ssh-key: add "randomart" fingerprint visualizations#77

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Merged
tarcieri merged 1 commit into from
Mar 7, 2023
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ssh-key: add "randomart" fingerprint visualizations #77

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1 change: 1 addition & 0 deletions ssh-key/README.md
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -44,6 +44,7 @@ respective SSH key algorithm.
- [x] Private key generation support: DSA, Ed25519, ECDSA (P-256+P-384), and RSA
- [x] FIDO/U2F key support (`sk-*`) as specified in [PROTOCOL.u2f]
- [x] Fingerprint support
- [x] "randomart" fingerprint visualizations
- [x] `no_std` support including support for "heapless" (no-`alloc`) targets
- [x] Parsing `authorized_keys` files
- [x] Parsing `known_hosts` files
Expand Down
60 changes: 50 additions & 10 deletions ssh-key/src/fingerprint.rs
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Open in desktop
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,8 @@
//! SSH public key fingerprints.

mod randomart;

use self::randomart::Randomart;
use crate::{public, Error, HashAlg, Result};
use core::{
fmt::{self, Display},
Expand All@@ -14,11 +17,11 @@ use sha2::{Digest, Sha256, Sha512};
/// Fingerprint encoding error message.
const FINGERPRINT_ERR_MSG: &str = "fingerprint encoding error";

#[cfg(feature = "alloc")]
use alloc::string::{String, ToString};

#[cfg(all(feature = "alloc", feature = "serde"))]
use {
alloc::string::{String, ToString},
serde::{de, ser, Deserialize, Serialize},
};
use serde::{de, ser, Deserialize, Serialize};

/// SSH public key fingerprints.
///
Expand DownExpand Up@@ -79,6 +82,22 @@ impl Fingerprint {
}
}

/// Get the name of the hash algorithm (upper case e.g. "SHA256").
pub fn prefix(self) -> &'static str {
match self.algorithm() {
HashAlg::Sha256 => "SHA256",
HashAlg::Sha512 => "SHA512",
}
}

/// Get the bracketed hash algorithm footer for use in "randomart".
fn footer(self) -> &'static str {
match self.algorithm() {
HashAlg::Sha256 => "[SHA256]",
HashAlg::Sha512 => "[SHA512]",
}
}

/// Get the raw digest output for the fingerprint as bytes.
pub fn as_bytes(&self) -> &[u8] {
match self {
Expand DownExpand Up@@ -112,6 +131,31 @@ impl Fingerprint {
pub fn is_sha512(self) -> bool {
matches!(self, Self::Sha512(_))
}

/// Format "randomart" for this fingerprint using the provided formatter.
pub fn fmt_randomart(self, header: &str, f: &mut fmt::Formatter<'_>) -> fmt::Result {
Randomart::new(header, self).fmt(f)
}

/// Render "randomart" hash visualization for this fingerprint as a string.
///
/// ```text
/// +--[ED25519 256]--+
/// |o+oO==+ o.. |
/// |.o++Eo+o.. |
/// |. +.oO.o . . |
/// | . o..B.. . . |
/// | ...+ .S. o |
/// | .o. . . . . |
/// | o.. o |
/// | B . |
/// | .o* |
/// +----[SHA256]-----+
/// ```
#[cfg(feature = "alloc")]
pub fn to_randomart(self, header: &str) -> String {
Randomart::new(header, self).to_string()
}
}

impl AsRef<[u8]> for Fingerprint {
Expand All@@ -122,16 +166,12 @@ impl AsRef<[u8]> for Fingerprint {

impl Display for Fingerprint {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
// Fingerprints use a special upper-case hash algorithm encoding.
let algorithm = match self.algorithm() {
HashAlg::Sha256 => "SHA256",
HashAlg::Sha512 => "SHA512",
};
let prefix = self.prefix();

// Buffer size is the largest digest size of of any supported hash function
let mut buf = [0u8; Self::SHA512_BASE64_SIZE];
let base64 = Base64Unpadded::encode(self.as_bytes(), &mut buf).map_err(|_| fmt::Error)?;
write!(f, "{algorithm}:{base64}")
write!(f, "{prefix}:{base64}")
}
}

Expand Down
112 changes: 112 additions & 0 deletions ssh-key/src/fingerprint/randomart.rs
View file
Open in desktop
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,112 @@
//! Support for the "drunken bishop" fingerprint algorithm, a.k.a. "randomart".
//!
//! The algorithm is described in the paper:
//!
//! "The drunken bishop: An analysis of the OpenSSH fingerprint visualization algorithm"
//!
//! <http://www.dirk-loss.de/sshvis/drunken_bishop.pdf>

use super::Fingerprint;
use core::fmt;

const WIDTH: usize = 17;
const HEIGHT: usize = 9;
const VALUES: &[u8; 17] = b" .o+=*BOX@%&#/^SE";
const NVALUES: usize = VALUES.len() - 1;

type Field = [[u8; WIDTH]; HEIGHT];

/// "randomart" renderer.
pub(super) struct Randomart<'a> {
header: &'a str,
field: Field,
footer: &'static str,
}

impl<'a> Randomart<'a> {
/// Create new "randomart" from the given fingerprint.
#[allow(clippy::integer_arithmetic)]
pub(super) fn new(header: &'a str, fingerprint: Fingerprint) -> Self {
let mut field = Field::default();
let mut x = WIDTH / 2;
let mut y = HEIGHT / 2;

for mut byte in fingerprint.as_bytes().iter().copied() {
for _ in 0..4 {
if byte & 0x1 == 0 {
x = x.saturating_sub(1);
} else {
x = x.saturating_add(1);
}

if byte & 0x2 == 0 {
y = y.saturating_sub(1);
} else {
y = y.saturating_add(1);
}

x = x.min(WIDTH.saturating_sub(1));
y = y.min(HEIGHT.saturating_sub(1));

if field[y][x] < NVALUES as u8 - 2 {
field[y][x] += 1;
}

byte >>= 2;
}
}

field[HEIGHT / 2][WIDTH / 2] = NVALUES as u8 - 1;
field[y][x] = NVALUES as u8;

Self {
header,
field,
footer: fingerprint.footer(),
}
}
}

impl fmt::Display for Randomart<'_> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
writeln!(f, "+{:-^width$}+", self.header, width = WIDTH)?;

for row in self.field {
write!(f, "|")?;

for c in row {
write!(f, "{}", VALUES[c as usize] as char)?;
}

writeln!(f, "|")?;
}

write!(f, "+{:-^width$}+", self.footer, width = WIDTH)
}
}

#[cfg(all(test, feature = "alloc"))]
mod tests {
use super::Fingerprint;

const EXAMPLE_FINGERPRINT: &str = "SHA256:UCUiLr7Pjs9wFFJMDByLgc3NrtdU344OgUM45wZPcIQ";
const EXAMPLE_RANDOMART: &str = "\
+--[ED25519 256]--+
|o+oO==+ o.. |
|.o++Eo+o.. |
|. +.oO.o . . |
| . o..B.. . . |
| ...+ .S. o |
| .o. . . . . |
| o.. o |
| B . |
| .o* |
+----[SHA256]-----+";

#[test]
fn generation() {
let fingerprint = EXAMPLE_FINGERPRINT.parse::<Fingerprint>().unwrap();
let randomart = fingerprint.to_randomart("[ED25519 256]");
assert_eq!(EXAMPLE_RANDOMART, randomart);
}
}
, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Add copy buttons to all 
 blocks\n(function() {\n function addCopyButtons() {\n document.querySelectorAll('pre code').forEach(function(codeBlock) {\n if (codeBlock.parentElement.hasAttribute('data-copy-added')) return;\n codeBlock.parentElement.setAttribute('data-copy-added', 'true');\n \n var btn = document.createElement('button');\n btn.textContent = 'Copy';\n btn.style.cssText = 'position:absolute;top:4px;right:4px;padding:2px 8px;font-size:11px;background:#4ecdc4;border:none;border-radius:4px;color:#1a1a2e;cursor:pointer;opacity:0.7;transition:opacity 0.2s;';\n btn.onmouseover = function() { this.style.opacity = '1'; };\n btn.onmouseout = function() { this.style.opacity = '0.7'; };\n btn.onclick = function() {\n navigator.clipboard.writeText(codeBlock.textContent).then(function() {\n btn.textContent = 'Copied!';\n setTimeout(function() { btn.textContent = 'Copy'; }, 1500);\n });\n };\n codeBlock.parentElement.style.position = 'relative';\n codeBlock.parentElement.appendChild(btn);\n });\n }\n \n addCopyButtons();\n \n // Re-run on dynamic content\n var observer = new MutationObserver(addCopyButtons);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Add Copy Buttons to Code Blocks");
}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '

