diff --git a/server/util/LiteHashDRBG.ts b/server/util/LiteHashDRBG.ts
index 69cabd7..6303736 100644
--- a/server/util/LiteHashDRBG.ts
+++ b/server/util/LiteHashDRBG.ts
@@ -1,9 +1,11 @@
 import type { RNG } from "./RNG";
 
-import { sha512 } from 'js-sha512';
+import { sha512 } from './sha2';
 
 import { convertBytesLikeToUint8Array } from "./convertBytesLikeToUint8Array";
 import type { BytesLike } from "./BytesLike";
+import { unwrap } from "./unwrap";
+import { delay } from "./delay";
 
 const maxRngSupportBit = 53;
 const maxInt = 0x1f_ffff_ffff_ffff; //      NOTE: b 0, 10000110011, 11...11
@@ -84,14 +86,16 @@ export class LiteHashDRBG implements RNG {
     protected hq: DataView;
     protected hqIdxPos: number;
 
+    protected ready: Promise<void>;
+
     public constructor(protected seed: BytesLike, protected stateIdx = 0, bufferIdx = 0) {
-        if(bufferIdx < 0){
+        if (bufferIdx < 0) {
             throw new Error(`bufferIdx ${bufferIdx} < 0`);
         }
-        if(bufferIdx >= bufferByteSize){
+        if (bufferIdx >= bufferByteSize) {
             throw new Error(`bufferidx ${bufferIdx} >= ${bufferByteSize}`);
         }
-        if(stateIdx < 0){
+        if (stateIdx < 0) {
             throw new Error(`stateIdx ${stateIdx} < 0`);
         }
 
@@ -103,13 +107,13 @@ export class LiteHashDRBG implements RNG {
         this.hq = new DataView(hqBuffer);
         this.hqIdxPos = seedU8.byteLength;
 
-        this.genNextBlock();
+        this.ready = this.genNextBlock();
         this.bufferIdx = bufferIdx;
     }
 
-    protected genNextBlock(): void {
+    protected async genNextBlock(): Promise<void> {
         this.hq.setUint32(this.hqIdxPos, this.stateIdx, true);
-        const digest = sha512.arrayBuffer(this.hq.buffer);
+        const digest = await sha512(this.hq.buffer);
         this.buffer = digest;
         this.bufferIdx = 0;
         this.stateIdx += 1;
@@ -119,57 +123,86 @@ export class LiteHashDRBG implements RNG {
         return maxInt;
     }
 
-    public nextBytes(bytes: number, baseBytes?: number): Uint8Array {
+    public async nextBytes(bytes: number, baseBytes?: number): Promise<Uint8Array> {
         bytes |= 0;
         if (bytes <= 0) {
             throw new Error(`${bytes} <= 0`);
         }
 
-        if (this.bufferIdx + bytes <= bufferByteSize) {
-            if(baseBytes === undefined || bytes >= baseBytes){
-                const result = this.buffer.slice(this.bufferIdx, this.bufferIdx + bytes);
-                this.bufferIdx += bytes;
-                if (this.bufferIdx === bufferByteSize) {
-                    this.genNextBlock();
+        const ticket = this.ready;
+
+        let waiter: Promise<Uint8Array | undefined> = Promise.resolve(undefined);
+
+        let nextBlockWait: (() => void) | null = (() => { throw 'something wrong'; });
+
+        this.ready = new Promise((resolve, reject) => {
+            waiter = (async () => {
+                await ticket;
+                nextBlockWait = resolve;
+
+                if (this.bufferIdx + bytes <= bufferByteSize) {
+                    if (baseBytes === undefined || bytes >= baseBytes) {
+                        const result = this.buffer.slice(this.bufferIdx, this.bufferIdx + bytes);
+                        this.bufferIdx += bytes;
+                        if (this.bufferIdx === bufferByteSize) {
+                            nextBlockWait = null;
+                            this.genNextBlock().then(resolve, reject);
+                        }
+                        return new Uint8Array(result);
+                    }
+
+                    const resultBuffer = new ArrayBuffer(Math.max(bytes, baseBytes ?? 0));
+                    const result = new Uint8Array(resultBuffer);
+                    result.set(new Uint8Array(this.buffer, this.bufferIdx, bytes));
+                    this.bufferIdx += bytes;
+                    if (this.bufferIdx === bufferByteSize) {
+                        nextBlockWait = null;
+                        this.genNextBlock().then(resolve, reject);
+                    }
+                    return result;
                 }
-                return new Uint8Array(result);
-            }
 
