Merge pull request #914 from Zokrates/update-book

Update book

changelogs/unreleased/914-dark64

@@ -0,0 +1 @@
+Documentation improvements, move examples to a separate section, remove deprecated `--light` flag used in a rng tutorial, add a simple file system resolver example to zokrates.js docs

zokrates_book/src/SUMMARY.md

@@ -25,6 +25,8 @@
     - [JSON ABI](toolbox/abi.md)
 	- [zokrates.js](toolbox/zokrates_js.md)
 
-- [Tutorial: A zkSNARK RNG](rng_tutorial.md)
+- [Examples](examples/index.md)
+	- [A SNARK Powered RNG](examples/rng_tutorial.md)
+	- [Proving knowledge of a hash preimage](examples/sha256example.md)
 
 - [Testing](testing.md)

zokrates_book/src/examples/index.md

@@ -0,0 +1,6 @@
+# ZoKrates Examples
+
+This section covers examples of using the ZoKrates programming language.
+
+- [A SNARK Powered RNG](./rng_tutorial.md)
+- [Proving knowledge of a hash preimage](./sha256example.md)

zokrates_book/src/examples/rng_tutorial.md

@@ -2,7 +2,7 @@
 
 ## Prerequisites
 
-Make sure you have followed the instructions in the [Getting Started](gettingstarted.md) chapter and are able to run the "Hello World" example described there.
+Make sure you have followed the instructions in the [Getting Started](../gettingstarted.md) chapter and are able to run the "Hello World" example described there.
 
 ## Description of the problem
 
@@ -30,15 +30,15 @@ There are many ways to calculate a hash, but here we use Zokrates.
 ```
 2. Compile the program to a form that is usable for zero knowledge proofs. This command writes 
 the binary to `get_hash`. You can see a textual representation, somewhat analogous to assembler 
-coming from a compiler, at `get_hash.ztf` if you remove the `--light` command line option.
+coming from a compiler, at `get_hash.ztf` enabled by the `--ztf` command line option.
 ```
-zokrates compile -i get_hash.zok -o get_hash --light
+zokrates compile -i get_hash.zok -o get_hash --ztf
 ```
 3. The input to the Zokrates program is sixteen 32 bit values, each in decimal. specify those values 
 to get a hash. For example, to calculate the hash of `0x00000000000000010000000200000003000000040000000500000006...`
 use this command:
 ```
-zokrates compute-witness --light -i get_hash -a 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
+zokrates compute-witness --verbose -i get_hash -a 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
 ```
 The result is:
 ```
@@ -104,8 +104,8 @@ The next step is to reveal a single bit.
 
 2. Compile and run as you did the previous program:
 ```bash
-zokrates compile -i reveal_bit.zok -o reveal_bit --light
-zokrates compute-witness --light -i reveal_bit -a 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 510
+zokrates compile -i reveal_bit.zok -o reveal_bit
+zokrates compute-witness --verbose -i reveal_bit -a 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 510
 ```
 3. The output should be similar to:
 ```
@@ -205,8 +205,8 @@ Proofs give us.
 
 2. Compile `reveal_bit.zok` and create the proving and verification keys.
    ```
-   zokrates compile -i reveal_bit.zok -o reveal_bit --light
-   zokrates setup -i reveal_bit --light
+   zokrates compile -i reveal_bit.zok -o reveal_bit
+   zokrates setup -i reveal_bit
    ```
 3. Copy the file `proving.key` to Alice's directory.
 
@@ -214,13 +214,13 @@ Proofs give us.
 
 4. Alice should compile `reveal_bit.zok` independently to make sure it doesn't disclose information she wants to keep secret.
    ```
-   zokrates compile -i reveal_bit.zok -o reveal_bit --light
+   zokrates compile -i reveal_bit.zok -o reveal_bit
    ```   
    
 5. Next, Alice creates the `witness` file with the values of all the parameters in the program. Using this `witness`, 
    Bob's `proving.key`, and the compiled program she generates the actual proof.
    ```
-   zokrates compute-witness -i reveal_bit -a 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 510 --light
+   zokrates compute-witness -i reveal_bit -a 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 510
    zokrates generate-proof -i reveal_bit
    ``` 
    

zokrates_book/src/examples/sha256example.md

@@ -7,7 +7,7 @@ In particular, we'll show how ZoKrates and the Ethereum blockchain can be used t
 
 ## Pre-requisites
 
-Make sure you have followed the instructions in the [Getting Started](gettingstarted.md) chapter and are able to run the "Hello World" example described there.
+Make sure you have followed the instructions in the [Getting Started](../gettingstarted.md) chapter and are able to run the "Hello World" example described there.
 
 ## Computing a Hash using ZoKrates
 

zokrates_book/src/gettingstarted.md

@@ -60,6 +60,8 @@ zokrates compute-witness -a 337 113569
 zokrates generate-proof
 # export a solidity verifier
 zokrates export-verifier
+# or verify natively
+zokrates verify
 ```
 
 The CLI commands are explained in more detail in the [CLI reference](toolbox/cli.md).

zokrates_book/src/toolbox/zokrates_js.md

@@ -90,7 +90,19 @@ const artifacts = zokratesProvider.compile(source, options);
 
 **Note:** The `resolveCallback` function is used to resolve dependencies. 
 This callback receives the current module location and the import location of the module which is being imported. 
-The callback must synchronously return either an error, `null` or a valid `ResolverResult` object like shown in the example above.
+The callback must synchronously return either an error, `null` or a valid `ResolverResult` object like shown in the example above. 
+A simple file system resolver for a node environment can be implemented as follows:
+
+```js
+const fs = require("fs");
+const path = require("path");
+
+const fileSystemResolver = (from, to) => {
+  const location = path.resolve(path.dirname(path.resolve(from)), to);
+  const source = fs.readFileSync(location).toString();
+  return { source, location };
+};
+```
 
 ##### computeWitness(artifacts, args)
 Computes a valid assignment of the variables, which include the results of the computation.