Skip to content
ssh-key: add "randomart" fingerprint visualizations#77

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to your account

 Merged

tarcieri
merged 1 commit into

from

Mar 7, 2023
 Merged


ssh-key: add "randomart" fingerprint visualizations
#77
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1 change: 1 addition & 0 deletions
ssh-key/README.md

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -44,6 +44,7 @@ respective SSH key algorithm.
- [x] Private key generation support: DSA, Ed25519, ECDSA (P-256+P-384), and RSA
- [x] FIDO/U2F key support (`sk-*`) as specified in [PROTOCOL.u2f]
- [x] Fingerprint support
 - [x] "randomart" fingerprint visualizations
- [x] `no_std` support including support for "heapless" (no-`alloc`) targets
- [x] Parsing `authorized_keys` files
- [x] Parsing `known_hosts` files
Expand Down

60 changes: 50 additions & 10 deletions
ssh-key/src/fingerprint.rs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -1,5 +1,8 @@
//! SSH public key fingerprints.

mod randomart;

use self::randomart::Randomart;
use crate::{public, Error, HashAlg, Result};
use core::{
 fmt::{self, Display},
Expand All@@ -14,11 +17,11 @@ use sha2::{Digest, Sha256, Sha512};
/// Fingerprint encoding error message.
const FINGERPRINT_ERR_MSG: &str = "fingerprint encoding error";

#[cfg(feature = "alloc")]
use alloc::string::{String, ToString};

#[cfg(all(feature = "alloc", feature = "serde"))]
use {
 alloc::string::{String, ToString},
 serde::{de, ser, Deserialize, Serialize},
};
use serde::{de, ser, Deserialize, Serialize};

/// SSH public key fingerprints.
///
Expand DownExpand Up@@ -79,6 +82,22 @@ impl Fingerprint {
 }
 }

 /// Get the name of the hash algorithm (upper case e.g. "SHA256").
 pub fn prefix(self) -> &'static str {
 match self.algorithm() {
 HashAlg::Sha256 => "SHA256",
 HashAlg::Sha512 => "SHA512",
 }
 }

 /// Get the bracketed hash algorithm footer for use in "randomart".
 fn footer(self) -> &'static str {
 match self.algorithm() {
 HashAlg::Sha256 => "[SHA256]",
 HashAlg::Sha512 => "[SHA512]",
 }
 }

 /// Get the raw digest output for the fingerprint as bytes.
 pub fn as_bytes(&self) -> &[u8] {
 match self {
Expand DownExpand Up@@ -112,6 +131,31 @@ impl Fingerprint {
 pub fn is_sha512(self) -> bool {
 matches!(self, Self::Sha512(_))
 }

 /// Format "randomart" for this fingerprint using the provided formatter.
 pub fn fmt_randomart(self, header: &str, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 Randomart::new(header, self).fmt(f)
 }

 /// Render "randomart" hash visualization for this fingerprint as a string.
 ///
 /// ```text
 /// +--[ED25519 256]--+
 /// |o+oO==+ o.. |
 /// |.o++Eo+o.. |
 /// |. +.oO.o . . |
 /// | . o..B.. . . |
 /// | ...+ .S. o |
 /// | .o. . . . . |
 /// | o.. o |
 /// | B . |
 /// | .o* |
 /// +----[SHA256]-----+
 /// ```
 #[cfg(feature = "alloc")]
 pub fn to_randomart(self, header: &str) -> String {
 Randomart::new(header, self).to_string()
 }
}

impl AsRef<[u8]> for Fingerprint {
Expand All@@ -122,16 +166,12 @@ impl AsRef<[u8]> for Fingerprint {

impl Display for Fingerprint {
 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 // Fingerprints use a special upper-case hash algorithm encoding.
 let algorithm = match self.algorithm() {
 HashAlg::Sha256 => "SHA256",
 HashAlg::Sha512 => "SHA512",
 };
 let prefix = self.prefix();

 // Buffer size is the largest digest size of of any supported hash function
 let mut buf = [0u8; Self::SHA512_BASE64_SIZE];
 let base64 = Base64Unpadded::encode(self.as_bytes(), &mut buf).map_err(|_| fmt::Error)?;
 write!(f, "{algorithm}:{base64}")
 write!(f, "{prefix}:{base64}")
 }
}

Expand Down

112 changes: 112 additions & 0 deletions
ssh-key/src/fingerprint/randomart.rs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,112 @@
//! Support for the "drunken bishop" fingerprint algorithm, a.k.a. "randomart".
//!
//! The algorithm is described in the paper:
//!
//! "The drunken bishop: An analysis of the OpenSSH fingerprint visualization algorithm"
//!
//! <http://www.dirk-loss.de/sshvis/drunken_bishop.pdf>

use super::Fingerprint;
use core::fmt;

const WIDTH: usize = 17;
const HEIGHT: usize = 9;
const VALUES: &[u8; 17] = b" .o+=*BOX@%&#/^SE";
const NVALUES: usize = VALUES.len() - 1;

type Field = [[u8; WIDTH]; HEIGHT];

/// "randomart" renderer.
pub(super) struct Randomart<'a> {
 header: &'a str,
 field: Field,
 footer: &'static str,
}

impl<'a> Randomart<'a> {
 /// Create new "randomart" from the given fingerprint.
 #[allow(clippy::integer_arithmetic)]
 pub(super) fn new(header: &'a str, fingerprint: Fingerprint) -> Self {
 let mut field = Field::default();
 let mut x = WIDTH / 2;
 let mut y = HEIGHT / 2;

 for mut byte in fingerprint.as_bytes().iter().copied() {
 for _ in 0..4 {
 if byte & 0x1 == 0 {
 x = x.saturating_sub(1);
 } else {
 x = x.saturating_add(1);
 }

 if byte & 0x2 == 0 {
 y = y.saturating_sub(1);
 } else {
 y = y.saturating_add(1);
 }

 x = x.min(WIDTH.saturating_sub(1));
 y = y.min(HEIGHT.saturating_sub(1));

 if field[y][x] < NVALUES as u8 - 2 {
 field[y][x] += 1;
 }

 byte >>= 2;
 }
 }

 field[HEIGHT / 2][WIDTH / 2] = NVALUES as u8 - 1;
 field[y][x] = NVALUES as u8;

 Self {
 header,
 field,
 footer: fingerprint.footer(),
 }
 }
}

impl fmt::Display for Randomart<'_> {
 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 writeln!(f, "+{:-^width$}+", self.header, width = WIDTH)?;

 for row in self.field {
 write!(f, "|")?;

 for c in row {
 write!(f, "{}", VALUES[c as usize] as char)?;
 }

 writeln!(f, "|")?;
 }

 write!(f, "+{:-^width$}+", self.footer, width = WIDTH)
 }
}

#[cfg(all(test, feature = "alloc"))]
mod tests {
 use super::Fingerprint;

 const EXAMPLE_FINGERPRINT: &str = "SHA256:UCUiLr7Pjs9wFFJMDByLgc3NrtdU344OgUM45wZPcIQ";
 const EXAMPLE_RANDOMART: &str = "\
+--[ED25519 256]--+
|o+oO==+ o.. |
|.o++Eo+o.. |
|. +.oO.o . . |
| . o..B.. . . |
| ...+ .S. o |
| .o. . . . . |
| o.. o |
| B . |
| .o* |
+----[SHA256]-----+";

 #[test]
 fn generation() {
 let fingerprint = EXAMPLE_FINGERPRINT.parse::<Fingerprint>().unwrap();
 let randomart = fingerprint.to_randomart("[ED25519 256]");
 assert_eq!(EXAMPLE_RANDOMART, randomart);
 }
}

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Force GitHub README to respect dark mode\n(function() {\n var style = document.createElement('style');\n style.textContent = '\n .markdown-body {\n color-scheme: dark light;\n }\n .markdown-body pre { background: #161b22 !important; }\n .markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }\n .markdown-body table th, .markdown-body table td { border-color: #30363d !important; }\n .markdown-body img { background: #0d1117; }\n .markdown-body blockquote { border-left-color: #8b949e; }\n .markdown-body hr { border-color: #30363d; }\n ';\n document.head.appendChild(style);\n})();", "GitHub Dark Mode README Fix");
}
} catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
ssh-key: add "randomart" fingerprint visualizations#77

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Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

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By clicking “Sign up for GitHub”, you agree to our terms of service and
privacy statement. We’ll occasionally send you account related emails.

