feat(cipher-factory,cli): add CBC mode support to CipherContext and CLI

Update CipherContext:
    - Add optional iv field for CBC mode
    - Add process_cbc() for CBC-specific handling
    - Add parse_hex() helper for decryption input
    - Separate ECB and CBC processing paths

Update CLI:
    - Add --iv argument for initialization vector
    - Pass IV through to CipherContext

cipher-factory/src/context.rs

@@ -1,11 +1,12 @@
 use crate::{Algorithm, OperationMode, OutputFormat};
-use cipher_core::{BlockCipher, CipherResult};
+use cipher_core::{BlockCipher, CipherError, CipherResult, Output};
 
 #[derive(Clone)]
 pub struct CipherContext {
     pub algorithm: Algorithm,
     pub operation: OperationMode,
     pub key: String,
+    pub iv: Option<String>,
     pub input_text: String,
     pub output_format: OutputFormat,
 }
@@ -17,6 +18,7 @@ impl CipherContext {
         algorithm: Algorithm,
         operation: OperationMode,
         key: String,
+        iv: Option<String>,
         input_text: String,
         output_format: OutputFormat,
     ) -> Self {
@@ -24,22 +26,57 @@ impl CipherContext {
             algorithm,
             operation,
             key,
+            iv,
             input_text,
             output_format,
         }
     }
 
+    /// Processes the input text using the configured cipher algorithm and operation.
+    ///
     /// # Errors
     ///
-    /// Returns `Err` if parsing the input text or creating the cipher fails,
-    /// or if the encryption/decryption process encounters an error.
+    /// Returns `Err` if:
+    /// - Parsing the input text or creating the cipher fails
+    /// - The encryption/decryption process encounters an error
+    /// - CBC mode is used without providing an IV
     pub fn process(&self) -> CipherResult<String> {
-        let text_bytes = self.algorithm.parse_text(&self.input_text)?;
-        let cipher = self.algorithm.new_cipher(&self.key)?;
-        self.execute(cipher.as_ref(), &text_bytes)
+        if self.algorithm.requires_iv() {
+            self.process_cbc()
+        } else {
+            self.process_ecb()
+        }
     }
 
-    fn execute(&self, cipher: &dyn BlockCipher, text_bytes: &[u8]) -> CipherResult<String> {
+    fn process_ecb(&self) -> CipherResult<String> {
+        let text_bytes = self.algorithm.parse_text(&self.input_text)?;
+        let cipher = self.algorithm.new_cipher(&self.key)?;
+        self.execute_ecb(cipher.as_ref(), &text_bytes)
+    }
+
+    fn process_cbc(&self) -> CipherResult<String> {
+        let iv = self.iv.as_ref().ok_or_else(|| {
+            CipherError::InvalidPadding("CBC mode requires an IV".into())
+        })?;
+
+        let cipher = self.algorithm.new_cbc_cipher(&self.key, iv)?;
+
+        match self.operation {
+            OperationMode::Encrypt => {
+                let ciphertext = cipher.encrypt(self.input_text.as_bytes())?;
+                Ok(format!("{:X}", Output::from(ciphertext)))
+            }
+            OperationMode::Decrypt => {
+                // Parse hex input for decryption
+                let ciphertext = parse_hex(&self.input_text)?;
+                let plaintext = cipher.decrypt(&ciphertext)?;
+                let output = self.output_format.format(&Output::from(plaintext));
+                Ok(output)
+            }
+        }
+    }
+
+    fn execute_ecb(&self, cipher: &dyn BlockCipher, text_bytes: &[u8]) -> CipherResult<String> {
         match self.operation {
             OperationMode::Encrypt => {
                 let ciphertext = cipher.encrypt(text_bytes)?;
@@ -53,3 +90,26 @@ impl CipherContext {
         }
     }
 }
+
+/// Parses a hex string into bytes.
+fn parse_hex(s: &str) -> CipherResult<Vec<u8>> {
+    let trimmed = s.trim();
+    let s = trimmed
+        .strip_prefix("0x")
+        .or_else(|| trimmed.strip_prefix("0X"))
+        .unwrap_or(trimmed);
+
+    if !s.len().is_multiple_of(2) {
+        return Err(CipherError::InvalidPadding(
+            "hex string must have even length".into(),
+        ));
+    }
+
+    (0..s.len())
+        .step_by(2)
+        .map(|i| {
+            u8::from_str_radix(&s[i..i + 2], 16)
+                .map_err(|_| CipherError::InvalidPadding(format!("invalid hex at position {i}")))
+        })
+        .collect()
+}

cli/src/args.rs

@@ -12,11 +12,15 @@ pub struct Args {
     #[arg(short, long)]
     pub algorithm: Algorithm,
 
-    /// Key used for encryption/decryption. Can be a string or a path to a file
+    /// Key used for encryption/decryption (hex string, e.g., 0x2b7e...)
     #[arg(short, long, required = true)]
     pub key: String,
 
-    /// The text to encrypt/decrypt. Can be a string or a path to a file
+    /// Initialization vector for CBC mode (hex string, e.g., 0x0001...)
+    #[arg(long)]
+    pub iv: Option<String>,
+
+    /// The text to encrypt/decrypt
     #[arg(value_name = "TEXT", required = true)]
     pub text: String,
 
@@ -31,6 +35,7 @@ impl From<Args> for CipherContext {
             algorithm: args.algorithm,
             operation: args.operation,
             key: args.key,
+            iv: args.iv,
             input_text: args.text,
             output_format: args.output_format.unwrap_or_default(),
         }