Implement minisign identity proofs

Cargo.lock

@@ -389,6 +389,15 @@ dependencies = [
  "wyz",
 ]
 
+[[package]]
+name = "blake2"
+version = "0.10.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b9cf849ee05b2ee5fba5e36f97ff8ec2533916700fc0758d40d92136a42f3388"
+dependencies = [
+ "digest 0.10.3",
+]
+
 [[package]]
 name = "blake2b_simd"
 version = "0.5.11"
@@ -690,9 +699,9 @@ dependencies = [
 
 [[package]]
 name = "curve25519-dalek"
-version = "3.2.1"
+version = "3.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "90f9d052967f590a76e62eb387bd0bbb1b000182c3cefe5364db6b7211651bc0"
+checksum = "0b9fdf9972b2bd6af2d913799d9ebc165ea4d2e65878e329d9c6b372c4491b61"
 dependencies = [
  "byteorder",
  "digest 0.9.0",
@@ -798,6 +807,29 @@ dependencies = [
  "signature",
 ]
 
+[[package]]
+name = "ed25519"
+version = "1.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "74e1069e39f1454367eb2de793ed062fac4c35c2934b76a81d90dd9abcd28816"
+dependencies = [
+ "signature",
+]
+
+[[package]]
+name = "ed25519-dalek"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c762bae6dcaf24c4c84667b8579785430908723d5c889f469d76a41d59cc7a9d"
+dependencies = [
+ "curve25519-dalek",
+ "ed25519",
+ "rand 0.7.3",
+ "serde",
+ "sha2 0.9.5",
+ "zeroize",
+]
+
 [[package]]
 name = "either"
 version = "1.8.0"
@@ -1687,6 +1719,7 @@ dependencies = [
  "ammonia",
  "anyhow",
  "base64",
+ "blake2",
  "bs58",
  "chrono",
  "clap",
@@ -1694,6 +1727,8 @@ dependencies = [
  "deadpool",
  "deadpool-postgres",
  "dotenv",
+ "ed25519",
+ "ed25519-dalek",
  "env_logger",
  "hex",
  "log",
@@ -3774,9 +3809,9 @@ dependencies = [
 
 [[package]]
 name = "zeroize"
-version = "1.3.0"
+version = "1.4.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4756f7db3f7b5574938c3eb1c117038b8e07f95ee6718c0efad4ac21508f1efd"
+checksum = "d68d9dcec5f9b43a30d38c49f91dfedfaac384cb8f085faca366c26207dd1619"
 dependencies = [
  "zeroize_derive",
 ]

Cargo.toml

@@ -39,6 +39,10 @@ hex = { version = "0.4.3", features = ["serde"] }
 # Used for logging
 log = { version = "0.4.14", features = ["serde"] }
 env_logger = { version = "0.9.0", default-features = false }
+# Used to verify minisign signatures
+ed25519-dalek = "1.0.1"
+ed25519 = "=1.3.0"
+blake2 = "0.10.4"
 # Used to guess media type of a file
 mime_guess = "2.0.3"
 mime-sniffer = "0.1.2"

docs/openapi.yaml

@@ -158,6 +158,7 @@ paths:
             type: string
             enum:
               - ethereum
+              - minisign
         - name: signer
           in: query
           description: Information about the signer.

