fwidgen: allow caller to select the FWID digest, add support for sha256, add IANA string id to output

fwidgen/Cargo.toml

@@ -8,5 +8,6 @@ anyhow.version = "1"
 clap = { version = "4.5.32", features = ["derive", "env", "wrap_help"] }
 hex = "0.4.3"
 hubtools.workspace = true
-sha3 = { version = "0.10.8", default-features = false }
+sha2 = "0.10.8"
+sha3 = "0.10.8"
 toml = { version = "0.7.8", default-features = false, features = ["parse"] }

fwidgen/src/main.rs

@@ -3,10 +3,11 @@
 // file, You can obtain one at https://mozilla.org/MPL/2.0/.
 
 use anyhow::{anyhow, Context, Result};
-use clap::Parser;
+use clap::{Parser, ValueEnum};
 use hubtools::RawHubrisArchive;
-use sha3::{Digest, Sha3_256};
-use std::{ops::Range, str};
+use sha2::{digest::DynDigest, Digest as _, Sha256};
+use sha3::Sha3_256;
+use std::{fmt, ops::Range, str};
 
 pub const LPC55_FLASH_PAGE_SIZE: usize = 512;
 
@@ -22,11 +23,46 @@ pub const LPC55_FLASH_PAGE_SIZE: usize = 512;
 /// of hubris archives
 #[derive(Parser, Debug)]
 struct Args {
+    /// Hash algorithm used to generate FWID
+    #[clap(default_value_t, env = "HUBEDIT_DIGEST", long, value_enum)]
+    digest: Digest,
+
     /// Hubris archive
     #[clap(env = "HUBEDIT_ARCHIVE")]
     archive: String,
 }
 
+// We provide names explicitly for each variant to map each to the IANA named
+// information hash algorithm registry hash name strings.
+#[derive(Clone, Debug, Default, ValueEnum)]
+enum Digest {
+    #[clap(name = "sha-256")]
+    Sha256,
+    #[clap(name = "sha3-256")]
+    #[default]
+    Sha3_256,
+}
+
+// Display string names for digest algorithms from IANA named information
+// hash algorithm registry
+impl fmt::Display for Digest {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Self::Sha256 => write!(f, "sha-256"),
+            Self::Sha3_256 => write!(f, "sha3-256"),
+        }
+    }
+}
+
+impl Digest {
+    fn to_dyn_digest(&self) -> Box<dyn DynDigest> {
+        match self {
+            Digest::Sha256 => Box::new(Sha256::new()),
+            Digest::Sha3_256 => Box::new(Sha3_256::new()),
+        }
+    }
+}
+
 #[derive(Debug)]
 enum Chip {
     Lpc55,
@@ -172,13 +208,16 @@ fn main() -> Result<()> {
         }
     };
 
-    let mut digest = Sha3_256::new();
+    let mut digest = args.digest.to_dyn_digest();
     digest.update(&image);
-    digest.update(vec![0xff; pad]);
+    digest.update(vec![0xff; pad].as_ref());
 
     let digest = digest.finalize();
 
-    println!("{}", hex::encode(digest));
+    // Display FWID as the string name for the digest from IANA registry and
+    // the output from the selected digest encoded as hex & separated by a
+    // `;`.
+    println!("{};{}", args.digest, hex::encode(digest));
 
     Ok(())
 }