feat: add base32 cipher implementation (#991)

Author: AliAlimohammadi

DIRECTORY.md

@@ -39,6 +39,7 @@
     * [Another ROT13](https://github.com/TheAlgorithms/Rust/blob/master/src/ciphers/another_rot13.rs)
     * [Baconian Cipher](https://github.com/TheAlgorithms/Rust/blob/master/src/ciphers/baconian_cipher.rs)
     * [Base16](https://github.com/TheAlgorithms/Rust/blob/master/src/ciphers/base16.rs)
+    * [Base32](https://github.com/TheAlgorithms/Rust/blob/master/src/ciphers/base32.rs)
     * [Base64](https://github.com/TheAlgorithms/Rust/blob/master/src/ciphers/base64.rs)
     * [Blake2B](https://github.com/TheAlgorithms/Rust/blob/master/src/ciphers/blake2b.rs)
     * [Caesar](https://github.com/TheAlgorithms/Rust/blob/master/src/ciphers/caesar.rs)

src/ciphers/base32.rs

@@ -0,0 +1,275 @@
+//! Base32 encoding and decoding implementation.
+//!
+//! Base32 is a binary-to-text encoding scheme that represents binary data using 32 ASCII characters
+//! (A-Z and 2-7). It's commonly used when case-insensitive encoding is needed or when avoiding
+//! characters that might be confused (like 0/O or 1/l).
+//!
+//! This implementation follows the standard Base32 alphabet as defined in RFC 4648.
+
+const B32_CHARSET: &[u8; 32] = b"ABCDEFGHIJKLMNOPQRSTUVWXYZ234567";
+
+/// Encodes the given bytes into base32.
+///
+/// The function converts binary data into base32 format using the standard alphabet.
+/// Output is padded with '=' characters to make the length a multiple of 8.
+///
+/// # Arguments
+///
+/// * `data` - A byte slice to encode
+///
+/// # Returns
+///
+/// A `Vec<u8>` containing the base32-encoded data with padding.
+///
+/// # Examples
+///
+/// ```
+/// use the_algorithms_rust::ciphers::base32_encode;
+/// assert_eq!(base32_encode(b"Hello World!"), b"JBSWY3DPEBLW64TMMQQQ====");
+/// assert_eq!(base32_encode(b"123456"), b"GEZDGNBVGY======");
+/// assert_eq!(base32_encode(b"some long complex string"), b"ONXW2ZJANRXW4ZZAMNXW24DMMV4CA43UOJUW4ZY=");
+/// ```
+pub fn base32_encode(data: &[u8]) -> Vec<u8> {
+    if data.is_empty() {
+        return Vec::new();
+    }
+
+    // Convert bytes to binary string representation
+    use std::fmt::Write;
+    let mut binary_data = String::with_capacity(data.len() * 8);
+    for byte in data {
+        write!(binary_data, "{byte:08b}").unwrap();
+    }
+
+    // Pad binary data to be a multiple of 5 bits
+    let padding_needed = (5 - (binary_data.len() % 5)) % 5;
+    for _ in 0..padding_needed {
+        binary_data.push('0');
+    }
+
+    // Convert 5-bit chunks to base32 characters
+    let mut result = Vec::new();
+    for chunk in binary_data.as_bytes().chunks(5) {
+        let chunk_str = std::str::from_utf8(chunk).unwrap();
+        let index = usize::from_str_radix(chunk_str, 2).unwrap();
+        result.push(B32_CHARSET[index]);
+    }
+
+    // Pad result to be a multiple of 8 characters
+    while !result.len().is_multiple_of(8) {
+        result.push(b'=');
+    }
+
+    result
+}
+
+/// Decodes base32-encoded data into bytes.
+///
+/// The function decodes base32 format back to binary data, removing padding characters.
+///
+/// # Arguments
+///
+/// * `data` - A byte slice containing base32-encoded data
+///
+/// # Returns
+///
+/// * `Ok(Vec<u8>)` - Successfully decoded bytes
+/// * `Err(String)` - Error message if the input is invalid
+///
+/// # Errors
+///
+/// Returns an error if:
+/// - The input contains invalid base32 characters
+/// - The input cannot be properly decoded
+///
+/// # Examples
+///
+/// ```
+/// use the_algorithms_rust::ciphers::base32_decode;
+/// assert_eq!(base32_decode(b"JBSWY3DPEBLW64TMMQQQ====").unwrap(), b"Hello World!");
+/// assert_eq!(base32_decode(b"GEZDGNBVGY======").unwrap(), b"123456");
+/// assert_eq!(base32_decode(b"ONXW2ZJANRXW4ZZAMNXW24DMMV4CA43UOJUW4ZY=").unwrap(), b"some long complex string");
+/// ```
+pub fn base32_decode(data: &[u8]) -> Result<Vec<u8>, String> {
+    if data.is_empty() {
+        return Ok(Vec::new());
+    }
+
+    // Remove padding and convert to string
+    let data_str =
+        std::str::from_utf8(data).map_err(|_| "Invalid UTF-8 in base32 data".to_string())?;
+    let data_stripped = data_str.trim_end_matches('=');
+
+    // Convert base32 characters to binary string
+    use std::fmt::Write;
+    let mut binary_chunks = String::with_capacity(data_stripped.len() * 5);
+    for ch in data_stripped.chars() {
+        // Find the index of this character in the charset
+        let index = B32_CHARSET
+            .iter()
+            .position(|&c| c == ch as u8)
+            .ok_or_else(|| format!("Invalid base32 character: {ch}"))?;
+
+        // Convert index to 5-bit binary string
+        write!(binary_chunks, "{index:05b}").unwrap();
+    }
+
+    // Convert 8-bit chunks back to bytes
+    let mut result = Vec::new();
+    for chunk in binary_chunks.as_bytes().chunks(8) {
+        if chunk.len() == 8 {
