypt-Logo.png)"
9 SlunkCrypt is an experimental cross-platform cryptography library and command-line tool. A fully-featured GUI is provided for the Windows platform.
11 Please refer to the section [*encryption algorithm*](#encryption-algorithm) for more details!
17 Use of SlunkCrypt may be illegal in countries where encryption is outlawed. We believe it is legal to use SlunkCrypt in many countries all around the world, but we are not lawyers, and so if in doubt you should seek legal advice before downloading it. You may find useful information at [cryptolaw.org](http://www.cryptolaw.org/), which collects information on cryptography laws in many countries.
23 The SlunkCrypt library and the command-line application currently run on the following platforms:
25 * **Microsoft Windows** (Windows XP SP-3, or later) — 32-Bit (i686) and 64-Bit (AMD64)
26 * **Linux** (kernel version 3.17, or later) — 32-Bit (i686) and 64-Bit (AMD64)
27 * **Various BSD flavors** (tested on NetBSD 9.2, FreeBSD 13.0 and OpenBSD 7.0) — 32-Bit (i686) and 64-Bit (AMD64)
28 * **Solaris** (tested on Solaris 11.4 and OmniOS/illumos) — 32-Bit (i686) and 64-Bit (AMD64)
29 * **Mac OS X** (tested on macOS 11 “Big Sur”) — Intel x86-64 (AMD64) and Apple Silicon (AArch64)
31 The SlunkCrypt GUI application currently runs on the following platforms:
33 * **Microsoft Windows** with .NET Framework 4.5 — can be installed on Windows Vista, or later
39 This is how the graphical user interface (GUI) for SlunkCrypt looks on [Windows 11](https://i.pinimg.com/736x/0f/57/4c/0f574c445b497cc4748a9e1ab7491582--taps-funny-stuff.jpg):
41 ![](etc/img/SlunkCrypt-GUI.jpg)
46 Please be sure to install the **.NET Framework 4.5**, or any later *.NET Framework 4.x* version, before running the SlunkCrypt GUI application:
47 <https://dotnet.microsoft.com/download/dotnet-framework>
49 ***Note:*** If you are running Windows 8 or later, then almost certainly a suitable version of the .NET Framework is already installed 😎
54 The following settings can be adjusted in the `slunkcrypt-gui.exe.config` configuration file:
56 - **`DisableBusyIndicator`:**
57 If set to `true`, the “busy indicator” animation will be *disabled* on application startup — default value: `false`.
60 Specifies the number of worker threads to use — default value: `0` (i.e. detect the number of available processors and create one thread for each processor).
62 - **`KeepIncompleteFiles`:**
63 If set to `true`, incomplete or corrupted output files will *not* be deleted — default value: `false`.
68 This section describes the SlunkCypt command-line application.
73 The SlunkCypt command-line program is invoked as follows:
75 slunkcrypt --encrypt [pass:<pass>|file:<file>] <input.txt> <output.enc>
76 slunkcrypt --decrypt [pass:<pass>|file:<file>] <input.enc> <output.txt>
77 slunkcrypt --make-pw [<length>]
82 One of the following commands **must** be chosen:
84 - **`--encrypt` (`-e`):**
85 Run application in ***encrypt*** mode. Reads the given *plaintext* and generates *ciphertext*.
86 - **`--decrypt` (`-d`):**
87 Run application in ***decrypt*** mode. Reads the given *ciphertext* and restores *plaintext*.
88 - **`--make-pw` (`-p`):**
89 Generate a "strong" random passphrase, suitable for use with SlunkCrypt.
90 - **`--self-test` (`-t`):**
91 Run the application in ***self-test*** mode. Program will exit after all test are completed.
96 The following command-line options are available:
99 * Specifies the "secret" passphrase directly on the command-line. This is considered *insecure*.
101 * Specifies a file to read the passphrase from. Only the *first* line of the file will be read!
102 * *Note:* It is also possible to specify **`-`** in order to read the passphrase from the *stdin*.
104 * In ***encrypt*** mode – specifies the *plaintext* file (unencrypted information) that is to be encrypted.
105 * In ***decrypt*** mode – specifies the *ciphertext* file (result of encryption) that is to be decrypted.
107 * In ***encrypt*** mode – specifies the file where the *ciphertext* (result of encryption) will be stored.
108 * In ***decrypt*** mode – specifies the file where the *plaintext* (unencrypted information) will be stored.
110 * Specifies the length of the passphrase to be generated. If *not* specified, defaults to 24.
112 ### Remarks {.unlisted}
114 - The same passphrase must be used for both, ***encrypt*** and ***decrypt*** mode. The decryption of the ciphertext will only be possible, if the "correct" passphrase is known. It is recommended to choose a "random" password that is at least 12 characters in length and consists of a mix of upper-case characters, lower-case characters, digits as well as special characters.
116 - Passing the passphrase directly on the command-line is insecure, because the full command-line may be visible to other users!
121 The following environment variables may be used:
123 - **`SLUNK_PASSPHRASE`**:
124 Specifies the "secret" passphrase. This environment variables is only evaluated, if the passphrase was **not** specified on the command-line.
125 Passing the passphrase via environment variable is considered more secure, because environment variables are not normally visible to other (unprivileged) users.
