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This allows implementing signing and verification with more than openssl PKey(Ref), like a TPM or AWS KMS keys (awslabs#5). It implements the abstracted methods for PKeyRef, and PKey calls out to PKeyRef. Signed-off-by: Patrick Uiterwijk <patrick@puiterwijk.org>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,48 @@ | ||
| //! (Signing) cryptography abstraction | ||
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| use openssl::{hash::MessageDigest, nid::Nid}; | ||
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| use crate::{error::COSEError, sign::SignatureAlgorithm}; | ||
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| #[cfg(feature = "key_openssl_pkey")] | ||
| pub mod openssl_pkey; | ||
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| /// A public key that can verify an existing signature | ||
| pub trait SigningPublicKey { | ||
| /// This returns the signature algorithm and message digest to be used for this | ||
| /// public key. | ||
| fn get_parameters(&self) -> Result<(SignatureAlgorithm, MessageDigest), COSEError>; | ||
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| /// Given a vector of data and a signature, returns a boolean whether the signature | ||
| /// was valid. | ||
| fn verify(&self, data: &[u8], signature: &[u8]) -> Result<bool, COSEError>; | ||
| } | ||
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| /// Follows the recommandations put in place by the RFC and doesn't deal with potential | ||
| /// mismatches: https://tools.ietf.org/html/rfc8152#section-8.1. | ||
| pub fn ec_curve_to_parameters( | ||
| curve_name: Nid, | ||
| ) -> Result<(SignatureAlgorithm, MessageDigest, usize), COSEError> { | ||
| match curve_name { | ||
| // Recommended to use with SHA256 | ||
| Nid::X9_62_PRIME256V1 => Ok((SignatureAlgorithm::ES256, MessageDigest::sha256(), 32)), | ||
| // Recommended to use with SHA384 | ||
| Nid::SECP384R1 => Ok((SignatureAlgorithm::ES384, MessageDigest::sha384(), 48)), | ||
| // Recommended to use with SHA512 | ||
| Nid::SECP521R1 => Ok(( | ||
| SignatureAlgorithm::ES512, | ||
| MessageDigest::sha512(), | ||
| 66, /* Not a typo */ | ||
| )), | ||
| _ => Err(COSEError::UnsupportedError(format!( | ||
| "Curve name {:?} is not supported", | ||
| curve_name | ||
| ))), | ||
| } | ||
| } | ||
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| /// A private key that can produce new signatures | ||
| pub trait SigningPrivateKey: SigningPublicKey { | ||
| /// Given a slice of data, returns a signature | ||
| fn sign(&self, data: &[u8]) -> Result<Vec<u8>, COSEError>; | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,121 @@ | ||
| //! OpenSSL PKey(Ref) implementation for cryptography | ||
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| use openssl::{ | ||
| bn::BigNum, | ||
| ecdsa::EcdsaSig, | ||
| hash::MessageDigest, | ||
| pkey::{HasPrivate, HasPublic, PKey, PKeyRef}, | ||
| }; | ||
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| use crate::{ | ||
| crypto::{ec_curve_to_parameters, SigningPrivateKey, SigningPublicKey}, | ||
| error::COSEError, | ||
| sign::SignatureAlgorithm, | ||
| }; | ||
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| impl<T> SigningPublicKey for PKey<T> | ||
| where | ||
| T: HasPublic, | ||
| { | ||
| fn get_parameters(&self) -> Result<(SignatureAlgorithm, MessageDigest), COSEError> { | ||
| self.as_ref().get_parameters() | ||
| } | ||
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| fn verify(&self, data: &[u8], signature: &[u8]) -> Result<bool, COSEError> { | ||
| self.as_ref().verify(data, signature) | ||
| } | ||
| } | ||
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| impl<T> SigningPublicKey for PKeyRef<T> | ||
| where | ||
| T: HasPublic, | ||
| { | ||
| fn get_parameters(&self) -> Result<(SignatureAlgorithm, MessageDigest), COSEError> { | ||
| let curve_name = self | ||
| .ec_key() | ||
| .map_err(|_| COSEError::UnsupportedError("Non-EC keys are not supported".to_string()))? | ||
| .group() | ||
| .curve_name() | ||
| .ok_or_else(|| { | ||
| COSEError::UnsupportedError("Anonymous EC keys are not supported".to_string()) | ||