+            let chunk_str = std::str::from_utf8(chunk).unwrap();
+            let byte_value = u8::from_str_radix(chunk_str, 2)
+                .map_err(|_| "Failed to parse binary chunk".to_string())?;
+            result.push(byte_value);
+        }
+    }
+
+    Ok(result)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_encode_hello_world() {
+        assert_eq!(base32_encode(b"Hello World!"), b"JBSWY3DPEBLW64TMMQQQ====");
+    }
+
+    #[test]
+    fn test_encode_numbers() {
+        assert_eq!(base32_encode(b"123456"), b"GEZDGNBVGY======");
+    }
+
+    #[test]
+    fn test_encode_long_string() {
+        assert_eq!(
+            base32_encode(b"some long complex string"),
+            b"ONXW2ZJANRXW4ZZAMNXW24DMMV4CA43UOJUW4ZY="
+        );
+    }
+
+    #[test]
+    fn test_encode_empty() {
+        assert_eq!(base32_encode(b""), b"");
+    }
+
+    #[test]
+    fn test_encode_single_char() {
+        assert_eq!(base32_encode(b"A"), b"IE======");
+    }
+
+    #[test]
+    fn test_decode_hello_world() {
+        assert_eq!(
+            base32_decode(b"JBSWY3DPEBLW64TMMQQQ====").unwrap(),
+            b"Hello World!"
+        );
+    }
+
+    #[test]
+    fn test_decode_numbers() {
+        assert_eq!(base32_decode(b"GEZDGNBVGY======").unwrap(), b"123456");
+    }
+
+    #[test]
+    fn test_decode_long_string() {
+        assert_eq!(
+            base32_decode(b"ONXW2ZJANRXW4ZZAMNXW24DMMV4CA43UOJUW4ZY=").unwrap(),
+            b"some long complex string"
+        );
+    }
+
+    #[test]
+    fn test_decode_empty() {
+        assert_eq!(base32_decode(b"").unwrap(), b"");
+    }
+
+    #[test]
+    fn test_decode_single_char() {
+        assert_eq!(base32_decode(b"IE======").unwrap(), b"A");
+    }
+
+    #[test]
+    fn test_decode_without_padding() {
+        assert_eq!(
+            base32_decode(b"JBSWY3DPEBLW64TMMQQQ").unwrap(),
+            b"Hello World!"
+        );
+    }
+
+    #[test]
+    fn test_decode_invalid_character() {
+        let result = base32_decode(b"INVALID!@#$");
+        assert!(result.is_err());
+        assert!(result.unwrap_err().contains("Invalid base32 character"));
+    }
+
+    #[test]
+    fn test_roundtrip_hello() {
+        let original = b"Hello";
+        let encoded = base32_encode(original);
+        let decoded = base32_decode(&encoded).unwrap();
+        assert_eq!(decoded, original);
+    }
+
+    #[test]
+    fn test_roundtrip_various_strings() {
+        let test_cases = vec![
+            b"a" as &[u8],
+            b"ab",
+            b"abc",
+            b"abcd",
+            b"abcde",
+            b"The quick brown fox jumps over the lazy dog",
+            b"1234567890",
+            b"!@#$%^&*()",
+        ];
+
+        for original in test_cases {
+            let encoded = base32_encode(original);
+            let decoded = base32_decode(&encoded).unwrap();
+            assert_eq!(decoded, original, "Failed for: {original:?}");
+        }
+    }
+
+    #[test]
+    fn test_all_charset_characters() {
+        // Test that all characters in the charset can be encoded/decoded
+        for i in 0..32 {
+            let data = vec![i * 8]; // Arbitrary byte values
+            let encoded = base32_encode(&data);
+            let decoded = base32_decode(&encoded).unwrap();
+            assert_eq!(decoded, data);
+        }
+    }
+
+    #[test]
+    fn test_binary_data() {
+        let binary_data = vec![0x00, 0x01, 0x02, 0xFF, 0xFE, 0xFD];
+        let encoded = base32_encode(&binary_data);
+        let decoded = base32_decode(&encoded).unwrap();
+        assert_eq!(decoded, binary_data);
+    }
+
+    #[test]
+    fn test_padding_variations() {
+        // Test different amounts of padding
+        let test_cases: Vec<(&[u8], &[u8])> = vec![
+            (b"f", b"MY======"),
+            (b"fo", b"MZXQ===="),
+            (b"foo", b"MZXW6==="),
+            (b"foob", b"MZXW6YQ="),
+            (b"fooba", b"MZXW6YTB"),
+            (b"foobar", b"MZXW6YTBOI======"),
+        ];
+
+        for (input, expected) in test_cases {
+            let encoded = base32_encode(input);
+            assert_eq!(encoded, expected, "Encoding failed for: {input:?}");
+            let decoded = base32_decode(&encoded).unwrap();
+            assert_eq!(decoded, input, "Roundtrip failed for: {input:?}");
+        }
+    }
+}

src/ciphers/mod.rs

@@ -3,6 +3,7 @@ mod affine_cipher;
 mod another_rot13;
 mod baconian_cipher;
 mod base16;
+mod base32;
 mod base64;
 mod blake2b;
 mod caesar;
@@ -30,6 +31,7 @@ pub use self::affine_cipher::{affine_decrypt, affine_encrypt, affine_generate_ke
 pub use self::another_rot13::another_rot13;
 pub use self::baconian_cipher::{baconian_decode, baconian_encode};
 pub use self::base16::{base16_decode, base16_encode};
+pub use self::base32::{base32_decode, base32_encode};
 pub use self::base64::{base64_decode, base64_encode};
 pub use self::blake2b::blake2b;
 pub use self::caesar::caesar;