127 - **`SLUNK_KEEP_INCOMPLETE`**:
128 If set to a *non-zero* value, incomplete or corrupted output files will **not** be deleted automatically. By default, the files will be deleted.
130 - **`SLUNK_THREADS`**:
131 Specifies the number of worker threads to use. By default, SlunkCrypt detects the number of available processors and creates one thread for each processor.
136 Here are some examples on how to use the SlunkCrypt command-line application:
138 ### Example #1 {.unlisted}
140 1. Let's generate a new random (secure) password first:
146 cdG2=fh<C=3[SSCzf[)iDjIV
148 2. Now, encrypt the plaintext message, using the generated password:
150 slunkcrypt --encrypt pass:"cdG2=fh<C=3[SSCzf[)iDjIV" plaintext.txt ciphertext.enc
152 Optionally, let's have a look at the ciphertext:
154 hexdump -C ciphertext.enc
156 3. Finally, decrypt the ciphertext, using the same password as before:
158 slunkcrypt --decrypt pass:"cdG2=fh<C=3[SSCzf[)iDjIV" ciphertext.enc plaintext.out
160 Optionally, verify that the decrypted file is identical to the original:
162 sha256sum -b plaintext.txt plaintext.out
164 ### Example #2 {.unlisted}
166 1. Generate a new password and store it to a text file:
168 slunkcrypt --make-pw > passwd.txt
170 Optionally, output the generated password to the terminal:
174 2. Encrypt file by reading the password from the text file:
176 slunkcrypt --encrypt file:passwd.txt plaintext.txt ciphertext.enc
178 ### Example #3 {.unlisted}
180 1. Generate a new password directly to an environment variable:
182 MY_PASSWD="$(slunkcrypt --make-pw)"
184 Optionally, output the generated password to the terminal:
188 2. Encrypt file by reading the password from the *stdin*:
190 slunkcrypt --encrypt - plaintext.txt ciphertext.enc <<< "${MY_PASSWD}"
196 The SlunkCrypt algorithm is based on core concepts of the well-known [**Enigma**](https://en.wikipedia.org/wiki/Enigma_machine) machine but with numerous improvements, largely inspired by R. Anderson's [***“A Modern Rotor Machine”***](https://rdcu.be/cBo8y):
198 - The original Enigma machine had only *three* (or, in some models, *four*) rotors, plus a static "reflector" wheel. In SlunkCrypt, we uses **256** simulated rotors for an improved security. Furthermore, the original Enigma machine supported only 26 distinct symbols, i.e. the letters `A` to `Z`. In SlunkCrypt, we use **256** distinct symbols, i.e. the byte values `0x00` to `0xFF`, which allows the encryption (and decryption) of arbitrary streams of bytes, rather than just plain text. Of course, SlunkCrypt can encrypt (and decrypt) text files as well.
200 - In the original Enigma machine, the signal passes through the rotors *twice*, once in forward direction and then again in backwards direction – thus the "reflector" wheel. This way, the Enigma's encryption was made *involutory*, i.e. encryption and decryption were the same operation. While this was highly convenient, it also severely weakened the cryptographic strength of the Enigma machine, because the number of possible permutations was reduced drastically! This is one of the main reasons why the Enigma machine eventually was defeated. In SlunkCrypt, the signal passes through the simulated rotors just *once*, in order to maximize the number of possible permutations. This eliminates the most important known weakness of the Enigma machine. Obviously, in SlunkCrypt, separate "modes" for encryption and decryption need to be provided, since encryption and decryption *no* longer are the same operation.
202 - In the original Enigma machine, the rightmost rotor was moved, by one step, after every symbol. Meanwhile, all other rotors were moved, by one step, *only* when their right-hand neighbor had completed a full turn – much like the odometer in a car. The fact that most of the rotors remained in the same "static" position most of the time was an important weakness of the Enigma machine. Also, the sequence of the Enigma's rotor positions started to repeat after only 16,900 characters. SlunkCrypt employs an improved stepping algorithm, based on a ***linear-feedback shift register* (LSFR)**, ensuring that *all* rotors move frequently and in a "randomized" unpredictable pattern. The rotor positions of SlunkCrypt practically *never* repeat.
204 - The internal wiring of each of the original Enigma machine's rotors was *fixed*. Each rotor "type" came with a different internal wiring (i.e. permutation). Some models had up to eight rotor "types" to choose from, but only three or four rotors were used at a time. Nonetheless, the internal wiring (i.e. permutation) of each of the supplied rotors was **not** modifiable. This severely restricted the key space of the Enigma machine, as far as the rotors are concerned, because *only* the order of the rotors and the initial position of each rotor could be varied. In SlunkCrypt, a fully *randomized* wiring (i.e. permutation) is generated from the password for each of the 256 simulated rotors. The initial rotor positions are *randomized* as well.
206 - SlunkCrypt does **not** currently implement the *plugboard* (“Steckerbrett”) of the original Enigma machine. That is because, even though the plugboard has a large key space, it is just a *fixed* substitution cipher that does *not* contribute much to the cryptographic strength of the Enigma machine. In fact, the plugboard could be "erased" by Welchman's [diagonal board](https://en.wikipedia.org/wiki/Bombe#Stecker_values).