Already on GitHub?
Sign in
to your account

 Merged

tarcieri
merged 1 commit into

from

Mar 7, 2023
 Merged


ssh-key: add "randomart" fingerprint visualizations
#77
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1 change: 1 addition & 0 deletions
ssh-key/README.md

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -44,6 +44,7 @@ respective SSH key algorithm.
- [x] Private key generation support: DSA, Ed25519, ECDSA (P-256+P-384), and RSA
- [x] FIDO/U2F key support (`sk-*`) as specified in [PROTOCOL.u2f]
- [x] Fingerprint support
 - [x] "randomart" fingerprint visualizations
- [x] `no_std` support including support for "heapless" (no-`alloc`) targets
- [x] Parsing `authorized_keys` files
- [x] Parsing `known_hosts` files
Expand Down

60 changes: 50 additions & 10 deletions
ssh-key/src/fingerprint.rs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -1,5 +1,8 @@
//! SSH public key fingerprints.

mod randomart;

use self::randomart::Randomart;
use crate::{public, Error, HashAlg, Result};
use core::{
 fmt::{self, Display},
Expand All@@ -14,11 +17,11 @@ use sha2::{Digest, Sha256, Sha512};
/// Fingerprint encoding error message.
const FINGERPRINT_ERR_MSG: &str = "fingerprint encoding error";

#[cfg(feature = "alloc")]
use alloc::string::{String, ToString};

#[cfg(all(feature = "alloc", feature = "serde"))]
use {
 alloc::string::{String, ToString},
 serde::{de, ser, Deserialize, Serialize},
};
use serde::{de, ser, Deserialize, Serialize};

/// SSH public key fingerprints.
///
Expand DownExpand Up@@ -79,6 +82,22 @@ impl Fingerprint {
 }
 }

 /// Get the name of the hash algorithm (upper case e.g. "SHA256").
 pub fn prefix(self) -> &'static str {
 match self.algorithm() {
 HashAlg::Sha256 => "SHA256",
 HashAlg::Sha512 => "SHA512",
 }
 }

 /// Get the bracketed hash algorithm footer for use in "randomart".
 fn footer(self) -> &'static str {
 match self.algorithm() {
 HashAlg::Sha256 => "[SHA256]",
 HashAlg::Sha512 => "[SHA512]",
 }
 }

 /// Get the raw digest output for the fingerprint as bytes.
 pub fn as_bytes(&self) -> &[u8] {
 match self {
Expand DownExpand Up@@ -112,6 +131,31 @@ impl Fingerprint {
 pub fn is_sha512(self) -> bool {
 matches!(self, Self::Sha512(_))
 }

 /// Format "randomart" for this fingerprint using the provided formatter.
 pub fn fmt_randomart(self, header: &str, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 Randomart::new(header, self).fmt(f)
 }

 /// Render "randomart" hash visualization for this fingerprint as a string.
 ///
 /// ```text
 /// +--[ED25519 256]--+
 /// |o+oO==+ o.. |
 /// |.o++Eo+o.. |
 /// |. +.oO.o . . |
 /// | . o..B.. . . |
 /// | ...+ .S. o |
 /// | .o. . . . . |
 /// | o.. o |
 /// | B . |
 /// | .o* |
 /// +----[SHA256]-----+
 /// ```
 #[cfg(feature = "alloc")]
 pub fn to_randomart(self, header: &str) -> String {
 Randomart::new(header, self).to_string()
 }
}

impl AsRef<[u8]> for Fingerprint {
Expand All@@ -122,16 +166,12 @@ impl AsRef<[u8]> for Fingerprint {

impl Display for Fingerprint {
 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 // Fingerprints use a special upper-case hash algorithm encoding.
 let algorithm = match self.algorithm() {
 HashAlg::Sha256 => "SHA256",
 HashAlg::Sha512 => "SHA512",
 };
 let prefix = self.prefix();

 // Buffer size is the largest digest size of of any supported hash function
 let mut buf = [0u8; Self::SHA512_BASE64_SIZE];
 let base64 = Base64Unpadded::encode(self.as_bytes(), &mut buf).map_err(|_| fmt::Error)?;
 write!(f, "{algorithm}:{base64}")
 write!(f, "{prefix}:{base64}")
 }
}

Expand Down

112 changes: 112 additions & 0 deletions
ssh-key/src/fingerprint/randomart.rs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,112 @@
//! Support for the "drunken bishop" fingerprint algorithm, a.k.a. "randomart".
//!
//! The algorithm is described in the paper:
//!
//! "The drunken bishop: An analysis of the OpenSSH fingerprint visualization algorithm"
//!
//! <http://www.dirk-loss.de/sshvis/drunken_bishop.pdf>

use super::Fingerprint;
use core::fmt;

const WIDTH: usize = 17;
const HEIGHT: usize = 9;
const VALUES: &[u8; 17] = b" .o+=*BOX@%&#/^SE";
const NVALUES: usize = VALUES.len() - 1;

type Field = [[u8; WIDTH]; HEIGHT];

/// "randomart" renderer.
pub(super) struct Randomart<'a> {
 header: &'a str,
 field: Field,
 footer: &'static str,
}

impl<'a> Randomart<'a> {
 /// Create new "randomart" from the given fingerprint.
 #[allow(clippy::integer_arithmetic)]
 pub(super) fn new(header: &'a str, fingerprint: Fingerprint) -> Self {
 let mut field = Field::default();
 let mut x = WIDTH / 2;
 let mut y = HEIGHT / 2;

 for mut byte in fingerprint.as_bytes().iter().copied() {
 for _ in 0..4 {
 if byte & 0x1 == 0 {
 x = x.saturating_sub(1);
 } else {
 x = x.saturating_add(1);
 }

 if byte & 0x2 == 0 {
 y = y.saturating_sub(1);
 } else {
 y = y.saturating_add(1);
 }

 x = x.min(WIDTH.saturating_sub(1));
 y = y.min(HEIGHT.saturating_sub(1));

 if field[y][x] < NVALUES as u8 - 2 {
 field[y][x] += 1;
 }

 byte >>= 2;
 }
 }

 field[HEIGHT / 2][WIDTH / 2] = NVALUES as u8 - 1;
 field[y][x] = NVALUES as u8;

 Self {
 header,
 field,
 footer: fingerprint.footer(),
 }
 }
}

impl fmt::Display for Randomart<'_> {
 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 writeln!(f, "+{:-^width$}+", self.header, width = WIDTH)?;

 for row in self.field {
 write!(f, "|")?;

 for c in row {
 write!(f, "{}", VALUES[c as usize] as char)?;
 }

 writeln!(f, "|")?;
 }

 write!(f, "+{:-^width$}+", self.footer, width = WIDTH)
 }
}

#[cfg(all(test, feature = "alloc"))]
mod tests {
 use super::Fingerprint;

 const EXAMPLE_FINGERPRINT: &str = "SHA256:UCUiLr7Pjs9wFFJMDByLgc3NrtdU344OgUM45wZPcIQ";
 const EXAMPLE_RANDOMART: &str = "\
+--[ED25519 256]--+
|o+oO==+ o.. |
|.o++Eo+o.. |
|. +.oO.o . . |
| . o..B.. . . |
| ...+ .S. o |
| .o. . . . . |
| o.. o |
| B . |
| .o* |
+----[SHA256]-----+";

 #[test]
 fn generation() {
 let fingerprint = EXAMPLE_FINGERPRINT.parse::<Fingerprint>().unwrap();
 let randomart = fingerprint.to_randomart("[ED25519 256]");
 assert_eq!(EXAMPLE_RANDOMART, randomart);
 }
}

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Highlight search terms from Google/DuckDuckGo/Bing referrer\n(function() {\n var ref = document.referrer;\n var terms = [];\n \n if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {\n var url = new URL(ref);\n var q = url.searchParams.get('q') || url.searchParams.get('p');\n if (q) {\n terms = q.split(/\\s+/).filter(function(t) { return t.length > 2; });\n }\n }\n \n if (terms.length === 0) return;\n \n var style = document.createElement('style');\n style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';\n document.head.appendChild(style);\n \n function highlight(node) {\n if (node.nodeType === 3) { // text node\n var text = node.textContent;\n var found = false;\n terms.forEach(function(term) {\n var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\\]\\\\]/g, '\\\\') + ')', 'gi');\n if (regex.test(text)) {\n found = true;\n var frag = document.createDocumentFragment();\n var parts = text.split(regex);\n parts.forEach(function(part, i) {\n if (i % 2 === 0) {\n frag.appendChild(document.createTextNode(part));\n } else {\n var span = document.createElement('span');\n span.className = 'userscript-highlight';\n span.textContent = part;\n frag.appendChild(span);\n }\n });\n node.parentNode.replaceChild(frag, node);\n }\n });\n } else if (node.nodeType === 1 && node.childNodes) { // element\n var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];\n if (!skipTags.includes(node.tagName)) {\n Array.from(node.childNodes).forEach(highlight);\n }\n }\n }\n \n highlight(document.body);\n \n // Re-highlight on dynamic content\n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1 || node.nodeType === 3) highlight(node);\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Highlight Search Terms");
}
} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

