diff --git a/Cargo.lock b/Cargo.lock
index d317a87..0cd5581 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1,5 +1,98 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
+[[package]]
+name = "autocfg"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cdb031dd78e28731d87d56cc8ffef4a8f36ca26c38fe2de700543e627f8a464a"
+
+[[package]]
+name = "chrono"
+version = "0.4.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "670ad68c9088c2a963aaa298cb369688cf3f9465ce5e2d4ca10e6e0098a1ce73"
+dependencies = [
+ "libc",
+ "num-integer",
+ "num-traits",
+ "time",
+ "winapi",
+]
+
+[[package]]
+name = "libc"
+version = "0.2.80"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4d58d1b70b004888f764dfbf6a26a3b0342a1632d33968e4a179d8011c760614"
+
+[[package]]
+name = "md5"
+version = "0.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "490cc448043f947bae3cbee9c203358d62dbee0db12107a74be5c30ccfd09771"
+
+[[package]]
+name = "num-integer"
+version = "0.1.44"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d2cc698a63b549a70bc047073d2949cce27cd1c7b0a4a862d08a8031bc2801db"
+dependencies = [
+ "autocfg",
+ "num-traits",
+]
+
+[[package]]
+name = "num-traits"
+version = "0.2.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9a64b1ec5cda2586e284722486d802acf1f7dbdc623e2bfc57e65ca1cd099290"
+dependencies = [
+ "autocfg",
+]
+
 [[package]]
 name = "radius-rs"
 version = "0.1.0"
+dependencies = [
+ "chrono",
+ "md5",
+]
+
+[[package]]
+name = "time"
+version = "0.1.44"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6db9e6914ab8b1ae1c260a4ae7a49b6c5611b40328a735b21862567685e73255"
+dependencies = [
+ "libc",
+ "wasi",
+ "winapi",
+]
+
+[[package]]
+name = "wasi"
+version = "0.10.0+wasi-snapshot-preview1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1a143597ca7c7793eff794def352d41792a93c481eb1042423ff7ff72ba2c31f"
+
+[[package]]
+name = "winapi"
+version = "0.3.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5c839a674fcd7a98952e593242ea400abe93992746761e38641405d28b00f419"
+dependencies = [
+ "winapi-i686-pc-windows-gnu",
+ "winapi-x86_64-pc-windows-gnu",
+]
+
+[[package]]
+name = "winapi-i686-pc-windows-gnu"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ac3b87c63620426dd9b991e5ce0329eff545bccbbb34f3be09ff6fb6ab51b7b6"
+
+[[package]]
+name = "winapi-x86_64-pc-windows-gnu"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"
diff --git a/Cargo.toml b/Cargo.toml
index f0978e9..189968f 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -7,3 +7,5 @@ edition = "2018"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+md5 = "0.7.0"
+chrono = "0.4"
diff --git a/src/attribute.rs b/src/attribute.rs
new file mode 100644
index 0000000..37343e3
--- /dev/null
+++ b/src/attribute.rs
@@ -0,0 +1,261 @@
+use std::convert::TryInto;
+use std::net::{Ipv4Addr, Ipv6Addr};
+use std::string::FromUtf8Error;
+
+use chrono::{DateTime, Utc, TimeZone};
+
+pub struct Attribute(Vec<u8>);
+
+impl Attribute {
+    pub fn from_integer32(v: &u32) -> Self {
+        Attribute(u32::to_be_bytes(*v).to_vec())
+    }
+
+    pub fn from_string(v: &String) -> Self {
+        Attribute(v.as_bytes().to_vec())
+    }
+
+    pub fn from_bytes(v: &Vec<u8>) -> Self {
+        Attribute(v.to_vec())
+    }
+
+    pub fn from_ipv4(v: &Ipv4Addr) -> Self {
+        Attribute(v.octets().to_vec())
+    }
+
+    pub fn from_ipv6(v: &Ipv6Addr) -> Self {
+        Attribute(v.octets().to_vec())
+    }
+
+    pub fn from_user_password(plain_text: &Vec<u8>, secret: &Vec<u8>, request_authenticator: &Vec<u8>) -> Result<Self, String> {
+        if plain_text.len() > 128 {
+            return Err("the length of plain_text has to be within 128, but the given value is longer".to_owned());
+        }
+
+        if secret.len() <= 0 {
+            return Err("secret hasn't be empty, but the given value is empty".to_owned());
+        }
+
+        if request_authenticator.len() != 16 {
+            return Err("request_authenticator has to have 16-bytes payload, but the given value doesn't".to_owned());
+        }
+
+        let mut enc: Vec<u8> = Vec::new();
+
+        let digest = md5::compute([&secret[..], &request_authenticator[..]].concat());
+        enc.extend(digest.to_vec());
+
+        let (head, _) = plain_text.split_at(16);
+
+        let mut i = 0;
+        for b in head {
+            enc[i] ^= b;
+            i += 1;
+        }
+
+        i = 16;
+        while i < plain_text.len() {
+            let digest = md5::compute([&secret[..], &enc[i - 16..i]].concat());
+            enc.extend(digest.to_vec());
+
+            let mut j = 0;
+            for b in &plain_text[i..i + 16] { // TODO this has to be 16 bounds, is this correct?