209 Programming Interface (API)
210 ===========================
212 This section describes the SlunkCypt library interface for software developers.
217 In order to use the SlunkCypt library in your C++ code, include **`<slunkcrypt.hpp>`** header and instantiate the appropriate SlunkCypt classes:
219 ### Example #1 {.unlisted}
221 Here is a simple example on how to use the SlunkCrypt [**`Encryptor`**](#encryptor) class:
223 #include <slunkcrypt.hpp>
229 /* Open input and output files here */
230 uint8_t buffer[BUFF_SIZE];
231 slunkcrypt::Encryptor slunk_encrypt(passphrase);
234 input.read(reinterpret_cast<char*>(buffer), BUFF_SIZE);
235 if ((!input.bad()) && (input.gcount() > 0))
237 if (!slunk_encrypt.inplace(buffer, (size_t)input.gcount()))
239 /* Implement error handling here */
241 output.write(reinterpret_cast<char*>(buffer), count);
244 std::cout << std::hex << slunk_encrypt.get_nonce() << std::endl;
247 ### Example #2 {.unlisted}
249 Here is a simple example on how to use the SlunkCrypt [**`Decryptor`**](#decryptor) class:
251 #include <slunkcrypt.hpp>
257 /* Open input and output files here */
258 uint8_t buffer[BUFF_SIZE];
259 slunkcrypt::Decryptor slunk_decrypt(passphrase, nonce);
262 input.read(reinterpret_cast<char*>(buffer), BUFF_SIZE);
263 if ((!input.bad()) && (input.gcount() > 0))
265 if (!slunk_decrypt.inplace(buffer, (size_t)input.gcount()))
267 /* Implement error handling here */
269 output.write(reinterpret_cast<char*>(buffer), count);
277 This section describes the "high-level" C++11 API of the SlunkCrypt library. All SlunkCrypt classes live in the **`slunkcrypt`** namespace.
281 Class for *encrypting* data using the SlunkCrypt library.
285 Create and initialize a new **``Encryptor``** instance. Also generated a new, random nonce.
287 Encryptor::Encryptor(
288 const std::string &passwd,
289 const size_t thread_count = 0U
295 The password to "protect" the message. The password is given as an `std::string`, e.g. UTF-8 encoded characters. The same password **may** be used to encrypt *multiple* messages. Also, the same password **must** be used for both, encryption *and* decryption; it will *only* be possible decrypt the ciphertext, if the "correct" password is known. The password must be kept confidential under all circumstances!
297 *Note:* In order to thwart *brute force* attacks, it is recommended to choose a "random" password that is at least 12 characters in length and that consists of upper-case characters, lower-case characters, digits as well as other "special" characters.
300 Specifies the number of worker threads to use (optional). By default, SlunkCrypt detects the number of available processors and creates one thread for each processor.
304 * Throws `std::runtime_error`, if the nonce could not be generated, or if the SlunkCrypt context could not be allocated.
306 #### Encryptor::process() [1]
308 Encrypt the next message chunk, using separate input/output buffers.
311 const uint8_t *const input,
312 uint8_t *const output,
319 A pointer to the *input* buffer containing the next chunk of the plaintext to be encrypted. The plaintext is given as a byte array (`uint8_t`). This can be arbitrary binary data, e.g. UTF-8 encoded text. NULL bytes are **not** treated specially.
321 The *input* buffer must contain *at least* `length` bytes of data. If the buffer is longer than `length` bytes, then only the first `length` bytes will be processed and the remainder is ignored!
324 A pointer to the *output* buffer where the ciphertext chunk that corresponds to the given plaintext chunk will be stored. The ciphertext is stored as a byte array (`uint8_t`); it has the same length as the plaintext data.
326 The *output* buffer must provide sufficient space for storing *at least* `length` bytes of encrypted data. If the buffer is longer than `length` bytes, then only the first `length` bytes of the buffer will be filled with encrypted data!
329 The length of the plaintext chunk contained in the *input* buffer given by the `input` parameter, in bytes. At the same time, this determines the minimum required size of the *output* buffer given by the `output` parameters, in bytes.
331 *Note:* It is recommended to process chunks of at least ∼64 KB each, in order to take full advantage of multi-threading.
335 * If successful, `true` is returned; otherwise `false` is returned.
337 #### Encryptor::process() [2]
339 Encrypt the next message chunk, using separate input/output containers (`std::vector`).
342 const std::vector<uint8_t> &input,
343 std::vector<uint8_t> &output
349 A reference to the `std::vector<uint8_t>` instance containing the next chunk of the plaintext to be encrypted. This can be arbitrary binary data, e.g. UTF-8 encoded text. NULL bytes are **not** treated specially.
352 A reference to the `std::vector<uint8_t>` instance where the ciphertext that corresponds to the given plaintext will be stored.
354 The `output.size()` must be *greater than or equal* to `input.size()`. If the `output.size()` is larger than the `input.size()`, then only the first `input.size()` elements of `output` will be filled with encrypted data!
358 * If successful, `true` is returned; otherwise `false` is returned. The function fails, if the *output* `std::vector` is too small.
