Added example for hashing and signature verification

.github/workflows/actions.yaml

@@ -77,6 +77,8 @@ jobs:
           'predicate',
           'script',
           'big_number',
+          'hashing',
+          'verify_signature',
         ]
 
     name: Forc build [ ${{ matrix.dir }} ]

docs/spell-check-custom-words.txt

@@ -10,4 +10,5 @@ cheatsheet
 enums
 Forc
 toml
-bytecode
+bytecode
+Keccak

docs/src/SUMMARY.md

@@ -29,3 +29,5 @@
 - [Script](./script.md)
 - [Big Numbers](./big-numbers.md)
 - [SRC20](./src20.md)
+- [Hashing](./hashing.md)
+- [Verify-Signature](./verify-signature.md)

docs/src/hashing.md

@@ -0,0 +1,7 @@
+# Hashing with Keccak256
+
+Example of how to compute hash in Sway using Keccak256
+
+```sway
+{{#include ../examples/hashing/src/main.sw}}
+```

docs/src/verify-signature.md

@@ -0,0 +1,7 @@
+# Verifying Signatures in Sway
+
+Example of how to verify signatures in Sway
+
+```sway
+{{#include ../examples/verify_signature/src/main.sw}}
+```

examples/hashing/.gitignore

@@ -0,0 +1,2 @@
+out
+target

examples/hashing/Forc.lock

@@ -0,0 +1,13 @@
+[[package]]
+name = "core"
+source = "path+from-root-CC22FE9C5CBB0084"
+
+[[package]]
+name = "hashing"
+source = "member"
+dependencies = ["std"]
+
+[[package]]
+name = "std"
+source = "git+https://github.com/fuellabs/sway?tag=v0.61.2#e1b1c2bee73e0ba825e07736cefa6c0abd079595"
+dependencies = ["core"]

examples/hashing/Forc.toml

@@ -0,0 +1,7 @@
+[project]
+authors = ["Laisha Wadhwa"]
+entry = "main.sw"
+license = "Apache-2.0"
+name = "hashing"
+
+[dependencies]

examples/hashing/src/main.sw

@@ -0,0 +1,42 @@
+contract;
+
+use std::hash::*;
+use std::bytes::Bytes;
+
+abi HashFunction {
+    fn hash(_text: str, _num: u64, _addr: b256) -> b256;
+    fn collision(_text: str, _anotherText: str) -> b256;
+    fn guess(_word: str) -> bool;
+}
+
+impl HashFunction for Contract {
+    fn hash(_text: str, _num: u64, _addr: b256) -> b256 {
+        keccak256({
+            let mut bytes = Bytes::new();
+            bytes.append(Bytes::from(core::codec::encode(_text)));
+            bytes.append(Bytes::from(core::codec::encode(_num)));
+            bytes.append(Bytes::from(core::codec::encode(_addr)));
+            bytes
+        })
+    }
+
+    // The collision function is not strictly necessary unless you have a specific use case that requires hashing two strings together. 
+    // If your primary goal is to hash individual strings you can remove the collision function.
+    fn collision(_text: str, _anotherText: str) -> b256 {
+        keccak256({
+            let mut bytes = Bytes::new();
+            bytes.append(Bytes::from(core::codec::encode(_text)));
+            bytes.append(Bytes::from(core::codec::encode(_anotherText)));
+            bytes
+        })
+    }
+
+    fn guess(_word: str) -> bool {
+        let answer: b256 = 0x60298f78cc0b47170ba79c10aa3851d7648bd96f2f8e46a19dbc777c36fb0c00;
+        keccak256({
+            let mut bytes = Bytes::new();
+            bytes.append(Bytes::from(core::codec::encode(_word)));
+            bytes
+        }) == answer
+    }
+}

examples/verify_signature/.gitignore

@@ -0,0 +1,2 @@
+out
+target

examples/verify_signature/Forc.lock

@@ -0,0 +1,13 @@
+[[package]]
+name = "core"
+source = "path+from-root-CC22FE9C5CBB0084"
+
+[[package]]
+name = "std"
+source = "git+https://github.com/fuellabs/sway?tag=v0.61.2#e1b1c2bee73e0ba825e07736cefa6c0abd079595"
+dependencies = ["core"]
+
+[[package]]
+name = "verify_signature"
+source = "member"
+dependencies = ["std"]

examples/verify_signature/Forc.toml

@@ -0,0 +1,7 @@
+[project]
+authors = ["Laisha Wadhwa"]
+entry = "main.sw"
+license = "Apache-2.0"
+name = "verify_signature"
+
+[dependencies]

examples/verify_signature/src/main.sw

@@ -0,0 +1,65 @@
+contract;
+
+use std::hash::*;
+use std::ecr::{ec_recover_address, EcRecoverError};
+use std::bytes::Bytes;
+use std::b512::B512;
+use std::constants::ZERO_B256;
+
+abi VerifySignature {
+    fn get_message_hash(_to: b256, _amount: u64, _message: str, _nonce: u64) -> b256;
+    fn get_eth_signed_message_hash(_message_hash: b256) -> b256;
+    fn recover_signer(_eth_signed_message_hash: b256, _signature: B512) -> b256;
+    fn verify(_signer: b256, _to: b256, _amount: u64, _message: str, _nonce: u64, _signature: B512) -> bool;
+
+}
+
+fn get_message_hash(_to: b256, _amount: u64, _message: str, _nonce: u64) -> b256 {
+        keccak256({
+        let mut bytes = Bytes::new();
+        bytes.append(Bytes::from(core::codec::encode(_to)));
+        bytes.append(Bytes::from(core::codec::encode(_amount)));
+        bytes.append(Bytes::from(core::codec::encode(_message)));
+        bytes.append(Bytes::from(core::codec::encode(_nonce)));
+        bytes
+    })
+    }
+
+    fn get_eth_signed_message_hash(_message_hash: b256) -> b256 {
+        keccak256({
+        let mut bytes = Bytes::new();
+        bytes.append(Bytes::from(core::codec::encode("\x19Fuel Signed Message:\n32")));
+        bytes.append(Bytes::from(core::codec::encode(_message_hash)));
+        bytes
+    })
+    }
+
+    fn recover_signer(_eth_signed_message_hash: b256, _signature: B512) -> b256 {
+        match ec_recover_address(_signature, _eth_signed_message_hash) {
+            Ok(address) => address.bits(),
+            Err(_) => ZERO_B256,
+        }
+    }
+
+impl VerifySignature for Contract {
+
+
+    fn get_message_hash(_to: b256, _amount: u64, _message: str, _nonce: u64) -> b256{
+        ::get_message_hash(_to, _amount, _message, _nonce)
+    }
+
+    fn get_eth_signed_message_hash(_message_hash: b256) -> b256 {
+        ::get_eth_signed_message_hash(_message_hash)
+    }
+
+    fn recover_signer(_eth_signed_message_hash: b256, _signature: B512) -> b256{
+        ::recover_signer(_eth_signed_message_hash, _signature)
+    }
+
+   fn verify(_signer: b256, _to: b256, _amount: u64, _message: str, _nonce: u64, _signature: B512) -> bool {   
+        let message_hash = get_message_hash(_to, _amount, _message, _nonce);
+        let eth_signed_message_hash = get_eth_signed_message_hash(message_hash);
+        let recovered_signer = recover_signer(eth_signed_message_hash, _signature);
+        recovered_signer == _signer
+    }
+}