atproto-identity-rs / crates / atproto-identity / src / key.rs

//! Cryptographic key operations for AT Protocol identity.
//!
//! Elliptic curve cryptography for P-256, P-384, and K-256 curves including
//! key identification, signature validation, and content signing.
//! - **P-384** (secp384r1/ES384): NIST standard curve, providing higher security than P-256
//! - **K-256** (secp256k1/ES256K): Bitcoin curve, widely used in blockchain applications
//!
//! # Key Operations
//!
//! - Key type identification from multibase-encoded DID key strings
//! - ECDSA signature validation for both public and private keys
//! - Content signing with private keys
//! - Cryptographic key generation for private keys
//! - Public key derivation from private keys
//! - DID key method prefix handling
//!
//! # Example
//!
//! ```rust
//! use atproto_identity::key::{identify_key, generate_key, to_public, validate, sign, KeyType, KeyData};
//! use elliptic_curve::JwkEcKey;
//!
//! fn main() -> Result<(), Box<dyn std::error::Error>> {
//!   // Identify existing keys
//!   let key_data = identify_key("did:key:zQ3shNzMp4oaaQ1gQRzCxMGXFrSW3NEM1M9T6KCY9eA7HhyEA")?;
//!   assert_eq!(*key_data.key_type(), KeyType::K256Public);
//!
//!   // Generate new private keys (P-256, P-384, or K-256)
//!   let p256_key = generate_key(KeyType::P256Private)?;
//!   let p384_key = generate_key(KeyType::P384Private)?;
//!   let k256_key = generate_key(KeyType::K256Private)?;
//!
//!   // Derive public key from private key
//!   let p384_public = to_public(&p384_key)?;
//!   assert_eq!(*p384_public.key_type(), KeyType::P384Public);
//!
//!   // Sign and verify with derived keys
//!   let message = b"Hello AT Protocol!";
//!   let signature = sign(&p384_key, message)?;
//!   validate(&p384_public, &signature, message)?;
//!
//!   // Convert to JWK format (P-256 and P-384 support JWK)
//!   let p256_key_data = identify_key("did:key:zDnaeXduWbJ1b1Kgjf3uCdCpMDF1LEDizUiyxAxGwerou3Nh2")?;
//!   let p256_jwk: JwkEcKey = (&p256_key_data).try_into()?;
//!   let p384_jwk: JwkEcKey = (&p384_key).try_into()?;
//!   Ok(())
//! }
//! ```

use anyhow::{Context, Result, anyhow};
use ecdsa::signature::Signer;
use elliptic_curve::JwkEcKey;
use elliptic_curve::sec1::ToEncodedPoint;

use crate::model::VerificationMethod;
use crate::traits::IdentityResolver;

pub use crate::traits::KeyResolver;
use std::sync::Arc;

use crate::errors::KeyError;

#[cfg(feature = "zeroize")]
use zeroize::{Zeroize, ZeroizeOnDrop};

/// Cryptographic key types supported for AT Protocol identity.
#[derive(Clone, PartialEq, Debug)]
#[cfg_attr(feature = "zeroize", derive(Zeroize, ZeroizeOnDrop))]
pub enum KeyType {
    /// A p256 (P-256 / secp256r1 / ES256) public key.
    /// The multibase / multicodec prefix is 8024.
    P256Public,

    /// A p256 (P-256 / secp256r1 / ES256) private key.
    /// The multibase / multicodec prefix is 8626.
    P256Private,

    /// A p384 (P-384 / secp384r1 / ES384) public key.
    /// The multibase / multicodec prefix is 1200.
    P384Public,

    /// A p384 (P-384 / secp384r1 / ES384) private key.
    /// The multibase / multicodec prefix is 1301.
    P384Private,

    /// A k256 (K-256 / secp256k1 / ES256K) public key.
    /// The multibase / multicodec prefix is e701.
    K256Public,

    /// A k256 (K-256 / secp256k1 / ES256K) private key.
    /// The multibase / multicodec prefix is 8126.
    K256Private,
}

impl std::fmt::Display for KeyType {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            KeyType::P256Public => write!(f, "P256Public"),
            KeyType::P256Private => write!(f, "P256Private"),
            KeyType::P384Public => write!(f, "P384Public"),
            KeyType::P384Private => write!(f, "P384Private"),
            KeyType::K256Public => write!(f, "K256Public"),
            KeyType::K256Private => write!(f, "K256Private"),
        }
    }
}

/// A wrapper for cryptographic key data containing the key type and raw bytes.
///
/// This struct encapsulates the result of key identification and provides methods
/// for accessing the key type and bytes, as well as conversion to JWK format.
///
/// When creating variables for instances of this type, they should have the
/// suffix `key_data`. Additionally the should have the prefix `public_` or
/// `private_` to indiciate how they are used. Examples include:
/// * `public_signing_key_data`
/// * `private_dpop_key_data`
///
#[derive(Clone)]
#[cfg_attr(feature = "zeroize", derive(zeroize::Zeroize, zeroize::ZeroizeOnDrop))]
pub struct KeyData(pub KeyType, pub Vec<u8>);

impl KeyData {
    /// Creates a new KeyData instance.
    pub fn new(key_type: KeyType, bytes: Vec<u8>) -> Self {
        KeyData(key_type, bytes)
    }

    /// Returns the key type.
    pub fn key_type(&self) -> &KeyType {
        &self.0
    }

    /// Returns the raw key bytes.
    pub fn bytes(&self) -> &[u8] {
        &self.1
    }

    /// Consumes self and returns the key type and bytes as a tuple.
    pub fn into_parts(self) -> (KeyType, Vec<u8>) {
        (self.0.clone(), self.1.clone())
    }
}

impl std::fmt::Display for KeyData {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        // Get the multicodec prefix based on key type
        let prefix = match self.key_type() {
            KeyType::P256Private => [0x86, 0x26],
            KeyType::P256Public => [0x80, 0x24],
            KeyType::P384Private => [0x13, 0x01],
            KeyType::P384Public => [0x12, 0x00],
            KeyType::K256Private => [0x81, 0x26],
            KeyType::K256Public => [0xe7, 0x01],
        };

        // Combine prefix and key bytes
        let mut multicodec_bytes = Vec::with_capacity(2 + self.bytes().len());
        multicodec_bytes.extend_from_slice(&prefix);
        multicodec_bytes.extend_from_slice(self.bytes());

        // Encode using multibase (base58btc)
        let multibase_encoded = multibase::encode(multibase::Base::Base58Btc, &multicodec_bytes);

        // Add DID key prefix
        write!(f, "did:key:{}", multibase_encoded)
    }
}

/// DID key method prefix.
const DID_METHOD_KEY_PREFIX: &str = "did:key:";

/// Extracts the value portion from a DID key string.
///
/// Removes the "did:key:" prefix if present, otherwise returns the original string.
pub fn did_method_key_value(key: &str) -> &str {
    match key.strip_prefix(DID_METHOD_KEY_PREFIX) {
        Some(value) => value,
        None => key,
    }
}

/// Identifies the key type and extracts the key data from a multibase-encoded key.
///
/// Returns a KeyData instance containing the key type and the raw key bytes.
pub fn identify_key(key: &str) -> Result<KeyData, KeyError> {
    let stripped_key = did_method_key_value(key);
    let (_, decoded_multibase_key) =
        multibase::decode(stripped_key).map_err(|error| KeyError::DecodeError { error })?;

    if decoded_multibase_key.len() < 3 {
        return Err(KeyError::UnidentifiedKeyType);
    }

