add Salsa20 and XSalsa20

.github/workflows/linux.yml

@@ -18,4 +18,4 @@ jobs:
         cd v
         make
     - name: test algorithms
-      run: ./v/v test md4/ tea/ xtea/ _cipher/
+      run: ./v/v test md4/ tea/ xtea/ _cipher/ salsa20/

.github/workflows/win.yml

@@ -18,4 +18,4 @@ jobs:
         cd v
         .\make.bat -tcc
     - name: test algorithms
-      run: ./v/v test md4/ tea/ xtea/ _cipher/
+      run: ./v/v test md4/ tea/ xtea/ _cipher/ salsa20/

README.md

@@ -2,7 +2,7 @@
 
 > **Attention!**<br>
 **V-crypto** has no connection to the official V community and is not maintained by it.<br> 
-**&rarr; It is not recommended to use the algorithms implemented here productively.** As a non-cryptographer, I cannot fully validate the security.
+**&rarr; It is not recommended to use the algorithms implemented here productively until the status is *implemented*.** As a non-cryptographer, I cannot fully validate the security.
 
 >**Contributions welcome!**
 
@@ -80,13 +80,13 @@ The V wrapper libsodium [[Git](https://github.com/vlang/libsodium)] has some of
 | Kyber(512,1024) | key encapsulation mechanism, post-quanten crypto | low | :x: |
 | MD4 | legacy hash-algorithm | low | experimental :yellow_circle: [[Git](https://github.com/bstnbuck/V-crypto/tree/main/md4)] |
 | **RIPEMD160** | legacy hash-algorithm | moderate | :x: |
-| **Salsa20** | symmetric stream cipher | high | :x: |
+| **(X)Salsa20** | symmetric stream cipher | high | experimental :yellow_circle: [[Git](https://github.com/bstnbuck/V-crypto/tree/main/salsa20)] |
 | **scrypt** | hash-algorithm / key derivation function | high | :x: |
 | TEA, XTEA | legacy block cipher | low | experimental :yellow_circle: [[Git](https://github.com/bstnbuck/V-crypto/tree/main/tea)] [[Git](https://github.com/bstnbuck/V-crypto/tree/main/xtea)]|
 | **Twofisch** | symmetric block cipher | moderate | :x: |
 | **yescrypt** | hash-algorithm / key derivation function | high | :x: |
 
-> Last Update: 18-04-2024
+> Last Update: 20-04-2024
 ---
 ## v_crypto
 ### Installation
@@ -95,6 +95,8 @@ v install https://github.com/bstnbuck/V-crypto
 ```
 
 ### Usage
+In general, the functionality is easy to understand based on the tests of the respective algorithm. For larger algorithms, a README file with the most important functions follows.
+
 ```v
 import v_crypto.md4
 
@@ -111,3 +113,5 @@ fn main(){
     _, _ := d.checksum('Hi from V_crypto. This is an example of a long long line.'.bytes())
 }
 ```
+
+> Please report security related issues to: bstnbuck (at) proton (dot) me

salsa20/README.md

@@ -0,0 +1,54 @@
+## Salsa20/XSalsa20 -- stream cipher encryption
+
+Salsa20 is a stream cipher based on a symmetric **256-Bit key**, a **64-bit** (or **192-bit for XSalsa20**) **nonce** and a **64-bit counter**. the plaintext can have a variable size. 
+The parameters key, nonce and counter can be adjusted at runtime (using **rekey()** and/or **set_counter()**).
+
+### Examples -- Salsa20
+```v
+import v_crypto.salsa20
+import encoding.hex
+
+fn main(){
+    key := hex.decode('0053A6F94C9FF24598EB3E91E4378ADD3083D6297CCF2275C81B6EC11467BA0D')!
+    nonce := hex.decode('0D74DB42A91077DE')!
+    plain := hex.decode('766572792073686f7274206d7367')! // very short msg
+
+     // short way to encrypt the given string `plain` using key and nonce
+    println("`very short msg` encrypted with Salsa20 is: " + salsa20.encrypt(key, nonce, plain)!) // >>> 839fa746598ab737b6da80bd9efd <<<
+
+    ciphertext := 'some-ciphertext'.bytes()
+
+    // decrypt a string `ciphertext` with a given key, nonce, a different counter and number of Salsa20 rounds
+    mut dec := []u8{len: plain4.len}
+    mut c := new_cipher(key, nonce)!
+    // if only the counter should be different
+    // c.set_counter(45)
+    c.rekey(key, nonce, 45, 8)! // key, nonce, counter, rounds
+    c.xor_key_stream(mut dec, ciphertext)
+    println("The decrypted ciphertext with initial counter 48 and 8 rounds is:" +dec.hex())
+}
+```
+
+### Examples -- XSalsa20
+```v
+import v_crypto.salsa20
+import encoding.hex
+
+fn main(){
+    key := hex.decode('0053A6F94C9FF24598EB3E91E4378ADD3083D6297CCF2275C81B6EC11467BA0D')!
+    nonce := hex.decode('404142434445464748494a4b4c4d4e4f5051525354555658')! // XSalsa20 has a larger Nonce
+    plain := hex.decode('766572792073686f7274206d7367')! // very short msg
+    
+    // short way to encrypt the given string `plain` using key and nonce
+    println("`very short msg` encrypted with XSalsa20 is: " + salsa20.encrypt(key, nonce, plain)!) // >>> d0df8be036e7d95728040244ef2f <<<
+
+    ciphertext := 'some-ciphertext'.bytes()
+
+    // decrypt a string `ciphertext` with a given key, nonce, a different counter and number of Salsa20 rounds
+    mut dec := []u8{len: plain4.len}
+    mut c := new_cipher(key, nonce)!
+    c.rekey(key, nonce, 45, 8)! // key, nonce, counter, rounds
+    c.xor_key_stream(mut dec, ciphertext)
+    println("The decrypted ciphertext with initial counter 48 and 8 rounds is:" +dec.hex())
+}
+```