+                enc[i + j] ^= b;
+                j += 1;
+            }
+
+            i += 16;
+        }
+
+        Ok(Attribute(enc))
+    }
+
+    pub fn from_date(dt: &DateTime<Utc>) -> Self {
+        Attribute(u32::to_be_bytes(dt.timestamp() as u32).to_vec())
+    }
+
+    pub fn to_integer32(&self) -> Result<u32, String> {
+        const EXPECTED_SIZE: usize = std::mem::size_of::<u32>();
+        if self.0.len() != EXPECTED_SIZE {
+            return Err("invalid attribute length for integer".to_owned());
+        }
+
+        let (int_bytes, _) = self.0.split_at(EXPECTED_SIZE);
+        match int_bytes.try_into() {
+            Ok(boxed_array) => Ok(u32::from_be_bytes(boxed_array)),
+            Err(e) => Err(e.to_string()),
+        }
+    }
+
+    pub fn to_string(&self) -> Result<String, FromUtf8Error> {
+        String::from_utf8(self.0.to_vec())
+    }
+
+    pub fn to_bytes(&self) -> Vec<u8> {
+        self.0.to_vec()
+    }
+
+    pub fn to_ipv4(&self) -> Result<Ipv4Addr, String> {
+        const IPV4_SIZE: usize = std::mem::size_of::<Ipv4Addr>();
+        if self.0.len() != IPV4_SIZE {
+            return Err("invalid attribute length for ipv4 address".to_owned());
+        }
+
+        let (int_bytes, _) = self.0.split_at(IPV4_SIZE);
+        match int_bytes.try_into() {
+            Ok::<[u8; IPV4_SIZE], _>(boxed_array) => Ok(Ipv4Addr::from(boxed_array)),
+            Err(e) => Err(e.to_string()),
+        }
+    }
+
+    pub fn to_ipv6(&self) -> Result<Ipv6Addr, String> {
+        const IPV6_SIZE: usize = std::mem::size_of::<Ipv6Addr>();
+        if self.0.len() != IPV6_SIZE {
+            return Err("invalid attribute length for ipv6 address".to_owned());
+        }
+
+        let (int_bytes, _) = self.0.split_at(IPV6_SIZE);
+        match int_bytes.try_into() {
+            Ok::<[u8; IPV6_SIZE], _>(boxed_array) => Ok(Ipv6Addr::from(boxed_array)),
+            Err(e) => Err(e.to_string()),
+        }
+    }
+
+    pub fn to_user_password(&self, secret: &Vec<u8>, request_authenticator: &Vec<u8>) -> Result<Vec<u8>, String> {
+        if self.0.len() < 16 || self.0.len() > 128 {
+            return Err(format!("invalid attribute length {}", self.0.len()));
+        }
+
+        if secret.len() <= 0 {
+            return Err("secret hasn't be empty, but the given value is empty".to_owned());
+        }
+
+        if request_authenticator.len() != 16 {
+            return Err("request_authenticator has to have 16-bytes payload, but the given value doesn't".to_owned());
+        }
+
+        let mut dec: Vec<u8> = Vec::new();
+
+        let digest = md5::compute([&secret[..], &request_authenticator[..]].concat());
+        dec.extend(digest.to_vec());
+
+        let (head, _) = self.0.split_at(16);
+
+        let mut i = 0;
+        let mut maybe_first_zero_byte_idx = Option::None;
+        for b in head {
+            dec[i] ^= b;
+            if dec[i] == 0 && maybe_first_zero_byte_idx.is_none() {
+                maybe_first_zero_byte_idx = Option::Some(i)
+            }
+            i += 1;
+        }
+
+        i = 16;
+        while i < self.0.len() {
+            let digest = md5::compute([&secret[..], &self.0[i - 16..i]].concat());
+            dec.extend(digest.to_vec());
+
+            let mut j = 0;
+            for b in &self.0[i..i + 16] { // TODO this has to be 16 bounds, is this correct?