    // These values were verified using the following method:
    //
    // 1. Use goat to generate p256 and k256 keys to sample.
    //    `goat key generate -t k256`
    //
    // 2. Use `multibase` and `xxd` to view the hex output
    //    `multibase decode zQ3shj41kYrAKpgMvWFZ8L4uFhQ6P57zpiQEuvL1LWWa8sZqN | xxd`
    //
    // See also: https://github.com/bluesky-social/indigo/tree/main/cmd/goat
    // See also: https://github.com/docknetwork/multibase-cli

    match &decoded_multibase_key[..2] {
        // P-256 / secp256r1 / ES256 private key
        [0x86, 0x26] => Ok(KeyData::new(
            KeyType::P256Private,
            decoded_multibase_key[2..].to_vec(),
        )),

        // P-256 / secp256r1 / ES256 public key
        [0x80, 0x24] => Ok(KeyData::new(
            KeyType::P256Public,
            decoded_multibase_key[2..].to_vec(),
        )),

        // P-384 / secp384r1 / ES384 private key
        [0x13, 0x01] => Ok(KeyData::new(
            KeyType::P384Private,
            decoded_multibase_key[2..].to_vec(),
        )),

        // P-384 / secp384r1 / ES384 public key
        [0x12, 0x00] => Ok(KeyData::new(
            KeyType::P384Public,
            decoded_multibase_key[2..].to_vec(),
        )),

        // K-256 / secp256k1 / ES256K private key
        [0x81, 0x26] => Ok(KeyData::new(
            KeyType::K256Private,
            decoded_multibase_key[2..].to_vec(),
        )),

        // K-256 / secp256k1 / ES256K public key
        [0xe7, 0x01] => Ok(KeyData::new(
            KeyType::K256Public,
            decoded_multibase_key[2..].to_vec(),
        )),

        _ => Err(KeyError::InvalidMultibaseKeyType {
            prefix: decoded_multibase_key[..2].to_vec(),
        }),
    }
}

/// Validates a signature against content using the provided key.
///
/// Supports both public and private keys for signature verification.
pub fn validate(key_data: &KeyData, signature: &[u8], content: &[u8]) -> Result<(), KeyError> {
    match *key_data.key_type() {
        KeyType::P256Public => {
            let signature = ecdsa::Signature::from_slice(signature)
                .map_err(|error| KeyError::SignatureError { error })?;
            let verifying_key = p256::ecdsa::VerifyingKey::from_sec1_bytes(key_data.bytes())
                .map_err(|error| KeyError::P256Error { error })?;
            ecdsa::signature::Verifier::verify(&verifying_key, content, &signature)
                .map_err(|error| KeyError::ECDSAError { error })
        }
        KeyType::P384Public => {
            let signature = ecdsa::Signature::from_slice(signature)
                .map_err(|error| KeyError::SignatureError { error })?;
            let verifying_key = p384::ecdsa::VerifyingKey::from_sec1_bytes(key_data.bytes())
                .map_err(|error| KeyError::P384Error { error })?;
            ecdsa::signature::Verifier::verify(&verifying_key, content, &signature)
                .map_err(|error| KeyError::ECDSAError { error })
        }
        KeyType::K256Public => {
            let signature = ecdsa::Signature::from_slice(signature)
                .map_err(|error| KeyError::SignatureError { error })?;
            let verifying_key = k256::ecdsa::VerifyingKey::from_sec1_bytes(key_data.bytes())
                .map_err(|error| KeyError::K256Error { error })?;
            ecdsa::signature::Verifier::verify(&verifying_key, content, &signature)
                .map_err(|error| KeyError::ECDSAError { error })
        }
        KeyType::P256Private => {
            let signature = ecdsa::Signature::from_slice(signature)
                .map_err(|error| KeyError::SignatureError { error })?;
            let secret_key: p256::SecretKey =
                ecdsa::elliptic_curve::SecretKey::from_slice(key_data.bytes())
                    .map_err(|error| KeyError::SecretKeyError { error })?;
            let public_key = secret_key.public_key();
            let verifying_key = p256::ecdsa::VerifyingKey::from(public_key);
            ecdsa::signature::Verifier::verify(&verifying_key, content, &signature)
                .map_err(|error| KeyError::ECDSAError { error })
        }
        KeyType::P384Private => {
            let signature = ecdsa::Signature::from_slice(signature)
                .map_err(|error| KeyError::SignatureError { error })?;
            let secret_key: p384::SecretKey =
                ecdsa::elliptic_curve::SecretKey::from_slice(key_data.bytes())
                    .map_err(|error| KeyError::SecretKeyError { error })?;
            let public_key = secret_key.public_key();
            let verifying_key = p384::ecdsa::VerifyingKey::from(public_key);
            ecdsa::signature::Verifier::verify(&verifying_key, content, &signature)
                .map_err(|error| KeyError::ECDSAError { error })
        }
        KeyType::K256Private => {
            let signature = ecdsa::Signature::from_slice(signature)
                .map_err(|error| KeyError::SignatureError { error })?;
            let secret_key: k256::SecretKey =
                ecdsa::elliptic_curve::SecretKey::from_slice(key_data.bytes())
                    .map_err(|error| KeyError::SecretKeyError { error })?;
            let public_key = secret_key.public_key();
            let verifying_key = k256::ecdsa::VerifyingKey::from(public_key);
            ecdsa::signature::Verifier::verify(&verifying_key, content, &signature)
                .map_err(|error| KeyError::ECDSAError { error })
        }
    }
}

/// Signs content using a private key.
///
/// Returns an error if a public key is provided instead of a private key.
pub fn sign(key_data: &KeyData, content: &[u8]) -> Result<Vec<u8>, KeyError> {
    match *key_data.key_type() {
        KeyType::K256Public | KeyType::P256Public | KeyType::P384Public => {
            Err(KeyError::PrivateKeyRequiredForSignature)
        }
        KeyType::P256Private => {
            let secret_key: p256::SecretKey =
                ecdsa::elliptic_curve::SecretKey::from_slice(key_data.bytes())
                    .map_err(|error| KeyError::SecretKeyError { error })?;
            let signing_key: p256::ecdsa::SigningKey = p256::ecdsa::SigningKey::from(secret_key);
            let signature: p256::ecdsa::Signature = signing_key
                .try_sign(content)
                .map_err(|error| KeyError::ECDSAError { error })?;
            Ok(signature.to_vec())
        }
        KeyType::P384Private => {
            let secret_key: p384::SecretKey =
                ecdsa::elliptic_curve::SecretKey::from_slice(key_data.bytes())
                    .map_err(|error| KeyError::SecretKeyError { error })?;
            let signing_key: p384::ecdsa::SigningKey = p384::ecdsa::SigningKey::from(secret_key);
            let signature: p384::ecdsa::Signature = signing_key
                .try_sign(content)
                .map_err(|error| KeyError::ECDSAError { error })?;
            Ok(signature.to_vec())
        }
        KeyType::K256Private => {
            let secret_key: k256::SecretKey =
                ecdsa::elliptic_curve::SecretKey::from_slice(key_data.bytes())
                    .map_err(|error| KeyError::SecretKeyError { error })?;
            let signing_key: k256::ecdsa::SigningKey = k256::ecdsa::SigningKey::from(secret_key);
            let signature: k256::ecdsa::Signature = signing_key
                .try_sign(content)
                .map_err(|error| KeyError::ECDSAError { error })?;
            Ok(signature.to_vec())
        }
    }
}

