97 lines
3.3 KiB
Rust
97 lines
3.3 KiB
Rust
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// Copyright 2022 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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////////////////////////////////////////////////////////////////////////////////
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//! Example program demonstrating signed CWT processing.
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use coset::{cbor::value::Value, cwt, iana, CborSerializable, CoseError};
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#[derive(Copy, Clone)]
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struct FakeSigner {}
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// Use a fake signer/verifier (to avoid pulling in lots of dependencies).
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impl FakeSigner {
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fn sign(&self, data: &[u8]) -> Vec<u8> {
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data.to_vec()
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}
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fn verify(&self, sig: &[u8], data: &[u8]) -> Result<(), String> {
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if sig != self.sign(data) {
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Err("failed to verify".to_owned())
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} else {
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Ok(())
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}
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}
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}
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fn main() -> Result<(), CoseError> {
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// Build a fake signer/verifier (to avoid pulling in lots of dependencies).
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let signer = FakeSigner {};
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let verifier = signer;
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// Build a CWT ClaimsSet (cf. RFC 8392 A.3).
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let claims = cwt::ClaimsSetBuilder::new()
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.issuer("coap://as.example.com".to_string())
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.subject("erikw".to_string())
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.audience("coap://light.example.com".to_string())
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.expiration_time(cwt::Timestamp::WholeSeconds(1444064944))
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.not_before(cwt::Timestamp::WholeSeconds(1443944944))
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.issued_at(cwt::Timestamp::WholeSeconds(1443944944))
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.cwt_id(vec![0x0b, 0x71])
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// Add additional standard claim.
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.claim(
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iana::CwtClaimName::Scope,
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Value::Text("email phone".to_string()),
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)
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// Add additional private-use claim.
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.private_claim(-70_000, Value::Integer(42.into()))
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.build();
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let aad = b"";
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// Build a `CoseSign1` object.
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let protected = coset::HeaderBuilder::new()
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.algorithm(iana::Algorithm::ES256)
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.build();
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let unprotected = coset::HeaderBuilder::new()
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.key_id(b"AsymmetricECDSA256".to_vec())
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.build();
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let sign1 = coset::CoseSign1Builder::new()
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.protected(protected)
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.unprotected(unprotected)
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.payload(claims.clone().to_vec()?)
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.create_signature(aad, |pt| signer.sign(pt))
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.build();
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// Serialize to bytes.
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let sign1_data = sign1.to_vec()?;
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// At the receiving end, deserialize the bytes back to a `CoseSign1` object.
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let sign1 = coset::CoseSign1::from_slice(&sign1_data)?;
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// Real code would:
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// - Use the key ID to identify the relevant local key.
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// - Check that the key is of the same type as `sign1.protected.algorithm`.
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// Check the signature.
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let result = sign1.verify_signature(aad, |sig, data| verifier.verify(sig, data));
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println!("Signature verified: {:?}.", result);
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assert!(result.is_ok());
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// Now it's safe to parse the payload.
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let recovered_claims = cwt::ClaimsSet::from_slice(&sign1.payload.unwrap())?;
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assert_eq!(recovered_claims, claims);
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Ok(())
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}
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