jacs 0.6.1

JACS JSON AI Communication Standard
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268

//! Key management for A2A integration
//! Handles dual key generation (PQC for JACS, RSA/ECDSA for A2A)

use crate::error::JacsError;
use base64::{Engine as _, engine::general_purpose};
use serde::{Deserialize, Serialize};
use serde_json::{Value, json};
use std::error::Error;
use tracing::info;

/// JWK (JSON Web Key) structure
#[derive(Debug, Serialize, Deserialize, Clone)]
pub struct Jwk {
    pub kty: String,
    pub kid: String,
    pub alg: String,
    pub use_: String,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub n: Option<String>, // RSA modulus
    #[serde(skip_serializing_if = "Option::is_none")]
    pub e: Option<String>, // RSA exponent
    #[serde(skip_serializing_if = "Option::is_none")]
    pub x: Option<String>, // ECDSA x coordinate
    #[serde(skip_serializing_if = "Option::is_none")]
    pub y: Option<String>, // ECDSA y coordinate
    #[serde(skip_serializing_if = "Option::is_none")]
    pub crv: Option<String>, // ECDSA curve
}

/// Dual key pair for JACS and A2A
pub struct DualKeyPair {
    pub jacs_private_key: Vec<u8>,
    pub jacs_public_key: Vec<u8>,
    pub jacs_algorithm: String,
    pub a2a_private_key: Vec<u8>,
    pub a2a_public_key: Vec<u8>,
    pub a2a_algorithm: String,
}

/// Create dual keys for both JACS (PQC) and A2A (RSA/ECDSA) compatibility
/// These keys are ephemeral (in-memory only) - they are NOT persisted to disk
pub fn create_jwk_keys(
    jacs_algorithm: Option<&str>,
    a2a_algorithm: Option<&str>,
) -> Result<DualKeyPair, Box<dyn Error>> {
    // Default algorithms
    let jacs_alg = jacs_algorithm.unwrap_or("dilithium");
    let a2a_alg = a2a_algorithm.unwrap_or("rsa");

    info!(
        "Generating ephemeral dual keys: JACS={}, A2A={}",
        jacs_alg, a2a_alg
    );

    // Generate keys directly in memory without file persistence
    let (jacs_private, jacs_public) = match jacs_alg {
        "dilithium" | "pq-dilithium" => crate::crypt::pq::generate_keys()?,
        "rsa" => crate::crypt::rsawrapper::generate_keys()?,
        "ring-Ed25519" => crate::crypt::ringwrapper::generate_keys()?,
        "ecdsa" | "es256" => {
            return Err(JacsError::CryptoError(
                "ECDSA key generation for A2A is not yet implemented in this build".to_string(),
            )
            .into());
        }
        _ => {
            return Err(JacsError::CryptoError(format!(
                "Unsupported JACS algorithm: {}",
                jacs_alg
            ))
            .into());
        }
    };

    let (a2a_private, a2a_public) = match a2a_alg {
        "rsa" => crate::crypt::rsawrapper::generate_keys()?,
        "ring-Ed25519" => crate::crypt::ringwrapper::generate_keys()?,
        "ecdsa" | "es256" => {
            return Err(JacsError::CryptoError(
                "ECDSA key generation for A2A is not yet implemented in this build".to_string(),
            )
            .into());
        }
        _ => {
            return Err(
                JacsError::CryptoError(format!("Unsupported A2A algorithm: {}", a2a_alg)).into(),
            );
        }
    };

    Ok(DualKeyPair {
        jacs_private_key: jacs_private,
        jacs_public_key: jacs_public,
        jacs_algorithm: jacs_alg.to_string(),
        a2a_private_key: a2a_private,
        a2a_public_key: a2a_public,
        a2a_algorithm: a2a_alg.to_string(),
    })
}

/// Export RSA public key as JWK
pub fn export_rsa_as_jwk(public_key: &[u8], key_id: &str) -> Result<Jwk, Box<dyn Error>> {
    use rsa::traits::PublicKeyParts;
    use rsa::{RsaPublicKey, pkcs1::DecodeRsaPublicKey, pkcs8::DecodePublicKey};

    // Parse PEM-encoded RSA public key
    let pem_str = std::str::from_utf8(public_key)?;
    let pem = pem::parse(pem_str)?;

    // Try PKCS#1 first; if it fails, fall back to PKCS#8 SubjectPublicKeyInfo
    let rsa_key = match RsaPublicKey::from_pkcs1_der(pem.contents()) {
        Ok(k) => k,
        Err(_) => RsaPublicKey::from_public_key_der(pem.contents())?,
    };

    // Extract modulus and exponent
    let n = rsa_key.n();
    let e = rsa_key.e();

