Fix/issue 18

src/lib.rs

@@ -226,6 +226,10 @@ pub trait Signable {
     fn verify(&mut self, pub_key: &ExtendedPoint) -> Result<(), OperationError>;
 }
 
+pub trait UpdateFinalize {
+    fn update(&mut self, data: &[u8]);
+    fn finalize(&mut self, output_length: u64) -> Result<(), OperationError>;
+}
 const RATE_IN_BYTES: usize = 136; // SHA3-256 r = 1088 / 8 = 136
 
 #[cfg(test)]

src/ops.rs

@@ -19,7 +19,7 @@ use crate::{
     },
     AesEncryptable, BitLength, Capacity, Hashable, KeyEncryptable, KeyPair, Message,
     OperationError, OutputLength, Rate, SecParam, Signable, Signature, SpongeEncryptable,
-    RATE_IN_BYTES,
+    UpdateFinalize, RATE_IN_BYTES,
 };
 use rayon::prelude::*;
 use tiny_ed448_goldilocks::curve::{extended_edwards::ExtendedPoint, field::scalar::Scalar};
@@ -883,6 +883,36 @@ impl AesEncryptable for Message {
     }
 }
 
+impl UpdateFinalize for Message {
+    fn update(&mut self, data: &[u8]) {
+        self.msg.append(&mut data.to_vec());
+    }
+    /// # Finalizes the message by computing the keyed hash of the message.
+    /// ## Replaces:
+    /// ## Usage:
+    /// ```
+    /// use capycrypt::{Message, SecParam,UpdateFinalize};
+    /// let mut m = Message::new(vec![]);
+    /// m.d = &D256;
+    /// m.update("foo");
+    /// m.update("bar");
+    /// m.update("baz");
+    /// assert_eq!(m.finalize(m.len()), vec!["foobarbaz"].compute_hash_sha3(&SecParam::D256));
+    /// ```
+    fn finalize(&mut self, output_length: u64) -> Result<(), OperationError> {
+        match self.d {
+            Some(d) => {
+                // Compute the SHA3 hash of accumulated message
+                self.compute_hash_sha3(&d)?;
+
+                self.digest = cshake(&self.msg , output_length, "", "", &d);
+                Ok(())
+            },
+            None => Err(OperationError::UnsupportedSecurityParameter)
+        }
+
+    }
+}
 ///
 /// TESTS
 ///
@@ -1165,3 +1195,20 @@ mod shake_tests {
             .unwrap_or(false));
     }
 }
+
+#[cfg(test)]
+mod update_finalize_tests {
+    use crate::{ops::UpdateFinalize, Hashable, Message, SecParam::D256};
+    #[test]
+    fn test_updated_message_256() {
+        let mut m = Message::new(vec![]);
+        m.d = Some(D256);
+        m.update(b"foo");
+        m.update(b"bar");
+        m.update(b"baz");
+
+        let mut expected = Message::new(b"foobarbaz".to_vec());
+        let output_length = m.msg.len() as u64 * 8;
+        assert_eq!(m.finalize(output_length), expected.compute_hash_sha3(&D256));
+    }
+}