Update src/cert.rs

src/cert.rs

@@ -0,0 +1,63 @@
+use crate::keydata::SPKI_DER;
+
+pub fn build_min_cert() -> Vec<u8> {
+    let sig_alg = der_seq(&der_oid(&[0x2a]));
+
+    let name = der_seq(&[]);
+
+    let not_before = der_tlv(0x17, b"000101000000Z");
+    let not_after = der_tlv(0x17, b"490101000000Z");
+    let validity = der_seq(&[not_before, not_after].concat());
+
+    let cert_spki = SPKI_DER.to_vec();
+    let tbs = der_seq(
+        &[
+            der_int(&[1]),
+            sig_alg.clone(),
+            name.clone(),
+            validity,
+            name,
+            cert_spki,
+        ]
+        .concat(),
+    );
+
+    let sig_bitstring = der_tlv(0x03, &[0x00]);
+
+    der_seq(&[tbs, sig_alg, sig_bitstring].concat())
+}
+
+fn der_len(len: usize) -> Vec<u8> {
+    if len < 0x80 {
+        vec![len as u8]
+    } else {
+        let mut b = Vec::new();
+        let mut l = len;
+        while l > 0 {
+            b.insert(0, (l & 0xff) as u8);
+            l >>= 8;
+        }
+        let mut out = vec![0x80 | b.len() as u8];
+        out.extend_from_slice(&b);
+        out
+    }
+}
+fn der_tlv(tag: u8, body: &[u8]) -> Vec<u8> {
+    let mut out = vec![tag];
+    out.extend_from_slice(&der_len(body.len()));
+    out.extend_from_slice(body);
+    out
+}
+fn der_seq(body: &[u8]) -> Vec<u8> {
+    der_tlv(0x30, body)
+}
+fn der_oid(bytes: &[u8]) -> Vec<u8> {
+    der_tlv(0x06, bytes)
+}
+fn der_int(bytes: &[u8]) -> Vec<u8> {
+    let mut b = bytes.to_vec();
+    if !b.is_empty() && b[0] & 0x80 != 0 {
+        b.insert(0, 0x00);
+    }
+    der_tlv(0x02, &b)
+}