    // Convert to base64url
    let n_bytes = n.to_bytes_be();
    let e_bytes = e.to_bytes_be();

    let jwk = Jwk {
        kty: "RSA".to_string(),
        kid: key_id.to_string(),
        alg: "RS256".to_string(),
        use_: "sig".to_string(),
        n: Some(general_purpose::URL_SAFE_NO_PAD.encode(&n_bytes)),
        e: Some(general_purpose::URL_SAFE_NO_PAD.encode(&e_bytes)),
        x: None,
        y: None,
        crv: None,
    };

    Ok(jwk)
}

/// Export ECDSA public key as JWK
pub fn export_ed25519_as_jwk(public_key: &[u8], key_id: &str) -> Result<Jwk, Box<dyn Error>> {
    let key_bytes = match public_key.len() {
        32 => public_key.to_vec(),
        _ => {
            return Err(JacsError::CryptoError(format!(
                "Ed25519 public key must be 32 bytes, got {} bytes",
                public_key.len()
            ))
            .into());
        }
    };

    Ok(Jwk {
        kty: "OKP".to_string(),
        kid: key_id.to_string(),
        alg: "EdDSA".to_string(),
        use_: "sig".to_string(),
        n: None,
        e: None,
        x: Some(general_purpose::URL_SAFE_NO_PAD.encode(key_bytes)),
        y: None,
        crv: Some("Ed25519".to_string()),
    })
}

/// Export a public key as JWK based on algorithm
pub fn export_as_jwk(
    public_key: &[u8],
    algorithm: &str,
    key_id: &str,
) -> Result<Jwk, Box<dyn Error>> {
    match algorithm {
        "rsa" => export_rsa_as_jwk(public_key, key_id),
        "ring-Ed25519" => export_ed25519_as_jwk(public_key, key_id),
        "ecdsa" | "es256" => Err(JacsError::CryptoError(
            "ECDSA JWK export is not yet implemented in this build".to_string(),
        )
        .into()),
        _ => Err(JacsError::CryptoError(format!("Cannot export {} key as JWK", algorithm)).into()),
    }
}

/// Create a JWK set document
pub fn create_jwk_set(jwks: Vec<Jwk>) -> Value {
    json!({
        "keys": jwks
    })
}

/// Sign data using JWS with the A2A-compatible key
pub fn sign_jws(
    payload: &[u8],
    private_key: &[u8],
    algorithm: &str,
    key_id: &str,
) -> Result<String, Box<dyn Error>> {
    // Create JWS header
    let header = json!({
        "alg": match algorithm {
            "rsa" => "RS256",
            "ring-Ed25519" => "EdDSA",
            "ecdsa" | "es256" => return Err(JacsError::CryptoError("ECDSA JWS signing is not yet implemented in this build".to_string()).into()),
            _ => return Err(JacsError::CryptoError(format!("Unsupported JWS algorithm: {}", algorithm)).into()),
        },
        "typ": "JWT",
        "kid": key_id
    });

    // Base64url encode header and payload
    let header_b64 = general_purpose::URL_SAFE_NO_PAD.encode(serde_json::to_vec(&header)?);
    let payload_b64 = general_purpose::URL_SAFE_NO_PAD.encode(payload);

    // Create signing input
    let signing_input = format!("{}.{}", header_b64, payload_b64);

    // Sign directly using the crypto wrappers
    let signature = match algorithm {
        "rsa" => {
            let sig_b64 =
                crate::crypt::rsawrapper::sign_string(private_key.to_vec(), &signing_input)?;
            general_purpose::STANDARD.decode(&sig_b64)?
        }
        "ring-Ed25519" => {
            let sig_b64 =
                crate::crypt::ringwrapper::sign_string(private_key.to_vec(), &signing_input)?;
            general_purpose::STANDARD.decode(&sig_b64)?
        }
        "ecdsa" | "es256" => {
            return Err(JacsError::CryptoError(
                "ECDSA JWS signing is not yet implemented in this build".to_string(),
            )
            .into());
        }
        _ => {
            return Err(
                JacsError::CryptoError(format!("Unsupported algorithm: {}", algorithm)).into(),
            );
        }
    };

    // Base64url encode signature
    let signature_b64 = general_purpose::URL_SAFE_NO_PAD.encode(&signature);

    // Construct JWS compact serialization
    Ok(format!("{}.{}.{}", header_b64, payload_b64, signature_b64))
}

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

    #[test]
    fn test_create_jwk_set() {
        let jwk = Jwk {
            kty: "RSA".to_string(),
            kid: "test-key".to_string(),
            alg: "RS256".to_string(),
            use_: "sig".to_string(),
            n: Some("test_n".to_string()),
            e: Some("AQAB".to_string()),
            x: None,
            y: None,
            crv: None,
        };

        let jwk_set = create_jwk_set(vec![jwk]);
        assert!(jwk_set["keys"].is_array());
    }
}