pixelveil 1.0.1

A performant steganography and steganalysis library for hiding data in images, audio files, and videos
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142

use crate::{
    errors::SteganographyError,
    image::lossless::bpcs::{
        bit_plane::{BitPlane, PLANE_SIZE, USIZE_PLANE_SIZE},
        dynamic_prefix::{
            data_bits_from_prefixed_planes, get_prefixed_planes, num_of_prefixed_planes_for_n_bits,
            prefix_length,
        },
    },
    utils::bit_operations_utils::{USIZE_BIT_DEPTH, bits_to_usize, unsigned_int_to_bits},
};

pub(crate) const MESSAGE_LENGTH_IV_BIT_NUMBER: usize = USIZE_BIT_DEPTH;
pub(crate) const MESSAGE_REMNANT_IV_BIT_NUMBER: usize = USIZE_BIT_DEPTH;

pub(crate) fn calculate_iv_plane_number(min_alpha: f64) -> usize {
    num_of_prefixed_planes_for_n_bits(MESSAGE_LENGTH_IV_BIT_NUMBER, prefix_length(min_alpha))
        + num_of_prefixed_planes_for_n_bits(MESSAGE_REMNANT_IV_BIT_NUMBER, prefix_length(min_alpha))
}

pub(crate) fn build_message_length_iv(message_plane_length: usize) -> Vec<bool> {
    unsigned_int_to_bits(message_plane_length)
}

pub(crate) fn build_message_remnant_iv(remnant_bit_number: usize) -> Vec<bool> {
    assert!(remnant_bit_number <= (USIZE_PLANE_SIZE * USIZE_PLANE_SIZE));
    unsigned_int_to_bits(remnant_bit_number)
}

pub(crate) fn build_iv_planes(
    min_alpha: f64,
    message_plane_length: usize,
    remnant_bit_number: usize,
) -> Vec<BitPlane> {
    let mut iv_planes: Vec<BitPlane> = Vec::new();
    iv_planes.extend(get_prefixed_planes(
        build_message_length_iv(message_plane_length),
        min_alpha,
    ));

    iv_planes.extend(get_prefixed_planes(
        build_message_remnant_iv(remnant_bit_number),
        min_alpha,
    ));

    iv_planes
}

pub(crate) fn build_conjugation_map_planes(
    conjugation_map: Vec<bool>,
    min_alpha: f64,
) -> Vec<BitPlane> {
    get_prefixed_planes(conjugation_map, min_alpha)
}

pub(crate) fn extract_iv_data_from_iv_planes(
    mut planes: Vec<BitPlane>,
    min_alpha: f64,
) -> Result<(usize, usize), SteganographyError> {
    let prefix_length = prefix_length(min_alpha);
    let msg_len_iv_plane_length =
        num_of_prefixed_planes_for_n_bits(MESSAGE_LENGTH_IV_BIT_NUMBER, prefix_length);
    let msg_rem_iv_plane_length =
        num_of_prefixed_planes_for_n_bits(MESSAGE_REMNANT_IV_BIT_NUMBER, prefix_length);

    let length_iv_bits = data_bits_from_prefixed_planes(
        planes.drain(0..msg_len_iv_plane_length).collect(),
        min_alpha,
    )
    .drain(0..MESSAGE_LENGTH_IV_BIT_NUMBER) // get only the bits of iv data, without the filling
    .collect::<Vec<bool>>();

    let message_plane_length = bits_to_usize(length_iv_bits.try_into().unwrap());

    let remnant_iv_bits = data_bits_from_prefixed_planes(
        planes.drain(0..msg_rem_iv_plane_length).collect(),
        min_alpha,
    )
    .drain(0..MESSAGE_REMNANT_IV_BIT_NUMBER)
    .collect::<Vec<bool>>();

    let message_remnant_length = bits_to_usize(remnant_iv_bits.try_into().unwrap());

    if message_remnant_length > USIZE_PLANE_SIZE * USIZE_PLANE_SIZE {
        let bits_per_plane = PLANE_SIZE * PLANE_SIZE;
        return Err(SteganographyError::InvalidIVData(String::from(format!(
            "Message remnant IV can't be more than the amount of bits per plane ({message_remnant_length} > {bits_per_plane})"
        ))));
    }

    Ok((message_plane_length, message_remnant_length))
}

pub(crate) fn extract_conj_map_data_from_conj_map_planes(
    planes: Vec<BitPlane>,
    min_alpha: f64,
    message_plane_length: usize,
) -> Result<Vec<bool>, SteganographyError> {
    let conjugation_map_data = data_bits_from_prefixed_planes(planes, min_alpha)
        .drain(0..message_plane_length) // get only the bits of iv data, without the filling
        .collect::<Vec<bool>>();
    Ok(conjugation_map_data)
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::image::lossless::bpcs::dynamic_prefix::get_n_random_bools;

    #[test]
    fn test_circular_iv_generation_and_data_extraction() -> Result<(), Box<dyn std::error::Error>> {
        let (min_alpha, message_plane_length, remnant_bit_number) = (0.3, 65832usize, 4);
        let iv_planes = build_iv_planes(min_alpha, message_plane_length, remnant_bit_number);

        assert_eq!(
            extract_iv_data_from_iv_planes(iv_planes, min_alpha)?,
            (message_plane_length, remnant_bit_number)
        );

        Ok(())
    }

    #[test]
    fn test_circular_conjugation_map_generation_and_data_extraction()
    -> Result<(), Box<dyn std::error::Error>> {
        let message_plane_length = 47usize;
        let min_alpha = 0.3f64;
        let conjugation_map = get_n_random_bools(message_plane_length);
        let conjugation_map_planes =
            build_conjugation_map_planes(conjugation_map.clone(), min_alpha);
        assert_eq!(
            extract_conj_map_data_from_conj_map_planes(
                conjugation_map_planes,
                min_alpha,
                message_plane_length
            )?,
            conjugation_map
        );

        Ok(())
    }
}