360 #### Encryptor::inplace() [1]
362 Encrypt the next message chunk, using a single buffer.
365 uint8_t *const buffer,
372 A pointer to the buffer initially containing the next chunk of the plaintext to be encrypted. The plaintext is given as a byte array (`uint8_t`). This can be arbitrary binary data, e.g. UTF-8 encoded text. NULL bytes are **not** treated specially. The ciphertext chunk that corresponds to the given plaintext chunk will be stored to the *same* buffer, thus replacing the plaintext data.
374 The buffer must initially contain *at least* `length` bytes of input data; the first `length` bytes of the buffer will be overwritten with the encrypted data. If the buffer is longer than `length` bytes, then only the first `length` bytes will be processed and overwritten.
377 The length of the plaintext chunk initially contained in the input/output buffer given by the `buffer` parameter, in bytes. At the same time, this determines the portion of the input/output buffer that will be overwritten with encrypted data, in bytes.
379 *Note:* It is recommended to process chunks of at least ∼64 KB each, in order to take full advantage of multi-threading.
383 * If successful, `true` is returned; otherwise `false` is returned.
385 #### Encryptor::inplace() [2]
387 Encrypt the next message chunk, using a single container (`std::vector`).
390 std::vector<uint8_t> &buffer
396 A reference to the `std::vector<uint8_t>` initially containing the next chunk of the plaintext to be encrypted. This can be arbitrary binary data, e.g. UTF-8 encoded text. NULL bytes are **not** treated specially. The ciphertext chunk that corresponds to the given plaintext chunk will be stored to the *same* `std::vector<uint8_t>`, thus replacing all the plaintext data.
400 * If successful, `true` is returned; otherwise `false` is returned.
402 #### Encryptor::get_nonce()
404 Retrieve the random nonce that is used to encrypt the message.
406 uint64_t get_nonce();
410 * Returns the nonce that is used to encrypt the message. The purpose of the nonce is to ensure that each message will be encrypted differently, even when the same password is used to encrypt multiple (possibly identical) messages. Therefore, a new random nonce must be chosen for each message! It is not necessary to keep the nonce confidential, but the same nonce must be used for both, encryption and decryption. Typically, the nonce is stored/transmitted alongside the ciphertext.
412 *Note:* The `Encryptor` class automatically generates a new, random nonce for each message to be encrypted. Use *this* function to retrieve that nonce, so that it can be passed to `Decryptor` for decryption later.
416 Class for *decrypting* data using the SlunkCrypt library.
420 Create and initialize a new **``Decryptor``** instance.
422 Decryptor::Decryptor(
423 const std::string &passwd,
424 const uint64_t nonce,
425 const size_t thread_count = 0U
431 The password to "protect" the message. The password is given as an `std::string`, e.g. UTF-8 encoded characters. The same password **may** be used to encrypt *multiple* messages. Also, the same password **must** be used for both, encryption *and* decryption; it will *only* be possible decrypt the ciphertext, if the "correct" password is known. The password must be kept confidential under all circumstances!
433 *Note:* In order to thwart *brute force* attacks, it is recommended to choose a "random" password that is at least 12 characters in length and that consists of upper-case characters, lower-case characters, digits as well as other "special" characters.
436 The *nonce* (number used once) to be used for the decryption process. The purpose of the nonce is to ensure that each message will be encrypted differently, even when the same password is used to encrypt *multiple* (possibly identical) messages. Therefore, a new *random* nonce **must** be chosen for each message! It is *not* necessary to keep the nonce confidential, but the same nonce **must** be used for both, encryption *and* decryption. Typically, the nonce is stored/transmitted alongside the ciphertext.
438 *Note:* The `Encryptor` class automatically generates a new, random nonce for each message to be encrypted. Use `Encryptor::get_nonce()` to retrieve that nonce, so that it can be passed to `Decryptor` for decryption later.
441 Specifies the number of worker threads to use (optional). By default, SlunkCrypt detects the number of available processors and creates one thread for each processor.
445 * Throws `std::runtime_error`, if the SlunkCrypt context could not be allocated.
447 #### Decryptor::process() [1]
449 Decrypt the next message chunk, using separate input/output buffers.
452 const uint8_t *const input,
453 uint8_t *const output,
460 A pointer to the *input* buffer containing the next chunk of the ciphertext to be decrypted. The ciphertext is given as a byte array (`uint8_t`).
462 The *input* buffer must contain *at least* `length` bytes of data. If the buffer is longer than `length` bytes, then only the first `length` bytes will be processed and the remainder is ignored!
465 A pointer to the *output* buffer where the plaintext chunk that corresponds to the given ciphertext chunk will be stored. The plaintext is stored as a byte array (`uint8_t`); it has the same length as the ciphertext data.
467 The *output* buffer must provide sufficient space for storing *at least* `length` bytes of decrypted data. If the buffer is longer than `length` bytes, then only the first `length` bytes of the buffer will be filled with decrypted data!
470 The length of the ciphertext chunk contained in the *input* buffer given by the `input` parameter, in bytes. At the same time, this determines the minimum required size of the *output* buffer given by the `output` parameters, in bytes.
472 *Note:* It is recommended to process chunks of at least ∼64 KB each, in order to take full advantage of multi-threading.
476 * If successful, `true` is returned; otherwise `false` is returned.