-            const resultBuffer = new ArrayBuffer(Math.max(bytes, baseBytes));
-            const result = new Uint8Array(resultBuffer);
-            result.set(new Uint8Array(this.buffer, this.bufferIdx, bytes));
-            this.bufferIdx += bytes;
-            if( this.bufferIdx === bufferByteSize){
-                this.genNextBlock();
-            }
-            return result;
+                const resultBuffer = new ArrayBuffer(baseBytes ? Math.max(bytes, baseBytes) : bytes);
+                const result = new Uint8Array(resultBuffer);
+
+                result.set(new Uint8Array(this.buffer, this.bufferIdx));
+                let offset = bufferByteSize - this.bufferIdx;
+                let remain = bytes - offset;
+
+                while (remain > bufferByteSize) {
+                    await this.genNextBlock();
+                    result.set(new Uint8Array(this.buffer), offset);
+                    offset += bufferByteSize;
+                    remain -= bufferByteSize;
+                }
+
+                if (remain === 0) {
+                    nextBlockWait = null;
+                    this.genNextBlock().then(resolve, reject);
+                    return result;
+                }
+
+                await this.genNextBlock();
+                result.set(new Uint8Array(this.buffer, 0, remain), offset);
+                this.bufferIdx = remain;
+                return result;
+            })();
+
+        });
+
+        //이 코드를 통해 Promise 내부가 실행된다
+        await delay(0);
+
+        const nextBlock = await waiter;
+        if (nextBlockWait instanceof Promise) {
+            nextBlockWait();
         }
-
-        const resultBuffer = new ArrayBuffer(baseBytes ? Math.max(bytes, baseBytes) : bytes);
-        const result = new Uint8Array(resultBuffer);
-
-        result.set(new Uint8Array(this.buffer, this.bufferIdx));
-        let offset = bufferByteSize - this.bufferIdx;
-        let remain = bytes - offset;
-
-        while (remain > bufferByteSize) {
-            this.genNextBlock();
-            result.set(new Uint8Array(this.buffer), offset);
-            offset += bufferByteSize;
-            remain -= bufferByteSize;
-        }
-
-        this.genNextBlock();
-        if (remain === 0) {
-            return result;
-        }
-
-        result.set(new Uint8Array(this.buffer, 0, remain), offset);
-        this.bufferIdx = remain;
-        return result;
+        return unwrap(nextBlock);
     }
 
-    public nextBits(bits: number, baseBytes?: number): Uint8Array {
+    public async nextBits(bits: number, baseBytes?: number): Promise<Uint8Array> {
+        await this.ready;
+
         bits |= 0;
         const bytes = (bits + 7) >> 3;
         const headBits = bits & 0x7;
@@ -183,15 +216,15 @@ export class LiteHashDRBG implements RNG {
         return result;
     }
 
-    protected _nextInt(bits: number): bigint{
-        const buffer = this.nextBits(bits, 8);
+    protected async _nextInt(bits: number): Promise<bigint> {
+        const buffer = await this.nextBits(bits, 8);
         const dataView = new DataView(buffer.buffer);
         return dataView.getBigUint64(0, true);
     }
 
-    public nextInt(max?: number): number {
+    public async nextInt(max?: number): Promise<number> {
         if (max === undefined || max === maxInt) {
-            return Number(this._nextInt(maxRngSupportBit));
+            return Number(await this._nextInt(maxRngSupportBit));
         }
         if (max > maxInt) {
             throw new Error('Over max int');
@@ -207,26 +240,26 @@ export class LiteHashDRBG implements RNG {
         const bits = intBitMapMask.get(mask) as number;
 
         let n = Number(this._nextInt(bits));
-        while (n > max){
+        while (n > max) {
             n = Number(this._nextInt(bits));
         }
         return n;
     }
 
-    public nextFloat1(): number {
+    public async nextFloat1(): Promise<number> {
         // eslint-disable-next-line no-constant-condition
-        while(true){
-            const nInt = this._nextInt(maxRngSupportBit + 1);
-            if(nInt < maxIntMore1){
+        while (true) {
+            const nInt = await this._nextInt(maxRngSupportBit + 1);
+            if (nInt < maxIntMore1) {
                 return Number(nInt) / maxIntMore1f;
             }
-            if(nInt === maxIntMore1){
+            if (nInt === maxIntMore1) {
                 return 1;
             }
         }
     }
 
-    public static build(seed: BytesLike, stateIdx = 0): LiteHashDRBG{
+    public static build(seed: BytesLike, stateIdx = 0): LiteHashDRBG {
         return new LiteHashDRBG(seed, stateIdx);
     }
 }
\ No newline at end of file