From e7e0d5b7827951ea26d9ae700e7a2b319187aa44 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Milan=20=C5=A0pinka?= <mspi21@protonmail.com>
Date: Mon, 27 Jan 2025 23:00:40 +0100
Subject: [PATCH] Prepare SHA constants and structures.

---
 src/primitive/digest/sha.zig | 96 ++++++++++++++++++++++++++++++++++++
 1 file changed, 96 insertions(+)
 create mode 100644 src/primitive/digest/sha.zig

diff --git a/src/primitive/digest/sha.zig b/src/primitive/digest/sha.zig
new file mode 100644
index 0000000..16f0aad
--- /dev/null
+++ b/src/primitive/digest/sha.zig
@@ -0,0 +1,96 @@
+const std = @import("std");
+const testing = std.testing;
+
+// ----------------------------------- ERROR DEFINITIONS -----------------------------------  //
+
+pub const MessageLengthLimitExceeded = error.MessageLengthLimitExceeded;
+
+// ----------------------------------- SHA CONSTANTS -----------------------------------  //
+
+pub const ShaAlgorithm = enum { Sha1, Sha224, Sha256, Sha384, Sha512, Sha512_224, Sha512_256 };
+
+const SHA_1_IV = [_]u32{
+    0x67452301, 0xefcdab89, 0x98badcfe, 0x10325476, 0xc3d2e1f0,
+};
+const SHA_224_IV = [_]u32{
+    0xc1059ed8, 0x367cd507, 0x3070dd17, 0xf70e5939, 0xffc00b31, 0x68581511, 0x64f98fa7, 0xbefa4fa4,
+};
+const SHA_256_IV = [_]u32{
+    0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a, 0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19,
+};
+const SHA_384_IV = [_]u64{
+    0xcbbb9d5dc1059ed8, 0x629a292a367cd507, 0x9159015a3070dd17, 0x152fecd8f70e5939,
+    0x67332667ffc00b31, 0x8eb44a8768581511, 0xdb0c2e0d64f98fa7, 0x47b5481dbefa4fa4,
+};
+const SHA_512_IV = [_]u64{
+    0x6a09e667f3bcc908, 0xbb67ae8584caa73b, 0x3c6ef372fe94f82b, 0xa54ff53a5f1d36f1,
+    0x510e527fade682d1, 0x9b05688c2b3e6c1f, 0x1f83d9abfb41bd6b, 0x5be0cd19137e2179,
+};
+const SHA_512_224_IV = [_]u64{
+    0x8C3D37C819544DA2, 0x73E1996689DCD4D6, 0x1DFAB7AE32FF9C82, 0x679DD514582F9FCF,
+    0x0F6D2B697BD44DA8, 0x77E36F7304C48942, 0x3F9D85A86A1D36C8, 0x1112E6AD91D692A1,
+};
+const SHA_512_256_IV = [_]u64{
+    0x22312194FC2BF72C, 0x9F555FA3C84C64C2, 0x2393B86B6F53B151, 0x963877195940EABD,
+    0x96283EE2A88EFFE3, 0xBE5E1E2553863992, 0x2B0199FC2C85B8AA, 0x0EB72DDC81C52CA2,
+};
+
+// ----------------------------------- SHA ALGORITHMS -----------------------------------  //
+
+const Sha1Ctx = struct {
+    const BLOCK_SIZE = 512 / 8;
+
+    message_schedule: [16]u32,
+    hash: [5]u32,
+    a: u32,
+    b: u32,
+    c: u32,
+    d: u32,
+    e: u32,
+
+    message_buffer: [BLOCK_SIZE]u8,
+    buffer_index: u6,
+};
+
+const Sha2Ctx = struct {
+    const BLOCK_SIZE = 512 / 8;
+
+    message_schedule: [16]u32,
+    hash: [8]u32,
+    a: u32,
+    b: u32,
+    c: u32,
+    d: u32,
+    e: u32,
+    f: u32,
+    g: u32,
+    h: u32,
+
+    message_buffer: [BLOCK_SIZE]u8,
+    buffer_index: u6,
+
+    t_is_224: bool,
+};
+
+const Sha3Ctx = struct {
+    const BLOCK_SIZE = 1024 / 8;
+
+    message_schedule: [16]u32,
+    hash: [8]u64,
+    a: u64,
+    b: u64,
+    c: u64,
+    d: u64,
+    e: u64,
+    f: u64,
+    g: u64,
+    h: u64,
+
+    message_buffer: [BLOCK_SIZE]u8,
+    buffer_index: u7,
+
+    // could be generalized in the future, like decribed in the standard
+    t_is_224: bool,
+    t_is_256: bool,
+    t_is_384: bool,
+};