478 #### Decryptor::process() [2]
480 Decrypt the next message chunk, using separate input/output containers (`std::vector`).
483 const std::vector<uint8_t> &input,
484 std::vector<uint8_t> &output
490 A reference to the `std::vector<uint8_t>` instance containing the next chunk of the ciphertext to be decrypted.
493 A reference to the `std::vector<uint8_t>` instance where the plaintext that corresponds to the given ciphertext will be stored.
495 The `output.size()` must be *greater than or equal* to `input.size()`. If the `output.size()` is greater than the `input.size()`, then only the first `input.size()` elements of `output` will be filled with decrypted data!
499 * If successful, `true` is returned; otherwise `false` is returned. The function fails, if the *output* `std::vector` is too small.
501 #### Decryptor::inplace() [1]
503 Decrypt the next message chunk, using a single buffer.
506 uint8_t *const buffer,
513 A pointer to the buffer initially containing the next chunk of the ciphertext to be decrypted. The ciphertext is given as a byte array (`uint8_t`). The plaintext that corresponds to the given ciphertext will be stored to the *same* buffer, replacing the plaintext data.
515 The buffer must initially contain *at least* `length` bytes of input data; the first `length` bytes of the buffer will be overwritten with the encrypted data. If the buffer is longer than `length` bytes, then only the first `length` bytes will be processed and overwritten.
518 The length of the ciphertext chunk initially contained in the input/output buffer given by the `buffer` parameter, in bytes. At the same time, this determines the portion of the input/output buffer that will be overwritten with decrypted data, in bytes.
520 *Note:* It is recommended to process chunks of at least ∼64 KB each, in order to take full advantage of multi-threading.
524 * If successful, `true` is returned; otherwise `false` is returned.
526 #### Decryptor::inplace() [2]
528 Decrypt the next message chunk, using a single container (`std::vector`).
531 std::vector<uint8_t> &buffer
537 A reference to the `std::vector<uint8_t>` initially containing the next chunk of the ciphertext to be decrypted. The plaintext that corresponds to the given ciphertext will be stored to the *same* `std::vector<uint8_t>`, replacing all the ciphertext data.
541 * If successful, `true` is returned; otherwise `false` is returned.
546 This section describes the "low-level" C99 API of the SlunkCypt library.
550 The SlunkCypt library defines the following functions:
552 #### slunkcrypt_alloc()
554 Allocate and initialize a new SlunkCrypt encryption/decryption context.
556 slunkcrypt_t slunkcrypt_alloc(
557 const uint64_t nonce,
558 const uint8_t *const passwd,
559 const size_t passwd_len,
566 The *nonce* (number used once) to be used for the encryption/decryption process. The purpose of the nonce is to ensure that each message will be encrypted differently, even when the same password is used to encrypt *multiple* (possibly identical) messages. Therefore, a new *random* nonce **must** be chosen for each message to be encrypted! It is *not* necessary to keep the nonce confidential, but the same nonce **must** be used for both, encryption *and* decryption. Typically, the nonce is stored/transmitted alongside the ciphertext.
568 *Note:* It is recommended to generate a random nonce via the [`slunkcrypt_generate_nonce()`](#slunkcrypt_generate_nonce) function for each message!
571 The password to "protect" the message. The password is given as a byte array (`uint8_t`), e.g. UTF-8 encoded characters; a terminating NULL character is *not* required, as the length of the password is specified explicitly. The same password **may** be used to encrypt *multiple* messages. Also, the same password **must** be used for both, encryption *and* decryption; it will *only* be possible decrypt the ciphertext, if the "correct" password is known. The password must be kept confidential under all circumstances!
573 *Note:* In order to thwart *brute force* attacks, it is recommended to choose a "random" password that is at least 12 characters in length and that consists of upper-case characters, lower-case characters, digits as well as other "special" characters.
576 The length of password given by the `passwd` parameter, in bytes, **not** counting a terminating NULL character. The minimum/maximum length of the password are given by the `SLUNKCRYPT_PWDLEN_MIN` and `SLUNKCRYPT_PWDLEN_MAX` constants, respectively.
579 The mode of operation. Use `SLUNKCRYPT_ENCRYPT` in order to set up this context for *encryption*, or use `SLUNKCRYPT_DECRYPT` in order to set up this context for *decryption*.
583 * If successful, a handle to the new SlunkCrypt context is return; otherwise `SLUNKCRYPT_NULL` is returned.
585 *Note:* Applications **should** treat `slunkcrypt_t` as an *opaque* handle type. Also, as soon as the SlunkCrypt context is *not* needed anymore, the application **shall** call [`slunkcrypt_free()`](#slunkcrypt_free) in order to "erase" and de-allocate that context. If a SlunkCrypt context is *not* de-allocated properly, it will result in a memory leak!
587 #### slunkcrypt_alloc_ext()
589 Allocate and initialize a new SlunkCrypt encryption/decryption context with additional parameters.
591 slunkcrypt_t slunkcrypt_alloc_ext(
592 const uint64_t nonce,
593 const uint8_t *const passwd,
594 const size_t passwd_len,
596 const slunkparam_t *const param
602 The *nonce* (number used once) to be used for the encryption/decryption process. The purpose of the nonce is to ensure that each message will be encrypted differently, even when the same password is used to encrypt *multiple* (possibly identical) messages. Therefore, a new *random* nonce **must** be chosen for each message to be encrypted! It is *not* necessary to keep the nonce confidential, but the same nonce **must** be used for both, encryption *and* decryption. Typically, the nonce is stored/transmitted alongside the ciphertext.