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ssh-key: add "randomart" fingerprint visualizations#77

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tarcieri
merged 1 commit into

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Mar 7, 2023
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ssh-key: add "randomart" fingerprint visualizations
#77
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1 change: 1 addition & 0 deletions
ssh-key/README.md

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -44,6 +44,7 @@ respective SSH key algorithm.
- [x] Private key generation support: DSA, Ed25519, ECDSA (P-256+P-384), and RSA
- [x] FIDO/U2F key support (`sk-*`) as specified in [PROTOCOL.u2f]
- [x] Fingerprint support
 - [x] "randomart" fingerprint visualizations
- [x] `no_std` support including support for "heapless" (no-`alloc`) targets
- [x] Parsing `authorized_keys` files
- [x] Parsing `known_hosts` files
Expand Down

60 changes: 50 additions & 10 deletions
ssh-key/src/fingerprint.rs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -1,5 +1,8 @@
//! SSH public key fingerprints.

mod randomart;

use self::randomart::Randomart;
use crate::{public, Error, HashAlg, Result};
use core::{
 fmt::{self, Display},
Expand All@@ -14,11 +17,11 @@ use sha2::{Digest, Sha256, Sha512};
/// Fingerprint encoding error message.
const FINGERPRINT_ERR_MSG: &str = "fingerprint encoding error";

#[cfg(feature = "alloc")]
use alloc::string::{String, ToString};

#[cfg(all(feature = "alloc", feature = "serde"))]
use {
 alloc::string::{String, ToString},
 serde::{de, ser, Deserialize, Serialize},
};
use serde::{de, ser, Deserialize, Serialize};

/// SSH public key fingerprints.
///
Expand DownExpand Up@@ -79,6 +82,22 @@ impl Fingerprint {
 }
 }

 /// Get the name of the hash algorithm (upper case e.g. "SHA256").
 pub fn prefix(self) -> &'static str {
 match self.algorithm() {
 HashAlg::Sha256 => "SHA256",
 HashAlg::Sha512 => "SHA512",
 }
 }

 /// Get the bracketed hash algorithm footer for use in "randomart".
 fn footer(self) -> &'static str {
 match self.algorithm() {
 HashAlg::Sha256 => "[SHA256]",
 HashAlg::Sha512 => "[SHA512]",
 }
 }

 /// Get the raw digest output for the fingerprint as bytes.
 pub fn as_bytes(&self) -> &[u8] {
 match self {
Expand DownExpand Up@@ -112,6 +131,31 @@ impl Fingerprint {
 pub fn is_sha512(self) -> bool {
 matches!(self, Self::Sha512(_))
 }

 /// Format "randomart" for this fingerprint using the provided formatter.
 pub fn fmt_randomart(self, header: &str, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 Randomart::new(header, self).fmt(f)
 }

 /// Render "randomart" hash visualization for this fingerprint as a string.
 ///
 /// ```text
 /// +--[ED25519 256]--+
 /// |o+oO==+ o.. |
 /// |.o++Eo+o.. |
 /// |. +.oO.o . . |
 /// | . o..B.. . . |
 /// | ...+ .S. o |
 /// | .o. . . . . |
 /// | o.. o |
 /// | B . |
 /// | .o* |
 /// +----[SHA256]-----+
 /// ```
 #[cfg(feature = "alloc")]
 pub fn to_randomart(self, header: &str) -> String {
 Randomart::new(header, self).to_string()
 }
}

impl AsRef<[u8]> for Fingerprint {
Expand All@@ -122,16 +166,12 @@ impl AsRef<[u8]> for Fingerprint {

impl Display for Fingerprint {
 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 // Fingerprints use a special upper-case hash algorithm encoding.
 let algorithm = match self.algorithm() {
 HashAlg::Sha256 => "SHA256",
 HashAlg::Sha512 => "SHA512",
 };
 let prefix = self.prefix();

 // Buffer size is the largest digest size of of any supported hash function
 let mut buf = [0u8; Self::SHA512_BASE64_SIZE];
 let base64 = Base64Unpadded::encode(self.as_bytes(), &mut buf).map_err(|_| fmt::Error)?;
 write!(f, "{algorithm}:{base64}")
 write!(f, "{prefix}:{base64}")
 }
}

Expand Down

112 changes: 112 additions & 0 deletions
ssh-key/src/fingerprint/randomart.rs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,112 @@
//! Support for the "drunken bishop" fingerprint algorithm, a.k.a. "randomart".
//!
//! The algorithm is described in the paper:
//!
//! "The drunken bishop: An analysis of the OpenSSH fingerprint visualization algorithm"
//!
//! <http://www.dirk-loss.de/sshvis/drunken_bishop.pdf>

use super::Fingerprint;
use core::fmt;

const WIDTH: usize = 17;
const HEIGHT: usize = 9;
const VALUES: &[u8; 17] = b" .o+=*BOX@%&#/^SE";
const NVALUES: usize = VALUES.len() - 1;

type Field = [[u8; WIDTH]; HEIGHT];

/// "randomart" renderer.
pub(super) struct Randomart<'a> {
 header: &'a str,
 field: Field,
 footer: &'static str,
}

impl<'a> Randomart<'a> {
 /// Create new "randomart" from the given fingerprint.
 #[allow(clippy::integer_arithmetic)]
 pub(super) fn new(header: &'a str, fingerprint: Fingerprint) -> Self {
 let mut field = Field::default();
 let mut x = WIDTH / 2;
 let mut y = HEIGHT / 2;

 for mut byte in fingerprint.as_bytes().iter().copied() {
 for _ in 0..4 {
 if byte & 0x1 == 0 {
 x = x.saturating_sub(1);
 } else {
 x = x.saturating_add(1);
 }

 if byte & 0x2 == 0 {
 y = y.saturating_sub(1);
 } else {
 y = y.saturating_add(1);
 }

 x = x.min(WIDTH.saturating_sub(1));
 y = y.min(HEIGHT.saturating_sub(1));

 if field[y][x] < NVALUES as u8 - 2 {
 field[y][x] += 1;
 }

 byte >>= 2;
 }
 }

 field[HEIGHT / 2][WIDTH / 2] = NVALUES as u8 - 1;
 field[y][x] = NVALUES as u8;

 Self {
 header,
 field,
 footer: fingerprint.footer(),
 }
 }
}

impl fmt::Display for Randomart<'_> {
 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 writeln!(f, "+{:-^width$}+", self.header, width = WIDTH)?;

 for row in self.field {
 write!(f, "|")?;

 for c in row {
 write!(f, "{}", VALUES[c as usize] as char)?;
 }

 writeln!(f, "|")?;
 }

 write!(f, "+{:-^width$}+", self.footer, width = WIDTH)
 }
}

#[cfg(all(test, feature = "alloc"))]
mod tests {
 use super::Fingerprint;

 const EXAMPLE_FINGERPRINT: &str = "SHA256:UCUiLr7Pjs9wFFJMDByLgc3NrtdU344OgUM45wZPcIQ";
 const EXAMPLE_RANDOMART: &str = "\
+--[ED25519 256]--+
|o+oO==+ o.. |
|.o++Eo+o.. |
|. +.oO.o . . |
| . o..B.. . . |
| ...+ .S. o |
| .o. . . . . |
| o.. o |
| B . |
| .o* |
+----[SHA256]-----+";

 #[test]
 fn generation() {
 let fingerprint = EXAMPLE_FINGERPRINT.parse::<Fingerprint>().unwrap();
 let randomart = fingerprint.to_randomart("[ED25519 256]");
 assert_eq!(EXAMPLE_RANDOMART, randomart);
 }
}

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Strip utm_, fbclid, gclid, etc. from all links on page\n(function() {\n var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',\n 'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',\n 'ref', 'ref_src', 'source', 'medium', 'campaign'];\n \n function cleanUrl(url) {\n try {\n var u = new URL(url, window.location.origin);\n var changed = false;\n trackingParams.forEach(function(p) {\n if (u.searchParams.has(p)) {\n u.searchParams.delete(p);\n changed = true;\n }\n });\n return changed ? u.toString() : url;\n } catch (e) {\n return url;\n }\n }\n \n function cleanLinks() {\n document.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n \n cleanLinks();\n \n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1) {\n if (node.tagName === 'A') cleanLinks();\n node.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Remove Tracking Parameters from Links");
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '

