diff --git a/src/certificate.rs b/src/certificate.rs
new file mode 100644
index 0000000..8807c4b
--- /dev/null
+++ b/src/certificate.rs
@@ -0,0 +1,54 @@
+use num_enum::IntoPrimitive;
+use num_enum::TryFromPrimitive;
+
+pub struct Certificate<'a> {
+    tbs_certificate: TBSCertificate<'a>,
+    signature_algorithm: AlgorithmIdentifier<'a>,
+    signature_value: &'a [u8]
+}
+
+pub struct TBSCertificate<'a> {
+    version: Version,
+    serial_number: &'a [u8],
+    signature: AlgorithmIdentifier<'a>,
+    issuer: &'a [u8],
+    validity: Validity<'a>,
+    subject: &'a [u8],
+    subject_public_key_info: SubjectPublicKeyInfo<'a>,
+    issuer_unique_id: Option<&'a [u8]>,
+    subject_unique_id: Option<&'a [u8]>,
+    extensions: Extensions,
+}
+
+#[derive(Debug, PartialEq, Eq, Clone, Copy, IntoPrimitive, TryFromPrimitive)]
+#[repr(u8)]
+pub enum Version {
+    #[num_enum(default)]
+    v1 = 0,
+    v2 = 1,
+    v3 = 2,
+}
+
+pub struct Validity<'a> {
+    not_before: Time<'a>,
+    not_after: Time<'a>,
+}
+
+pub enum Time<'a> {
+    UTCTime(&'a [u8]),
+    GeneralizedTime(&'a [u8]),
+}
+
+pub struct SubjectPublicKeyInfo<'a> {
+    algorithm: AlgorithmIdentifier<'a>,
+    subject_public_key: &'a [u8],
+}
+
+pub struct Extensions {
+    
+}
+
+pub struct AlgorithmIdentifier<'a> {
+    pub algorithm: &'a [u8],
+    pub parameters: &'a [u8],
+}