604 *Note:* It is recommended to generate a random nonce via the [`slunkcrypt_generate_nonce()`](#slunkcrypt_generate_nonce) function for each message!
607 The password to "protect" the message. The password is given as a byte array (`uint8_t`), e.g. UTF-8 encoded characters; a terminating NULL character is *not* required, as the length of the password is specified explicitly. The same password **may** be used to encrypt *multiple* messages. Also, the same password **must** be used for both, encryption *and* decryption; it will *only* be possible decrypt the ciphertext, if the "correct" password is known. The password must be kept confidential under all circumstances!
609 *Note:* In order to thwart *brute force* attacks, it is recommended to choose a "random" password that is at least 12 characters in length and that consists of upper-case characters, lower-case characters, digits as well as other "special" characters.
612 The length of password given by the `passwd` parameter, in bytes, **not** counting a terminating NULL character. The minimum/maximum length of the password are given by the `SLUNKCRYPT_PWDLEN_MIN` and `SLUNKCRYPT_PWDLEN_MAX` constants, respectively.
615 The mode of operation. Use `SLUNKCRYPT_ENCRYPT` in order to set up this context for *encryption*, or use `SLUNKCRYPT_DECRYPT` in order to set up this context for *decryption*.
618 Additional parameters used to initialize the SlunkCrypt context, given as a pointer to a [`slunkparam_t`](#slunkcrypt-parameters) struct. The memory for the struct must be allocated by the caller and SlunkCrypt does **not** take owner ship of this memory; it will *copy* the relevant fields. The caller is responsible to free the struct; it can be allocated with automatic storage duration.
622 * If successful, a handle to the new SlunkCrypt context is return; otherwise `SLUNKCRYPT_NULL` is returned.
624 *Note:* Applications **should** treat `slunkcrypt_t` as an *opaque* handle type. Also, as soon as the SlunkCrypt context is *not* needed anymore, the application **shall** call [`slunkcrypt_free()`](#slunkcrypt_free) in order to "erase" and de-allocate that context. If a SlunkCrypt context is *not* de-allocated properly, it will result in a memory leak!
626 #### slunkcrypt_reset()
628 Re-initialize an existing SlunkCrypt encryption/decryption context.
630 int slunkcrypt_reset(
631 const slunkcrypt_t context,
632 const uint64_t nonce,
633 const uint8_t *const passwd,
634 const size_t passwd_len,
641 The existing SlunkCrypt context to be re-initialized. This must be a valid handle that was returned by a previous invocation of the [`slunkcrypt_alloc()`](#slunkcrypt_alloc) function.
643 * *other parameters*:
644 Please refer to the [`slunkcrypt_alloc()`](#slunkcrypt_alloc) function for details!
648 * If successful, `SLUNKCRYPT_SUCCESS` is returned; otherwise `SLUNKCRYPT_FAILURE` or `SLUNKCRYPT_ABORTED` is returned.
650 #### slunkcrypt_free()
652 De-allocate an existing SlunkCrypt encryption/decryption context. This will "clear" and release any memory occupied by the context.
654 void slunkcrypt_free(
655 const slunkcrypt_t context
661 The existing SlunkCrypt context to be de-allocated. This must be a valid handle that was returned by a previous invocation of the [`slunkcrypt_alloc()`](#slunkcrypt_alloc) function.
663 *Note:* Once a handle has been passed to this function, that handle is *invalidated* and **must not** be used again!
665 #### slunkcrypt_generate_nonce()
667 Generate a new random *nonce* (number used once), using the system's "cryptographically secure" entropy source.
669 int slunkcrypt_generate_nonce(
676 A pointer to a variable of type `int64_t` that receives the new random nonce.
680 * If successful, `SLUNKCRYPT_SUCCESS` is returned; otherwise `SLUNKCRYPT_FAILURE` or `SLUNKCRYPT_ABORTED` is returned.
682 #### slunkcrypt_process()
684 Encrypt or decrypt the next message chunk, using separate input/output buffers.
686 int slunkcrypt_process(
687 const slunkcrypt_t context,
688 const uint8_t *const input,
689 uint8_t *const output,
696 The existing SlunkCrypt context to be used for processing the message chunk. This context will be updated.
698 *Note:* This function operates either in "encryption" mode or in "decryption" mode, depending on how the given SlunkCrypt context has been [initialized](#slunkcrypt_alloc) or [re-initialized](#slunkcrypt_reset).
701 A pointer to the *input* buffer containing the next chunk of the plaintext to be encrypted (*encryption* mode), or the next chunk of the ciphertext to be decrypted (*decryption* mode). The input data is given as a byte array (`uint8_t`). This can be arbitrary binary data, e.g. UTF-8 encoded text. NULL bytes are **not** treated specially by this function.