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ssh-key: add "randomart" fingerprint visualizations#77

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 Merged

tarcieri
merged 1 commit into

from

Mar 7, 2023
 Merged


ssh-key: add "randomart" fingerprint visualizations
#77
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1 change: 1 addition & 0 deletions
ssh-key/README.md

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -44,6 +44,7 @@ respective SSH key algorithm.
- [x] Private key generation support: DSA, Ed25519, ECDSA (P-256+P-384), and RSA
- [x] FIDO/U2F key support (`sk-*`) as specified in [PROTOCOL.u2f]
- [x] Fingerprint support
 - [x] "randomart" fingerprint visualizations
- [x] `no_std` support including support for "heapless" (no-`alloc`) targets
- [x] Parsing `authorized_keys` files
- [x] Parsing `known_hosts` files
Expand Down

60 changes: 50 additions & 10 deletions
ssh-key/src/fingerprint.rs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -1,5 +1,8 @@
//! SSH public key fingerprints.

mod randomart;

use self::randomart::Randomart;
use crate::{public, Error, HashAlg, Result};
use core::{
 fmt::{self, Display},
Expand All@@ -14,11 +17,11 @@ use sha2::{Digest, Sha256, Sha512};
/// Fingerprint encoding error message.
const FINGERPRINT_ERR_MSG: &str = "fingerprint encoding error";

#[cfg(feature = "alloc")]
use alloc::string::{String, ToString};

#[cfg(all(feature = "alloc", feature = "serde"))]
use {
 alloc::string::{String, ToString},
 serde::{de, ser, Deserialize, Serialize},
};
use serde::{de, ser, Deserialize, Serialize};

/// SSH public key fingerprints.
///
Expand DownExpand Up@@ -79,6 +82,22 @@ impl Fingerprint {
 }
 }

 /// Get the name of the hash algorithm (upper case e.g. "SHA256").
 pub fn prefix(self) -> &'static str {
 match self.algorithm() {
 HashAlg::Sha256 => "SHA256",
 HashAlg::Sha512 => "SHA512",
 }
 }

 /// Get the bracketed hash algorithm footer for use in "randomart".
 fn footer(self) -> &'static str {
 match self.algorithm() {
 HashAlg::Sha256 => "[SHA256]",
 HashAlg::Sha512 => "[SHA512]",
 }
 }

 /// Get the raw digest output for the fingerprint as bytes.
 pub fn as_bytes(&self) -> &[u8] {
 match self {
Expand DownExpand Up@@ -112,6 +131,31 @@ impl Fingerprint {
 pub fn is_sha512(self) -> bool {
 matches!(self, Self::Sha512(_))
 }

 /// Format "randomart" for this fingerprint using the provided formatter.
 pub fn fmt_randomart(self, header: &str, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 Randomart::new(header, self).fmt(f)
 }

 /// Render "randomart" hash visualization for this fingerprint as a string.
 ///
 /// ```text
 /// +--[ED25519 256]--+
 /// |o+oO==+ o.. |
 /// |.o++Eo+o.. |
 /// |. +.oO.o . . |
 /// | . o..B.. . . |
 /// | ...+ .S. o |
 /// | .o. . . . . |
 /// | o.. o |
 /// | B . |
 /// | .o* |
 /// +----[SHA256]-----+
 /// ```
 #[cfg(feature = "alloc")]
 pub fn to_randomart(self, header: &str) -> String {
 Randomart::new(header, self).to_string()
 }
}

impl AsRef<[u8]> for Fingerprint {
Expand All@@ -122,16 +166,12 @@ impl AsRef<[u8]> for Fingerprint {

impl Display for Fingerprint {
 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 // Fingerprints use a special upper-case hash algorithm encoding.
 let algorithm = match self.algorithm() {
 HashAlg::Sha256 => "SHA256",
 HashAlg::Sha512 => "SHA512",
 };
 let prefix = self.prefix();

 // Buffer size is the largest digest size of of any supported hash function
 let mut buf = [0u8; Self::SHA512_BASE64_SIZE];
 let base64 = Base64Unpadded::encode(self.as_bytes(), &mut buf).map_err(|_| fmt::Error)?;
 write!(f, "{algorithm}:{base64}")
 write!(f, "{prefix}:{base64}")
 }
}

Expand Down

112 changes: 112 additions & 0 deletions
ssh-key/src/fingerprint/randomart.rs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,112 @@
//! Support for the "drunken bishop" fingerprint algorithm, a.k.a. "randomart".
//!
//! The algorithm is described in the paper:
//!
//! "The drunken bishop: An analysis of the OpenSSH fingerprint visualization algorithm"
//!
//! <http://www.dirk-loss.de/sshvis/drunken_bishop.pdf>

use super::Fingerprint;
use core::fmt;

const WIDTH: usize = 17;
const HEIGHT: usize = 9;
const VALUES: &[u8; 17] = b" .o+=*BOX@%&#/^SE";
const NVALUES: usize = VALUES.len() - 1;

type Field = [[u8; WIDTH]; HEIGHT];

/// "randomart" renderer.
pub(super) struct Randomart<'a> {
 header: &'a str,
 field: Field,
 footer: &'static str,
}

impl<'a> Randomart<'a> {
 /// Create new "randomart" from the given fingerprint.
 #[allow(clippy::integer_arithmetic)]
 pub(super) fn new(header: &'a str, fingerprint: Fingerprint) -> Self {
 let mut field = Field::default();
 let mut x = WIDTH / 2;
 let mut y = HEIGHT / 2;

 for mut byte in fingerprint.as_bytes().iter().copied() {
 for _ in 0..4 {
 if byte & 0x1 == 0 {
 x = x.saturating_sub(1);
 } else {
 x = x.saturating_add(1);
 }

 if byte & 0x2 == 0 {
 y = y.saturating_sub(1);
 } else {
 y = y.saturating_add(1);
 }

 x = x.min(WIDTH.saturating_sub(1));
 y = y.min(HEIGHT.saturating_sub(1));

 if field[y][x] < NVALUES as u8 - 2 {
 field[y][x] += 1;
 }

 byte >>= 2;
 }
 }

 field[HEIGHT / 2][WIDTH / 2] = NVALUES as u8 - 1;
 field[y][x] = NVALUES as u8;

 Self {
 header,
 field,
 footer: fingerprint.footer(),
 }
 }
}

impl fmt::Display for Randomart<'_> {
 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 writeln!(f, "+{:-^width$}+", self.header, width = WIDTH)?;

 for row in self.field {
 write!(f, "|")?;

 for c in row {
 write!(f, "{}", VALUES[c as usize] as char)?;
 }

 writeln!(f, "|")?;
 }

 write!(f, "+{:-^width$}+", self.footer, width = WIDTH)
 }
}

#[cfg(all(test, feature = "alloc"))]
mod tests {
 use super::Fingerprint;

 const EXAMPLE_FINGERPRINT: &str = "SHA256:UCUiLr7Pjs9wFFJMDByLgc3NrtdU344OgUM45wZPcIQ";
 const EXAMPLE_RANDOMART: &str = "\
+--[ED25519 256]--+
|o+oO==+ o.. |
|.o++Eo+o.. |
|. +.oO.o . . |
| . o..B.. . . |
| ...+ .S. o |
| .o. . . . . |
| o.. o |
| B . |
| .o* |
+----[SHA256]-----+";

 #[test]
 fn generation() {
 let fingerprint = EXAMPLE_FINGERPRINT.parse::<Fingerprint>().unwrap();
 let randomart = fingerprint.to_randomart("[ED25519 256]");
 assert_eq!(EXAMPLE_RANDOMART, randomart);
 }
}

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Auto-enable theater mode on YouTube\n(function() {\n function tryTheater() {\n var btn = document.querySelector('button[aria-label=\"Theater mode\"], ytd-player #player button[title=\"Theater mode\"]');\n if (btn && !btn.classList.contains('activated')) {\n btn.click();\n }\n }\n \n // Try immediately\n tryTheater();\n \n // Try after navigation (SPA)\n var lastUrl = location.href;\n setInterval(function() {\n if (location.href !== lastUrl) {\n lastUrl = location.href;\n setTimeout(tryTheater, 500);\n }\n }, 1000);\n \n // Also try on player load\n var observer = new MutationObserver(tryTheater);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "YouTube Theater Mode Default");
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
ssh-key: add "randomart" fingerprint visualizations#77

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Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

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privacy statement. We’ll occasionally send you account related emails.