src/identity/minisign.rs

@@ -0,0 +1,136 @@
+/// https://jedisct1.github.io/minisign/
+use blake2::{Blake2b512, Digest};
+use ed25519_dalek::{
+    PublicKey,
+    Signature,
+    SignatureError,
+    Verifier,
+};
+
+use super::did_key::{DidKey, MulticodecError};
+
+pub const IDENTITY_PROOF_MINISIGN: &str = "MinisignSignatureDemo0";
+
+const MINISIGN_SIGNATURE_CODE: [u8; 2] = *b"Ed";
+const MINISIGN_SIGNATURE_HASHED_CODE: [u8; 2] = *b"ED";
+
+#[derive(thiserror::Error, Debug)]
+pub enum ParseError {
+    #[error("invalid encoding")]
+    InvalidEncoding(#[from] base64::DecodeError),
+
+    #[error("invalid key length")]
+    InvalidKeyLength,
+
+    #[error("invalid signature length")]
+    InvalidSignatureLength,
+
+    #[error("invalid signature type")]
+    InvalidSignatureType,
+}
+
+// Public key format:
+// base64(<signature_algorithm> || <key_id> || <public_key>)
+fn parse_minisign_public_key(key_b64: &str)
+    -> Result<[u8; 32], ParseError>
+{
+    let key_bin = base64::decode(key_b64)?;
+    if key_bin.len() != 42 {
+        return Err(ParseError::InvalidKeyLength);
+    };
+
+    let mut signature_algorithm = [0; 2];
+    let mut _key_id = [0; 8];
+    let mut key = [0; 32];
+    signature_algorithm.copy_from_slice(&key_bin[0..2]);
+    _key_id.copy_from_slice(&key_bin[2..10]);
+    key.copy_from_slice(&key_bin[10..42]);
+
+    if signature_algorithm.as_ref() != MINISIGN_SIGNATURE_CODE {
+        return Err(ParseError::InvalidSignatureType);
+    };
+    Ok(key)
+}
+
+pub fn minisign_key_to_did(key_b64: &str) -> Result<DidKey, ParseError> {
+    let key = parse_minisign_public_key(key_b64)?;
+    let did_key = DidKey::from_ed25519_key(key);
+    Ok(did_key)
+}
+
+// Signature format:
+// base64(<signature_algorithm> || <key_id> || <signature>)
+fn parse_minisign_signature(signature_b64: &str)
+    -> Result<[u8; 64], ParseError>
+{
+    let signature_bin = base64::decode(signature_b64)?;
+    if signature_bin.len() != 74 {
+        return Err(ParseError::InvalidSignatureLength);
+    };
+
+    let mut signature_algorithm = [0; 2];
+    let mut _key_id = [0; 8];
+    let mut signature = [0; 64];
+    signature_algorithm.copy_from_slice(&signature_bin[0..2]);
+    _key_id.copy_from_slice(&signature_bin[2..10]);
+    signature.copy_from_slice(&signature_bin[10..74]);
+
+    if signature_algorithm.as_ref() != MINISIGN_SIGNATURE_HASHED_CODE {
+        return Err(ParseError::InvalidSignatureType);
+    };
+    Ok(signature)
+}
+
+fn verify_signature(
+    message: &str,
+    signer: [u8; 32],
+    signature: [u8; 64],
+) -> Result<(), SignatureError> {
+    let signature = Signature::from_bytes(&signature)?;
+    let public_key = PublicKey::from_bytes(&signer)?;
+    let mut hasher = Blake2b512::new();
+    hasher.update(message);
+    let hash = hasher.finalize();
+    public_key.verify(&hash, &signature)?;
+    Ok(())
+}
+
+#[derive(thiserror::Error, Debug)]
+pub enum VerificationError {
+    #[error(transparent)]
+    InvalidKey(#[from] MulticodecError),
+
+    #[error(transparent)]
+    ParseError(#[from] ParseError),
+
+    #[error(transparent)]
+    SignatureError(#[from] SignatureError),
+}
+
+pub fn verify_minisign_identity_proof(
+    signer: &DidKey,
+    message: &str,
+    signature: &str,
+) -> Result<(), VerificationError> {
+    let ed25519_key = signer.try_ed25519_key()?;
+    let ed25519_signature = parse_minisign_signature(signature)?;
+    let message = format!("{}\n", message);
+    verify_signature(&message, ed25519_key, ed25519_signature)?;
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_verify_minisign_identity_proof() {
+        let minisign_key =
+            "RWSA58rRENpGFYwAjRjbdST7VHFoIuH9JBHfO2u6i5JgANPIoQhABAF/";
+        let message = "test";
+        let minisign_signature =
+            "RUSA58rRENpGFVKxdZGMG1WdIJ+dlyP83qOqw6GP0H/Li6Brug2A3mFKLtleIRLi6IIG0smzOlX5CEsisNnc897OUHIOSNLsQQs=";
+        let signer = minisign_key_to_did(minisign_key).unwrap();
+        verify_minisign_identity_proof(&signer, message, minisign_signature).unwrap();
+    }
+}