703 The *input* buffer must contain *at least* `length` bytes of data. If the buffer is longer than `length` bytes, then only the first `length` bytes will be processed; the remainder is ignored!
706 A pointer to the *output* buffer where the ciphertext that corresponds to the given plaintext chunk (*encryption* mode), or the plaintext that corresponds to the given ciphertext chunk (*decryption* mode) will be stored. The output data is stored as a byte array (`uint8_t`) and it always has the same length as the input data.
708 The *output* buffer **must** provide sufficient space for storing *at least* `length` bytes. If the buffer is longer than `length` bytes, then only the first `length` bytes will be filled!
711 The length of the given plaintext chunk (*encryption* mode), or the length of the given ciphertext chunk (*decryption* mode) in the `input` buffer, in bytes. At the same time, this parameter determines the minimum required size of the `output` buffer, in bytes. If this parameter is set to *zero*, the function does nothing; this is *not* considered an error.
713 *Note:* It is recommended to process chunks of at least ∼64 KB each, in order to take full advantage of multi-threading.
717 * If successful, `SLUNKCRYPT_SUCCESS` is returned; otherwise `SLUNKCRYPT_FAILURE` or `SLUNKCRYPT_ABORTED` is returned.
719 #### slunkcrypt_inplace()
721 Encrypt or decrypt the next message chunk, using a *single* input/output buffer.
723 int slunkcrypt_inplace(
724 const slunkcrypt_t context,
725 uint8_t *const buffer,
732 The existing SlunkCrypt context to be used for processing the message chunk. This context will be updated.
734 *Note:* This function operates either in "encryption" mode or in "decryption" mode, depending on how the given SlunkCrypt context has been [initialized](#slunkcrypt_alloc) or [re-initialized](#slunkcrypt_reset).
737 A pointer to the buffer containing the next chunk of the plaintext to be encrypted (*encryption* mode), or the next chunk of the ciphertext to be decrypted (*decryption* mode). The input data is given as a byte array (`uint8_t`). This can be arbitrary binary data, e.g. UTF-8 encoded text. NULL bytes are **not** treated specially by this function. The ciphertext that corresponds to the given plaintext chunk (*encryption* mode), or the plaintext that corresponds to the given ciphertext chunk (*decryption* mode) will be stored to the ***same*** buffer.
739 The given buffer **must** initially contain *at least* `length` bytes of input data. The first `length` bytes in the buffer will be processed and will be *overwritten* with the corresponding output data. If the buffer is longer than `length` bytes, then only the first `length` bytes in the buffer will be processed; the remainder is ignored!
742 The length of the plaintext chunk (*encryption* mode), or the length of the ciphertext chunk (*decryption* mode) initially contained in the input/output buffer, in bytes.
744 *Note:* It is recommended to process chunks of at least ∼64 KB each, in order to take full advantage of multi-threading.
748 * If successful, `SLUNKCRYPT_SUCCESS` is returned; otherwise `SLUNKCRYPT_FAILURE` or `SLUNKCRYPT_ABORTED` is returned.
750 #### slunkcrypt_random_bytes()
752 Generate a sequence of random bytes, using the system's "cryptographically secure" entropy source.
754 size_t slunkcrypt_random_bytes(
755 uint8_t *const buffer,
762 A pointer to the *output* buffer where the random bytes will be stored.
764 The *output* buffer **must** provide sufficient space for storing *at least* `length` bytes of random data. *At most* the first `length` bytes of the buffer will be filled with random data!
767 The number of random bytes to be generated. At the same time, this parameter determines the minimum required size of the `output` buffer, in bytes.
771 * The number of random bytes that have been generated and that have been stored to the `output` buffer buffer is returned.
773 The number of generated random bytes can be *at most* `length`. Less than `length` random bytes will be generated, if and only if the the system's "cryptographically secure" entropy source could *not* provide the requested number of bytes at this time – in that case, you can try again later. The number of generated bytes can be as low as **0**.
776 #### slunkcrypt_bzero()
778 Erase the contents of a byte array, by overwriting it with *zero* bytes. Compiler optimizations will **not** remove the erase operation.
780 void slunkcrypt_bzero(
788 A pointer to the buffer whose content is to be erased.
790 The buffer **must** be *at least* `length` bytes in size. If the buffer is longer than `length` bytes, then *only* the first `length` bytes of the buffer will be erased!
793 The size of the buffer to be erased, in bytes.
797 #### SlunkCrypt parameters
799 The `slunkparam_t` struct is used to pass additional parameters that will be used for initializing the SlunkCrypt context. It contains the following fields:
801 * `version` – The version of the parameter struct; **must** be set to *`SLUNKCRYPT_PARAM_VERSION`*.
802 * `thread_count` – The number of worker threads to use. If this parameter is set to **0**, which is the *default* value, then SlunkCrypt automatically detects the number of available (logical) processors and creates one thread for each processor. Also, the number of threads is capped to a maximum of `MAX_THREADS` (currently defined as **16**).
806 The SlunkCypt library defines the following global variables:
808 #### Version information
810 These variables can be used to determine the version of the SlunkCrypt library at runtime, using the [semantic versioning](https://semver.org/spec/v2.0.0.html) scheme:
812 * `const uint16_t SLUNKCRYPT_VERSION_MAJOR` – The current *major* version.
