I have encrypted an image using pixel encryption method. I just used a bmp image for that. What I did is, I retrieved each pixel value from the image and obtained the value of red, green and blue value individually and XOR-ed it with a pseudo random value. For pseudo random number generation I used the SecureRandom with the SHA1PRNG algorithm. The seed value set for generating the random numbers is obtained from the password that we give.
Detailed description of the code and the ouput is available in zone4java
My question is how long will it take to any utility, if available, to decrypt the image without knowing the password? Is this kind of encryption methods secure?
Note: If my question is being downvoted, please comment the reason.