Extended crypto API by variants that write the result into a destination buffer, instead of returning it

core/crypto/sm3/sm3.odin

@@ -15,16 +15,22 @@ import "core:io"
 
 import "../util"
 
+/*
+    High level API
+*/
+
+DIGEST_SIZE :: 32
+
 // hash_string will hash the given input and return the
 // computed hash
-hash_string :: proc(data: string) -> [32]byte {
+hash_string :: proc(data: string) -> [DIGEST_SIZE]byte {
     return hash_bytes(transmute([]byte)(data))
 }
 
 // hash_bytes will hash the given input and return the
 // computed hash
-hash_bytes :: proc(data: []byte) -> [32]byte {
-    hash: [32]byte
+hash_bytes :: proc(data: []byte) -> [DIGEST_SIZE]byte {
+    hash: [DIGEST_SIZE]byte
     ctx: Sm3_Context
     init(&ctx)
     update(&ctx, data)
@@ -32,10 +38,28 @@ hash_bytes :: proc(data: []byte) -> [32]byte {
     return hash
 }
 
+// hash_string_to_buffer will hash the given input and assign the
+// computed hash to the second parameter.
+// It requires that the destination buffer is at least as big as the digest size
+hash_string_to_buffer :: proc(data: string, hash: []byte) {
+    hash_bytes_to_buffer(transmute([]byte)(data), hash);
+}
+
+// hash_bytes_to_buffer will hash the given input and write the
+// computed hash into the second parameter.
+// It requires that the destination buffer is at least as big as the digest size
+hash_bytes_to_buffer :: proc(data, hash: []byte) {
+    assert(len(hash) >= DIGEST_SIZE, "Size of destination buffer is smaller than the digest size")
+    ctx: Sm3_Context
+    init(&ctx)
+    update(&ctx, data)
+    final(&ctx, hash)
+}
+
 // hash_stream will read the stream in chunks and compute a
 // hash from its contents
-hash_stream :: proc(s: io.Stream) -> ([32]byte, bool) {
-    hash: [32]byte
+hash_stream :: proc(s: io.Stream) -> ([DIGEST_SIZE]byte, bool) {
+    hash: [DIGEST_SIZE]byte
     ctx: Sm3_Context
     init(&ctx)
     buf := make([]byte, 512)
@@ -53,7 +77,7 @@ hash_stream :: proc(s: io.Stream) -> ([32]byte, bool) {
 
 // hash_file will read the file provided by the given handle
 // and compute a hash
-hash_file :: proc(hd: os.Handle, load_at_once := false) -> ([32]byte, bool) {
+hash_file :: proc(hd: os.Handle, load_at_once := false) -> ([DIGEST_SIZE]byte, bool) {
     if !load_at_once {
         return hash_stream(os.stream_from_handle(hd))
     } else {
@@ -61,7 +85,7 @@ hash_file :: proc(hd: os.Handle, load_at_once := false) -> ([32]byte, bool) {
             return hash_bytes(buf[:]), ok
         }
     }
-    return [32]byte{}, false
+    return [DIGEST_SIZE]byte{}, false
 }
 
 hash :: proc {
@@ -69,6 +93,8 @@ hash :: proc {
     hash_file,
     hash_bytes,
     hash_string,
+    hash_bytes_to_buffer,
+    hash_string_to_buffer,
 }
 
 /*
@@ -146,9 +172,6 @@ Sm3_Context :: struct {
     length:    u64,
 }
 
-BLOCK_SIZE_IN_BYTES :: 64
-BLOCK_SIZE_IN_32    :: 16
-
 IV := [8]u32 {
     0x7380166f, 0x4914b2b9, 0x172442d7, 0xda8a0600,
     0xa96f30bc, 0x163138aa, 0xe38dee4d, 0xb0fb0e4e,