/// Key resolver implementation that fetches DID documents using an [`IdentityResolver`].
#[derive(Clone)]
pub struct IdentityDocumentKeyResolver {
    identity_resolver: Arc<dyn IdentityResolver>,
}

impl IdentityDocumentKeyResolver {
    /// Creates a new key resolver backed by an [`IdentityResolver`].
    pub fn new(identity_resolver: Arc<dyn IdentityResolver>) -> Self {
        Self { identity_resolver }
    }
}

#[async_trait::async_trait]
impl KeyResolver for IdentityDocumentKeyResolver {
    async fn resolve(&self, key: &str) -> Result<KeyData> {
        if let Some(did_key) = key.split('#').next() {
            if let Ok(key_data) = identify_key(did_key) {
                return Ok(key_data);
            }
        } else if let Ok(key_data) = identify_key(key) {
            return Ok(key_data);
        }

        let (did, fragment) = key
            .split_once('#')
            .context("Key reference must contain a DID fragment (e.g., did:example#key)")?;

        if did.is_empty() || fragment.is_empty() {
            return Err(anyhow!(
                "Key reference must include both DID and fragment (received `{key}`)"
            ));
        }

        let document = self.identity_resolver.resolve(did).await?;
        let fragment_with_hash = format!("#{fragment}");

        let public_key_multibase = document
            .verification_method
            .iter()
            .find_map(|method| match method {
                VerificationMethod::Multikey {
                    id,
                    public_key_multibase,
                    ..
                } if id == key || *id == fragment_with_hash => Some(public_key_multibase.clone()),
                _ => None,
            })
            .context(format!(
                "Verification method `{key}` not found in DID document `{did}`"
            ))?;

        let full_key = if public_key_multibase.starts_with("did:key:") {
            public_key_multibase
        } else {
            format!("did:key:{}", public_key_multibase)
        };

        identify_key(&full_key).context("Failed to parse key data from verification method")
    }
}

impl TryInto<JwkEcKey> for &KeyData {
    type Error = KeyError;

    fn try_into(self) -> Result<JwkEcKey, Self::Error> {
        match *self.key_type() {
            KeyType::P256Public => {
                let public_key = p256::PublicKey::from_sec1_bytes(self.bytes()).map_err(|e| {
                    KeyError::JWKConversionFailed {
                        error: format!("Failed to parse P256 public key: {}", e),
                    }
                })?;
                Ok(public_key.to_jwk())
            }
            KeyType::P256Private => {
                let secret_key = p256::SecretKey::from_slice(self.bytes())
                    .map_err(|error| KeyError::SecretKeyError { error })?;
                Ok(secret_key.to_jwk())
            }
            KeyType::P384Public => {
                let public_key = p384::PublicKey::from_sec1_bytes(self.bytes()).map_err(|e| {
                    KeyError::JWKConversionFailed {
                        error: format!("Failed to parse P384 public key: {}", e),
                    }
                })?;
                Ok(public_key.to_jwk())
            }
            KeyType::P384Private => {
                let secret_key = p384::SecretKey::from_slice(self.bytes())
                    .map_err(|error| KeyError::SecretKeyError { error })?;
                Ok(secret_key.to_jwk())
            }
            KeyType::K256Public => {
                let public_key = k256::PublicKey::from_sec1_bytes(self.bytes()).map_err(|e| {
                    KeyError::JWKConversionFailed {
                        error: format!("Failed to parse k256 public key: {}", e),
                    }
                })?;
                Ok(public_key.to_jwk())
            }
            KeyType::K256Private => {
                let secret_key = k256::SecretKey::from_slice(self.bytes())
                    .map_err(|error| KeyError::SecretKeyError { error })?;
                Ok(secret_key.to_jwk())
            }
        }
    }
}

/// Generates a new cryptographic key of the specified type.
///
/// # Arguments
/// * `key_type` - The type of key to generate
///
/// # Returns
/// A `KeyData` containing the generated key material
///
/// # Errors
/// * Returns `KeyError::PublicKeyGenerationNotSupported` for public key types
/// * Returns `KeyError::SecretKeyError` if key generation fails
///
/// # Example
/// ```rust
/// use atproto_identity::key::{generate_key, KeyType};
///
/// let private_key = generate_key(KeyType::P256Private)?;
/// assert_eq!(*private_key.key_type(), KeyType::P256Private);
/// # Ok::<(), atproto_identity::errors::KeyError>(())
/// ```
pub fn generate_key(key_type: KeyType) -> Result<KeyData, KeyError> {
    match key_type {
        KeyType::P256Private => {
            let secret_key = p256::SecretKey::random(&mut rand::thread_rng());
            Ok(KeyData::new(
                KeyType::P256Private,
                secret_key.to_bytes().to_vec(),
            ))
        }
        KeyType::P384Private => {
            let secret_key = p384::SecretKey::random(&mut rand::thread_rng());
            Ok(KeyData::new(
                KeyType::P384Private,
                secret_key.to_bytes().to_vec(),
            ))
        }
        KeyType::K256Private => {
            let secret_key = k256::SecretKey::random(&mut rand::thread_rng());
            Ok(KeyData::new(
                KeyType::K256Private,
                secret_key.to_bytes().to_vec(),
            ))
        }
        KeyType::P256Public => Err(KeyError::PublicKeyGenerationNotSupported),
        KeyType::P384Public => Err(KeyError::PublicKeyGenerationNotSupported),
        KeyType::K256Public => Err(KeyError::PublicKeyGenerationNotSupported),
    }
}

/// Derives a public key from a private key, or returns the key if it's already public.
///
/// # Arguments
/// * `key_data` - The key data to convert to public key format
///
/// # Returns
/// A `KeyData` containing the corresponding public key
///
/// # Errors
/// * Returns `KeyError::SecretKeyError` if private key parsing fails
///
/// # Example
/// ```rust
/// use atproto_identity::key::{generate_key, to_public, KeyType};
///
/// let private_key = generate_key(KeyType::P256Private)?;
/// let public_key = to_public(&private_key)?;
/// assert_eq!(*public_key.key_type(), KeyType::P256Public);
///
/// // Works with public keys too
/// let same_public_key = to_public(&public_key)?;
/// assert_eq!(public_key.bytes(), same_public_key.bytes());
/// # Ok::<(), atproto_identity::errors::KeyError>(())
/// ```
pub fn to_public(key_data: &KeyData) -> Result<KeyData, KeyError> {
    match key_data.key_type() {
        KeyType::P256Private => {
            let secret_key: p256::SecretKey =
                ecdsa::elliptic_curve::SecretKey::from_slice(key_data.bytes())
                    .map_err(|error| KeyError::SecretKeyError { error })?;
            let public_key = secret_key.public_key();
            let compressed = public_key.to_encoded_point(true);
            let public_key_bytes = compressed.to_bytes();
            Ok(KeyData::new(KeyType::P256Public, public_key_bytes.to_vec()))
        }
        KeyType::P384Private => {
            let secret_key: p384::SecretKey =
                ecdsa::elliptic_curve::SecretKey::from_slice(key_data.bytes())
                    .map_err(|error| KeyError::SecretKeyError { error })?;
            let public_key = secret_key.public_key();
            let compressed = public_key.to_encoded_point(true);
            let public_key_bytes = compressed.to_bytes();
            Ok(KeyData::new(KeyType::P384Public, public_key_bytes.to_vec()))
        }
        KeyType::K256Private => {
            let secret_key: k256::SecretKey =
                ecdsa::elliptic_curve::SecretKey::from_slice(key_data.bytes())
                    .map_err(|error| KeyError::SecretKeyError { error })?;
            let public_key = secret_key.public_key();
            let public_key_bytes = public_key.to_sec1_bytes();
            Ok(KeyData::new(KeyType::K256Public, public_key_bytes.to_vec()))
        }
        KeyType::P256Public | KeyType::P384Public | KeyType::K256Public => {
            // Return a clone of the existing public key
            Ok(key_data.clone())
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_identify_key() {
        // Test valid K256 private key (repeat 4 times as in original test)
        for _ in 0..4 {
            let result = identify_key("z3vLVqpQveB3w8G6MQsLVseJ1Z2E1JyQzUj6WgRYNNwB9jdE");
            assert!(result.is_ok());
            let key_data = result.unwrap();
            assert_eq!(*key_data.key_type(), KeyType::K256Private);
        }

