diff --git a/tools/src/bin/opgpcard/cli.rs b/tools/src/bin/opgpcard/cli.rs
index 8328fd5..714ca23 100644
--- a/tools/src/bin/opgpcard/cli.rs
+++ b/tools/src/bin/opgpcard/cli.rs
@@ -78,21 +78,7 @@ pub enum Command {
     Decrypt(commands::decrypt::DecryptCommand),
 
     /// Sign data using a card
-    Sign {
-        #[clap(name = "card ident", short = 'c', long = "card")]
-        ident: String,
-
-        /// User PIN file
-        #[clap(short = 'p', long = "user-pin")]
-        user_pin: Option<PathBuf>,
-
-        #[clap(name = "detached", short = 'd', long = "detached")]
-        detached: bool,
-
-        /// Input file (stdin if unset)
-        #[clap(name = "input")]
-        input: Option<PathBuf>,
-    },
+    Sign(commands::sign::SignCommand),
 
     /// Attestation management (Yubico)
     Attestation {
diff --git a/tools/src/bin/opgpcard/commands/mod.rs b/tools/src/bin/opgpcard/commands/mod.rs
index 7746aec..b692df3 100644
--- a/tools/src/bin/opgpcard/commands/mod.rs
+++ b/tools/src/bin/opgpcard/commands/mod.rs
@@ -5,5 +5,6 @@
 pub mod decrypt;
 pub mod info;
 pub mod pubkey;
+pub mod sign;
 pub mod ssh;
 pub mod status;
diff --git a/tools/src/bin/opgpcard/commands/sign.rs b/tools/src/bin/opgpcard/commands/sign.rs
new file mode 100644
index 0000000..807fac9
--- /dev/null
+++ b/tools/src/bin/opgpcard/commands/sign.rs
@@ -0,0 +1,68 @@
+// SPDX-FileCopyrightText: 2021-2022 Heiko Schaefer <heiko@schaefer.name>
+// SPDX-FileCopyrightText: 2022 Nora Widdecke <mail@nora.pink>
+// SPDX-License-Identifier: MIT OR Apache-2.0
+
+use anyhow::{anyhow, Result};
+use clap::Parser;
+
+use std::path::{Path, PathBuf};
+
+use sequoia_openpgp::serialize::stream::{Armorer, Message, Signer};
+
+use openpgp_card_sequoia::card::Card;
+
+use crate::util;
+
+#[derive(Parser, Debug)]
+pub struct SignCommand {
+    #[clap(name = "card ident", short = 'c', long = "card")]
+    pub ident: String,
+
+    /// User PIN file
+    #[clap(short = 'p', long = "user-pin")]
+    pub user_pin: Option<PathBuf>,
+
+    #[clap(name = "detached", short = 'd', long = "detached")]
+    pub detached: bool,
+
+    /// Input file (stdin if unset)
+    #[clap(name = "input")]
+    pub input: Option<PathBuf>,
+}
+
+pub fn sign(command: SignCommand) -> Result<(), Box<dyn std::error::Error>> {
+    if command.detached {
+        sign_detached(&command.ident, command.user_pin, command.input.as_deref())
+    } else {
+        Err(anyhow::anyhow!("Only detached signatures are supported for now").into())
+    }
+}
+
+pub fn sign_detached(
+    ident: &str,
+    pin_file: Option<PathBuf>,
+    input: Option<&Path>,
+) -> Result<(), Box<dyn std::error::Error>> {
+    let mut input = util::open_or_stdin(input)?;
+
+    let backend = util::open_card(ident)?;
+    let mut card = Card::new(backend);
+    let mut open = card.transaction()?;
+
+    if open.fingerprints()?.signature().is_none() {
+        return Err(anyhow!("Can't sign: this card has no key in the signing slot.").into());
+    }
+
+    let user_pin = util::get_pin(&mut open, pin_file, crate::ENTER_USER_PIN);
+
+    let mut sign = util::verify_to_sign(&mut open, user_pin.as_deref())?;
+    let s = sign.signer(&|| println!("Touch confirmation needed for signing"))?;
+
+    let message = Armorer::new(Message::new(std::io::stdout())).build()?;
+    let mut signer = Signer::new(message, s).detached().build()?;
+
+    std::io::copy(&mut input, &mut signer)?;
+    signer.finalize()?;
+
+    Ok(())
+}
diff --git a/tools/src/bin/opgpcard/main.rs b/tools/src/bin/opgpcard/main.rs
index 4087f98..8e24c7d 100644
--- a/tools/src/bin/opgpcard/main.rs
+++ b/tools/src/bin/opgpcard/main.rs
@@ -5,14 +5,13 @@
 use anyhow::{anyhow, Result};
 use clap::Parser;
 use cli::BaseKeySlot;
-use std::path::{Path, PathBuf};
+use std::path::PathBuf;
 
 use sequoia_openpgp::cert::prelude::ValidErasedKeyAmalgamation;
 use sequoia_openpgp::packet::key::{SecretParts, UnspecifiedRole};
 use sequoia_openpgp::packet::Key;
 use sequoia_openpgp::parse::Parse;
 use sequoia_openpgp::policy::{Policy, StandardPolicy};
-use sequoia_openpgp::serialize::stream::{Armorer, Message, Signer};
 use sequoia_openpgp::serialize::SerializeInto;
 use sequoia_openpgp::types::{HashAlgorithm, SymmetricAlgorithm};
 use sequoia_openpgp::Cert;
@@ -67,19 +66,8 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
         cli::Command::Decrypt(cmd) => {
             commands::decrypt::decrypt(cmd)?;
         }
-        cli::Command::Sign {
-            ident,
-            user_pin,
-            detached,
-            input,
-        } => {
-            if detached {
-                sign_detached(&ident, user_pin, input.as_deref())?;
-            } else {
-                return Err(
-                    anyhow::anyhow!("Only detached signatures are supported for now").into(),
-                );
-            }
+        cli::Command::Sign(cmd) => {
+            commands::sign::sign(cmd)?;
         }
         cli::Command::Attestation { cmd } => match cmd {
             cli::AttCommand::Cert { ident } => {
@@ -591,35 +579,6 @@ fn pick_card_for_reading(ident: Option<String>) -> Result<Box<dyn CardBackend +
     }
 }
 
-fn sign_detached(
-    ident: &str,
-    pin_file: Option<PathBuf>,
-    input: Option<&Path>,
-) -> Result<(), Box<dyn std::error::Error>> {
-    let mut input = util::open_or_stdin(input)?;
-
-    let backend = util::open_card(ident)?;
-    let mut card = Card::new(backend);
-    let mut open = card.transaction()?;
-
-    if open.fingerprints()?.signature().is_none() {
-        return Err(anyhow!("Can't sign: this card has no key in the signing slot.").into());
-    }
-
-    let user_pin = util::get_pin(&mut open, pin_file, ENTER_USER_PIN);
-
-    let mut sign = util::verify_to_sign(&mut open, user_pin.as_deref())?;
-    let s = sign.signer(&|| println!("Touch confirmation needed for signing"))?;
-
-    let message = Armorer::new(Message::new(std::io::stdout())).build()?;
-    let mut signer = Signer::new(message, s).detached().build()?;
-
-    std::io::copy(&mut input, &mut signer)?;
-    signer.finalize()?;
-
-    Ok(())
-}
-
 fn factory_reset(ident: &str) -> Result<()> {
     println!("Resetting Card {}", ident);
     let card = util::open_card(ident)?;