| })?; | ||
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| let curve_parameters = ec_curve_to_parameters(curve_name)?; | ||
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| Ok((curve_parameters.0, curve_parameters.1)) | ||
| } | ||
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| fn verify(&self, data: &[u8], signature: &[u8]) -> Result<bool, COSEError> { | ||
| let key = self.ec_key().map_err(|_| { | ||
| COSEError::UnsupportedError("Non-EC keys are not yet supported".to_string()) | ||
| })?; | ||
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| let curve_name = key.group().curve_name().ok_or_else(|| { | ||
| COSEError::UnsupportedError("Anonymous EC keys are not supported".to_string()) | ||
| })?; | ||
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| let (_, _, key_length) = ec_curve_to_parameters(curve_name)?; | ||
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| // Recover the R and S factors from the signature contained in the object | ||
| let (bytes_r, bytes_s) = signature.split_at(key_length); | ||
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| let r = BigNum::from_slice(&bytes_r).map_err(COSEError::SignatureError)?; | ||
| let s = BigNum::from_slice(&bytes_s).map_err(COSEError::SignatureError)?; | ||
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| let sig = EcdsaSig::from_private_components(r, s).map_err(COSEError::SignatureError)?; | ||
| sig.verify(data, &key).map_err(COSEError::SignatureError) | ||
| } | ||
| } | ||
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| impl<T> SigningPrivateKey for PKey<T> | ||
| where | ||
| T: HasPrivate, | ||
| { | ||
| fn sign(&self, data: &[u8]) -> Result<Vec<u8>, COSEError> { | ||
| self.as_ref().sign(data) | ||
| } | ||
| } | ||
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| impl<T> SigningPrivateKey for PKeyRef<T> | ||
| where | ||
| T: HasPrivate, | ||
| { | ||
| fn sign(&self, data: &[u8]) -> Result<Vec<u8>, COSEError> { | ||
| let key = self.ec_key().map_err(|_| { | ||
| COSEError::UnsupportedError("Non-EC keys are not yet supported".to_string()) | ||
| })?; | ||
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| let curve_name = key.group().curve_name().ok_or_else(|| { | ||
| COSEError::UnsupportedError("Anonymous EC keys are not supported".to_string()) | ||
| })?; | ||
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| let (_, _, key_length) = ec_curve_to_parameters(curve_name)?; | ||
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| // The spec defines the signature as: | ||
| // Signature = I2OSP(R, n) | I2OSP(S, n), where n = ceiling(key_length / 8) | ||
| // The Signer interface doesn't provide this, so this will use EcdsaSig interface instead | ||
| // and concatenate R and S. | ||
| // See https://tools.ietf.org/html/rfc8017#section-4.1 for details. | ||
| let signature = EcdsaSig::sign(data, &key).map_err(COSEError::SignatureError)?; | ||
| let bytes_r = signature.r().to_vec(); | ||
| let bytes_s = signature.s().to_vec(); | ||
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| // These should *never* exceed ceiling(key_length / 8) | ||
| assert!(bytes_r.len() <= key_length); | ||
| assert!(bytes_s.len() <= key_length); | ||
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| let mut signature_bytes = vec![0u8; key_length * 2]; | ||
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| // This is big-endian encoding so padding might be added at the start if the factor is | ||
| // too short. | ||
| let offset_copy = key_length - bytes_r.len(); | ||
| signature_bytes[offset_copy..offset_copy + bytes_r.len()].copy_from_slice(&bytes_r); | ||
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| // This is big-endian encoding so padding might be added at the start if the factor is | ||
| // too short. | ||
| let offset_copy = key_length - bytes_s.len() + key_length; | ||
| signature_bytes[offset_copy..offset_copy + bytes_s.len()].copy_from_slice(&bytes_s); | ||
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| Ok(signature_bytes) | ||
| } | ||
| } |
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