Already on GitHub?
Sign in
to your account

 Merged

tarcieri
merged 1 commit into

from

Mar 7, 2023
 Merged


ssh-key: add "randomart" fingerprint visualizations
#77
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1 change: 1 addition & 0 deletions
ssh-key/README.md

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -44,6 +44,7 @@ respective SSH key algorithm.
- [x] Private key generation support: DSA, Ed25519, ECDSA (P-256+P-384), and RSA
- [x] FIDO/U2F key support (`sk-*`) as specified in [PROTOCOL.u2f]
- [x] Fingerprint support
 - [x] "randomart" fingerprint visualizations
- [x] `no_std` support including support for "heapless" (no-`alloc`) targets
- [x] Parsing `authorized_keys` files
- [x] Parsing `known_hosts` files
Expand Down

60 changes: 50 additions & 10 deletions
ssh-key/src/fingerprint.rs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -1,5 +1,8 @@
//! SSH public key fingerprints.

mod randomart;

use self::randomart::Randomart;
use crate::{public, Error, HashAlg, Result};
use core::{
 fmt::{self, Display},
Expand All@@ -14,11 +17,11 @@ use sha2::{Digest, Sha256, Sha512};
/// Fingerprint encoding error message.
const FINGERPRINT_ERR_MSG: &str = "fingerprint encoding error";

#[cfg(feature = "alloc")]
use alloc::string::{String, ToString};

#[cfg(all(feature = "alloc", feature = "serde"))]
use {
 alloc::string::{String, ToString},
 serde::{de, ser, Deserialize, Serialize},
};
use serde::{de, ser, Deserialize, Serialize};

/// SSH public key fingerprints.
///
Expand DownExpand Up@@ -79,6 +82,22 @@ impl Fingerprint {
 }
 }

 /// Get the name of the hash algorithm (upper case e.g. "SHA256").
 pub fn prefix(self) -> &'static str {
 match self.algorithm() {
 HashAlg::Sha256 => "SHA256",
 HashAlg::Sha512 => "SHA512",
 }
 }

 /// Get the bracketed hash algorithm footer for use in "randomart".
 fn footer(self) -> &'static str {
 match self.algorithm() {
 HashAlg::Sha256 => "[SHA256]",
 HashAlg::Sha512 => "[SHA512]",
 }
 }

 /// Get the raw digest output for the fingerprint as bytes.
 pub fn as_bytes(&self) -> &[u8] {
 match self {
Expand DownExpand Up@@ -112,6 +131,31 @@ impl Fingerprint {
 pub fn is_sha512(self) -> bool {
 matches!(self, Self::Sha512(_))
 }

 /// Format "randomart" for this fingerprint using the provided formatter.
 pub fn fmt_randomart(self, header: &str, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 Randomart::new(header, self).fmt(f)
 }

 /// Render "randomart" hash visualization for this fingerprint as a string.
 ///
 /// ```text
 /// +--[ED25519 256]--+
 /// |o+oO==+ o.. |
 /// |.o++Eo+o.. |
 /// |. +.oO.o . . |
 /// | . o..B.. . . |
 /// | ...+ .S. o |
 /// | .o. . . . . |
 /// | o.. o |
 /// | B . |
 /// | .o* |
 /// +----[SHA256]-----+
 /// ```
 #[cfg(feature = "alloc")]
 pub fn to_randomart(self, header: &str) -> String {
 Randomart::new(header, self).to_string()
 }
}

impl AsRef<[u8]> for Fingerprint {
Expand All@@ -122,16 +166,12 @@ impl AsRef<[u8]> for Fingerprint {

impl Display for Fingerprint {
 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 // Fingerprints use a special upper-case hash algorithm encoding.
 let algorithm = match self.algorithm() {
 HashAlg::Sha256 => "SHA256",
 HashAlg::Sha512 => "SHA512",
 };
 let prefix = self.prefix();

 // Buffer size is the largest digest size of of any supported hash function
 let mut buf = [0u8; Self::SHA512_BASE64_SIZE];
 let base64 = Base64Unpadded::encode(self.as_bytes(), &mut buf).map_err(|_| fmt::Error)?;
 write!(f, "{algorithm}:{base64}")
 write!(f, "{prefix}:{base64}")
 }
}

Expand Down

112 changes: 112 additions & 0 deletions
ssh-key/src/fingerprint/randomart.rs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,112 @@
//! Support for the "drunken bishop" fingerprint algorithm, a.k.a. "randomart".
//!
//! The algorithm is described in the paper:
//!
//! "The drunken bishop: An analysis of the OpenSSH fingerprint visualization algorithm"
//!
//! <http://www.dirk-loss.de/sshvis/drunken_bishop.pdf>

use super::Fingerprint;
use core::fmt;

const WIDTH: usize = 17;
const HEIGHT: usize = 9;
const VALUES: &[u8; 17] = b" .o+=*BOX@%&#/^SE";
const NVALUES: usize = VALUES.len() - 1;

type Field = [[u8; WIDTH]; HEIGHT];

/// "randomart" renderer.
pub(super) struct Randomart<'a> {
 header: &'a str,
 field: Field,
 footer: &'static str,
}

impl<'a> Randomart<'a> {
 /// Create new "randomart" from the given fingerprint.
 #[allow(clippy::integer_arithmetic)]
 pub(super) fn new(header: &'a str, fingerprint: Fingerprint) -> Self {
 let mut field = Field::default();
 let mut x = WIDTH / 2;
 let mut y = HEIGHT / 2;

 for mut byte in fingerprint.as_bytes().iter().copied() {
 for _ in 0..4 {
 if byte & 0x1 == 0 {
 x = x.saturating_sub(1);
 } else {
 x = x.saturating_add(1);
 }

 if byte & 0x2 == 0 {
 y = y.saturating_sub(1);
 } else {
 y = y.saturating_add(1);
 }

 x = x.min(WIDTH.saturating_sub(1));
 y = y.min(HEIGHT.saturating_sub(1));

 if field[y][x] < NVALUES as u8 - 2 {
 field[y][x] += 1;
 }

 byte >>= 2;
 }
 }

 field[HEIGHT / 2][WIDTH / 2] = NVALUES as u8 - 1;
 field[y][x] = NVALUES as u8;

 Self {
 header,
 field,
 footer: fingerprint.footer(),
 }
 }
}

impl fmt::Display for Randomart<'_> {
 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 writeln!(f, "+{:-^width$}+", self.header, width = WIDTH)?;

 for row in self.field {
 write!(f, "|")?;

 for c in row {
 write!(f, "{}", VALUES[c as usize] as char)?;
 }

 writeln!(f, "|")?;
 }

 write!(f, "+{:-^width$}+", self.footer, width = WIDTH)
 }
}

#[cfg(all(test, feature = "alloc"))]
mod tests {
 use super::Fingerprint;

 const EXAMPLE_FINGERPRINT: &str = "SHA256:UCUiLr7Pjs9wFFJMDByLgc3NrtdU344OgUM45wZPcIQ";
 const EXAMPLE_RANDOMART: &str = "\
+--[ED25519 256]--+
|o+oO==+ o.. |
|.o++Eo+o.. |
|. +.oO.o . . |
| . o..B.. . . |
| ...+ .S. o |
| .o. . . . . |
| o.. o |
| B . |
| .o* |
+----[SHA256]-----+";

 #[test]
 fn generation() {
 let fingerprint = EXAMPLE_FINGERPRINT.parse::<Fingerprint>().unwrap();
 let randomart = fingerprint.to_randomart("[ED25519 256]");
 assert_eq!(EXAMPLE_RANDOMART, randomart);
 }
}

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Remove or un-stick sticky/fixed headers that block content\n(function() {\n function unstick() {\n document.querySelectorAll('header, nav, [role=\"banner\"], .header, .navbar, .sticky, .fixed-top, [style*=\"position: fixed\"], [style*=\"position:sticky\"]').forEach(function(el) {\n if (el.style.position === 'fixed' || el.style.position === 'sticky' || \n getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {\n el.style.position = 'static';\n el.style.top = 'auto';\n el.style.zIndex = 'auto';\n }\n });\n }\n \n unstick();\n \n var observer = new MutationObserver(unstick);\n observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });\n})();", "Kill Sticky Headers");
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

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ssh-key: add "randomart" fingerprint visualizations#77

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 Merged

tarcieri
merged 1 commit into

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Mar 7, 2023
 Merged


ssh-key: add "randomart" fingerprint visualizations
#77
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1 change: 1 addition & 0 deletions
ssh-key/README.md

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -44,6 +44,7 @@ respective SSH key algorithm.
- [x] Private key generation support: DSA, Ed25519, ECDSA (P-256+P-384), and RSA
- [x] FIDO/U2F key support (`sk-*`) as specified in [PROTOCOL.u2f]
- [x] Fingerprint support
 - [x] "randomart" fingerprint visualizations
- [x] `no_std` support including support for "heapless" (no-`alloc`) targets
- [x] Parsing `authorized_keys` files
- [x] Parsing `known_hosts` files
Expand Down