813 * `const uint16_t SLUNKCRYPT_VERSION_MINOR` – The current *minor* version.
814 * `const uint16_t SLUNKCRYPT_VERSION_PATCH` – The current *patch* version.
815 * `const char *SLUNKCRYPT_BUILD` – The build date and time, as a C string, in the *`"mmm dd yyyy, hh:mm:ss"`* format.
819 If this flag is set to a non-zero value by the application, any ongoing SlunkCypt library invocation will be aborted as quickly as possible:
821 * `volatile int g_slunkcrypt_abort_flag` – The global abort flag.
823 *Note:* Applications may set this flag in their signal handler, e.g. when a `SIGINT` is received, in order to "gracefully" shut down the SlunkCypt library. All long-running library functions will return `SLUNKCRYPT_ABORTED`, if the invocation was interrupted. The application still is responsible for [free](#slunkcrypt_free)'ing any SlunkCypt contexts that it allocated successfully!
827 The SlunkCypt library defines the following constants:
829 #### Mode of operation
831 The SlunkCypt library supports the following modes of operation:
833 * `SLUNKCRYPT_ENCRYPT` – Run library in *encryption* mode, i.e. consume plaintext and produce ciphertext.
834 * `SLUNKCRYPT_DECRYPT` – Run library in *decryption* mode, i.e. consume ciphertext and produce plaintext.
838 The following limits are defined for the SlunkCypt library:
840 * `SLUNKCRYPT_PWDLEN_MIN` – The *minimum* required length of a password, currently **8** bytes.
841 * `SLUNKCRYPT_PWDLEN_MAX` – The *maximum* allowed length of a password, currently **256** bytes.
845 SlunkCypt library functions that return an error code may return one of the following constants:
847 * `SLUNKCRYPT_SUCCESS` – The operation completed successfully.
848 * `SLUNKCRYPT_FAILURE` – The operation has failed.
849 * `SLUNKCRYPT_ABORTED` – The operation was aborted before completion, as requested by the application.
854 The following functions are fully "thread-safe" and thus may safely be called by *any* thread at *any* time ***without*** the need for synchronization:
856 * `slunkcrypt_alloc()`
857 * `slunkcrypt_generate_nonce()`
858 * `slunkcrypt_random_bytes()`
859 * `slunkcrypt_bzero()`
860 * `Encryptor::Encryptor()`
861 * `Decryptor::Decryptor()`
863 The following functions are "reentrant" and thus may safely be called by *any* thread at *any* time ***without*** the need for synchronization – provided that each instance of `slunkcrypt_t`, `Encryptor` or `Decryptor` is "owned" by a *single* thread **and** that each instance will *exclusively* be access by its respective "owner" thread:
865 * `slunkcrypt_reset()`
866 * `slunkcrypt_free()`
867 * `slunkcrypt_process()`
868 * `slunkcrypt_inplace()`
869 * `Encryptor::process()`
870 * `Encryptor::inplace()`
871 * `Encryptor::get_nonce()`
872 * `Decryptor::process()`
873 * `Decryptor::inplace()`
875 ***Note:*** If the same `slunkcrypt_t`, `Encryptor` or `Decryptor` instance needs to be shared across *multiple* threads (i.e. the same instance is accessed by *concurrent* threads), then the application **must** *serialize* any invocation of the above functions on that shared instance, by using a suitable synchronization mechanism! This can be achieved by using a [*mutex*](https://linux.die.net/man/3/pthread_mutex_lock).
881 This work has been released under the **CC0 1.0 Universal** license.
883 For details, please refer to:
884 <https://creativecommons.org/publicdomain/zero/1.0/legalcode>
889 SlunkCrypt incorporates code from the following *third-party* software projects:
891 * The "checksum" algorithm used by the SlunkCrypt command-line application was adapted from the **BLAKE2** reference C implementation.
893 BLAKE2 reference source code package - reference C implementations
894 Copyright 2012, Samuel Neves <sneves@dei.uc.pt>. You may use this under the
895 terms of the CC0, the OpenSSL Licence, or the Apache Public License 2.0, at
896 your option. The terms of these licenses can be found at:
897 - CC0 1.0 Universal : http://creativecommons.org/publicdomain/zero/1.0
898 - OpenSSL license : https://www.openssl.org/source/license.html
899 - Apache 2.0 : http://www.apache.org/licenses/LICENSE-2.0
901 More information about the BLAKE2 hash function can be found at
905 * ***Windows only:*** Builds of SlunkCypt that have multi-threading enabled use the **POSIX Threads for Windows (pthreads4w)** library.
907 Pthreads4w - POSIX Threads for Windows
908 Copyright 1998 John E. Bossom
909 Copyright 1999-2018, Pthreads4w contributors
911 Homepage: https://sourceforge.net/projects/pthreads4w/
913 Licensed under the Apache License, Version 2.0 (the "License");
914 you may not use this file except in compliance with the License.
915 You may obtain a copy of the License at
917 http://www.apache.org/licenses/LICENSE-2.0
919 Unless required by applicable law or agreed to in writing, software
920 distributed under the License is distributed on an "AS IS" BASIS,
921 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
922 See the License for the specific language governing permissions and
923 limitations under the License.