        // Test invalid multibase encoding
        assert!(matches!(
            identify_key("asdasdasd"),
            Err(KeyError::DecodeError { .. })
        ));

        // Test invalid key type prefix
        assert!(matches!(
            identify_key("z4vLVqpQveB3w8G6MQsLVseJ1Z2E1JyQzUj6WgRYNNwB9jdE"),
            Err(KeyError::InvalidMultibaseKeyType { .. })
        ));
    }

    #[test]
    fn test_sign_p256() -> Result<()> {
        let private_key = "did:key:z42tnbHmmnhF11nwSnp5kQJbcZQw2Vbw5WF3ABDSxPtDgU2o";
        let public_key = "did:key:zDnaeXduWbJ1b1Kgjf3uCdCpMDF1LEDizUiyxAxGwerou3Nh2";

        let private_key_data = identify_key(private_key);
        assert!(private_key_data.is_ok());
        let private_key_data = private_key_data.unwrap();
        assert_eq!(*private_key_data.key_type(), KeyType::P256Private);

        let public_key_data = identify_key(public_key);
        assert!(public_key_data.is_ok());
        let public_key_data = public_key_data.unwrap();
        assert_eq!(*public_key_data.key_type(), KeyType::P256Public);

        let content = "hello world".as_bytes();

        let signature = sign(&private_key_data, content);
        assert!(signature.is_ok());
        let signature = signature.unwrap();

        {
            let validation = validate(&public_key_data, &signature, content);
            assert!(validation.is_ok());
        }
        {
            let validation = validate(&private_key_data, &signature, content);
            assert!(validation.is_ok());
        }
        Ok(())
    }

    #[test]
    fn test_sign_k256() -> Result<()> {
        let private_key = "did:key:z3vLY4nbXy2rV4Qr65gUtfnSF3A8Be7gmYzUiCX6eo2PR1Rt";
        let public_key = "did:key:zQ3shNzMp4oaaQ1gQRzCxMGXFrSW3NEM1M9T6KCY9eA7HhyEA";

        let private_key_data = identify_key(private_key);
        assert!(private_key_data.is_ok());
        let private_key_data = private_key_data.unwrap();
        assert_eq!(*private_key_data.key_type(), KeyType::K256Private);

        let public_key_data = identify_key(public_key);
        assert!(public_key_data.is_ok());
        let public_key_data = public_key_data.unwrap();
        assert_eq!(*public_key_data.key_type(), KeyType::K256Public);

        let content = "hello world".as_bytes();

        let signature = sign(&private_key_data, content);
        assert!(signature.is_ok());
        let signature = signature.unwrap();

        {
            let validation = validate(&public_key_data, &signature, content);
            assert!(validation.is_ok());
        }
        {
            let validation = validate(&private_key_data, &signature, content);
            assert!(validation.is_ok());
        }
        Ok(())
    }

    #[test]
    fn test_to_jwk_p256() -> Result<()> {
        let private_key = "did:key:z42tnbHmmnhF11nwSnp5kQJbcZQw2Vbw5WF3ABDSxPtDgU2o";
        let public_key = "did:key:zDnaeXduWbJ1b1Kgjf3uCdCpMDF1LEDizUiyxAxGwerou3Nh2";

        let private_key_data = identify_key(private_key);
        assert!(private_key_data.is_ok());
        let private_key_data = private_key_data.unwrap();
        assert_eq!(*private_key_data.key_type(), KeyType::P256Private);

        let public_key_data = identify_key(public_key);
        assert!(public_key_data.is_ok());
        let public_key_data = public_key_data.unwrap();
        assert_eq!(*public_key_data.key_type(), KeyType::P256Public);

        // Test private key to JWK conversion
        let private_jwk: Result<elliptic_curve::JwkEcKey, _> = (&private_key_data).try_into();
        assert!(private_jwk.is_ok());

        // Test public key to JWK conversion
        let public_jwk: Result<elliptic_curve::JwkEcKey, _> = (&public_key_data).try_into();
        assert!(public_jwk.is_ok());

        Ok(())
    }

    #[test]
    fn test_to_jwk_k256_supported() -> Result<()> {
        let private_key = "did:key:z3vLY4nbXy2rV4Qr65gUtfnSF3A8Be7gmYzUiCX6eo2PR1Rt";
        let public_key = "did:key:zQ3shNzMp4oaaQ1gQRzCxMGXFrSW3NEM1M9T6KCY9eA7HhyEA";

        let private_key_data = identify_key(private_key);
        assert!(private_key_data.is_ok());
        let private_key_data = private_key_data.unwrap();
        assert_eq!(*private_key_data.key_type(), KeyType::K256Private);

        let public_key_data = identify_key(public_key);
        assert!(public_key_data.is_ok());
        let public_key_data = public_key_data.unwrap();
        assert_eq!(*public_key_data.key_type(), KeyType::K256Public);

        // Test that K256 keys successfully convert to JWK format
        let private_jwk: Result<elliptic_curve::JwkEcKey, _> = (&private_key_data).try_into();
        assert!(private_jwk.is_ok());
        let private_jwk = private_jwk.unwrap();
        assert_eq!(private_jwk.crv(), "secp256k1");

        let public_jwk: Result<elliptic_curve::JwkEcKey, _> = (&public_key_data).try_into();
        assert!(public_jwk.is_ok());
        let public_jwk = public_jwk.unwrap();
        assert_eq!(public_jwk.crv(), "secp256k1");

        Ok(())
    }

    #[test]
    fn test_try_into_jwk_keydata() -> Result<()> {
        let private_key = "did:key:z42tnbHmmnhF11nwSnp5kQJbcZQw2Vbw5WF3ABDSxPtDgU2o";
        let public_key = "did:key:zDnaeXduWbJ1b1Kgjf3uCdCpMDF1LEDizUiyxAxGwerou3Nh2";

        let private_key_data = identify_key(private_key);
        assert!(private_key_data.is_ok());
        let private_key_data = private_key_data.unwrap();
        assert_eq!(*private_key_data.key_type(), KeyType::P256Private);

        let public_key_data = identify_key(public_key);
        assert!(public_key_data.is_ok());
        let public_key_data = public_key_data.unwrap();
        assert_eq!(*public_key_data.key_type(), KeyType::P256Public);

        // Test TryInto with KeyData directly
        let private_jwk: Result<JwkEcKey, KeyError> = (&private_key_data).try_into();
        assert!(private_jwk.is_ok());

        let public_jwk: Result<JwkEcKey, KeyError> = (&public_key_data).try_into();
        assert!(public_jwk.is_ok());

        Ok(())
    }

    #[test]
    fn test_generate_key_p256_private() -> Result<()> {
        let key_data = generate_key(KeyType::P256Private)?;
        assert_eq!(*key_data.key_type(), KeyType::P256Private);
        assert_eq!(key_data.bytes().len(), 32); // P-256 private keys are 32 bytes