60 changes: 50 additions & 10 deletions
ssh-key/src/fingerprint.rs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -1,5 +1,8 @@
//! SSH public key fingerprints.

mod randomart;

use self::randomart::Randomart;
use crate::{public, Error, HashAlg, Result};
use core::{
 fmt::{self, Display},
Expand All@@ -14,11 +17,11 @@ use sha2::{Digest, Sha256, Sha512};
/// Fingerprint encoding error message.
const FINGERPRINT_ERR_MSG: &str = "fingerprint encoding error";

#[cfg(feature = "alloc")]
use alloc::string::{String, ToString};

#[cfg(all(feature = "alloc", feature = "serde"))]
use {
 alloc::string::{String, ToString},
 serde::{de, ser, Deserialize, Serialize},
};
use serde::{de, ser, Deserialize, Serialize};

/// SSH public key fingerprints.
///
Expand DownExpand Up@@ -79,6 +82,22 @@ impl Fingerprint {
 }
 }

 /// Get the name of the hash algorithm (upper case e.g. "SHA256").
 pub fn prefix(self) -> &'static str {
 match self.algorithm() {
 HashAlg::Sha256 => "SHA256",
 HashAlg::Sha512 => "SHA512",
 }
 }

 /// Get the bracketed hash algorithm footer for use in "randomart".
 fn footer(self) -> &'static str {
 match self.algorithm() {
 HashAlg::Sha256 => "[SHA256]",
 HashAlg::Sha512 => "[SHA512]",
 }
 }

 /// Get the raw digest output for the fingerprint as bytes.
 pub fn as_bytes(&self) -> &[u8] {
 match self {
Expand DownExpand Up@@ -112,6 +131,31 @@ impl Fingerprint {
 pub fn is_sha512(self) -> bool {
 matches!(self, Self::Sha512(_))
 }

 /// Format "randomart" for this fingerprint using the provided formatter.
 pub fn fmt_randomart(self, header: &str, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 Randomart::new(header, self).fmt(f)
 }

 /// Render "randomart" hash visualization for this fingerprint as a string.
 ///
 /// ```text
 /// +--[ED25519 256]--+
 /// |o+oO==+ o.. |
 /// |.o++Eo+o.. |
 /// |. +.oO.o . . |
 /// | . o..B.. . . |
 /// | ...+ .S. o |
 /// | .o. . . . . |
 /// | o.. o |
 /// | B . |
 /// | .o* |
 /// +----[SHA256]-----+
 /// ```
 #[cfg(feature = "alloc")]
 pub fn to_randomart(self, header: &str) -> String {
 Randomart::new(header, self).to_string()
 }
}

impl AsRef<[u8]> for Fingerprint {
Expand All@@ -122,16 +166,12 @@ impl AsRef<[u8]> for Fingerprint {

impl Display for Fingerprint {
 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 // Fingerprints use a special upper-case hash algorithm encoding.
 let algorithm = match self.algorithm() {
 HashAlg::Sha256 => "SHA256",
 HashAlg::Sha512 => "SHA512",
 };
 let prefix = self.prefix();

 // Buffer size is the largest digest size of of any supported hash function
 let mut buf = [0u8; Self::SHA512_BASE64_SIZE];
 let base64 = Base64Unpadded::encode(self.as_bytes(), &mut buf).map_err(|_| fmt::Error)?;
 write!(f, "{algorithm}:{base64}")
 write!(f, "{prefix}:{base64}")
 }
}

Expand Down

112 changes: 112 additions & 0 deletions
ssh-key/src/fingerprint/randomart.rs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,112 @@
//! Support for the "drunken bishop" fingerprint algorithm, a.k.a. "randomart".
//!
//! The algorithm is described in the paper:
//!
//! "The drunken bishop: An analysis of the OpenSSH fingerprint visualization algorithm"
//!
//! <http://www.dirk-loss.de/sshvis/drunken_bishop.pdf>

use super::Fingerprint;
use core::fmt;

const WIDTH: usize = 17;
const HEIGHT: usize = 9;
const VALUES: &[u8; 17] = b" .o+=*BOX@%&#/^SE";
const NVALUES: usize = VALUES.len() - 1;

type Field = [[u8; WIDTH]; HEIGHT];

/// "randomart" renderer.
pub(super) struct Randomart<'a> {
 header: &'a str,
 field: Field,
 footer: &'static str,
}

impl<'a> Randomart<'a> {
 /// Create new "randomart" from the given fingerprint.
 #[allow(clippy::integer_arithmetic)]
 pub(super) fn new(header: &'a str, fingerprint: Fingerprint) -> Self {
 let mut field = Field::default();
 let mut x = WIDTH / 2;
 let mut y = HEIGHT / 2;

 for mut byte in fingerprint.as_bytes().iter().copied() {
 for _ in 0..4 {
 if byte & 0x1 == 0 {
 x = x.saturating_sub(1);
 } else {
 x = x.saturating_add(1);
 }

 if byte & 0x2 == 0 {
 y = y.saturating_sub(1);
 } else {
 y = y.saturating_add(1);
 }

 x = x.min(WIDTH.saturating_sub(1));
 y = y.min(HEIGHT.saturating_sub(1));

 if field[y][x] < NVALUES as u8 - 2 {
 field[y][x] += 1;
 }

 byte >>= 2;
 }
 }

 field[HEIGHT / 2][WIDTH / 2] = NVALUES as u8 - 1;
 field[y][x] = NVALUES as u8;

 Self {
 header,
 field,
 footer: fingerprint.footer(),
 }
 }
}

impl fmt::Display for Randomart<'_> {
 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 writeln!(f, "+{:-^width$}+", self.header, width = WIDTH)?;

 for row in self.field {
 write!(f, "|")?;

 for c in row {
 write!(f, "{}", VALUES[c as usize] as char)?;
 }

 writeln!(f, "|")?;
 }

 write!(f, "+{:-^width$}+", self.footer, width = WIDTH)
 }
}

#[cfg(all(test, feature = "alloc"))]
mod tests {
 use super::Fingerprint;

 const EXAMPLE_FINGERPRINT: &str = "SHA256:UCUiLr7Pjs9wFFJMDByLgc3NrtdU344OgUM45wZPcIQ";
 const EXAMPLE_RANDOMART: &str = "\
+--[ED25519 256]--+
|o+oO==+ o.. |
|.o++Eo+o.. |
|. +.oO.o . . |
| . o..B.. . . |
| ...+ .S. o |
| .o. . . . . |
| o.. o |
| B . |
| .o* |
+----[SHA256]-----+";

 #[test]
 fn generation() {
 let fingerprint = EXAMPLE_FINGERPRINT.parse::<Fingerprint>().unwrap();
 let randomart = fingerprint.to_randomart("[ED25519 256]");
 assert_eq!(EXAMPLE_RANDOMART, randomart);
 }
}

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Universal Dark Mode - works on any site\n(function() {\n var enabled = true;\n \n function applyDarkMode() {\n if (!enabled) return;\n \n // Create style element if it doesn't exist\n var style = document.getElementById('universal-dark-mode-style');\n if (!style) {\n style = document.createElement('style');\n style.id = 'universal-dark-mode-style';\n document.head.appendChild(style);\n }\n \n // Dark mode CSS - inverts colors but preserves images/video\n style.textContent = '\n /* Invert everything except media */\n html {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #1a1a2e !important;\n }\n \n /* Restore images, videos, iframes, canvas */\n img, video, iframe, canvas, svg, picture, [style*=\"background-image\"] {\n filter: invert(1) hue-rotate(180deg) !important;\n }\n \n /* Preserve specific elements that should not be inverted */\n .no-dark-mode, .no-dark-mode *,\n [data-theme=\"light\"], [data-theme=\"light\"],\n .ace_editor, .ace_editor *,\n .CodeMirror, .CodeMirror *,\n .monaco-editor, .monaco-editor *,\n .markdown-body pre, .markdown-body pre *,\n .highlight, .highlight *,\n pre code, pre code * {\n filter: none !important;\n }\n \n /* Fix common UI elements */\n .modal, .popup, .dropdown-menu, .tooltip, .popover {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #2d2d44 !important;\n border-color: #444 !important;\n }\n \n /* Scrollbars */\n ::-webkit-scrollbar { background: #1a1a2e !important; }\n ::-webkit-scrollbar-thumb { background: #444 !important; }\n ::-webkit-scrollbar-thumb:hover { background: #555 !important; }\n \n /* Selection */\n ::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ';\n }\n \n function removeDarkMode() {\n var style = document.getElementById('universal-dark-mode-style');\n if (style) style.remove();\n }\n \n // Toggle with Alt+Shift+D\n document.addEventListener('keydown', function(e) {\n if (e.altKey && e.shiftKey && e.key === 'D') {\n e.preventDefault();\n enabled = !enabled;\n if (enabled) {\n applyDarkMode();\n console.log('[Universal Dark Mode] Enabled');\n } else {\n removeDarkMode();\n console.log('[Universal Dark Mode] Disabled');\n }\n }\n });\n \n // Apply on load\n applyDarkMode();\n \n // Re-apply on dynamic content\n var observer = new MutationObserver(function(mutations) {\n if (enabled && !document.getElementById('universal-dark-mode-style')) {\n applyDarkMode();\n }\n });\n observer.observe(document.head, { childList: true });\n \n console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');\n})();", "Universal Dark Mode");
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();

Skip to content
ssh-key: add "randomart" fingerprint visualizations#77

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privacy statement. We’ll occasionally send you account related emails.