src/identity/mod.rs

@@ -2,3 +2,4 @@ pub mod claims;
 pub mod did;
 pub mod did_key;
 pub mod did_pkh;
+pub mod minisign;

src/mastodon_api/accounts/views.rs

@@ -28,6 +28,11 @@ use crate::identity::{
     claims::create_identity_claim,
     did::Did,
     did_pkh::DidPkh,
+    minisign::{
+        minisign_key_to_did,
+        verify_minisign_identity_proof,
+        IDENTITY_PROOF_MINISIGN,
+    },
 };
 use crate::json_signatures::{
     canonicalization::canonicalize_object,
@@ -305,6 +310,11 @@ async fn get_identity_claim(
             );
             Did::Pkh(did_pkh)
         },
+        "minisign" => {
+            let did_key = minisign_key_to_did(&query_params.signer)
+                .map_err(|_| ValidationError("invalid key"))?;
+            Did::Key(did_key)
+        },
         _ => return Err(ValidationError("unknown proof type").into()),
     };
     let actor_id = current_user.profile.actor_id(&config.instance_url());
@@ -341,32 +351,41 @@ async fn create_identity_proof(
         .map_err(|_| ValidationError("invalid claim"))?;
 
     // Verify proof
-    let did_pkh = match did {
-        Did::Key(_) => return Err(ValidationError("unsupported DID type").into()),
-        Did::Pkh(ref did_pkh) => did_pkh,
+    let proof_type = match did {
+        Did::Key(ref did_key) => {
+            verify_minisign_identity_proof(
+                did_key,
+                &message,
+                &proof_data.signature,
+            ).map_err(|_| ValidationError("invalid signature"))?;
+            IDENTITY_PROOF_MINISIGN
+        },
+        Did::Pkh(ref did_pkh) => {
+            if did_pkh.chain_id != ChainId::ethereum_mainnet() {
+                // DID must point to Ethereum Mainnet because it is a valid
+                // identifier on any Ethereum chain
+                return Err(ValidationError("unsupported chain ID").into());
+            };
+            let maybe_public_address =
+                current_user.public_wallet_address(&Currency::Ethereum);
+            if let Some(address) = maybe_public_address {
+                // Do not allow to add more than one address proof
+                if did_pkh.address != address {
+                    return Err(ValidationError("DID doesn't match current identity").into());
+                };
+            };
+            verify_eip191_identity_proof(
+                did_pkh,
+                &message,
+                &proof_data.signature,
+            )?;
+            ETHEREUM_EIP191_PROOF
+        },
     };
-    if did_pkh.chain_id != ChainId::ethereum_mainnet() {
-        // DID must point to Ethereum Mainnet because it is a valid
-        // identifier on any Ethereum chain
-        return Err(ValidationError("unsupported chain ID").into());
-    };
-    let maybe_public_address =
-        current_user.public_wallet_address(&Currency::Ethereum);
-    if let Some(address) = maybe_public_address {
-        // Do not allow to add more than one address proof
-        if did_pkh.address != address {
-            return Err(ValidationError("DID doesn't match current identity").into());
-        };
-    };
-    verify_eip191_identity_proof(
-        did_pkh,
-        &message,
-        &proof_data.signature,
-    )?;
 
     let proof = IdentityProof {
         issuer: did,
-        proof_type: ETHEREUM_EIP191_PROOF.to_string(),
+        proof_type: proof_type.to_string(),
         value: proof_data.signature.clone(),
     };
     let mut profile_data = ProfileUpdateData::from(&current_user.profile);