        // Test that we can sign with the generated key
        let content = "test content".as_bytes();
        let signature = sign(&key_data, content)?;
        let validation = validate(&key_data, &signature, content);
        assert!(validation.is_ok());

        Ok(())
    }

    #[test]
    fn test_generate_key_k256_private() -> Result<()> {
        let key_data = generate_key(KeyType::K256Private)?;
        assert_eq!(*key_data.key_type(), KeyType::K256Private);
        assert_eq!(key_data.bytes().len(), 32); // K-256 private keys are 32 bytes

        // Test that we can sign with the generated key
        let content = "test content".as_bytes();
        let signature = sign(&key_data, content)?;
        let validation = validate(&key_data, &signature, content);
        assert!(validation.is_ok());

        Ok(())
    }

    #[test]
    fn test_generate_key_public_not_supported() {
        let result = generate_key(KeyType::P256Public);
        assert!(matches!(
            result,
            Err(KeyError::PublicKeyGenerationNotSupported)
        ));

        let result = generate_key(KeyType::K256Public);
        assert!(matches!(
            result,
            Err(KeyError::PublicKeyGenerationNotSupported)
        ));
    }

    #[test]
    fn test_generate_key_uniqueness() -> Result<()> {
        // Generate multiple keys and ensure they're different
        let key1 = generate_key(KeyType::P256Private)?;
        let key2 = generate_key(KeyType::P256Private)?;
        assert_ne!(key1.bytes(), key2.bytes());

        let key3 = generate_key(KeyType::K256Private)?;
        let key4 = generate_key(KeyType::K256Private)?;
        assert_ne!(key3.bytes(), key4.bytes());

        Ok(())
    }

    #[test]
    fn test_keydata_display_p256_private() -> Result<()> {
        // Generate a P-256 private key
        let original_key = generate_key(KeyType::P256Private)?;

        // Convert to string using Display trait
        let key_string = format!("{}", original_key);

        // Verify it has the correct prefix
        assert!(key_string.starts_with("did:key:"));

        // Parse it back using identify_key
        let parsed_key = identify_key(&key_string)?;

        // Verify round-trip: key type should match
        assert_eq!(original_key.key_type(), parsed_key.key_type());

        // Verify round-trip: bytes should match
        assert_eq!(original_key.bytes(), parsed_key.bytes());

        // Test signing and verification with both keys
        let content = "test message for p256".as_bytes();

        // Sign with original key
        let signature = sign(&original_key, content)?;

        // Verify with original key
        validate(&original_key, &signature, content)?;

        // Verify with parsed key
        validate(&parsed_key, &signature, content)?;

        // Sign with parsed key
        let signature2 = sign(&parsed_key, content)?;

        // Verify both signatures are the same (deterministic signing)
        // Note: ECDSA signatures may not be deterministic, so we just verify both work
        validate(&original_key, &signature2, content)?;
        validate(&parsed_key, &signature2, content)?;

        Ok(())
    }

    #[test]
    fn test_keydata_display_k256_private() -> Result<()> {
        // Generate a K-256 private key
        let original_key = generate_key(KeyType::K256Private)?;

        // Convert to string using Display trait
        let key_string = format!("{}", original_key);

        // Verify it has the correct prefix
        assert!(key_string.starts_with("did:key:"));

        // Parse it back using identify_key
        let parsed_key = identify_key(&key_string)?;

        // Verify round-trip: key type should match
        assert_eq!(original_key.key_type(), parsed_key.key_type());

        // Verify round-trip: bytes should match
        assert_eq!(original_key.bytes(), parsed_key.bytes());

        // Test signing and verification with both keys
        let content = "test message for k256".as_bytes();

        // Sign with original key
        let signature = sign(&original_key, content)?;

        // Verify with original key
        validate(&original_key, &signature, content)?;

        // Verify with parsed key
        validate(&parsed_key, &signature, content)?;

        // Sign with parsed key
        let signature2 = sign(&parsed_key, content)?;

        // Verify both signatures work
        validate(&original_key, &signature2, content)?;
        validate(&parsed_key, &signature2, content)?;

        Ok(())
    }

    #[test]
    fn test_keydata_display_existing_keys() -> Result<()> {
        // Test with known existing keys from other tests
        let p256_private_key = "did:key:z42tnbHmmnhF11nwSnp5kQJbcZQw2Vbw5WF3ABDSxPtDgU2o";
        let k256_private_key = "did:key:z3vLY4nbXy2rV4Qr65gUtfnSF3A8Be7gmYzUiCX6eo2PR1Rt";

        // Parse and re-serialize P-256 key
        let parsed_p256 = identify_key(p256_private_key)?;
        let reserialized_p256 = format!("{}", parsed_p256);
        assert_eq!(p256_private_key, reserialized_p256);

        // Parse and re-serialize K-256 key
        let parsed_k256 = identify_key(k256_private_key)?;
        let reserialized_k256 = format!("{}", parsed_k256);
        assert_eq!(k256_private_key, reserialized_k256);

        Ok(())
    }

    #[test]
    fn test_keydata_display_cross_verification() -> Result<()> {
        // Generate keys and test cross-verification scenarios
        let p256_key = generate_key(KeyType::P256Private)?;
        let k256_key = generate_key(KeyType::K256Private)?;

        // Serialize both keys
        let p256_string = format!("{}", p256_key);
        let k256_string = format!("{}", k256_key);

        // Verify they produce different strings
        assert_ne!(p256_string, k256_string);

        // Parse them back
        let parsed_p256 = identify_key(&p256_string)?;
        let parsed_k256 = identify_key(&k256_string)?;

        // Verify types are preserved
        assert_eq!(*parsed_p256.key_type(), KeyType::P256Private);
        assert_eq!(*parsed_k256.key_type(), KeyType::K256Private);

        // Test that keys from different curves can't be used interchangeably
        let content = "cross verification test".as_bytes();

        // Sign with P-256
        let p256_signature = sign(&p256_key, content)?;

        // Sign with K-256
        let k256_signature = sign(&k256_key, content)?;

        // Verify P-256 signature with P-256 key (should work)
        assert!(validate(&p256_key, &p256_signature, content).is_ok());
        assert!(validate(&parsed_p256, &p256_signature, content).is_ok());

        // Verify K-256 signature with K-256 key (should work)
        assert!(validate(&k256_key, &k256_signature, content).is_ok());
        assert!(validate(&parsed_k256, &k256_signature, content).is_ok());

        // Cross-verification should fail
        assert!(validate(&p256_key, &k256_signature, content).is_err());
        assert!(validate(&k256_key, &p256_signature, content).is_err());

        Ok(())
    }

    #[test]
    fn test_keydata_display_format_consistency() -> Result<()> {
        // Test that the Display format matches expected patterns
        let p256_key = generate_key(KeyType::P256Private)?;
        let k256_key = generate_key(KeyType::K256Private)?;

        let p256_string = format!("{}", p256_key);
        let k256_string = format!("{}", k256_key);

        // Verify format structure
        assert!(p256_string.starts_with("did:key:z"));
        assert!(k256_string.starts_with("did:key:z"));

        // Verify they can be parsed
        let _parsed_p256 = identify_key(&p256_string)?;
        let _parsed_k256 = identify_key(&k256_string)?;

        // Verify string lengths are reasonable (multibase encoded keys should be consistent length)
        // P-256 private keys: 2 bytes prefix + 32 bytes key = 34 bytes -> ~46 chars base58 + "did:key:z" prefix
        assert!(p256_string.len() > 50 && p256_string.len() < 60);

