api.py

# Importing the required libraries
import cv2
from fastapi import FastAPI, File, UploadFile, HTTPException, Response, Form
from fastapi.middleware.cors import CORSMiddleware
import numpy as np
import json
import base64

app = FastAPI()

# Allowing CORS (Cross-Origin Resource Sharing)
app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],  
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

# @app.on_event("startup")
# def save_openapi_json():
#     openapi_data = app.openapi()
#     with open("openapi.json", "w") as file:
#         json.dump(openapi_data, file)

# Converting types to binary  
def msg_to_bin(msg):  
    if type(msg) == str:  
        return ''.join([format(ord(i), "08b") for i in msg])  
    elif type(msg) == bytes or type(msg) == np.ndarray:  
        return [format(i, "08b") for i in msg]  
    elif type(msg) == int or type(msg) == np.uint8:  
        return format(msg, "08b")  
    else:  
        raise TypeError("Input type not supported")  

# defining function to hide the secret message into the image  
def hide_data(img, secret_msg):  
    # calculating the maximum bytes for encoding  
    nBytes = img.shape[0] * img.shape[1] * 3 // 8  
    print("Maximum Bytes for encoding:", nBytes)  
    # checking whether the number of bytes for encoding is less  
    # than the maximum bytes in the image  
    if len(secret_msg) > nBytes:  
        raise ValueError("Error encountered insufficient bytes, need bigger image or less data!!")  
    secret_msg += '#####'       # we can utilize any string as the delimiter  
    dataIndex = 0  
    # converting the input data to binary format using the msg_to_bin() function  
    bin_secret_msg = msg_to_bin(secret_msg)  
  
    # finding the length of data that requires to be hidden  
    dataLen = len(bin_secret_msg)  
    for values in img:  
        for pixels in values:  
            # converting RGB values to binary format  
            r, g, b = msg_to_bin(pixels)  
            # modifying the LSB only if there is data remaining to store  
            if dataIndex < dataLen:  
                # hiding the data into LSB of Red pixel  
                pixels[0] = int(r[:-1] + bin_secret_msg[dataIndex], 2)  
                dataIndex += 1  
            if dataIndex < dataLen:  
                # hiding the data into LSB of Green pixel  
                pixels[1] = int(g[:-1] + bin_secret_msg[dataIndex], 2)  
                dataIndex += 1  
            if dataIndex < dataLen:  
                # hiding the data into LSB of Blue pixel  
                pixels[2] = int(b[:-1] + bin_secret_msg[dataIndex], 2)  
                dataIndex += 1  
            # if data is encoded, break out the loop  
            if dataIndex >= dataLen:  
                break  
      
    return img  
  
def show_data(img):  
    bin_data = ""  
    for values in img:  
        for pixels in values:  
            # converting the Red, Green, Blue values into binary format  
            r, g, b = msg_to_bin(pixels)  
            # data extraction from the LSB of Red pixel  
            bin_data += r[-1]  
            # data extraction from the LSB of Green pixel  
            bin_data += g[-1]  
            # data extraction from the LSB of Blue pixel  
            bin_data += b[-1]  
    # split by 8-Bits  
    allBytes = [bin_data[i: i + 8] for i in range(0, len(bin_data), 8)]  
    # converting from bits to characters  
    decodedData = ""  
    for bytes in allBytes:  
        decodedData += chr(int(bytes, 2))  
        # checking if we have reached the delimiter which is "#####"  
        if decodedData[-5:] == "#####":  
            break  
    # print(decodedData)  
    # removing the delimiter to display the actual hidden message  
    return decodedData[:-5]  

@app.get("/")
async def root():
    return {"message": "Server is alive"}

@app.post("/hide_message")
async def hide_message(image: UploadFile = File(...), secret_msg: str = Form(...)):
    try:
        # Read image using OpenCV
        content = await image.read()
        nparr = np.frombuffer(content, np.uint8)
        img = cv2.imdecode(nparr, cv2.IMREAD_UNCHANGED)

        # Hide the secret message in the image
        encoded_image = hide_data(img, secret_msg)

        # Convert the image to bytes
        _, encoded_image_data = cv2.imencode(".png", encoded_image)
        encoded_image_bytes = encoded_image_data.tobytes()

        # Encode the image bytes to base64
        encoded_image_base64 = base64.b64encode(encoded_image_bytes).decode()

        # Return the base64 encoded image
        return {"base64_image": encoded_image_base64}
    except Exception as e:
        raise HTTPException(status_code=500, detail=str(e))


# API endpoint to retrieve the secret message from an image
@app.post("/retrieve_message")
async def retrieve_message(image: UploadFile = File(...)):
    try:
        # Read image using OpenCV
        content = await image.read()
        nparr = np.frombuffer(content, np.uint8)
        img = cv2.imdecode(nparr, cv2.IMREAD_UNCHANGED)

        # Retrieve the hidden message from the image
        decoded_message = show_data(img)

        return {"decoded_message": decoded_message}
    except Exception as e:
        raise HTTPException(status_code=500, detail=str(e))