chore: import upstream snapshot with attribution

src/encryption/constants.rs

@@ -0,0 +1,27 @@
+//! Constants for the `.mv2e` encrypted capsule format.
+
+/// Magic bytes identifying an encrypted capsule file.
+pub const MV2E_MAGIC: [u8; 4] = *b"MV2E";
+
+/// Current `.mv2e` format version.
+pub const MV2E_VERSION: u16 = 1;
+
+/// Fixed header size for `.mv2e`.
+pub const MV2E_HEADER_SIZE: usize = 64;
+
+/// KDF algorithm identifiers.
+pub const KDF_ARGON2ID: u8 = 1;
+
+/// Cipher algorithm identifiers.
+pub const CIPHER_AES_256_GCM: u8 = 1;
+
+/// Cryptographic parameter sizes.
+pub const SALT_SIZE: usize = 32;
+pub const NONCE_SIZE: usize = 12;
+pub const TAG_SIZE: usize = 16;
+pub const KEY_SIZE: usize = 32;
+
+/// Argon2id parameters (OWASP 2024 recommendations).
+pub const ARGON2_MEMORY_KIB: u32 = 64 * 1024; // 64 MiB
+pub const ARGON2_ITERATIONS: u32 = 3;
+pub const ARGON2_PARALLELISM: u32 = 4;