1 files changed, 78 insertions, 0 deletions
diff --git a/vendor/pasetors/src/pae.rs b/vendor/pasetors/src/pae.rs
new file mode 100644
index 0000000..7bb7746
--- /dev/null
+++ b/vendor/pasetors/src/pae.rs
@@ -0,0 +1,78 @@
+use crate::errors::Error;
+use alloc::vec::Vec;
+use core::convert::TryInto;
+
+/// Encode `n` to little-endian bytes. The MSB is cleared.
+pub fn le64(n: u64) -> [u8; core::mem::size_of::<u64>()] {
+    let mut out = [0u8; core::mem::size_of::<u64>()];
+    let mut n_tmp = n;
+
+    out[0] = (n_tmp & 255) as u8;
+    n_tmp >>= 8;
+    out[1] = (n_tmp & 255) as u8;
+    n_tmp >>= 8;
+    out[2] = (n_tmp & 255) as u8;
+    n_tmp >>= 8;
+    out[3] = (n_tmp & 255) as u8;
+    n_tmp >>= 8;
+    out[4] = (n_tmp & 255) as u8;
+    n_tmp >>= 8;
+    out[5] = (n_tmp & 255) as u8;
+    n_tmp >>= 8;
+    out[6] = (n_tmp & 255) as u8;
+    n_tmp >>= 8;
+    n_tmp &= 127; // Clear the MSB for interoperability
+    out[7] = (n_tmp & 255) as u8;
+
+    out
+}
+
+/// Pre-Authentication Encoding. See [specification](https://github.com/paragonie/paseto/blob/master/docs/01-Protocol-Versions/Common.md#pae-definition).
+pub fn pae(pieces: &[&[u8]]) -> Result<Vec<u8>, Error> {
+    let mut out: Vec<u8> = Vec::with_capacity(64);
+
+    out.extend_from_slice(&le64(pieces.len().try_into()?));
+    for elem in pieces.iter() {
+        out.extend_from_slice(&le64(elem.len().try_into()?));
+        out.extend_from_slice(elem);
+    }
+
+    Ok(out)
+}
+
+#[cfg(test)]
+mod unit_tests {
+    use super::*;
+
+    #[test]
+    fn test_le64() {
+        assert_eq!(vec![0, 0, 0, 0, 0, 0, 0, 0], le64(0));
+        assert_eq!(vec![10, 0, 0, 0, 0, 0, 0, 0], le64(10));
+    }
+
+    #[test]
+    fn test_pae() {
+        // Source: https://github.com/paragonie/paseto/blob/master/tests/UtilTest.php
+        assert_eq!("0000000000000000", hex::encode(pae(&[]).unwrap()));
+        assert_eq!(
+            "01000000000000000000000000000000",
+            hex::encode(pae(&[b""]).unwrap())
+        );
+        assert_eq!(
+            "020000000000000000000000000000000000000000000000",
+            hex::encode(pae(&[b"", b""]).unwrap())
+        );
+        assert_eq!(
+            "0100000000000000070000000000000050617261676f6e",
+            hex::encode(pae(&[b"Paragon"]).unwrap())
+        );
+        assert_eq!(
+            "0200000000000000070000000000000050617261676f6e0a00000000000000496e6974696174697665",
+            hex::encode(pae(&[b"Paragon", b"Initiative",]).unwrap())
+        );
+        assert_eq!(
+            "0100000000000000190000000000000050617261676f6e0a00000000000000496e6974696174697665",
+            hex::encode(pae(&[b"Paragon\n\0\0\0\0\0\0\0Initiative"]).unwrap())
+        );
+    }
+}