@Override
    public int read(byte[] buffer, int offset, int length) throws IOException {
        abortIfNeeded();
        int numBytesRead;
        // If no more bytes are available, do not read any bytes into the buffer
        if(this.virtualAvailable <= 0) {
            numBytesRead = -1;
        } else {
            // If the desired read length is greater than the number of available bytes,
            // shorten the read length to the number of available bytes.
            if(length > this.virtualAvailable) {
                // If the number of available bytes is greater than the maximum value of a 32 bit int, then
                // read as many bytes as an int can.
                length = (this.virtualAvailable < Integer.MAX_VALUE) ? (int)this.virtualAvailable : Integer.MAX_VALUE;
            }
            // Read bytes into the buffer.
            numBytesRead = this.decryptedContents.read(buffer, offset, length);
        }
        // If we were able to read bytes, decrement the number of bytes available to be read.
        if(numBytesRead != -1) {
            this.virtualAvailable -= numBytesRead;
        } else {
            // If we've reached the end of the stream, close it
            this.virtualAvailable = 0;
            close();
        }
        return numBytesRead;
    }
Skip to the start location of the range of bytes desired by the user.
aws-java-sdk-s3/src/main/java/com/amazonaws/services/s3/internal/crypto/AdjustedRangeInputStream.java