+                dec[i + j] ^= b;
+                if dec[i + j] == 0 && maybe_first_zero_byte_idx.is_none() {
+                    maybe_first_zero_byte_idx = Option::Some(i + j)
+                }
+                j += 1;
+            }
+
+            i += 16;
+        }
+
+        match maybe_first_zero_byte_idx {
+            None => Ok(dec),
+            Some(idx) => Ok(dec[..idx].to_vec())
+        }
+    }
+
+    pub fn to_date(&self) -> Result<DateTime<Utc>, String> {
+        let (int_bytes, _) = self.0.split_at(std::mem::size_of::<u32>());
+        match int_bytes.try_into() {
+            Ok(boxed_array) => {
+                let timestamp = u32::from_be_bytes(boxed_array);
+                Ok(Utc.timestamp(timestamp as i64, 0))
+            }
+            Err(e) => Err(e.to_string()),
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::net::{Ipv4Addr, Ipv6Addr};
+    use std::string::FromUtf8Error;
+
+    use crate::attribute::Attribute;
+    use chrono::Utc;
+
+    #[test]
+    fn it_should_convert_attribute_to_integer32() -> Result<(), String> {
+        assert_eq!(Attribute(vec![1, 2, 3, 4]).to_integer32()?, 16909060);
+        Ok(())
+    }
+
+    #[test]
+    fn it_should_convert_attribute_to_string() -> Result<(), FromUtf8Error> {
+        assert_eq!(
+            Attribute(vec![0x48, 0x65, 0x6c, 0x6c, 0x6f, 0x2c, 0x20, 0x57, 0x6f, 0x72, 0x6c, 0x64]).to_string()?,
+            "Hello, World"
+        );
+        Ok(())
+    }
+
+    #[test]
+    fn it_should_convert_ipv4() -> Result<(), String> {
+        let given_ipv4 = Ipv4Addr::new(192, 0, 2, 1);
+        let ipv4_attr = Attribute::from_ipv4(&given_ipv4);
+        assert_eq!(
+            ipv4_attr.to_ipv4()?,
+            given_ipv4,
+        );
+        Ok(())
+    }
+
+    #[test]
+    fn it_should_convert_ipv6() -> Result<(), String> {
+        let given_ipv6 = Ipv6Addr::new(0x2001, 0x0db8, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0001);
+        let ipv6_attr = Attribute::from_ipv6(&given_ipv6);
+        assert_eq!(
+            ipv6_attr.to_ipv6()?,
+            given_ipv6,
+        );
+        Ok(())
+    }
+
+    #[test]
+    fn it_should_convert_user_password() {
+        let plain_text = b"texttexttexttexttexttexttexttext".to_vec();
+        let secret = b"secret".to_vec();
+        let request_authenticator = b"0123456789abcdef".to_vec();
+        let user_password_attr_result = Attribute::from_user_password(&plain_text, &secret, &request_authenticator);
+        let user_password_attr = user_password_attr_result.unwrap();
+        assert_eq!(
+            user_password_attr.0,
+            vec![0xb7, 0xb0, 0xcb, 0x5d, 0x4f, 0x96, 0xd4, 0x75, 0x1c, 0xea, 0x3a, 0xb6, 0xf, 0xc, 0xea, 0xa5, 0xc9, 0x22, 0xac, 0x26, 0x28, 0x23, 0x93, 0xef, 0x19, 0x67, 0xcc, 0xeb, 0x9d, 0x33, 0xd7, 0x46],
+        );
+        assert_eq!(
+            user_password_attr.to_user_password(&secret, &request_authenticator).unwrap(),
+            plain_text,
+        );
+    }
+
+    #[test]
+    fn it_should_convert_date() -> Result<(), String> {
+        let now = Utc::now();
+        let attr = Attribute::from_date(&now);
+        assert_eq!(
+            attr.to_date()?.timestamp(),
+            now.timestamp(),
+        );
+        Ok(())
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
index 9de50d4..37d8952 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1 +1,2 @@
 pub mod code;
+pub mod attribute;