Merge commit 'd803bfe2b1fe7f5e219e50ac20d6801a0a58ac75' as 'vendor/ruvector'

vendor/ruvector/crates/rvf/rvf-crypto/src/footer.rs

@@ -0,0 +1,113 @@
+//! Signature footer codec for RVF segments.
+//!
+//! Encodes/decodes `rvf_types::SignatureFooter` to/from wire-format bytes.
+//! Wire layout:
+//!   [0..2]   sig_algo   (u16 LE)
+//!   [2..4]   sig_length (u16 LE)
+//!   [4..4+sig_length]   signature bytes
+//!   [4+sig_length..4+sig_length+4]  footer_length (u32 LE)
+
+use alloc::vec::Vec;
+use rvf_types::{ErrorCode, RvfError, SignatureFooter};
+
+/// Minimum footer wire size: 2 (algo) + 2 (sig_len) + 4 (footer_len) = 8 bytes.
+const FOOTER_MIN_SIZE: usize = 8;
+
+/// Encode a `SignatureFooter` into wire-format bytes.
+pub fn encode_signature_footer(footer: &SignatureFooter) -> Vec<u8> {
+    let sig_len = footer.sig_length as usize;
+    let total = 2 + 2 + sig_len + 4;
+    let mut buf = Vec::with_capacity(total);
+    buf.extend_from_slice(&footer.sig_algo.to_le_bytes());
+    buf.extend_from_slice(&footer.sig_length.to_le_bytes());
+    buf.extend_from_slice(&footer.signature[..sig_len]);
+    buf.extend_from_slice(&footer.footer_length.to_le_bytes());
+    buf
+}
+
+/// Decode a `SignatureFooter` from wire-format bytes.
+pub fn decode_signature_footer(data: &[u8]) -> Result<SignatureFooter, RvfError> {
+    if data.len() < FOOTER_MIN_SIZE {
+        return Err(RvfError::Code(ErrorCode::TruncatedSegment));
+    }
+    let sig_algo = u16::from_le_bytes([data[0], data[1]]);
+    let sig_length = u16::from_le_bytes([data[2], data[3]]);
+    let sig_len = sig_length as usize;
+
+    if sig_len > SignatureFooter::MAX_SIG_LEN {
+        return Err(RvfError::Code(ErrorCode::InvalidSignature));
+    }
+    if data.len() < 4 + sig_len + 4 {
+        return Err(RvfError::Code(ErrorCode::TruncatedSegment));
+    }
+
+    let mut signature = [0u8; SignatureFooter::MAX_SIG_LEN];
+    signature[..sig_len].copy_from_slice(&data[4..4 + sig_len]);
+
+    let fl_offset = 4 + sig_len;
+    let footer_length = u32::from_le_bytes([
+        data[fl_offset],
+        data[fl_offset + 1],
+        data[fl_offset + 2],
+        data[fl_offset + 3],
+    ]);
+
+    Ok(SignatureFooter {
+        sig_algo,
+        sig_length,
+        signature,
+        footer_length,
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn make_footer(algo: u16, sig_len: u16, fill: u8) -> SignatureFooter {
+        let mut signature = [0u8; SignatureFooter::MAX_SIG_LEN];
+        signature[..sig_len as usize].fill(fill);
+        SignatureFooter {
+            sig_algo: algo,
+            sig_length: sig_len,
+            signature,
+            footer_length: SignatureFooter::compute_footer_length(sig_len),
+        }
+    }
+
+    #[test]
+    fn round_trip_ed25519() {
+        let footer = make_footer(0, 64, 0xAB);
+        let encoded = encode_signature_footer(&footer);
+        assert_eq!(encoded.len(), 2 + 2 + 64 + 4);
+        let decoded = decode_signature_footer(&encoded).unwrap();
+        assert_eq!(decoded.sig_algo, footer.sig_algo);
+        assert_eq!(decoded.sig_length, footer.sig_length);
+        assert_eq!(&decoded.signature[..64], &footer.signature[..64]);
+        assert_eq!(decoded.footer_length, footer.footer_length);
+    }
+
+    #[test]
+    fn decode_truncated_header() {
+        let result = decode_signature_footer(&[0u8; 5]);
+        assert!(result.is_err());
+    }
+
+    #[test]
+    fn decode_truncated_signature() {
+        let footer = make_footer(0, 64, 0xCC);
+        let encoded = encode_signature_footer(&footer);
+        let result = decode_signature_footer(&encoded[..10]);
+        assert!(result.is_err());
+    }
+
+    #[test]
+    fn empty_signature() {
+        let footer = make_footer(1, 0, 0);
+        let encoded = encode_signature_footer(&footer);
+        assert_eq!(encoded.len(), FOOTER_MIN_SIZE);
+        let decoded = decode_signature_footer(&encoded).unwrap();
+        assert_eq!(decoded.sig_algo, 1);
+        assert_eq!(decoded.sig_length, 0);
+    }
+}