Already on GitHub?
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to your account

 Merged

tarcieri
merged 1 commit into

from

Mar 7, 2023
 Merged


ssh-key: add "randomart" fingerprint visualizations
#77
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1 change: 1 addition & 0 deletions
ssh-key/README.md

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -44,6 +44,7 @@ respective SSH key algorithm.
- [x] Private key generation support: DSA, Ed25519, ECDSA (P-256+P-384), and RSA
- [x] FIDO/U2F key support (`sk-*`) as specified in [PROTOCOL.u2f]
- [x] Fingerprint support
 - [x] "randomart" fingerprint visualizations
- [x] `no_std` support including support for "heapless" (no-`alloc`) targets
- [x] Parsing `authorized_keys` files
- [x] Parsing `known_hosts` files
Expand Down

60 changes: 50 additions & 10 deletions
ssh-key/src/fingerprint.rs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -1,5 +1,8 @@
//! SSH public key fingerprints.

mod randomart;

use self::randomart::Randomart;
use crate::{public, Error, HashAlg, Result};
use core::{
 fmt::{self, Display},
Expand All@@ -14,11 +17,11 @@ use sha2::{Digest, Sha256, Sha512};
/// Fingerprint encoding error message.
const FINGERPRINT_ERR_MSG: &str = "fingerprint encoding error";

#[cfg(feature = "alloc")]
use alloc::string::{String, ToString};

#[cfg(all(feature = "alloc", feature = "serde"))]
use {
 alloc::string::{String, ToString},
 serde::{de, ser, Deserialize, Serialize},
};
use serde::{de, ser, Deserialize, Serialize};

/// SSH public key fingerprints.
///
Expand DownExpand Up@@ -79,6 +82,22 @@ impl Fingerprint {
 }
 }

 /// Get the name of the hash algorithm (upper case e.g. "SHA256").
 pub fn prefix(self) -> &'static str {
 match self.algorithm() {
 HashAlg::Sha256 => "SHA256",
 HashAlg::Sha512 => "SHA512",
 }
 }

 /// Get the bracketed hash algorithm footer for use in "randomart".
 fn footer(self) -> &'static str {
 match self.algorithm() {
 HashAlg::Sha256 => "[SHA256]",
 HashAlg::Sha512 => "[SHA512]",
 }
 }

 /// Get the raw digest output for the fingerprint as bytes.
 pub fn as_bytes(&self) -> &[u8] {
 match self {
Expand DownExpand Up@@ -112,6 +131,31 @@ impl Fingerprint {
 pub fn is_sha512(self) -> bool {
 matches!(self, Self::Sha512(_))
 }

 /// Format "randomart" for this fingerprint using the provided formatter.
 pub fn fmt_randomart(self, header: &str, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 Randomart::new(header, self).fmt(f)
 }

 /// Render "randomart" hash visualization for this fingerprint as a string.
 ///
 /// ```text
 /// +--[ED25519 256]--+
 /// |o+oO==+ o.. |
 /// |.o++Eo+o.. |
 /// |. +.oO.o . . |
 /// | . o..B.. . . |
 /// | ...+ .S. o |
 /// | .o. . . . . |
 /// | o.. o |
 /// | B . |
 /// | .o* |
 /// +----[SHA256]-----+
 /// ```
 #[cfg(feature = "alloc")]
 pub fn to_randomart(self, header: &str) -> String {
 Randomart::new(header, self).to_string()
 }
}

impl AsRef<[u8]> for Fingerprint {
Expand All@@ -122,16 +166,12 @@ impl AsRef<[u8]> for Fingerprint {

impl Display for Fingerprint {
 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 // Fingerprints use a special upper-case hash algorithm encoding.
 let algorithm = match self.algorithm() {
 HashAlg::Sha256 => "SHA256",
 HashAlg::Sha512 => "SHA512",
 };
 let prefix = self.prefix();

 // Buffer size is the largest digest size of of any supported hash function
 let mut buf = [0u8; Self::SHA512_BASE64_SIZE];
 let base64 = Base64Unpadded::encode(self.as_bytes(), &mut buf).map_err(|_| fmt::Error)?;
 write!(f, "{algorithm}:{base64}")
 write!(f, "{prefix}:{base64}")
 }
}

Expand Down

112 changes: 112 additions & 0 deletions
ssh-key/src/fingerprint/randomart.rs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,112 @@
//! Support for the "drunken bishop" fingerprint algorithm, a.k.a. "randomart".
//!
//! The algorithm is described in the paper:
//!
//! "The drunken bishop: An analysis of the OpenSSH fingerprint visualization algorithm"
//!
//! <http://www.dirk-loss.de/sshvis/drunken_bishop.pdf>

use super::Fingerprint;
use core::fmt;

const WIDTH: usize = 17;
const HEIGHT: usize = 9;
const VALUES: &[u8; 17] = b" .o+=*BOX@%&#/^SE";
const NVALUES: usize = VALUES.len() - 1;

type Field = [[u8; WIDTH]; HEIGHT];

/// "randomart" renderer.
pub(super) struct Randomart<'a> {
 header: &'a str,
 field: Field,
 footer: &'static str,
}

impl<'a> Randomart<'a> {
 /// Create new "randomart" from the given fingerprint.
 #[allow(clippy::integer_arithmetic)]
 pub(super) fn new(header: &'a str, fingerprint: Fingerprint) -> Self {
 let mut field = Field::default();
 let mut x = WIDTH / 2;
 let mut y = HEIGHT / 2;

 for mut byte in fingerprint.as_bytes().iter().copied() {
 for _ in 0..4 {
 if byte & 0x1 == 0 {
 x = x.saturating_sub(1);
 } else {
 x = x.saturating_add(1);
 }

 if byte & 0x2 == 0 {
 y = y.saturating_sub(1);
 } else {
 y = y.saturating_add(1);
 }

 x = x.min(WIDTH.saturating_sub(1));
 y = y.min(HEIGHT.saturating_sub(1));

 if field[y][x] < NVALUES as u8 - 2 {
 field[y][x] += 1;
 }

 byte >>= 2;
 }
 }

 field[HEIGHT / 2][WIDTH / 2] = NVALUES as u8 - 1;
 field[y][x] = NVALUES as u8;

 Self {
 header,
 field,
 footer: fingerprint.footer(),
 }
 }
}

impl fmt::Display for Randomart<'_> {
 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 writeln!(f, "+{:-^width$}+", self.header, width = WIDTH)?;

 for row in self.field {
 write!(f, "|")?;

 for c in row {
 write!(f, "{}", VALUES[c as usize] as char)?;
 }

 writeln!(f, "|")?;
 }

 write!(f, "+{:-^width$}+", self.footer, width = WIDTH)
 }
}

#[cfg(all(test, feature = "alloc"))]
mod tests {
 use super::Fingerprint;

 const EXAMPLE_FINGERPRINT: &str = "SHA256:UCUiLr7Pjs9wFFJMDByLgc3NrtdU344OgUM45wZPcIQ";
 const EXAMPLE_RANDOMART: &str = "\
+--[ED25519 256]--+
|o+oO==+ o.. |
|.o++Eo+o.. |
|. +.oO.o . . |
| . o..B.. . . |
| ...+ .S. o |
| .o. . . . . |
| o.. o |
| B . |
| .o* |
+----[SHA256]-----+";

 #[test]
 fn generation() {
 let fingerprint = EXAMPLE_FINGERPRINT.parse::<Fingerprint>().unwrap();
 let randomart = fingerprint.to_randomart("[ED25519 256]");
 assert_eq!(EXAMPLE_RANDOMART, randomart);
 }
}