        // K-256 private keys: 2 bytes prefix + 32 bytes key = 34 bytes -> ~46 chars base58 + "did:key:z" prefix
        assert!(k256_string.len() > 50 && k256_string.len() < 60);

        Ok(())
    }

    #[test]
    fn test_complete_workflow_demonstration() -> Result<()> {
        println!("\n=== KeyData Display Implementation Test ===");

        // Step 1: Generate keys
        println!("1. Generating keys...");
        let p256_key = generate_key(KeyType::P256Private)?;
        let k256_key = generate_key(KeyType::K256Private)?;

        // Step 2: Display keys (serialize)
        println!("2. Serializing keys to DID format...");
        let p256_did = format!("{}", p256_key);
        let k256_did = format!("{}", k256_key);
        println!("   P-256 DID: {}", p256_did);
        println!("   K-256 DID: {}", k256_did);

        // Step 3: Parse keys back (identify)
        println!("3. Parsing DIDs back to KeyData...");
        let parsed_p256 = identify_key(&p256_did)?;
        let parsed_k256 = identify_key(&k256_did)?;
        println!("   P-256 parsed successfully: {:?}", parsed_p256.key_type());
        println!("   K-256 parsed successfully: {:?}", parsed_k256.key_type());

        // Step 4: Verify round-trip
        println!("4. Verifying round-trip integrity...");
        assert_eq!(p256_key.bytes(), parsed_p256.bytes());
        assert_eq!(k256_key.bytes(), parsed_k256.bytes());
        println!("   Round-trip successful for both keys!");

        // Step 5: Sign and verify
        println!("5. Testing signing and verification...");
        let test_data = "Hello AT Protocol!".as_bytes();

        // Sign with original keys
        let p256_signature = sign(&p256_key, test_data)?;
        let k256_signature = sign(&k256_key, test_data)?;

        // Verify with parsed keys
        validate(&parsed_p256, &p256_signature, test_data)?;
        validate(&parsed_k256, &k256_signature, test_data)?;
        println!("   Signatures verified successfully with parsed keys!");

        // Step 6: Cross-verification should fail
        println!("6. Testing cross-curve verification (should fail)...");
        assert!(validate(&parsed_p256, &k256_signature, test_data).is_err());
        assert!(validate(&parsed_k256, &p256_signature, test_data).is_err());
        println!("   Cross-curve verification correctly failed!");

        println!("=== All tests completed successfully! ===\n");

        Ok(())
    }

    #[test]
    fn test_to_public_p256() -> Result<()> {
        // Generate a P-256 private key
        let private_key = generate_key(KeyType::P256Private)?;

        // Convert to public key
        let public_key = to_public(&private_key)?;

        // Verify the key type is correct
        assert_eq!(*public_key.key_type(), KeyType::P256Public);

        // Test that the derived public key can verify signatures from the private key
        let content = "test message for p256 public key derivation".as_bytes();
        let signature = sign(&private_key, content)?;

        // Public key should be able to verify the signature
        validate(&public_key, &signature, content)?;

        // Test that the public key produces a valid DID string
        let public_key_did = format!("{}", public_key);
        assert!(public_key_did.starts_with("did:key:"));

        // Parse the DID back and verify it's the same
        let parsed_public_key = identify_key(&public_key_did)?;
        assert_eq!(*parsed_public_key.key_type(), KeyType::P256Public);
        assert_eq!(public_key.bytes(), parsed_public_key.bytes());

        Ok(())
    }

    #[test]
    fn test_to_public_k256() -> Result<()> {
        // Generate a K-256 private key
        let private_key = generate_key(KeyType::K256Private)?;

        // Convert to public key
        let public_key = to_public(&private_key)?;

        // Verify the key type is correct
        assert_eq!(*public_key.key_type(), KeyType::K256Public);

        // Test that the derived public key can verify signatures from the private key
        let content = "test message for k256 public key derivation".as_bytes();
        let signature = sign(&private_key, content)?;

        // Public key should be able to verify the signature
        validate(&public_key, &signature, content)?;

        // Test that the public key produces a valid DID string
        let public_key_did = format!("{}", public_key);
        assert!(public_key_did.starts_with("did:key:"));

        // Parse the DID back and verify it's the same
        let parsed_public_key = identify_key(&public_key_did)?;
        assert_eq!(*parsed_public_key.key_type(), KeyType::K256Public);
        assert_eq!(public_key.bytes(), parsed_public_key.bytes());

        Ok(())
    }

    #[test]
    fn test_to_public_with_public_keys() -> Result<()> {
        // Test that passing a public key returns the same key
        let p256_private = generate_key(KeyType::P256Private)?;
        let p256_public = to_public(&p256_private)?;

        // Calling to_public on a public key should return the same key
        let result = to_public(&p256_public)?;
        assert_eq!(*result.key_type(), KeyType::P256Public);
        assert_eq!(p256_public.bytes(), result.bytes());

        let k256_private = generate_key(KeyType::K256Private)?;
        let k256_public = to_public(&k256_private)?;

        let result = to_public(&k256_public)?;
        assert_eq!(*result.key_type(), KeyType::K256Public);
        assert_eq!(k256_public.bytes(), result.bytes());

        Ok(())
    }

    #[test]
    fn test_to_public_existing_keys() -> Result<()> {
        // Test with known private keys to ensure consistent behavior
        let p256_private_key = "did:key:z42tj8ZrAza9WkewDELwWMN37TS3coEbGdZh8bp1URfMVnpx";
        let k256_private_key = "did:key:z3vLW46Z1UHwnr7vN33MoFt2sBQDQagn9HTvWnsQDHegUixP";

        // Parse the private keys
        let parsed_p256_private = identify_key(p256_private_key)?;
        let parsed_k256_private = identify_key(k256_private_key)?;

        // Convert to public keys
        let p256_public = to_public(&parsed_p256_private)?;
        let k256_public = to_public(&parsed_k256_private)?;

        // Verify types
        assert_eq!(*p256_public.key_type(), KeyType::P256Public);
        assert_eq!(*k256_public.key_type(), KeyType::K256Public);

        // Test signing and verification
        let content = "test with existing keys".as_bytes();

        let p256_signature = sign(&parsed_p256_private, content)?;
        let k256_signature = sign(&parsed_k256_private, content)?;

        // Verify with derived public keys
        validate(&p256_public, &p256_signature, content)?;
        validate(&k256_public, &k256_signature, content)?;

        Ok(())
    }

    #[test]
    fn test_to_public_comprehensive_workflow() -> Result<()> {
        println!("\n=== Public Key Derivation Test ===");

        // Generate private keys
        println!("1. Generating private keys...");
        let p256_private = generate_key(KeyType::P256Private)?;
        let k256_private = generate_key(KeyType::K256Private)?;

        // Derive public keys
        println!("2. Deriving public keys...");
        let p256_public = to_public(&p256_private)?;
        let k256_public = to_public(&k256_private)?;

        // Serialize all keys
        println!("3. Serializing keys to DID format...");
        let p256_private_did = format!("{}", p256_private);
        let p256_public_did = format!("{}", p256_public);
        let k256_private_did = format!("{}", k256_private);
        let k256_public_did = format!("{}", k256_public);

        println!("   P-256 Private: {}", p256_private_did);
        println!("   P-256 Public:  {}", p256_public_did);
        println!("   K-256 Private: {}", k256_private_did);
        println!("   K-256 Public:  {}", k256_public_did);

        // Verify different DID patterns
        assert_ne!(p256_private_did, p256_public_did);
        assert_ne!(k256_private_did, k256_public_did);
        assert_ne!(p256_public_did, k256_public_did);

        // Test signing and verification
        println!("4. Testing signature verification...");
        let test_data = "Public key derivation test data".as_bytes();

        let p256_signature = sign(&p256_private, test_data)?;
        let k256_signature = sign(&k256_private, test_data)?;

        // Verify with derived public keys
        validate(&p256_public, &p256_signature, test_data)?;
        validate(&k256_public, &k256_signature, test_data)?;
        println!("   Signatures verified successfully with derived public keys!");

        // Parse public key DIDs and re-verify
        println!("5. Testing DID round-trip with public keys...");
        let parsed_p256_public = identify_key(&p256_public_did)?;
        let parsed_k256_public = identify_key(&k256_public_did)?;

        validate(&parsed_p256_public, &p256_signature, test_data)?;
        validate(&parsed_k256_public, &k256_signature, test_data)?;
        println!("   Parsed public keys also verify signatures correctly!");

        println!("=== Public key derivation workflow completed successfully! ===\n");

        Ok(())
    }

    #[test]
    fn test_to_public_key_properties() -> Result<()> {
        // Test that derived public keys have expected properties
        let p256_private = generate_key(KeyType::P256Private)?;
        let k256_private = generate_key(KeyType::K256Private)?;

        let p256_public = to_public(&p256_private)?;
        let k256_public = to_public(&k256_private)?;

        // P-256 public keys should be 65 bytes (uncompressed) or 33 bytes (compressed)
        // SEC1 format is typically uncompressed for public keys: 0x04 + 32 bytes x + 32 bytes y
        assert!(p256_public.bytes().len() == 65 || p256_public.bytes().len() == 33);

        // K-256 public keys should also be 65 bytes (uncompressed) or 33 bytes (compressed)
        assert!(k256_public.bytes().len() == 65 || k256_public.bytes().len() == 33);

        // Test that multiple derivations from the same private key produce the same public key
        let p256_public2 = to_public(&p256_private)?;
        let k256_public2 = to_public(&k256_private)?;

        assert_eq!(p256_public.bytes(), p256_public2.bytes());
        assert_eq!(k256_public.bytes(), k256_public2.bytes());

        Ok(())
    }

    #[test]
    fn test_to_public_with_existing_public_keys() -> Result<()> {
        // Test with known public keys from the test suite
        let p256_public_key = "did:key:zDnaeXduWbJ1b1Kgjf3uCdCpMDF1LEDizUiyxAxGwerou3Nh2";
        let k256_public_key = "did:key:zQ3shNzMp4oaaQ1gQRzCxMGXFrSW3NEM1M9T6KCY9eA7HhyEA";

        // Parse the public keys
        let parsed_p256_public = identify_key(p256_public_key)?;
        let parsed_k256_public = identify_key(k256_public_key)?;

        // Verify they are public keys
        assert_eq!(*parsed_p256_public.key_type(), KeyType::P256Public);
        assert_eq!(*parsed_k256_public.key_type(), KeyType::K256Public);

        // Calling to_public should return the same keys
        let same_p256_public = to_public(&parsed_p256_public)?;
        let same_k256_public = to_public(&parsed_k256_public)?;

        // Verify they are identical
        assert_eq!(*same_p256_public.key_type(), KeyType::P256Public);
        assert_eq!(*same_k256_public.key_type(), KeyType::K256Public);
        assert_eq!(parsed_p256_public.bytes(), same_p256_public.bytes());
        assert_eq!(parsed_k256_public.bytes(), same_k256_public.bytes());

        // Verify they serialize to the same DID strings
        assert_eq!(format!("{}", same_p256_public), p256_public_key);
        assert_eq!(format!("{}", same_k256_public), k256_public_key);

        Ok(())
    }

    // ===== P-384 SPECIFIC TESTS =====

    #[test]
    fn test_generate_key_p384_private() -> Result<()> {
        let key_data = generate_key(KeyType::P384Private)?;
        assert_eq!(*key_data.key_type(), KeyType::P384Private);
        assert_eq!(key_data.bytes().len(), 48); // P-384 private keys are 48 bytes

        // Test that we can sign with the generated key
        let content = "test content for p384".as_bytes();
        let signature = sign(&key_data, content)?;
        let validation = validate(&key_data, &signature, content);
        assert!(validation.is_ok());

        Ok(())
    }

    #[test]
    fn test_generate_key_p384_public_not_supported() {
        let result = generate_key(KeyType::P384Public);
        assert!(matches!(
            result,
            Err(KeyError::PublicKeyGenerationNotSupported)
        ));
    }

    #[test]
    fn test_generate_key_p384_uniqueness() -> Result<()> {
        // Generate multiple P-384 keys and ensure they're different
        let key1 = generate_key(KeyType::P384Private)?;
        let key2 = generate_key(KeyType::P384Private)?;
        assert_ne!(key1.bytes(), key2.bytes());

        Ok(())
    }

    #[test]
    fn test_sign_and_validate_p384() -> Result<()> {
        // Generate a P-384 private key
        let private_key = generate_key(KeyType::P384Private)?;

        // Derive the corresponding public key
        let public_key = to_public(&private_key)?;
        assert_eq!(*public_key.key_type(), KeyType::P384Public);

        let content = "hello world p384 test".as_bytes();

        // Sign with private key
        let signature = sign(&private_key, content)?;
        assert!(!signature.is_empty());

        // Verify with public key
        validate(&public_key, &signature, content)?;

        // Verify with private key (should also work)
        validate(&private_key, &signature, content)?;

        // Test signature verification fails with wrong content
        let wrong_content = "wrong content".as_bytes();
        assert!(validate(&public_key, &signature, wrong_content).is_err());

        Ok(())
    }

    #[test]
    fn test_p384_keydata_display_round_trip() -> Result<()> {
        // Generate a P-384 private key
        let original_key = generate_key(KeyType::P384Private)?;

        // Convert to string using Display trait
        let key_string = format!("{}", original_key);

        // Verify it has the correct prefix
        assert!(key_string.starts_with("did:key:"));

        // Parse it back using identify_key
        let parsed_key = identify_key(&key_string)?;

        // Verify round-trip: key type should match
        assert_eq!(original_key.key_type(), parsed_key.key_type());

        // Verify round-trip: bytes should match
        assert_eq!(original_key.bytes(), parsed_key.bytes());

        // Test signing and verification with both keys
        let content = "test message for p384 round trip".as_bytes();

        // Sign with original key
        let signature = sign(&original_key, content)?;

        // Verify with original key
        validate(&original_key, &signature, content)?;

        // Verify with parsed key
        validate(&parsed_key, &signature, content)?;

        // Sign with parsed key
        let signature2 = sign(&parsed_key, content)?;

        // Verify both signatures work
        validate(&original_key, &signature2, content)?;
        validate(&parsed_key, &signature2, content)?;

        Ok(())
    }

    #[test]
    fn test_p384_to_public_key_derivation() -> Result<()> {
        // Generate a P-384 private key
        let private_key = generate_key(KeyType::P384Private)?;

        // Convert to public key
        let public_key = to_public(&private_key)?;

        // Verify the key type is correct
        assert_eq!(*public_key.key_type(), KeyType::P384Public);

        // Test that the derived public key can verify signatures from the private key
        let content = "test message for p384 public key derivation".as_bytes();
        let signature = sign(&private_key, content)?;

        // Public key should be able to verify the signature
        validate(&public_key, &signature, content)?;

        // Test that the public key produces a valid DID string
        let public_key_did = format!("{}", public_key);
        assert!(public_key_did.starts_with("did:key:"));

        // Parse the DID back and verify it's the same
        let parsed_public_key = identify_key(&public_key_did)?;
        assert_eq!(*parsed_public_key.key_type(), KeyType::P384Public);
        assert_eq!(public_key.bytes(), parsed_public_key.bytes());

        // Calling to_public on a public key should return the same key
        let result = to_public(&public_key)?;
        assert_eq!(*result.key_type(), KeyType::P384Public);
        assert_eq!(public_key.bytes(), result.bytes());

        Ok(())
    }

    #[test]
    fn test_p384_jwk_conversion() -> Result<()> {
        // Generate P-384 keys
        let private_key = generate_key(KeyType::P384Private)?;
        let public_key = to_public(&private_key)?;

        // Test private key to JWK conversion
        let private_jwk: Result<elliptic_curve::JwkEcKey, _> = (&private_key).try_into();
        assert!(private_jwk.is_ok());

        // Test public key to JWK conversion
        let public_jwk: Result<elliptic_curve::JwkEcKey, _> = (&public_key).try_into();
        assert!(public_jwk.is_ok());

        Ok(())
    }

    #[test]
    fn test_p384_key_properties() -> Result<()> {
        // Test that P-384 keys have expected properties
        let private_key = generate_key(KeyType::P384Private)?;
        let public_key = to_public(&private_key)?;

        // P-384 private keys should be 48 bytes
        assert_eq!(private_key.bytes().len(), 48);

        // P-384 public keys should be 97 bytes (uncompressed) or 49 bytes (compressed)
        // SEC1 format: 0x04 + 48 bytes x + 48 bytes y = 97 bytes uncompressed
        // or 0x02/0x03 + 48 bytes x = 49 bytes compressed
        assert!(public_key.bytes().len() == 97 || public_key.bytes().len() == 49);

        // Test that multiple derivations from the same private key produce the same public key
        let public_key2 = to_public(&private_key)?;
        assert_eq!(public_key.bytes(), public_key2.bytes());

        Ok(())
    }

    #[test]
    fn test_p384_cross_curve_verification_fails() -> Result<()> {
        // Generate keys from different curves
        let p256_key = generate_key(KeyType::P256Private)?;
        let p384_key = generate_key(KeyType::P384Private)?;
        let k256_key = generate_key(KeyType::K256Private)?;

        // Get their public keys
        let p256_public = to_public(&p256_key)?;
        let p384_public = to_public(&p384_key)?;
        let k256_public = to_public(&k256_key)?;

        let content = "cross curve verification test".as_bytes();

        // Sign with each private key
        let p256_signature = sign(&p256_key, content)?;
        let p384_signature = sign(&p384_key, content)?;
        let k256_signature = sign(&k256_key, content)?;

        // Verify each signature works with its corresponding key
        validate(&p256_public, &p256_signature, content)?;
        validate(&p384_public, &p384_signature, content)?;
        validate(&k256_public, &k256_signature, content)?;

        // Cross-verification should fail - P-384 vs others
        assert!(validate(&p256_public, &p384_signature, content).is_err());
        assert!(validate(&p384_public, &p256_signature, content).is_err());
        assert!(validate(&k256_public, &p384_signature, content).is_err());
        assert!(validate(&p384_public, &k256_signature, content).is_err());

        Ok(())
    }

    #[test]
    fn test_p384_sign_with_public_key_fails() {
        let private_key = generate_key(KeyType::P384Private).unwrap();
        let public_key = to_public(&private_key).unwrap();

        let content = "test content".as_bytes();

        // Signing with public key should fail
        let result = sign(&public_key, content);
        assert!(matches!(
            result,
            Err(KeyError::PrivateKeyRequiredForSignature)
        ));
    }

    #[test]
    fn test_p384_comprehensive_workflow() -> Result<()> {
        println!("\n=== P-384 Comprehensive Workflow Test ===");

        // Step 1: Generate P-384 private key
        println!("1. Generating P-384 private key...");
        let private_key = generate_key(KeyType::P384Private)?;
        assert_eq!(*private_key.key_type(), KeyType::P384Private);
        assert_eq!(private_key.bytes().len(), 48);

        // Step 2: Derive public key
        println!("2. Deriving P-384 public key...");
        let public_key = to_public(&private_key)?;
        assert_eq!(*public_key.key_type(), KeyType::P384Public);

        // Step 3: Serialize keys to DID format
        println!("3. Serializing keys to DID format...");
        let private_did = format!("{}", private_key);
        let public_did = format!("{}", public_key);
        println!("   P-384 Private: {}", private_did);
        println!("   P-384 Public:  {}", public_did);

        assert!(private_did.starts_with("did:key:"));
        assert!(public_did.starts_with("did:key:"));
        assert_ne!(private_did, public_did);

        // Step 4: Parse DIDs back to KeyData
        println!("4. Parsing DIDs back to KeyData...");
        let parsed_private = identify_key(&private_did)?;
        let parsed_public = identify_key(&public_did)?;

        assert_eq!(*parsed_private.key_type(), KeyType::P384Private);
        assert_eq!(*parsed_public.key_type(), KeyType::P384Public);

        // Step 5: Verify round-trip integrity
        println!("5. Verifying round-trip integrity...");
        assert_eq!(private_key.bytes(), parsed_private.bytes());
        assert_eq!(public_key.bytes(), parsed_public.bytes());

        // Step 6: Test signing and verification
        println!("6. Testing signing and verification...");
        let test_data = "P-384 comprehensive test data".as_bytes();

        // Sign with original private key
        let signature = sign(&private_key, test_data)?;

        // Verify with all key variants
        validate(&private_key, &signature, test_data)?;
        validate(&public_key, &signature, test_data)?;
        validate(&parsed_private, &signature, test_data)?;
        validate(&parsed_public, &signature, test_data)?;

        // Step 7: Test JWK conversion
        println!("7. Testing JWK conversion...");
        let private_jwk: elliptic_curve::JwkEcKey = (&private_key).try_into()?;
        let public_jwk: elliptic_curve::JwkEcKey = (&public_key).try_into()?;

        assert_eq!(private_jwk.crv(), "P-384");
        assert_eq!(public_jwk.crv(), "P-384");

        println!("=== P-384 comprehensive workflow completed successfully! ===\n");

        Ok(())
    }

    #[test]
    fn test_p384_multicodec_prefix_identification() -> Result<()> {
        // Test that we can identify P-384 keys by their multicodec prefixes
        let private_key = generate_key(KeyType::P384Private)?;
        let public_key = to_public(&private_key)?;

        // Convert to DID strings
        let private_did = format!("{}", private_key);
        let public_did = format!("{}", public_key);

        // Parse back and verify the multicodec prefixes were correctly identified
        let parsed_private = identify_key(&private_did)?;
        let parsed_public = identify_key(&public_did)?;

        assert_eq!(*parsed_private.key_type(), KeyType::P384Private);
        assert_eq!(*parsed_public.key_type(), KeyType::P384Public);

        // Verify the actual multicodec prefixes in the DID strings
        let private_value = did_method_key_value(&private_did);
        let public_value = did_method_key_value(&public_did);

        let (_, private_decoded) = multibase::decode(private_value)?;
        let (_, public_decoded) = multibase::decode(public_value)?;

        // Check the multicodec prefixes
        assert_eq!(&private_decoded[..2], &[0x13, 0x01]); // P-384 private key prefix
        assert_eq!(&public_decoded[..2], &[0x12, 0x00]); // P-384 public key prefix

        Ok(())
    }
}